Volume 17,Issue 4,2019 Table of Contents
WANG Jianhua
,
HE Guohua
,
HE Fan
,
ZHAO Yong
,
WANG Haiye
,
LI Haihong
,
ZHU Yongnan
,
LIU Hanqing
2019, 17(4):1-8.
Abstract:
The degree of utilization of water and land resources and their matching patterns not only determine the scale of economic development,but also affect regional ecological security.In order to objectively evaluate the spatial matching of the water and land resources in China, data from 346 municipal districts were used in this study to analyze the development conditions of water and land resources in China in 2005,2010 and 2015,respectively,and the Gini coefficient was also used to explore the matching characteristics of water and land resources in different provinces. It was found that the North China Plain,the Hexi Corridor and the western part of the Tarim Basin were the regions having the highest development degree of water resources in China.The Northeast Plain,the North China Plain,the Guanzhong Plain,the Sichuan Basin and the coastal areas of Guangdong were the regions having the highest development degree of land resources. In addition,Gansu,Shaanxi,Inner Mongolia and Tibet were the provinces with the widest gap between water and land resources,among which Gansu,Shaanxi and Inner Mongolia had the widest gap because the water resources could not support the local land resources,while Tibet was due to the land resources being unable to match rich water resources.
The degree of utilization of water and land resources and their matching patterns not only determine the scale of economic development,but also affect regional ecological security.In order to objectively evaluate the spatial matching of the water and land resources in China, data from 346 municipal districts were used in this study to analyze the development conditions of water and land resources in China in 2005,2010 and 2015,respectively,and the Gini coefficient was also used to explore the matching characteristics of water and land resources in different provinces. It was found that the North China Plain,the Hexi Corridor and the western part of the Tarim Basin were the regions having the highest development degree of water resources in China.The Northeast Plain,the North China Plain,the Guanzhong Plain,the Sichuan Basin and the coastal areas of Guangdong were the regions having the highest development degree of land resources. In addition,Gansu,Shaanxi,Inner Mongolia and Tibet were the provinces with the widest gap between water and land resources,among which Gansu,Shaanxi and Inner Mongolia had the widest gap because the water resources could not support the local land resources,while Tibet was due to the land resources being unable to match rich water resources.
CHEN Xin
,
,
LIU Yanli
,
,
DIAO Yanfang
,
WANG Guoqing
,
,
JIN Junliang
,
,
BAO Zhenxin
,
，LIU Cuishan
,
,
HE Ruimin
,
，ZHOU Meina
2019, 17(4):9-18.
Abstract:
In recent years,under the combined influence of climate change and human activities,the runoff in the Haihe River Basin showed a serious decreasing trend.In order to clarify the impact of climate change and human activities on runoff changes in different types of watersheds,Two typical catchments was selected in this study:one was the upper reaches of the Zhanghe River,which was significantly affected by human activities in the Haihe River Basin;the other was the upper reaches of the Luanhe River,which was not significantly affected by human activities.Based on the observed runoff data of nearly 60 years,the applicability of the SWAT model in the typical watersheds of Haihe River was verified.The runoff variation attribution was investigated,and the characteristics of runoff variation and the contribution rate of two influencing factors in two different types of watersheds were analyzed.The differences of runoff variation in the two basins under different driving factors were investigated and compared.The results showed that the runoff in both basins had declined in the past 60 years.The upper reach of the Zhanghe River was dominated by human activities with a contribution rate of 65%.The upper reach of the Luanhe River was dominated by climate change with a contribution rate of 89%.Compared with the upper reaches of the Luanhe River,the runoff in the upper reach of the Zhanghe,which was significantly affected by human activities,was more scattered and its trend was more significant,as well as a more departure in the normal and the dry year.
In recent years,under the combined influence of climate change and human activities,the runoff in the Haihe River Basin showed a serious decreasing trend.In order to clarify the impact of climate change and human activities on runoff changes in different types of watersheds,Two typical catchments was selected in this study:one was the upper reaches of the Zhanghe River,which was significantly affected by human activities in the Haihe River Basin;the other was the upper reaches of the Luanhe River,which was not significantly affected by human activities.Based on the observed runoff data of nearly 60 years,the applicability of the SWAT model in the typical watersheds of Haihe River was verified.The runoff variation attribution was investigated,and the characteristics of runoff variation and the contribution rate of two influencing factors in two different types of watersheds were analyzed.The differences of runoff variation in the two basins under different driving factors were investigated and compared.The results showed that the runoff in both basins had declined in the past 60 years.The upper reach of the Zhanghe River was dominated by human activities with a contribution rate of 65%.The upper reach of the Luanhe River was dominated by climate change with a contribution rate of 89%.Compared with the upper reaches of the Luanhe River,the runoff in the upper reach of the Zhanghe,which was significantly affected by human activities,was more scattered and its trend was more significant,as well as a more departure in the normal and the dry year.
