Volume 14,Issue 6,2016 Table of Contents
2016, 14(6):1-5.
Abstract:
The concept of return period is commonly used to evaluate the severity of drought events. To compute the return period for a given drought contains drought recognition and selection of distribution function and so on, which relies on the determination of drought threshold. This paper proposed to use the maximum survey period of historical drought as a reference to determine the drought threshold, in other words, the resulting return period based on frequency analysis should not exceed the maximum survey period of historical drought. Besides, considering that the drought duration samples tend to concentrate on several values and lead to the platform-concentrated phenomenon of empirical points, the distribution function of run length was suggested to fit the drought duration samples. The monthly precipitation series of Minhe County in Qinghai province covering the period from 1932 to 2010 was used to demonstrate the proposed methods, where the Copula function was employed to build a bivariate joint distribution of drought duration and drought severity to compute the return period of drought event.
The concept of return period is commonly used to evaluate the severity of drought events. To compute the return period for a given drought contains drought recognition and selection of distribution function and so on, which relies on the determination of drought threshold. This paper proposed to use the maximum survey period of historical drought as a reference to determine the drought threshold, in other words, the resulting return period based on frequency analysis should not exceed the maximum survey period of historical drought. Besides, considering that the drought duration samples tend to concentrate on several values and lead to the platform-concentrated phenomenon of empirical points, the distribution function of run length was suggested to fit the drought duration samples. The monthly precipitation series of Minhe County in Qinghai province covering the period from 1932 to 2010 was used to demonstrate the proposed methods, where the Copula function was employed to build a bivariate joint distribution of drought duration and drought severity to compute the return period of drought event.
2016, 14(6):6-11.
Abstract:
Antecedent soil moisture content and slope gradient are significant influential factors for rainfall-runoff (RR) process. In order to study the RR mechanism of semi-arid region in the North China, artificial RR simulation test was carried out in the condition of different slope gradient and antecedent soil moisture content. According to the results: (1) In the whole RR process, the overland flow increased with the increase of antecedent soil moisture and slope, and the relationship between cumulative runoff and rainfall duration complied with a linear function. (2) Soil infiltration rate and runoff lag time decreased with the increase of antecedent soil moisture content and slope, and the influence of antecedent soil moisture on soil infiltration rate and runoff lag time was more obvious than that of slope. （3）Horton model was better than Kostiakov and Philip model in fitting the relationship between rainfall and infiltration.
Antecedent soil moisture content and slope gradient are significant influential factors for rainfall-runoff (RR) process. In order to study the RR mechanism of semi-arid region in the North China, artificial RR simulation test was carried out in the condition of different slope gradient and antecedent soil moisture content. According to the results: (1) In the whole RR process, the overland flow increased with the increase of antecedent soil moisture and slope, and the relationship between cumulative runoff and rainfall duration complied with a linear function. (2) Soil infiltration rate and runoff lag time decreased with the increase of antecedent soil moisture content and slope, and the influence of antecedent soil moisture on soil infiltration rate and runoff lag time was more obvious than that of slope. （3）Horton model was better than Kostiakov and Philip model in fitting the relationship between rainfall and infiltration.
2016, 14(6):12-17.
Abstract:
Hydrological prediction is an important aspect of hydrology’s service for economic and society. The prediction result not only provides decision support for reservoir generation operation, but also is of great significance to the economical operation of hydropower systems, navigation, flood control and so on. The autoregressive model (AR model), artificial neural network (ANN) and adaptive neural fuzzy inference system (ANFIS) have been widely applied in the daily runoff time series prediction. In this paper, these three models were applied in daily runoff prediction at Tongzilin station. Nash–Sutcliffe efficiency coefficient (NS coefficient), root mean square error (RMSE) and mean absolute relative error (MARE) were used to evaluate the performances of three models. Threshold statistics index was used to analyze prediction error distribution of three models. At the same time, the prediction ability of three models was studied by gradually increasing the prediction period. The results showed that ANFIS had not only better simulation ability and generalization ability, but also better model performance in the same prediction period compared to ANN and AR model. As a result, ANFIS can be a recommended prediction model for daily runoff time series.
Hydrological prediction is an important aspect of hydrology’s service for economic and society. The prediction result not only provides decision support for reservoir generation operation, but also is of great significance to the economical operation of hydropower systems, navigation, flood control and so on. The autoregressive model (AR model), artificial neural network (ANN) and adaptive neural fuzzy inference system (ANFIS) have been widely applied in the daily runoff time series prediction. In this paper, these three models were applied in daily runoff prediction at Tongzilin station. Nash–Sutcliffe efficiency coefficient (NS coefficient), root mean square error (RMSE) and mean absolute relative error (MARE) were used to evaluate the performances of three models. Threshold statistics index was used to analyze prediction error distribution of three models. At the same time, the prediction ability of three models was studied by gradually increasing the prediction period. The results showed that ANFIS had not only better simulation ability and generalization ability, but also better model performance in the same prediction period compared to ANN and AR model. As a result, ANFIS can be a recommended prediction model for daily runoff time series.
2016, 14(6):18-26.
Abstract:
Drought is the most severe agricultural meteorological disaster in Heilonggang District, assessment of drought risk during different growing stages of winter wheat may provide basis to determine rational irrigation schedule and to prevent and control drought. Based on the simulated soil water dynamics of 31 profiles for 1961-2005using the calibrated APSIM model, relative soil moisture drought indexes were calculated for different growth stages of winter wheat, and the spatial and temporal characteristics of agricultural drought of two scenarios, Farm Scenario (FS) and Optimized Scenario (OS) were analyzed. The results showed that, from the point of view of different growth stages of winter wheat, high-frequency drought occurred in sowing-overwintering stage and turning green-jointing stage for FS, with frequencies of 48.89% and 27.6% respectively, and in overwintering-turning green stage, turning green-jointing stage and grain filling-harvesting stage for OS, with drought frequencies of 51.61%, 39.78% and 62.22% respectively. High drought risk frequently occurred in central region and Xingtai, south part of Hengshui and north part of Handan. The time series of relative soil moisture drought index in the different growth stages of winter wheat showed the same change trend in the time series of relative soil moisture drought index of two scenarios. This study suggested that, in general, the relative soil moisture drought index was higher in FS than OS, but the OS, which based on ‘Wuqiao Mode’, brought the soil root zone reservoir into play enough, reduced the irrigation water and could use soil water with high efficiency. The total water amount of 61785 mm could be saved in OS compared to that in FS, if irrigation schedule of the OS was adopted in 31 profiles through the district in the period of 1961-2005. It showed that ‘Wuqiao Mode’ can be extended to application in Heilonggang District, and this mode may avoid drought risk in some degree, and can reach the goal of saving water and maintaining high yield.
Drought is the most severe agricultural meteorological disaster in Heilonggang District, assessment of drought risk during different growing stages of winter wheat may provide basis to determine rational irrigation schedule and to prevent and control drought. Based on the simulated soil water dynamics of 31 profiles for 1961-2005using the calibrated APSIM model, relative soil moisture drought indexes were calculated for different growth stages of winter wheat, and the spatial and temporal characteristics of agricultural drought of two scenarios, Farm Scenario (FS) and Optimized Scenario (OS) were analyzed. The results showed that, from the point of view of different growth stages of winter wheat, high-frequency drought occurred in sowing-overwintering stage and turning green-jointing stage for FS, with frequencies of 48.89% and 27.6% respectively, and in overwintering-turning green stage, turning green-jointing stage and grain filling-harvesting stage for OS, with drought frequencies of 51.61%, 39.78% and 62.22% respectively. High drought risk frequently occurred in central region and Xingtai, south part of Hengshui and north part of Handan. The time series of relative soil moisture drought index in the different growth stages of winter wheat showed the same change trend in the time series of relative soil moisture drought index of two scenarios. This study suggested that, in general, the relative soil moisture drought index was higher in FS than OS, but the OS, which based on ‘Wuqiao Mode’, brought the soil root zone reservoir into play enough, reduced the irrigation water and could use soil water with high efficiency. The total water amount of 61785 mm could be saved in OS compared to that in FS, if irrigation schedule of the OS was adopted in 31 profiles through the district in the period of 1961-2005. It showed that ‘Wuqiao Mode’ can be extended to application in Heilonggang District, and this mode may avoid drought risk in some degree, and can reach the goal of saving water and maintaining high yield.
2016, 14(6):27-32.
Abstract:
Haerbin city one of the typical cities with frequent floods in China, and the region with occurrence of flood disaster changes every year. It would be beneficial if the disaster prevention and reduction department could make timely and accurate flood control planning by understanding the risk of flood disaster dynamic distribution rules. Firstly, through the nature disaster risk formation four-factor theory, assessment model of flood disaster risk of Haerbin Province was established, using metrological, hydrological, social and economical features as indicators. Secondly, comprehensive dynamic degree of flood risk in Haerbin from 2000 to 2010 was analyzed by means of the dynamic degree of single risk, the dynamic degree of integrated risk, gravity center migration of risk and risk replacement coefficient. Mapping and analysis of the risk zoning of flood disaster was conducted by GIS, and the risk spatial evolution pattern was classified. Seven risk spatial evolution patterns were included as follows: edge contact expansion, inwards sudden increase, swing, leapfrogging, marginal deflation, internal sudden decrease and regional deflation.
Haerbin city one of the typical cities with frequent floods in China, and the region with occurrence of flood disaster changes every year. It would be beneficial if the disaster prevention and reduction department could make timely and accurate flood control planning by understanding the risk of flood disaster dynamic distribution rules. Firstly, through the nature disaster risk formation four-factor theory, assessment model of flood disaster risk of Haerbin Province was established, using metrological, hydrological, social and economical features as indicators. Secondly, comprehensive dynamic degree of flood risk in Haerbin from 2000 to 2010 was analyzed by means of the dynamic degree of single risk, the dynamic degree of integrated risk, gravity center migration of risk and risk replacement coefficient. Mapping and analysis of the risk zoning of flood disaster was conducted by GIS, and the risk spatial evolution pattern was classified. Seven risk spatial evolution patterns were included as follows: edge contact expansion, inwards sudden increase, swing, leapfrogging, marginal deflation, internal sudden decrease and regional deflation.
2016, 14(6):33-38.
Abstract:
The identification of changes and reasons for hydrological factors has practical significance for resource utilization and the ecological health of river basin. Based on the data from 1951-2013 of Weihe River in Guanzhong area, the trend and mutation of temperature and precipitation were analyzed with linear regression, Mann-Kendall test, concentration degree and concentration time. The change reasons of temperature and precipitation were elaborated. The results were as follows: 1) The annual average temperature showed a significant increasing trend, with 0.206℃/10a, and winter contributed most. Obvious mutations occurred in the mid-1990s for the annual and seasonal mean temperature. 2) The annual precipitation showed an insignificant decrease of about 0.5775 mm per year. Spring and autumn contributed greatly to the downward trend. The mutations were complicated, with varying degrees in each era. The distribution of precipitation was stable, with concentration degree and concentration time remaining at 0.5~0.6 and in July, respectively. 3) The changes of temperature and precipitation were mainly the combined results of natural factors and human factors. Natural factors included solar activity, atmospheric circulation and monsoon impact, and the human factors were mainly greenhouse gas emissions and land cover changes.
The identification of changes and reasons for hydrological factors has practical significance for resource utilization and the ecological health of river basin. Based on the data from 1951-2013 of Weihe River in Guanzhong area, the trend and mutation of temperature and precipitation were analyzed with linear regression, Mann-Kendall test, concentration degree and concentration time. The change reasons of temperature and precipitation were elaborated. The results were as follows: 1) The annual average temperature showed a significant increasing trend, with 0.206℃/10a, and winter contributed most. Obvious mutations occurred in the mid-1990s for the annual and seasonal mean temperature. 2) The annual precipitation showed an insignificant decrease of about 0.5775 mm per year. Spring and autumn contributed greatly to the downward trend. The mutations were complicated, with varying degrees in each era. The distribution of precipitation was stable, with concentration degree and concentration time remaining at 0.5~0.6 and in July, respectively. 3) The changes of temperature and precipitation were mainly the combined results of natural factors and human factors. Natural factors included solar activity, atmospheric circulation and monsoon impact, and the human factors were mainly greenhouse gas emissions and land cover changes.
2016, 14(6):39-44.
Abstract:
The Tuhai River is located in the south of the Haihe River Basin in Shandong Province and provides water resources for the development of the northern region of Shandong Province. The imbalance between supply and demand of water resources has become more prominent with the rapid development of the society. This paper selected 2010 as the status quo year, 2020 and 2030 as the forecast years. The water supply and demand in the Tuhai River Basin was forecasted according to the typical characteristics and the social and economic development planning, regardless of the east route of south-to-north water diversion project, and then the balance between supply and demand of water resources was analyzed. The results showed that when P=50%(normal year), P=75% (low flow year), the water deficit of the Tuhai River Basin was respectively 11.2×108 m3, 5.86×108 m3, the water deficient ratio was 19.66%,11.31% in 2020. When P=50%(normal flow year), P=75% (low flow year), the water deficit of the Tuhai River Basin was respectively 13.98×108 m3, 8.82×108 m3, the water deficient ratio was 3.20%,16.01% in 2030. The water resources in the Tuhai River Basin would not fully meet the requirements of production, life, ecological system in next 10-20 years, and some effective measures are required to ensure the sustainable utilization of water resources.
The Tuhai River is located in the south of the Haihe River Basin in Shandong Province and provides water resources for the development of the northern region of Shandong Province. The imbalance between supply and demand of water resources has become more prominent with the rapid development of the society. This paper selected 2010 as the status quo year, 2020 and 2030 as the forecast years. The water supply and demand in the Tuhai River Basin was forecasted according to the typical characteristics and the social and economic development planning, regardless of the east route of south-to-north water diversion project, and then the balance between supply and demand of water resources was analyzed. The results showed that when P=50%(normal year), P=75% (low flow year), the water deficit of the Tuhai River Basin was respectively 11.2×108 m3, 5.86×108 m3, the water deficient ratio was 19.66%,11.31% in 2020. When P=50%(normal flow year), P=75% (low flow year), the water deficit of the Tuhai River Basin was respectively 13.98×108 m3, 8.82×108 m3, the water deficient ratio was 3.20%,16.01% in 2030. The water resources in the Tuhai River Basin would not fully meet the requirements of production, life, ecological system in next 10-20 years, and some effective measures are required to ensure the sustainable utilization of water resources.
2016, 14(6):45-49.
Abstract:
Based on the daily temperature and precipitation data of Kunming meteorological station in 1951-2013, the author used methods of linear trend, Sen slope estimation, Mann-Kendall methods to analyze the characteristics and trends of precipitation, temperature and extreme weather in Kunming. The results showed that, from 1951 to 2013, the average temperature mutation took place in 1994; Annual average temperature and the temperature of the four seasons showed a tendency of warming. Besides, it showed a decreasing trend in annual precipitation, summer rainfall and autumn rainfall, while spring rainfall and winter rainfall showed an upward trend, but the trend was not significant; In the extreme precipitation index, Consecutive wet days showed a downward trend, consecutive dry days and maximum 1-day precipitation amount had a upward trend, but the trend was not significant. In the extreme temperature index, Warm spell duration indicator ,Warm nights and Warm days increased significantly, while cold spell duration indicator, cool nights and cool days reduced significantly.
Based on the daily temperature and precipitation data of Kunming meteorological station in 1951-2013, the author used methods of linear trend, Sen slope estimation, Mann-Kendall methods to analyze the characteristics and trends of precipitation, temperature and extreme weather in Kunming. The results showed that, from 1951 to 2013, the average temperature mutation took place in 1994; Annual average temperature and the temperature of the four seasons showed a tendency of warming. Besides, it showed a decreasing trend in annual precipitation, summer rainfall and autumn rainfall, while spring rainfall and winter rainfall showed an upward trend, but the trend was not significant; In the extreme precipitation index, Consecutive wet days showed a downward trend, consecutive dry days and maximum 1-day precipitation amount had a upward trend, but the trend was not significant. In the extreme temperature index, Warm spell duration indicator ,Warm nights and Warm days increased significantly, while cold spell duration indicator, cool nights and cool days reduced significantly.