2019, 17(4):19-26.
Abstract:
In order to provide technical support for flood control and drought relief decision-making in the Hongze Lake and the the lower reaches of Huaihe River,a simulation model is needed.The API model and Xin′anjiang model by a unit-block method dividing units for sub-catchments and unit-block for lake-inflow were used in this study.The rainfall runoff and flood hydrograph were produce based on the current situation of hydro-projects and flood retarding areas in the river basin.The mode parameters were calibrated with observation from 2000 to 2018 at sub-catchments of Bengbu,the north and south areas of the Huaihe River basin above Hongze Lake. Lake-inflow which was calculated by water balance method was regarded as the measured inflow into the Hongze Lake.The Muskingum method was used in flood confluence process of sub-catchments,and flood forecasting model into Lake was built.The results showed that the two models performed well for sub-catchments in terms of rainfall runoff simulation,especially for flood events.At rising limb,the prediction results of both models were of high accuracy.At falling limb and a long forecast periods,the prediction accuracy of the Xin′anjiang model was higher than that of the API model,and the simulated flood process was closer to the reversed deduction of lake-inflow.
In order to provide technical support for flood control and drought relief decision-making in the Hongze Lake and the the lower reaches of Huaihe River,a simulation model is needed.The API model and Xin′anjiang model by a unit-block method dividing units for sub-catchments and unit-block for lake-inflow were used in this study.The rainfall runoff and flood hydrograph were produce based on the current situation of hydro-projects and flood retarding areas in the river basin.The mode parameters were calibrated with observation from 2000 to 2018 at sub-catchments of Bengbu,the north and south areas of the Huaihe River basin above Hongze Lake. Lake-inflow which was calculated by water balance method was regarded as the measured inflow into the Hongze Lake.The Muskingum method was used in flood confluence process of sub-catchments,and flood forecasting model into Lake was built.The results showed that the two models performed well for sub-catchments in terms of rainfall runoff simulation,especially for flood events.At rising limb,the prediction results of both models were of high accuracy.At falling limb and a long forecast periods,the prediction accuracy of the Xin′anjiang model was higher than that of the API model,and the simulated flood process was closer to the reversed deduction of lake-inflow.
2019, 17(4):27-36.
Abstract:
In recent years,the accuracy and applicability of TRMM satellite rainfall data have attracted much attention.In this study,we evaluated the TRMM data set over the Feilaixia catchment of the Beijiang river basin from 1998 to 2015 using gauged rainfall data from 24 stations. We first evaluated the accuracy of the TRMM at daily scale by using eight statistical performance indices.Then we used three consecutive extreme indices,including consecutive dry days (CDD),consecutive wet days (CWD),and maximum consecutive 5day precipitation (RX5day), together with Cox-Stuart test method to explore the extreme consecutive climate and its trends in the catchment,with special focus on the ability of TRMM in capturing consecutive extreme rainfall.The results revealed that (1) TRMM had better precision and accuracy in regions with low latitude and low altitude,but in regions with high latitude and large topographic changes,it performed poorly and was prone to false alarms and errors.(2) TRMM tended to underestimate CWD and RX5day (in the post-flood period) and it could capture the consecutive drought trends in the western part of the catchment,but failed to capture the significant increase trends of consecutive rainfall in the southeastern part.The conclusions obtained in this study can provide a scientific basis for water resources management and runoff monitoring within the catchment,and can also be used as reference for catchments with similar latitudes.
In recent years,the accuracy and applicability of TRMM satellite rainfall data have attracted much attention.In this study,we evaluated the TRMM data set over the Feilaixia catchment of the Beijiang river basin from 1998 to 2015 using gauged rainfall data from 24 stations. We first evaluated the accuracy of the TRMM at daily scale by using eight statistical performance indices.Then we used three consecutive extreme indices,including consecutive dry days (CDD),consecutive wet days (CWD),and maximum consecutive 5day precipitation (RX5day), together with Cox-Stuart test method to explore the extreme consecutive climate and its trends in the catchment,with special focus on the ability of TRMM in capturing consecutive extreme rainfall.The results revealed that (1) TRMM had better precision and accuracy in regions with low latitude and low altitude,but in regions with high latitude and large topographic changes,it performed poorly and was prone to false alarms and errors.(2) TRMM tended to underestimate CWD and RX5day (in the post-flood period) and it could capture the consecutive drought trends in the western part of the catchment,but failed to capture the significant increase trends of consecutive rainfall in the southeastern part.The conclusions obtained in this study can provide a scientific basis for water resources management and runoff monitoring within the catchment,and can also be used as reference for catchments with similar latitudes.
2019, 17(4):37-45.
Abstract:
The effects of rainfall spatial inconsistency on urban flood inundation was investigated in this study with a numerical model under the conditions of designed rainstorm and uneven coefficient Cv from different return periods for the Xixian New Area,Shaanxi Province,China.Total volumes of peak waterlogging,volumes of severe peak waterlogging and their reduction rates under uniform rainfall were compared and analyzed.It is found that the waterlogging volumes under uneven spatial distribution decreases in each return periods in comparison with the spatial uniform rainfall..The waterlogging [JP2]reduction magnitudes under uneven rainfall increases as the Cv value increases for every return period.,For example,when the Cv values are 0.07、0.11、0.15 and 0.2,the reduction rates are 2.05%~1.94%,3.00%~3.02%,4.23%~4.08%,4.86%~5.10%,respectively.In the case of severe waterlogging,in comparison with spatial uniform rainfall with same Cv values,the longer the return period,the higher the reduction amount of waterlogging increases.For example,when the Cv value are 0.07,0.11,0.15 and 0.2,the reduction rates are 2.00% to 2.51%,2.60% to 3.82%,3.66% to 4.98%,and 3.80% to 5.83%,respectively.The simulation demonstrates the effects of rainfall spatial inconsistency on urban flood inundation and provides a theoretical basis for urban flood management.
The effects of rainfall spatial inconsistency on urban flood inundation was investigated in this study with a numerical model under the conditions of designed rainstorm and uneven coefficient Cv from different return periods for the Xixian New Area,Shaanxi Province,China.Total volumes of peak waterlogging,volumes of severe peak waterlogging and their reduction rates under uniform rainfall were compared and analyzed.It is found that the waterlogging volumes under uneven spatial distribution decreases in each return periods in comparison with the spatial uniform rainfall..The waterlogging [JP2]reduction magnitudes under uneven rainfall increases as the Cv value increases for every return period.,For example,when the Cv values are 0.07、0.11、0.15 and 0.2,the reduction rates are 2.05%~1.94%,3.00%~3.02%,4.23%~4.08%,4.86%~5.10%,respectively.In the case of severe waterlogging,in comparison with spatial uniform rainfall with same Cv values,the longer the return period,the higher the reduction amount of waterlogging increases.For example,when the Cv value are 0.07,0.11,0.15 and 0.2,the reduction rates are 2.00% to 2.51%,2.60% to 3.82%,3.66% to 4.98%,and 3.80% to 5.83%,respectively.The simulation demonstrates the effects of rainfall spatial inconsistency on urban flood inundation and provides a theoretical basis for urban flood management.
CHEN Hongxin
,
JIANG Shanhu
,
LI Guofang
,
LI Qing
,
LIU Changjun
,
ZHANG Xiaoxiang
,
REN Liliang
2019, 17(4):46-53.
Abstract:
This study proposes a formula for computing composite warning index according to critical rainfall based on the critical rainfall data of flash flood disaster prevention and control sections obtained from national flash flood disaster investigation and evaluation.According to principles of basin runoff yield and concentration,this formula takes into full consideration the different effects of antecedent influence rainfall(Pa),critical rainfall(P),and early warning period(H) on composite warning index.In addition, this paper takes Wuyuan County in Jiangxi Province as a case study of the feasibility and application of this formula and proposes a complete warning plan for flash flood disasters.The results show that the average range of the composite warning index threshold in Wuyuan County is 5.4,and the average dispersion coefficient is 0.029.It is feasible to derive the composite warning index from the critical rainfall.The early warning plan is as follows:first,substitute the antecedent influence rainfall at the start of rainfall,the measured or forecast rainfall and its duration into the formula to obtain the real-time composite warning index value;then compare it with the cross-section composite warning index threshold.If it reaches or exceeds the warning threshold,then issue the flash flood warning;if not,repeat the steps according to the subsequent rainfall situation.This method makes full use of the existing information before the event and can calculate the warning value at any time.So it can be a new effective method for flash flood disaster warning.