2016, 14(6):50-55.
Abstract:
Variation characteristics of potential evapotranspiration (ET0) has important significance in water cycle research and water resource assessment in the background of global climate change in Danjiangkou reservoir area. ET0 and dry index (DI) measured by Penman-Monteith model were analyzed based on the measured meteorological data during 1970-2009, which came from the National Meteorological Center public network. The results showed that: 1) Annual precipitation with a mean value of 839.9 mm decreased with the increment of annual series, and the annual, rainy season and dry season precipitation decreased by 14.3, 4.5 and 9.0 mm/10a respectively. 2) Annual ET0 with a mean value of 860.0 mm increased with the increment of annual series, and the annual, rainy season and dry season ET0 increased by 12.2, 10.2 and 2.9 mm/10a respectively. 3) Annual DI with a mean value of 1.07 increased with the increment of annual series, and the annual, rainy season and dry season DI increased by 0.02, 0.17 and 0.31 mm/10a respectively. 4) ET0 and DI had significant negative correlation with relative humid, and significant positive correlation with mean wind speed and sunshine hours. The climate in Danjiangkou reservoir area had a drought trend stem from the decrease of precipitation and increase of ET0 in the recent 40 years.
Variation characteristics of potential evapotranspiration (ET0) has important significance in water cycle research and water resource assessment in the background of global climate change in Danjiangkou reservoir area. ET0 and dry index (DI) measured by Penman-Monteith model were analyzed based on the measured meteorological data during 1970-2009, which came from the National Meteorological Center public network. The results showed that: 1) Annual precipitation with a mean value of 839.9 mm decreased with the increment of annual series, and the annual, rainy season and dry season precipitation decreased by 14.3, 4.5 and 9.0 mm/10a respectively. 2) Annual ET0 with a mean value of 860.0 mm increased with the increment of annual series, and the annual, rainy season and dry season ET0 increased by 12.2, 10.2 and 2.9 mm/10a respectively. 3) Annual DI with a mean value of 1.07 increased with the increment of annual series, and the annual, rainy season and dry season DI increased by 0.02, 0.17 and 0.31 mm/10a respectively. 4) ET0 and DI had significant negative correlation with relative humid, and significant positive correlation with mean wind speed and sunshine hours. The climate in Danjiangkou reservoir area had a drought trend stem from the decrease of precipitation and increase of ET0 in the recent 40 years.
2016, 14(6):56-61.
Abstract:
Based on the use of generalized water resources and the existing evaluation index system of agricultural water, considering regional irrigation efficiency、water productive efficiency、source of water resources and consumptive ways to build agricultural water utilization composite index (C-index). Collecting data from major irrigation districts of China, this paper quantified irrigation C-index from 1998 to 2010, explored the spatial differentiation characteristics. Results showed that: the C-index on provincial level presented an increasing trend, national C-index increased from 0.550 to 0.704, the structure of water for food production trended to be rationalization; Spatial autocorrelation analysis results showed that, C- index on provincial scale gathered significantly in space, Moran's I inspection values were higher than confidence level (0.01). High value provinces concentrated in Huang-Huai-HaiPlain and north of ChangJiang River, low value provinces widely concentrated in the south of Chang Jiang River, Northeast and Southeast China; Attribute of local autocorrelation is stable, about 20 provinces showed high-high positive autocorrelation (HH) and low-low positive autocorrelation (LL). Spatial differentiation characteristics of C-index from natural features, agricultural production conditions are also analyzed. This paper provides references for making evaluation methods for agricultural water use and making macro policies of water resources management.
Based on the use of generalized water resources and the existing evaluation index system of agricultural water, considering regional irrigation efficiency、water productive efficiency、source of water resources and consumptive ways to build agricultural water utilization composite index (C-index). Collecting data from major irrigation districts of China, this paper quantified irrigation C-index from 1998 to 2010, explored the spatial differentiation characteristics. Results showed that: the C-index on provincial level presented an increasing trend, national C-index increased from 0.550 to 0.704, the structure of water for food production trended to be rationalization; Spatial autocorrelation analysis results showed that, C- index on provincial scale gathered significantly in space, Moran's I inspection values were higher than confidence level (0.01). High value provinces concentrated in Huang-Huai-HaiPlain and north of ChangJiang River, low value provinces widely concentrated in the south of Chang Jiang River, Northeast and Southeast China; Attribute of local autocorrelation is stable, about 20 provinces showed high-high positive autocorrelation (HH) and low-low positive autocorrelation (LL). Spatial differentiation characteristics of C-index from natural features, agricultural production conditions are also analyzed. This paper provides references for making evaluation methods for agricultural water use and making macro policies of water resources management.
2016, 14(6):62-67.
Abstract:
Considering that the unconfined shear strength of large columnar-grained freshwater ice is associated with loading directions, loading strain rate and temperature, we conducted the unconfined shear test at the temperature of -0.5°C, -2°C, -5°C, -10°C and strain rates of 5.0 ? 10–5 s–1 to 5.0×10–2 s–1. Two loading modes were used in our test: vertical loading (the loading force was parallel to the crystal growth direction) and horizontal loading (the loading force was perpendicular to the crystal growth direction). The experimental results showed that (a) the shear strength increased with the decrease of temperature and strain rate under the given experimental conditions; (b) comparison of shear strength under the two loading directions showed that the anisotropy of mechanical properties was more obvious at the temperature of -5°C and -10°C, and the shear strength under the two loading directions had no visible distinction at the temperature of -0.5°C and -2°C; and (c) there was no significant correlation between the shear strength and gas bubble content when the gas bubble content was less than 8.65%.
Considering that the unconfined shear strength of large columnar-grained freshwater ice is associated with loading directions, loading strain rate and temperature, we conducted the unconfined shear test at the temperature of -0.5°C, -2°C, -5°C, -10°C and strain rates of 5.0 ? 10–5 s–1 to 5.0×10–2 s–1. Two loading modes were used in our test: vertical loading (the loading force was parallel to the crystal growth direction) and horizontal loading (the loading force was perpendicular to the crystal growth direction). The experimental results showed that (a) the shear strength increased with the decrease of temperature and strain rate under the given experimental conditions; (b) comparison of shear strength under the two loading directions showed that the anisotropy of mechanical properties was more obvious at the temperature of -5°C and -10°C, and the shear strength under the two loading directions had no visible distinction at the temperature of -0.5°C and -2°C; and (c) there was no significant correlation between the shear strength and gas bubble content when the gas bubble content was less than 8.65%.
2016, 14(6):68-74.
Abstract:
Because of the low temperature in winter, different degree of ice cover will grow in the main canal of the middle route of South-to-North Water Transfer Project in the north of the Yellow River. The main canal would be operated in different manners such as ice-free, drifting ice and ice cover mode, and improper operation will lead to disasters like ice jam and ice dam. In order to anticipate the forming procedure of ice cover in main canals, a mathematical model was used in this paper to simulate the growth and decay of ice cover under different conditions by calculating the detailed heat exchange. According to the field observation data of ice cover in 2012, a set of parameters were calibrated with simulation result by minimizing the quadratic error with measured ice thickness. Then the sensitivity of six parameters in the ice prediction model was evaluated: reflection coefficient α, cloudiness C, virtual ice thickness Δh, wind speed Va, the reduction factor Cc and Ce, initial water temperature. The results showed that the reflection coefficient α, cloudiness C and virtual ice thickness Δh were more sensitive to the prediction of ice thickness. When the value of cloudiness was high, its sensitivity was extremely high. These results can be used to develop and calibrate the ice cover prediction model of canal system in clod region.
Because of the low temperature in winter, different degree of ice cover will grow in the main canal of the middle route of South-to-North Water Transfer Project in the north of the Yellow River. The main canal would be operated in different manners such as ice-free, drifting ice and ice cover mode, and improper operation will lead to disasters like ice jam and ice dam. In order to anticipate the forming procedure of ice cover in main canals, a mathematical model was used in this paper to simulate the growth and decay of ice cover under different conditions by calculating the detailed heat exchange. According to the field observation data of ice cover in 2012, a set of parameters were calibrated with simulation result by minimizing the quadratic error with measured ice thickness. Then the sensitivity of six parameters in the ice prediction model was evaluated: reflection coefficient α, cloudiness C, virtual ice thickness Δh, wind speed Va, the reduction factor Cc and Ce, initial water temperature. The results showed that the reflection coefficient α, cloudiness C and virtual ice thickness Δh were more sensitive to the prediction of ice thickness. When the value of cloudiness was high, its sensitivity was extremely high. These results can be used to develop and calibrate the ice cover prediction model of canal system in clod region.
2016, 14(6):75-80.
Abstract:
Experiments on Flexural Strength and Elastic Modulus of natural freshwater of Ulansuhai Lake in Inner Mongolia were conducted by in situ cantilever beam method. Applying the mechanics of materials method, under the conditions of assuming that the ice is homogeneous and isotropic, the rear of beam is rigidly connected, and there is no water buoyancy supported, the flexural strength and elastic modulus of ice sheet and ice sheet temperature vertical profile were calculated. First, the initial relationship between bending strength, elastic modulus and ice temperature in the middle of ice cantilever was established. Then the formula of the ice temperature vertical profile was brought into the initial relationship between the elastic modulus and the ice temperature, and then the elastic modulus vertical profile distribution was available. According to this, the approximate position of the neutral axis was determined when the ice had flexural failure. Using ice temperature at the approximate position of the neutral axis, the relationship between the elastic modulus and the ice temperature was established again. The more accurate position of the neutral axis could be determined by the iteration method. After four iterations, the position of the neutral axis was accurate. The ice temperature at the precise location of the neutral axis was used as the equivalent temperature of the ice layer. The experimental relationship between bending strength, elastic modulus and equivalent ice temperature was established. Analysis results showed that the temperature ranged from 1.831°C to 7.726°C, the flexural strength ranged from 436.12 kPa to 750.31 kPa and the elastic modulus ranged from 3.62 GPa to 6.71 GPa. The overall trends of flexural strength and elastic modulus were basically increasing with decreasing temperature.
Experiments on Flexural Strength and Elastic Modulus of natural freshwater of Ulansuhai Lake in Inner Mongolia were conducted by in situ cantilever beam method. Applying the mechanics of materials method, under the conditions of assuming that the ice is homogeneous and isotropic, the rear of beam is rigidly connected, and there is no water buoyancy supported, the flexural strength and elastic modulus of ice sheet and ice sheet temperature vertical profile were calculated. First, the initial relationship between bending strength, elastic modulus and ice temperature in the middle of ice cantilever was established. Then the formula of the ice temperature vertical profile was brought into the initial relationship between the elastic modulus and the ice temperature, and then the elastic modulus vertical profile distribution was available. According to this, the approximate position of the neutral axis was determined when the ice had flexural failure. Using ice temperature at the approximate position of the neutral axis, the relationship between the elastic modulus and the ice temperature was established again. The more accurate position of the neutral axis could be determined by the iteration method. After four iterations, the position of the neutral axis was accurate. The ice temperature at the precise location of the neutral axis was used as the equivalent temperature of the ice layer. The experimental relationship between bending strength, elastic modulus and equivalent ice temperature was established. Analysis results showed that the temperature ranged from 1.831°C to 7.726°C, the flexural strength ranged from 436.12 kPa to 750.31 kPa and the elastic modulus ranged from 3.62 GPa to 6.71 GPa. The overall trends of flexural strength and elastic modulus were basically increasing with decreasing temperature.
2016, 14(6):81-86.
Abstract:
The open waters were dug to simulate ice-channel system in Wuliangsu Lake during melt period and the change of lateral interface between ice and water was continuously observed. On the basis of the measured data, analysis was conducted to study the change of lateral interface and the influencing factors on thermodynamic melting rate. The results showed that the shape in the middle of the interface was like a straight line and the bottom interface presented an arc shape. However, the top inclined inside or outside under the influence of air temperature. Air temperature, as a principal factor, influenced the melting rate, and the melting rate increased with increasing air temperature. Because higher wind speed did not only usually accompany with lower air temperature but also accelerated the evaporation to reduce the water temperature, melting rate decreased with increasing wind speed. The wind pulled the water body to produce eddy at windward side, accelerated heat exchange and reduced water temperature, and finally reduced the melting rate. Moreover, the correlation between melting rate, air temperature as well as wind speed was established with binary regression.
The open waters were dug to simulate ice-channel system in Wuliangsu Lake during melt period and the change of lateral interface between ice and water was continuously observed. On the basis of the measured data, analysis was conducted to study the change of lateral interface and the influencing factors on thermodynamic melting rate. The results showed that the shape in the middle of the interface was like a straight line and the bottom interface presented an arc shape. However, the top inclined inside or outside under the influence of air temperature. Air temperature, as a principal factor, influenced the melting rate, and the melting rate increased with increasing air temperature. Because higher wind speed did not only usually accompany with lower air temperature but also accelerated the evaporation to reduce the water temperature, melting rate decreased with increasing wind speed. The wind pulled the water body to produce eddy at windward side, accelerated heat exchange and reduced water temperature, and finally reduced the melting rate. Moreover, the correlation between melting rate, air temperature as well as wind speed was established with binary regression.
2016, 14(6):87-90.
Abstract:
Ice jam is a common phenomenon for rives in cold regions. Lodgment and gorging can easily occur especially in curved channels. The formation of ice jam and its thickness distribution in curved channels were not fully understood. By changing the flow conditions and ice discharge in a flume in the laboratory, the condition of ice jam forming in a curved channel and straight flute was studied and comparatively analyzed. The experiment results showed that the threshold Fr number of ice jam forming for curved channel was larger than that for straight flute, that is to say under the condition of the same water depth, the bigger velocity of curved channel could also form ice jam. The Fr number of ice jam formation in a curved channel ranged larger than that in straight flute. The curved channel was more likely to form ice jam. Balance of ice jam thickness decreased with the increase of initial velocity, roughly increased as the initial water depth increased, and increased with the increase of the ice flow rule.
Ice jam is a common phenomenon for rives in cold regions. Lodgment and gorging can easily occur especially in curved channels. The formation of ice jam and its thickness distribution in curved channels were not fully understood. By changing the flow conditions and ice discharge in a flume in the laboratory, the condition of ice jam forming in a curved channel and straight flute was studied and comparatively analyzed. The experiment results showed that the threshold Fr number of ice jam forming for curved channel was larger than that for straight flute, that is to say under the condition of the same water depth, the bigger velocity of curved channel could also form ice jam. The Fr number of ice jam formation in a curved channel ranged larger than that in straight flute. The curved channel was more likely to form ice jam. Balance of ice jam thickness decreased with the increase of initial velocity, roughly increased as the initial water depth increased, and increased with the increase of the ice flow rule.
16 Measuring ice thickness around the curve and piers in the Yellow River with ground penetrating radar
2016, 14(6):91-95.
Abstract:
The freezing process of yellow river is a key point of the study of Yellow River ice flood prevention, detection of the ice thickness around the curve and piers has important significance for prevention of the ice flood. The ground penetrating radar has the advantages of portability, high efficiency, continuous, fast and real time for ice thickness detection. The frequency of the radar antenna determines the penetration depth and resolution of the radar wave. From the radar images could clearly identify the air - water interface and ice - water interface. The accuracy of the measurement results was further improved by using ice thickness data from the field drilling to calculate radar propagation velocity in the ice. The measurement results clearly showed that the distribution of ice thickness at the bend and pier is uneven. The thickness of the ice on the north side of piers and the main channel of the curve is thicker. The ground penetrating radar with 200 Mhz antenna can penetrate the Yellow River ice, the radar images can clearly show the ice-water interface. Provide the basic data for the analysis of the yellow river ice freezing and melting process and governance the ice jam in break-up period.
The freezing process of yellow river is a key point of the study of Yellow River ice flood prevention, detection of the ice thickness around the curve and piers has important significance for prevention of the ice flood. The ground penetrating radar has the advantages of portability, high efficiency, continuous, fast and real time for ice thickness detection. The frequency of the radar antenna determines the penetration depth and resolution of the radar wave. From the radar images could clearly identify the air - water interface and ice - water interface. The accuracy of the measurement results was further improved by using ice thickness data from the field drilling to calculate radar propagation velocity in the ice. The measurement results clearly showed that the distribution of ice thickness at the bend and pier is uneven. The thickness of the ice on the north side of piers and the main channel of the curve is thicker. The ground penetrating radar with 200 Mhz antenna can penetrate the Yellow River ice, the radar images can clearly show the ice-water interface. Provide the basic data for the analysis of the yellow river ice freezing and melting process and governance the ice jam in break-up period.