This study proposes a formula for computing composite warning index according to critical rainfall based on the critical rainfall data of flash flood disaster prevention and control sections obtained from national flash flood disaster investigation and evaluation.According to principles of basin runoff yield and concentration,this formula takes into full consideration the different effects of antecedent influence rainfall(Pa),critical rainfall(P),and early warning period(H) on composite warning index.In addition, this paper takes Wuyuan County in Jiangxi Province as a case study of the feasibility and application of this formula and proposes a complete warning plan for flash flood disasters.The results show that the average range of the composite warning index threshold in Wuyuan County is 5.4,and the average dispersion coefficient is 0.029.It is feasible to derive the composite warning index from the critical rainfall.The early warning plan is as follows:first,substitute the antecedent influence rainfall at the start of rainfall,the measured or forecast rainfall and its duration into the formula to obtain the real-time composite warning index value;then compare it with the cross-section composite warning index threshold.If it reaches or exceeds the warning threshold,then issue the flash flood warning;if not,repeat the steps according to the subsequent rainfall situation.This method makes full use of the existing information before the event and can calculate the warning value at any time.So it can be a new effective method for flash flood disaster warning.
2019, 17(4):54-62.
Abstract:
The establishment of Xiong′an New Area in Hebei Province has attracted wide attentions from the whole scientific community.The Daqing River Basin,where the New Area is located,becomes a new focus for hydrological scientists.Particularly,the changing characteristics and causes of its water resources were of great importance to understanding the water resources situation of Xiong′an New Area.The relative influences of human activities and climate change on the runoff processes in the upper reaches of Daqing River Basin have been investigated with SWAT model.Elasticity method was also applied to compare the simulation results about the relative contributions of human activities and climate change to the runoff variations.Results showed that the runoff showed a generally decreasing trend from 1981 to 2015,with magnitudes of -0.10 m3/(s·a） and -0.07 m3/(s·a） at Daomaguan and Zijingguan stations,respectively.Human activities served as the leading factor,which contributed to 53.4% to 60.8% of the runoff variation,while climate change and variability contributed 39.2% to 46.6%.The research results are useful to understand the hydrological fluctuations in the upper reaches of the Daqing River,and can also be used as a reference for the future [JP]planning and management of regional water resources for the construction of Xiong′an New Area.
The establishment of Xiong′an New Area in Hebei Province has attracted wide attentions from the whole scientific community.The Daqing River Basin,where the New Area is located,becomes a new focus for hydrological scientists.Particularly,the changing characteristics and causes of its water resources were of great importance to understanding the water resources situation of Xiong′an New Area.The relative influences of human activities and climate change on the runoff processes in the upper reaches of Daqing River Basin have been investigated with SWAT model.Elasticity method was also applied to compare the simulation results about the relative contributions of human activities and climate change to the runoff variations.Results showed that the runoff showed a generally decreasing trend from 1981 to 2015,with magnitudes of -0.10 m3/(s·a） and -0.07 m3/(s·a） at Daomaguan and Zijingguan stations,respectively.Human activities served as the leading factor,which contributed to 53.4% to 60.8% of the runoff variation,while climate change and variability contributed 39.2% to 46.6%.The research results are useful to understand the hydrological fluctuations in the upper reaches of the Daqing River,and can also be used as a reference for the future [JP]planning and management of regional water resources for the construction of Xiong′an New Area.
MO Chongxun
,
,
LIU Peng
,
,
ZHU Xinrong
,
,
RUAN Yuli
,
,
YANG Yunchuan
,
,
SUN Guikai
,
2019, 17(4):63-70.
Abstract:
Eight intraannual indexes of runoff,including non-uniform adjustment coefficient and concentration ratio,were calculated for Bashou and Pingtang stations during 1963-2014 in the Chengbi River Basin.,The trend of annual runoff was detected with linear regression,Mann-Kendall trend test and R/S analysis.The results show that the intraannual runoff distribution is highly uneven in the past 52 years and varies with time in the Chengbi River Basin.The inhomogeneity of runoff distribution is increasing,and all other indices decrease.The concentration period is mainly in July,and Lorenz asymmetry coefficient shows that the main cause of uneven annual runoff distribution is the months with larger runoff.The Hurst values of eight indices are all greater than 0.5,which can be used to predict the annual distribution of runoff in the Chengbi River Basin.A positive continuity is consistent with the overall trend of the past.The intraannual distribution of runoff became lower and lower as time goes,which gradually transform from non-uniformity to homogeneity processes in the Chengbi River Basin.
Eight intraannual indexes of runoff,including non-uniform adjustment coefficient and concentration ratio,were calculated for Bashou and Pingtang stations during 1963-2014 in the Chengbi River Basin.,The trend of annual runoff was detected with linear regression,Mann-Kendall trend test and R/S analysis.The results show that the intraannual runoff distribution is highly uneven in the past 52 years and varies with time in the Chengbi River Basin.The inhomogeneity of runoff distribution is increasing,and all other indices decrease.The concentration period is mainly in July,and Lorenz asymmetry coefficient shows that the main cause of uneven annual runoff distribution is the months with larger runoff.The Hurst values of eight indices are all greater than 0.5,which can be used to predict the annual distribution of runoff in the Chengbi River Basin.A positive continuity is consistent with the overall trend of the past.The intraannual distribution of runoff became lower and lower as time goes,which gradually transform from non-uniformity to homogeneity processes in the Chengbi River Basin.
2019, 17(4):71-78.
Abstract:
The temporal characteristics of intraannual and interannual precipitation and runoff in the Biliu River reservoir basin were investigated in this study based on daily data from 1958 to 2011.The Gini coefficient method,R/S analysis method and wavelet method were used to explore the intraannual variation.Interannual variation and trend,and periodicity of precipitation and runoff.The results showed that the intraannual distributions of precipitation and runoff in the basin were extremely uneven with a unimodal type.The peak values of monthly precipitation moved backwards after the 1980s.Both annual precipitation and runoff had decreased, and the trend of runoff was more significant than that of precipitation,which implied that runoff was also affected by other factors besides precipitation,such as human activities.Both precipitation and runoff sequences exhibited a cycle of abundance and drought change,and the main cycle was 12-16 years,which might be explained by sunspot cycle activity.The oscillation of runoff cycle was weaker than that of precipitation cycle after 1980s,which indicated that other factors also effected runoff generation besides precipitation.
The temporal characteristics of intraannual and interannual precipitation and runoff in the Biliu River reservoir basin were investigated in this study based on daily data from 1958 to 2011.The Gini coefficient method,R/S analysis method and wavelet method were used to explore the intraannual variation.Interannual variation and trend,and periodicity of precipitation and runoff.The results showed that the intraannual distributions of precipitation and runoff in the basin were extremely uneven with a unimodal type.The peak values of monthly precipitation moved backwards after the 1980s.Both annual precipitation and runoff had decreased, and the trend of runoff was more significant than that of precipitation,which implied that runoff was also affected by other factors besides precipitation,such as human activities.Both precipitation and runoff sequences exhibited a cycle of abundance and drought change,and the main cycle was 12-16 years,which might be explained by sunspot cycle activity.The oscillation of runoff cycle was weaker than that of precipitation cycle after 1980s,which indicated that other factors also effected runoff generation besides precipitation.
2019, 17(4):79-86.
Abstract:
The Global Precipitation Measurement (GPM) with high spatial and temporal resolution,the new generation of global satellite precipitation products after Tropical Rainfall Measuring Mission (TRMM),provides strong data support for global climate change studies, and flood and drought monitoring.The applicability of GPM IMERG product was evaluated in this study using statistical metrics including correlation coefficient (CC),relative error (BIAS) and root mean square error (RMSE),based on the daily precipitation from 59 meteorological stations in the Huang-Huai-Hai Plain for the period of March 2015 to February [JP]2016.The results showed that:（1) GPM IMERG precipitation agreed well with observations at daily scale (CC=0.95).However it overestimated precipitation by 17.90%;（2) At monthly scale,RMSE was the highest from June to August and CC for nine months was greater than 0.80;（3)At seasonal scale,CC was less than 0.90 in autumn and RMSE was the largest in summer:（4) GPM IMERG can simulate the spatial pattern of precipitation decreasing from south to north in the Huang-Huai-Hai Plain;（5) It was also found that the trends from GPM IMERG and observations were consistent.In summary,GPM IMERG satellite precipitation presented a good correlation with the observations at meteorological stations, although there is an overestimation.