17 Ice regime analysis and safe dispatch research
on long distance water diversion project in winter
2016, 14(6):96-104.
Abstract:
Administration Bureau of South-to-North Water Diversion Middle Route Project, Beijing 100038, China） Abstract: The paper analyzed the temporal and spatial distribution characteristics of ice regime and ice thickness, with ice regime prototype observation data at South-to-North Water Diversion Middle Route Project in 5 winters during 2011~2016. In the winter of 2015 to 2016, ice jam occurred in local canal, because of large discharge, 0.25m/s~0.67m/s flow velocity and cold air(- 18.6℃) . Combined with the dispatching mode of constant water level in front of the gate and canal pool flow characteristics, water control condition was proposed to avoid the formation of ice jam disaster. The upstream section of canal pool should be controlled with V?0.40m/s，Fr?0.065. the downstream section should be controlled with V?0.35m/s，Fr?0.055. It was recommended to increase the full line of ice regime observation and collect more ice observation data, in order to set up scientific basis to optimize the water supply operation scheduling and ice regime forecast in winter.
Administration Bureau of South-to-North Water Diversion Middle Route Project, Beijing 100038, China） Abstract: The paper analyzed the temporal and spatial distribution characteristics of ice regime and ice thickness, with ice regime prototype observation data at South-to-North Water Diversion Middle Route Project in 5 winters during 2011~2016. In the winter of 2015 to 2016, ice jam occurred in local canal, because of large discharge, 0.25m/s~0.67m/s flow velocity and cold air(- 18.6℃) . Combined with the dispatching mode of constant water level in front of the gate and canal pool flow characteristics, water control condition was proposed to avoid the formation of ice jam disaster. The upstream section of canal pool should be controlled with V?0.40m/s，Fr?0.065. the downstream section should be controlled with V?0.35m/s，Fr?0.055. It was recommended to increase the full line of ice regime observation and collect more ice observation data, in order to set up scientific basis to optimize the water supply operation scheduling and ice regime forecast in winter.
2016, 14(6):105-110.
Abstract:
Jinping-ⅠDam is the highest hyperbolic arch dam in the world. Vibration and safe protection of plunge pool is particularly significant. Based on the spillway vibration test archetypal observation of plunge pool of Jinping-Ⅰarch dam, the flow-induced vibration response of slabs in plunge pool in different groups were analyzed and studied. The results showed Jinping-I plunge Pool vibration intensity increased along the way at a separate middle outlets flood, slabs had serious vibration in plunge pool during surface outlet and both surface and middle outlet discharge; the dominant frequency of vibration of slabs was distributed between 0.3 and 1.3Hz, belonging to the frequency range of fluctuating, the slabs had forced vibration under water load; the correlation of slabs vibration between adjacent measuring points was remarkable, the spatial integral scale of slabs vibration was kept above 45 m in all groups, the integrity and structure of the slabs were good. The results had a certain reference value for reasonable dispatching, scientific operational and protection of the safe operation of the downstream flood releasing structure of Jinping-Ⅰhydropower station.
Jinping-ⅠDam is the highest hyperbolic arch dam in the world. Vibration and safe protection of plunge pool is particularly significant. Based on the spillway vibration test archetypal observation of plunge pool of Jinping-Ⅰarch dam, the flow-induced vibration response of slabs in plunge pool in different groups were analyzed and studied. The results showed Jinping-I plunge Pool vibration intensity increased along the way at a separate middle outlets flood, slabs had serious vibration in plunge pool during surface outlet and both surface and middle outlet discharge; the dominant frequency of vibration of slabs was distributed between 0.3 and 1.3Hz, belonging to the frequency range of fluctuating, the slabs had forced vibration under water load; the correlation of slabs vibration between adjacent measuring points was remarkable, the spatial integral scale of slabs vibration was kept above 45 m in all groups, the integrity and structure of the slabs were good. The results had a certain reference value for reasonable dispatching, scientific operational and protection of the safe operation of the downstream flood releasing structure of Jinping-Ⅰhydropower station.
19 Application of modified variable dimension fractal method by Markov chain in dam safety monitoring
2016, 14(6):111-115.
Abstract:
Previous forecast models have strong dependence on the length of the data, and the data often appears strong nonlinear. Both of these will increase the complexity of the prediction. So in order to make the monitoring data to show a certain linear relationship, this paper changed constant dimension fractal method to variable dimension fractal method to predict short-term monitoring data based on fractal theory short-term monitoring data. The corresponding mathematical model was set up. However, inevitably, there were some fluctuation errors in the results predicted by the variable dimension fractal method. This paper used the Markov chain to modify these predicted results based on the characteristic of no aftereffect. The results analyzed by Xixi reservoir monitoring data showed that the revised error could be optimized by 0.89%. Obviously, it could be concluded that the variable dimension fractal method modified by Markov chain could effectively reduce error and improve the precision of prediction.
Previous forecast models have strong dependence on the length of the data, and the data often appears strong nonlinear. Both of these will increase the complexity of the prediction. So in order to make the monitoring data to show a certain linear relationship, this paper changed constant dimension fractal method to variable dimension fractal method to predict short-term monitoring data based on fractal theory short-term monitoring data. The corresponding mathematical model was set up. However, inevitably, there were some fluctuation errors in the results predicted by the variable dimension fractal method. This paper used the Markov chain to modify these predicted results based on the characteristic of no aftereffect. The results analyzed by Xixi reservoir monitoring data showed that the revised error could be optimized by 0.89%. Obviously, it could be concluded that the variable dimension fractal method modified by Markov chain could effectively reduce error and improve the precision of prediction.
2016, 14(6):116-121.
Abstract:
Dam deformation prediction plays an important role in the safety assessment of dam operation. Traditional models lack forecasting precision and the simulation effect is not stable enough. Besides, if abnormal values of dam deformation exist, traditional machine algorithm model lacks the flexibility of dealing with these abnormal data, which will lead to the deviation of the forecasting results. In order to solve these problems, random forest algorithm was introduced to the field of dam deformation monitoring for the first time. Similarity matrix of random forest was applied to divide dam deformation monitoring points into several parts. Random forests prediction model was established for each part, which will avoid the defects of traditional models such as modeling of single point or using the same model for all deformation monitoring points. Establishing forecasting model for different parts of dam was more in line with engineering practice. Deformation data of one arch dam was analyzed and the feasibility of random forest model was verified. The results showed that partition of dam deformation points based on similarity matrix of random forest conformed to the physical and engineering practical significance. Compared with support vector machine and BP neural network model, the prediction model of random forests for each part had the higher prediction precision and stability, which provided a new approach in the area of dam safety monitoring.
Dam deformation prediction plays an important role in the safety assessment of dam operation. Traditional models lack forecasting precision and the simulation effect is not stable enough. Besides, if abnormal values of dam deformation exist, traditional machine algorithm model lacks the flexibility of dealing with these abnormal data, which will lead to the deviation of the forecasting results. In order to solve these problems, random forest algorithm was introduced to the field of dam deformation monitoring for the first time. Similarity matrix of random forest was applied to divide dam deformation monitoring points into several parts. Random forests prediction model was established for each part, which will avoid the defects of traditional models such as modeling of single point or using the same model for all deformation monitoring points. Establishing forecasting model for different parts of dam was more in line with engineering practice. Deformation data of one arch dam was analyzed and the feasibility of random forest model was verified. The results showed that partition of dam deformation points based on similarity matrix of random forest conformed to the physical and engineering practical significance. Compared with support vector machine and BP neural network model, the prediction model of random forests for each part had the higher prediction precision and stability, which provided a new approach in the area of dam safety monitoring.
2016, 14(6):122-127.