The Global Precipitation Measurement (GPM) with high spatial and temporal resolution,the new generation of global satellite precipitation products after Tropical Rainfall Measuring Mission (TRMM),provides strong data support for global climate change studies, and flood and drought monitoring.The applicability of GPM IMERG product was evaluated in this study using statistical metrics including correlation coefficient (CC),relative error (BIAS) and root mean square error (RMSE),based on the daily precipitation from 59 meteorological stations in the Huang-Huai-Hai Plain for the period of March 2015 to February [JP]2016.The results showed that:（1) GPM IMERG precipitation agreed well with observations at daily scale (CC=0.95).However it overestimated precipitation by 17.90%;（2) At monthly scale,RMSE was the highest from June to August and CC for nine months was greater than 0.80;（3)At seasonal scale,CC was less than 0.90 in autumn and RMSE was the largest in summer:（4) GPM IMERG can simulate the spatial pattern of precipitation decreasing from south to north in the Huang-Huai-Hai Plain;（5) It was also found that the trends from GPM IMERG and observations were consistent.In summary,GPM IMERG satellite precipitation presented a good correlation with the observations at meteorological stations, although there is an overestimation.
2019, 17(4):87-93.
Abstract:
Water resources security is a complex system composing of natural and social factors,with complex and fuzzy features.In this paper,a network hierarchy division and a weight calculation have been proposed for the main control factors of the water resource safety assessment on the basis of Analytic Network Process (ANP),comprehensively considering four aspects of water resource security,namely,water supply security,social security,economic security,and ecological environment security.In addition,a comprehensive evaluation model of water resources security was established by combining Grey Relation Analysis (GRA).The water resource security of Guizhou province from 2008 to 2015 was then evaluated with this model.The results showed that its security was overall in a relatively stable state,which was between safer and near safe condition,and the safety grade steadily ws on the rising.This result was coincided with the reality,which indicated that the comprehensive evaluation model with the applications of GRA-ANP was reasonable and effective.The evaluation method and results thus can provide a reference for regional assessment of water resources security and the development and utilization of water resources.
Water resources security is a complex system composing of natural and social factors,with complex and fuzzy features.In this paper,a network hierarchy division and a weight calculation have been proposed for the main control factors of the water resource safety assessment on the basis of Analytic Network Process (ANP),comprehensively considering four aspects of water resource security,namely,water supply security,social security,economic security,and ecological environment security.In addition,a comprehensive evaluation model of water resources security was established by combining Grey Relation Analysis (GRA).The water resource security of Guizhou province from 2008 to 2015 was then evaluated with this model.The results showed that its security was overall in a relatively stable state,which was between safer and near safe condition,and the safety grade steadily ws on the rising.This result was coincided with the reality,which indicated that the comprehensive evaluation model with the applications of GRA-ANP was reasonable and effective.The evaluation method and results thus can provide a reference for regional assessment of water resources security and the development and utilization of water resources.
2019, 17(4):94-103.
Abstract:
The idea of "summarizing while researching and demonstrating" is adopted for the current water right reform and the progress of the comprehensive pilot project of groundwater overexploitation in Hebei Province.The methodology of water rights confirmation in Hebei is explored from three aspects:the distribution method,the key problems and the affirmation steps of water right.An universal method of confirming water rights in Hebei is proposed.The practical use of water right confirmation in Hebei,is also investigated and its significance is summarized.The results can provide technical supports for water rights reform in Hebei Province,as well as offer useful experience for the construction of water right system in the North China and even in the whole country.
The idea of "summarizing while researching and demonstrating" is adopted for the current water right reform and the progress of the comprehensive pilot project of groundwater overexploitation in Hebei Province.The methodology of water rights confirmation in Hebei is explored from three aspects:the distribution method,the key problems and the affirmation steps of water right.An universal method of confirming water rights in Hebei is proposed.The practical use of water right confirmation in Hebei,is also investigated and its significance is summarized.The results can provide technical supports for water rights reform in Hebei Province,as well as offer useful experience for the construction of water right system in the North China and even in the whole country.
13 Causes of excessive use of chemical fertilizer and its impacts on China′s water environment security
2019, 17(4):104-114.