Abstract:
Targeting at the fuzziness and uncertainty faced in the process of tailings dam risk evaluation, tailings dam risk was taken as a whole and appropriate evaluation factors were selected, in combination with the improved AHP and cloud model theory, a model suitable for tailings dam risk fuzzy evaluation was established. Numerical examples showed that, the corresponding cloud model generated based on the standard of each evaluation factor assignment could fully characterize the fuzziness, randomness and discreteness in the process of evaluation. After calculating the weight of each evaluation factor using the improved AHP, comprehensive evaluation was conducted according to the principle of maximum membership degree. The result was consistent with the actual situation，which further evidenced the correctness and validity of the evaluation model, and provides a new way for tailings dam risk evaluation.
Targeting at the fuzziness and uncertainty faced in the process of tailings dam risk evaluation, tailings dam risk was taken as a whole and appropriate evaluation factors were selected, in combination with the improved AHP and cloud model theory, a model suitable for tailings dam risk fuzzy evaluation was established. Numerical examples showed that, the corresponding cloud model generated based on the standard of each evaluation factor assignment could fully characterize the fuzziness, randomness and discreteness in the process of evaluation. After calculating the weight of each evaluation factor using the improved AHP, comprehensive evaluation was conducted according to the principle of maximum membership degree. The result was consistent with the actual situation，which further evidenced the correctness and validity of the evaluation model, and provides a new way for tailings dam risk evaluation.
2016, 14(6):128-134.
Abstract:
Siphon outlet conduit is one of the main forms of outlet conduit of large pumping station. Due to the limitation of actual engineering topographic features, the siphon outlet conduit adopted by the South to North Water Diversion Project—Jiangdu NO.1 pumping station is not common in engineering design. According to the siphon discharge conduit in Jiangdu NO.1 pumping station, numerical simulation of the whole flow passage was conducted by CFX, the internal water flow movement characteristics of the siphon outlet conduit were studied and the hydraulic performance was predicted. The results showed that the lower head loss mainly came from the head loss of bending section. In outlet passage, vorticity showed a downward trend, but the cross section area was too large to cause the uneven distribution of the velocity of the outlet section and increase of the vorticity. External characteristics of the pump device prediction results were consistent with the test data of the overall trend, demonstrating that the calculation results were reliable.
Siphon outlet conduit is one of the main forms of outlet conduit of large pumping station. Due to the limitation of actual engineering topographic features, the siphon outlet conduit adopted by the South to North Water Diversion Project—Jiangdu NO.1 pumping station is not common in engineering design. According to the siphon discharge conduit in Jiangdu NO.1 pumping station, numerical simulation of the whole flow passage was conducted by CFX, the internal water flow movement characteristics of the siphon outlet conduit were studied and the hydraulic performance was predicted. The results showed that the lower head loss mainly came from the head loss of bending section. In outlet passage, vorticity showed a downward trend, but the cross section area was too large to cause the uneven distribution of the velocity of the outlet section and increase of the vorticity. External characteristics of the pump device prediction results were consistent with the test data of the overall trend, demonstrating that the calculation results were reliable.
2016, 14(6):135-140.
Abstract:
During the construction process of tunnel excavation in a hydro-project, the method of all excavation completed before lining was commonly used. As for the seepage flow stability calculation on tunnel excavation temporary state to impact groundwater environment, which is not in line with the actual situation, and often amplifies the water level fluctuation and effective range. In view of this, adopting the technique of unsteady seepage numerical simulation to assess the impact on groundwater environment will be more reasonable. Taking the construction process of a diversion tunnel as an example, based on unsteady saturated and unsaturated seepage theory, the three-dimensional finite element numerical model was established to calculate the transient seepage field of tunnel excavation area. The tunnel groundwater variation from commencement to completion of works was summarized. Groundwater environmental impact assessment on the process of tunnel excavation was done. The results showed that (1) it was feasible to predict the process of water level falling and affective range enlarging by three-dimensional unsteady seepage flow analysis; (2) the groundwater in this region was less effected by excavation of diversion tunnel and groundwater recharge and discharge relations remained unchanged.
During the construction process of tunnel excavation in a hydro-project, the method of all excavation completed before lining was commonly used. As for the seepage flow stability calculation on tunnel excavation temporary state to impact groundwater environment, which is not in line with the actual situation, and often amplifies the water level fluctuation and effective range. In view of this, adopting the technique of unsteady seepage numerical simulation to assess the impact on groundwater environment will be more reasonable. Taking the construction process of a diversion tunnel as an example, based on unsteady saturated and unsaturated seepage theory, the three-dimensional finite element numerical model was established to calculate the transient seepage field of tunnel excavation area. The tunnel groundwater variation from commencement to completion of works was summarized. Groundwater environmental impact assessment on the process of tunnel excavation was done. The results showed that (1) it was feasible to predict the process of water level falling and affective range enlarging by three-dimensional unsteady seepage flow analysis; (2) the groundwater in this region was less effected by excavation of diversion tunnel and groundwater recharge and discharge relations remained unchanged.
2016, 14(6):141-147.
Abstract:
Landslide disaster is one of the most frequently happening geological disasters, the process of which is governed by terrain geometry, characteristic of landslide rock mass, characteristic of slip surface and external environment loads such as earthquake, rainstorm and human activity. Based on the fact of landslide disaster at bedding rock slope of left bank of Tiger-leap-Gorger at Liangjiaren hydropower station, on October 28,1996, a landslide model was built up to fit the slide rock mass, slip face, as well as the effect of earthquake and rainstorm according to a large number of geological surveys. Then a series of numerical simulation of landslide was proposed to study the influencing rules of slip friction coefficient and strength of slide rock mass on the landslide geometry, debris size and velocity of landslide, so the process of landslide of bedding rock slope was feedback analyzed and the slope stability was discussed. This method could be used in following stability research of similar slopes and corresponding assessment of geological hazards.
Landslide disaster is one of the most frequently happening geological disasters, the process of which is governed by terrain geometry, characteristic of landslide rock mass, characteristic of slip surface and external environment loads such as earthquake, rainstorm and human activity. Based on the fact of landslide disaster at bedding rock slope of left bank of Tiger-leap-Gorger at Liangjiaren hydropower station, on October 28,1996, a landslide model was built up to fit the slide rock mass, slip face, as well as the effect of earthquake and rainstorm according to a large number of geological surveys. Then a series of numerical simulation of landslide was proposed to study the influencing rules of slip friction coefficient and strength of slide rock mass on the landslide geometry, debris size and velocity of landslide, so the process of landslide of bedding rock slope was feedback analyzed and the slope stability was discussed. This method could be used in following stability research of similar slopes and corresponding assessment of geological hazards.
2016, 14(6):148-153.
Abstract:
In order to study the effect of improving water flow in bend of spilling chute using diversion wall, hydraulic model experiments with diversion wall were carried out under different hydraulic conditions in this paper. The results showed that: After setting diversion wall, the surface difference of cross section in concave and convex banks was significantly lower than that in the absence of diversion wall, but the surface difference still existed; Variation of the surface difference was the same as that without diversion, the surface difference increased with the increase of flow rate and bottom slopes, and decreased with the increase of the radius of bend; After setting diversion wall in the bend of spillway chute, the position of the maximum surface difference changed. The maximum surface difference was seen in the vertically adjacent section of middle bend in the presence of diversion wall, whereas in the upstream section before middle bend in the absence of bend.
In order to study the effect of improving water flow in bend of spilling chute using diversion wall, hydraulic model experiments with diversion wall were carried out under different hydraulic conditions in this paper. The results showed that: After setting diversion wall, the surface difference of cross section in concave and convex banks was significantly lower than that in the absence of diversion wall, but the surface difference still existed; Variation of the surface difference was the same as that without diversion, the surface difference increased with the increase of flow rate and bottom slopes, and decreased with the increase of the radius of bend; After setting diversion wall in the bend of spillway chute, the position of the maximum surface difference changed. The maximum surface difference was seen in the vertically adjacent section of middle bend in the presence of diversion wall, whereas in the upstream section before middle bend in the absence of bend.
2016, 14(6):154-158.