Abstract:
China is the largest consumer of chemical fertilizer in the world,with high application intensity and low utilization efficiency.In this study,we analyzed the data of China′s chemical fertilizer consumption amount and application intensity,and compared them with the situation of major developed countries.The results are as follows:In the recent 30 years, the amount of agricultural fertilizer applied in China increased by 3.4 times,and the application intensity of nitrogen and phosphorus fertilizer was 3-5 times of that in developed countries,but the utilization efficiency of chemical fertilizer was less than 50% of that in developed countries.The overuse of chemical fertilizer has caused water environment problems such as eutrophication of surface water and nitrate contamination of groundwater.The excessive use of chemical fertilizer has led to non-point source pollution.Its main causes are the over reliance of agricultural production on chemical fertilizer and the lack of legal constraints on non-point source pollution.We recommend that the excessive application of chemical fertilizer be controlled by the establishment of a system that encompasses subsides on environmental quality and national agricultural support and protection and linking of land contracting rights to management rights.Public participation should be encouraged to promote consumption upgrading,so that market demands will force agricultural producers to adopt environmental measures and reduce agricultural non-point source pollution;thus,coordinated development of food security and water environment security will be achieved.
China is the largest consumer of chemical fertilizer in the world,with high application intensity and low utilization efficiency.In this study,we analyzed the data of China′s chemical fertilizer consumption amount and application intensity,and compared them with the situation of major developed countries.The results are as follows:In the recent 30 years, the amount of agricultural fertilizer applied in China increased by 3.4 times,and the application intensity of nitrogen and phosphorus fertilizer was 3-5 times of that in developed countries,but the utilization efficiency of chemical fertilizer was less than 50% of that in developed countries.The overuse of chemical fertilizer has caused water environment problems such as eutrophication of surface water and nitrate contamination of groundwater.The excessive use of chemical fertilizer has led to non-point source pollution.Its main causes are the over reliance of agricultural production on chemical fertilizer and the lack of legal constraints on non-point source pollution.We recommend that the excessive application of chemical fertilizer be controlled by the establishment of a system that encompasses subsides on environmental quality and national agricultural support and protection and linking of land contracting rights to management rights.Public participation should be encouraged to promote consumption upgrading,so that market demands will force agricultural producers to adopt environmental measures and reduce agricultural non-point source pollution;thus,coordinated development of food security and water environment security will be achieved.
14 Ecological water requirement for natural grassland vegetation in the Sunan Yugur Autonomous County
2019, 17(4):115-122.
Abstract:
Estimation of ecological water requirement for natural grassland can provide reference for regional grassland ecological construction planning and water resources allocation,in order to solve the regional water shortage problems.The methods of estimating ecological water requirement for non-pristine and non-full coverage natural vegetation were proposed by FAO.The Sunan Yugu Autonomous County in the typical western pastoral areas was chosen as a case study in this paper.The reference crop evapotranspiration of vegetation in the regional and its trend in the crop growing season from March to October were computed.The characteristics of the relationship between effective precipitation and ecological water requirement quota for different grassland types were also investigated.It is found that the Sunan County had a shortage of ecological water requirement at all different hydrological years,while comparing demands and supply.The situation is more serious in the Minghua,implying its fragile ecological environment.The regional development planning should be adjusted to ensure the harmony and stability of grassland ecosystems.
Estimation of ecological water requirement for natural grassland can provide reference for regional grassland ecological construction planning and water resources allocation,in order to solve the regional water shortage problems.The methods of estimating ecological water requirement for non-pristine and non-full coverage natural vegetation were proposed by FAO.The Sunan Yugu Autonomous County in the typical western pastoral areas was chosen as a case study in this paper.The reference crop evapotranspiration of vegetation in the regional and its trend in the crop growing season from March to October were computed.The characteristics of the relationship between effective precipitation and ecological water requirement quota for different grassland types were also investigated.It is found that the Sunan County had a shortage of ecological water requirement at all different hydrological years,while comparing demands and supply.The situation is more serious in the Minghua,implying its fragile ecological environment.The regional development planning should be adjusted to ensure the harmony and stability of grassland ecosystems.
2019, 17(4):123-128.
Abstract:
Addressing the algal proliferation risk in the Middle Route of the South-to-North Water Transfer Project,the trend of the accumulation of nutrients is estimated for the entire Middle Route by applying the Vollenweider model and assuming nitrogen and phosphorus nutrients and the atmospheric deposition of algae spores as the source of sinking and averaging nitrogen deposition in Henan,Shandong and Beijing-Tianjin-Hebei regions and phosphorus deposition of the whole country.The results show that the cumulative concentration of nutrients in the canal exceeds the eutrophication threshold at Sanlitun monitoring point and beyond.Taking into account the effects of algae spore settlement in the atmosphere,the [JP]reported spatial distribution of algae is fitted by coupling with the Monod model.In the main canal of the Middle Route,algae grow at the rate of 0.21/d~0.46/d,with the relative median error of 23.71%.Based on the results achieved,a monitoring scheme is proposed to improve the accuracy of algal bloom forecasting.