Abstract:
The connection bridge spacing will influence the water conveyance capacity of the middle route of South-to-North Water Transfer. Therefore, reasonable layout of the cross ditch bridge for residents on both sides should not only ensure the channel capacity but also cater for the daily needs of the residents at both sides. On the basis of the layout rationality analysis for the middle route of the South-to-North Water Diversion project, this paper presented general principles of optimal layout about connection bridge on long distance open channel. And then, taking into account the influence of different characteristics of bridge spacing on channel capacity, the maximum distance of the cross ditch bridge was obtained combining with the longest tolerable detouring distance for residents, the connection bridge layout alternatives were drawn up, the layout decision model for selecting the site of connection bridges was established based on the principle of minimum synthetic detouring coefficient, and eventually the final specific location was determined. In the end, the method was applied to the case of the middle route of South-to-North Water Transfer (from Beijing to Shijiazhuang), which was proved satisfying. Decision-making model of layout scheme, based on the principle of minimum synthetic detouring coefficient, has suitable and extensive application in site optimization of the connection bridge on long distance water transfer channel.
The connection bridge spacing will influence the water conveyance capacity of the middle route of South-to-North Water Transfer. Therefore, reasonable layout of the cross ditch bridge for residents on both sides should not only ensure the channel capacity but also cater for the daily needs of the residents at both sides. On the basis of the layout rationality analysis for the middle route of the South-to-North Water Diversion project, this paper presented general principles of optimal layout about connection bridge on long distance open channel. And then, taking into account the influence of different characteristics of bridge spacing on channel capacity, the maximum distance of the cross ditch bridge was obtained combining with the longest tolerable detouring distance for residents, the connection bridge layout alternatives were drawn up, the layout decision model for selecting the site of connection bridges was established based on the principle of minimum synthetic detouring coefficient, and eventually the final specific location was determined. In the end, the method was applied to the case of the middle route of South-to-North Water Transfer (from Beijing to Shijiazhuang), which was proved satisfying. Decision-making model of layout scheme, based on the principle of minimum synthetic detouring coefficient, has suitable and extensive application in site optimization of the connection bridge on long distance water transfer channel.
27 Study of hydro-chemical characteristics and genesis in Kashi Reach of Kizil River Basin in Xinjiang
2016, 14(6):159-164.
Abstract:
Based on analyzing water chemistry data of 17 river water samples, the hydro-chemical characteristics and genesis in Kashi reach of Kizil River were studied by the means of Piper trilinear nomograph, principal component analysis and factor analysis. The results showed that the differences of hydrochemical types between the upstream and the middle or lower reaches reflected that the weathering dissolution of evaporates was the dominant influencing factor of the hydrochemical compositions of the river water, while the high quantity of SO42- in river originated from the weathering dissolution of the gypsum salt series in neogene stratigraphic. The evaporites weathering was dominated by gypsum salt weathering, while rock salt weathering took the second place, carbonate weathering contributed less, and the last was albite weathering.
Based on analyzing water chemistry data of 17 river water samples, the hydro-chemical characteristics and genesis in Kashi reach of Kizil River were studied by the means of Piper trilinear nomograph, principal component analysis and factor analysis. The results showed that the differences of hydrochemical types between the upstream and the middle or lower reaches reflected that the weathering dissolution of evaporates was the dominant influencing factor of the hydrochemical compositions of the river water, while the high quantity of SO42- in river originated from the weathering dissolution of the gypsum salt series in neogene stratigraphic. The evaporites weathering was dominated by gypsum salt weathering, while rock salt weathering took the second place, carbonate weathering contributed less, and the last was albite weathering.
2016, 14(6):165-170.
Abstract:
Suide county is located in the hinterland of the Loess plateau. The topography is tattered, the hilly is up and down, the geological environment condition is fragile, and landslides occur frequently. According to the detailed investigation of geological hazards, there were 48 landslides. On the basis of detailed surveying and mapping, the development characteristics, distribution and influencing factors of landslides were studied in depth, and the results showed that: (1)The landslides in Suide county all belonged to shallow loess landslide and were mainly in form of small landslide. (2)There was a close relationship between distribution of landslide and geomorphology, area, rainfall. The spatial distribution characteristics of landslide was all developed in loess ridge and river terrace and mostly developed in the county with more people and more human engineering activity. The temporal distribution characteristics of landslide was mostly developed in time of human engineering activity and in the rainy season, especially in the time between June and September.(3)The main influencing factor of landslide was the geomorphology, the soil, human engineering activity, rainfall.
Suide county is located in the hinterland of the Loess plateau. The topography is tattered, the hilly is up and down, the geological environment condition is fragile, and landslides occur frequently. According to the detailed investigation of geological hazards, there were 48 landslides. On the basis of detailed surveying and mapping, the development characteristics, distribution and influencing factors of landslides were studied in depth, and the results showed that: (1)The landslides in Suide county all belonged to shallow loess landslide and were mainly in form of small landslide. (2)There was a close relationship between distribution of landslide and geomorphology, area, rainfall. The spatial distribution characteristics of landslide was all developed in loess ridge and river terrace and mostly developed in the county with more people and more human engineering activity. The temporal distribution characteristics of landslide was mostly developed in time of human engineering activity and in the rainy season, especially in the time between June and September.(3)The main influencing factor of landslide was the geomorphology, the soil, human engineering activity, rainfall.
2016, 14(6):171-175.
Abstract:
The continuous heavy rainfall in the evening of 31 July 2008 led to the outbreak of Shaofang ditch debris flow in Yunnan Dong chuan Shekuai district, and it caused casualties and damage to roads, houses and a number of public infrastructure. The debris flow occurred in the geological environment of vulnerable mining areas，and the outbreak of debris flow was the result of interaction between unreasonable spoil pile and heavy rainfall. The rainfall conditions, terrain conditions and source conditions of debris flow were analyzed, and the starting, circulation and accumulation process of the debris flow in the Shaofang ditch were studied by field survey and test methods. The research results showed that: the loose residue source and strong rainfall were the main reasons for the occurrence of debris flow of Shaofang Ditch. Judging from the trend，the Shaofang ditch debris flow was at the stage of development, and the possibility of the outbreak of debris flow still existed. According to the characteristics of debris flow, the following measures were put forward, and these measures were stopping and supporting, combined with dam energy dissipation, vegetation restoration,;timely dredging, real-time monitoring, and disaster early-warning.
The continuous heavy rainfall in the evening of 31 July 2008 led to the outbreak of Shaofang ditch debris flow in Yunnan Dong chuan Shekuai district, and it caused casualties and damage to roads, houses and a number of public infrastructure. The debris flow occurred in the geological environment of vulnerable mining areas，and the outbreak of debris flow was the result of interaction between unreasonable spoil pile and heavy rainfall. The rainfall conditions, terrain conditions and source conditions of debris flow were analyzed, and the starting, circulation and accumulation process of the debris flow in the Shaofang ditch were studied by field survey and test methods. The research results showed that: the loose residue source and strong rainfall were the main reasons for the occurrence of debris flow of Shaofang Ditch. Judging from the trend，the Shaofang ditch debris flow was at the stage of development, and the possibility of the outbreak of debris flow still existed. According to the characteristics of debris flow, the following measures were put forward, and these measures were stopping and supporting, combined with dam energy dissipation, vegetation restoration,;timely dredging, real-time monitoring, and disaster early-warning.
2016, 14(6):176-182.
Abstract:
In earthquake disturbance and alpine-gorge area, instability slope with crushing rock is caused by active faults and frequent earthquakes. Particle migration in the deposits is caused by water infiltration, resulting in the change of saturation， density， thus weakening its strength， which subsequently induces occurrence of debris flow initiation. Debris flow gullies in two areas including Gansu Zhouqu county in the west Qinling mountains fault zone and Duwen highway in Longmen mountain fault zone were taken as an example， physical and mechanical properties tests of the loose accumulation body were carried out. Experimental results showed that the two groups of debris flow deposits were silty gravel soil with wide and non-uniform grading. Fine grain content in Zhouqu debris deposits was relatively high， its specific gravity， liquid limit, plastic limit, liquid index，and plasticity index were greater than those of soil sample of Duwen highway. When the moisture content of Zhouqu debris flow soil and Duwen highway slope soil increased to 15%-18% and 12%-15% respectively， the soil cohesion c reduced sharply. It hinted the existence of critical moisture content in soil strength decline process. The specific moisture content could be used as the critical water content of debris flow initiation. Further statistical analysis showed one-hour critical rainfall before occurrence of debris flow and the critical moisture content was closely related. By fitting the linear relativity between them, the critical rainfall of debris flow could be deduced, which can provide technical support for the prevention and early warning of debris flow in earthquake disturbed area.
In earthquake disturbance and alpine-gorge area, instability slope with crushing rock is caused by active faults and frequent earthquakes. Particle migration in the deposits is caused by water infiltration, resulting in the change of saturation， density， thus weakening its strength， which subsequently induces occurrence of debris flow initiation. Debris flow gullies in two areas including Gansu Zhouqu county in the west Qinling mountains fault zone and Duwen highway in Longmen mountain fault zone were taken as an example， physical and mechanical properties tests of the loose accumulation body were carried out. Experimental results showed that the two groups of debris flow deposits were silty gravel soil with wide and non-uniform grading. Fine grain content in Zhouqu debris deposits was relatively high， its specific gravity， liquid limit, plastic limit, liquid index，and plasticity index were greater than those of soil sample of Duwen highway. When the moisture content of Zhouqu debris flow soil and Duwen highway slope soil increased to 15%-18% and 12%-15% respectively， the soil cohesion c reduced sharply. It hinted the existence of critical moisture content in soil strength decline process. The specific moisture content could be used as the critical water content of debris flow initiation. Further statistical analysis showed one-hour critical rainfall before occurrence of debris flow and the critical moisture content was closely related. By fitting the linear relativity between them, the critical rainfall of debris flow could be deduced, which can provide technical support for the prevention and early warning of debris flow in earthquake disturbed area.
2016, 14(6):183-189.
Abstract:
Although there are a number of water quality evaluation methods, it is a basic and scientific work to choose a suitable method for water quality evaluation. In this study, four evaluation methods (i.e., single factor evaluation, comprehensive pollution index method, fuzzy comprehensive evaluation and gray relational evaluation) were used to evaluate the water quality condition of a reservoir in Guangdong province according to the monitoring data during 2008-2013. The rationality and defects of these four methods were also explored by comparing their results. The results showed that: (1) Remarkable differences existed among the results obtained by different evaluation methods. The evaluation results of gray relational analysis were the best while those of single factor evaluation method were the worst. (2) The different evaluation methods were influenced differently by weight. The gray relational analysis was least impacted while the fuzzy comprehensive evaluation method was highly influenced. (3) The fuzzy comprehensive evaluation method is suitable for users with rich experience in determining the weight, otherwise, gray relational evaluation method is recommended. Single factor evaluation method is suitable for the most strict water resources management. Comprehensive pollution index method could only determine whether the water bodies were polluted, but could not determine the degree of water quality, so it can be used as a complementary method. (4) In order to evaluate water quality accurately, and reduce the effects of weight and method, a variety of evaluation methods are recommended.
Although there are a number of water quality evaluation methods, it is a basic and scientific work to choose a suitable method for water quality evaluation. In this study, four evaluation methods (i.e., single factor evaluation, comprehensive pollution index method, fuzzy comprehensive evaluation and gray relational evaluation) were used to evaluate the water quality condition of a reservoir in Guangdong province according to the monitoring data during 2008-2013. The rationality and defects of these four methods were also explored by comparing their results. The results showed that: (1) Remarkable differences existed among the results obtained by different evaluation methods. The evaluation results of gray relational analysis were the best while those of single factor evaluation method were the worst. (2) The different evaluation methods were influenced differently by weight. The gray relational analysis was least impacted while the fuzzy comprehensive evaluation method was highly influenced. (3) The fuzzy comprehensive evaluation method is suitable for users with rich experience in determining the weight, otherwise, gray relational evaluation method is recommended. Single factor evaluation method is suitable for the most strict water resources management. Comprehensive pollution index method could only determine whether the water bodies were polluted, but could not determine the degree of water quality, so it can be used as a complementary method. (4) In order to evaluate water quality accurately, and reduce the effects of weight and method, a variety of evaluation methods are recommended.
32 Regionalization of An Evaluation Index System for Water Conservancy Development in Yunnan Province
2016, 14(6):190-195.
Abstract:
There were different characteristics of the water conservancy development in different areas of Yunnan Province. Differentially established evaluation index systems of regional water conservancy development would better guide the regional water conservancy construction, and promote balanced and sustainable development of Yunnan Province. According to certain principle of partition, Yunnan could be divided into five areas. Adjustment of target values of the regional index was on the basis of province target, and referred to the analysis of water conservancy development priorities in every area. The weight of each area was calculated using the comprehensive weighting method based on the analytic hierarchy process and entropy weight method. The water conservancy development level of five areas in 2013 was evaluated. According to the result of the evaluation, suggestions were put forward in view of every regional water conservancy development.
There were different characteristics of the water conservancy development in different areas of Yunnan Province. Differentially established evaluation index systems of regional water conservancy development would better guide the regional water conservancy construction, and promote balanced and sustainable development of Yunnan Province. According to certain principle of partition, Yunnan could be divided into five areas. Adjustment of target values of the regional index was on the basis of province target, and referred to the analysis of water conservancy development priorities in every area. The weight of each area was calculated using the comprehensive weighting method based on the analytic hierarchy process and entropy weight method. The water conservancy development level of five areas in 2013 was evaluated. According to the result of the evaluation, suggestions were put forward in view of every regional water conservancy development.
2016, 14(6):196-200.
Abstract:
In order to solve the problems of multi blade large solid, low coefficient of wind power utilization, and high production cost of traditional wind water machine, this paper investigate a novel wind water pumping machine with design of low degree and high gas dynamic performance model. Then the similarity theory was deducted which was used in wind turbine, and the physical model of the novel wind water device was established. The blowing experiment was carried out in the wind tunnel laboratory of Hohai University, to measure the wind energy utilization coefficient of wind wheel under rated condition and the flow of the device under different conditions, and draw the flow characteristic curve. Experimental results showed that the device could start at 2.8m/s, the wind energy utilization coefficient of the device could reach more than 0.43 under the rated condition, and could meet the design requirements. The wind turbine and pump could match the best performance under the design head, and the efficiency could reach the maximum under this condition.
In order to solve the problems of multi blade large solid, low coefficient of wind power utilization, and high production cost of traditional wind water machine, this paper investigate a novel wind water pumping machine with design of low degree and high gas dynamic performance model. Then the similarity theory was deducted which was used in wind turbine, and the physical model of the novel wind water device was established. The blowing experiment was carried out in the wind tunnel laboratory of Hohai University, to measure the wind energy utilization coefficient of wind wheel under rated condition and the flow of the device under different conditions, and draw the flow characteristic curve. Experimental results showed that the device could start at 2.8m/s, the wind energy utilization coefficient of the device could reach more than 0.43 under the rated condition, and could meet the design requirements. The wind turbine and pump could match the best performance under the design head, and the efficiency could reach the maximum under this condition.
2016, 14(6):201-208.
Abstract:
Water culture is a kind of spiritual culture related to using water, saving water, protection of water and worship water, which is characterized by thickness, diversity and dominancy. It is not only the characteristics of culture water in the conservancy industry, but also an important part of our traditional culture in China. Our academic circles have reaped rich achievements in the research on water culture since propaganda working conference of harness of the Huai River in October of 1988. Combined with new trends, new morphology and new form, through a comprehensive, systematic collection of the latest literatures on the water culture, the article discussed the research progress in theory of water culture, heritage of water culture, propagation of water culture and regional water culture and prospected the research object, research range, research direction and research means of water culture on this basis, in order to promote and deepen it and push excellent traditional culture of the Chinese research forward.
Water culture is a kind of spiritual culture related to using water, saving water, protection of water and worship water, which is characterized by thickness, diversity and dominancy. It is not only the characteristics of culture water in the conservancy industry, but also an important part of our traditional culture in China. Our academic circles have reaped rich achievements in the research on water culture since propaganda working conference of harness of the Huai River in October of 1988. Combined with new trends, new morphology and new form, through a comprehensive, systematic collection of the latest literatures on the water culture, the article discussed the research progress in theory of water culture, heritage of water culture, propagation of water culture and regional water culture and prospected the research object, research range, research direction and research means of water culture on this basis, in order to promote and deepen it and push excellent traditional culture of the Chinese research forward.
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