Addressing the algal proliferation risk in the Middle Route of the South-to-North Water Transfer Project,the trend of the accumulation of nutrients is estimated for the entire Middle Route by applying the Vollenweider model and assuming nitrogen and phosphorus nutrients and the atmospheric deposition of algae spores as the source of sinking and averaging nitrogen deposition in Henan,Shandong and Beijing-Tianjin-Hebei regions and phosphorus deposition of the whole country.The results show that the cumulative concentration of nutrients in the canal exceeds the eutrophication threshold at Sanlitun monitoring point and beyond.Taking into account the effects of algae spore settlement in the atmosphere,the [JP]reported spatial distribution of algae is fitted by coupling with the Monod model.In the main canal of the Middle Route,algae grow at the rate of 0.21/d~0.46/d,with the relative median error of 23.71%.Based on the results achieved,a monitoring scheme is proposed to improve the accuracy of algal bloom forecasting.
2019, 17(4):129-137.
Abstract:
With great and practical significance to green agricultural development and clean production,accurate evaluation of groundwater environmental quality may reduce the risk,caused by water quality uncertainty,in decisionmaking for agricultural water management.As ELM may randomly generate the connection weight and hidden layer threshold of input layer and hidden layer,resulting in decrease in network generalization ability and evaluation distortion caused by over-fitting,a comprehensive evaluation model of groundwater quality is developed based on PSO-ELM.In the case study area,Jiansanjiang in Heilongjiang Province,by field sampling of groundwater in the typical irrigation wells,the PSO-ELM model is applied for comprehensive evaluation of groundwater quality.The results show that the PSO-ELM model presents higher goodness of fit than the traditional ELM model and RBF model,thus improving the simulation evaluation of regional groundwater quality.Covering 15 farms,Jansanjiang area has good groundwater quality in general.The groundwater quality grades in the study area are characterized by concentrated areal distribution,as observing the farms with poorer groundwater quality located in the middle-east part and those with better groundwater quality located in the east and west parts.The pattern of regional distribution of groundwater quality in Jiansanjiang area is mainly related to fertilizer application.While ensuring food and water securities,managing fertilizer application should be considered and new measures adopted for high crop yield.
With great and practical significance to green agricultural development and clean production,accurate evaluation of groundwater environmental quality may reduce the risk,caused by water quality uncertainty,in decisionmaking for agricultural water management.As ELM may randomly generate the connection weight and hidden layer threshold of input layer and hidden layer,resulting in decrease in network generalization ability and evaluation distortion caused by over-fitting,a comprehensive evaluation model of groundwater quality is developed based on PSO-ELM.In the case study area,Jiansanjiang in Heilongjiang Province,by field sampling of groundwater in the typical irrigation wells,the PSO-ELM model is applied for comprehensive evaluation of groundwater quality.The results show that the PSO-ELM model presents higher goodness of fit than the traditional ELM model and RBF model,thus improving the simulation evaluation of regional groundwater quality.Covering 15 farms,Jansanjiang area has good groundwater quality in general.The groundwater quality grades in the study area are characterized by concentrated areal distribution,as observing the farms with poorer groundwater quality located in the middle-east part and those with better groundwater quality located in the east and west parts.The pattern of regional distribution of groundwater quality in Jiansanjiang area is mainly related to fertilizer application.While ensuring food and water securities,managing fertilizer application should be considered and new measures adopted for high crop yield.
2019, 17(4):138-148.
Abstract:
Vegetation plays an important role in regulating hydrological processes and maintaining ecological balance in the basin.It is of great significance to analyze vegetation changes and their driving factors in the upper reaches of the Han River.This paper uses NDVI data of MODIS/Terra and Land Cover remote sensing data to analyze NDVI changes of different land use types in the upper reaches of the Han River,and combines meteorological data and DMSP light data to analyze the impacts of climate change and human activities on vegetation NDVI,in order to find out the dominant driving factors of vegetation index changes. The results show that,the NDVI in the upper reaches of the Han River increased from 2001 to 2017,averaging between 0.5 and 0.62.The inter-annual NDVI variation of the same land use type was not significant.The NDVI change trends of different land use types were basically the same.The vegetation types sorted by NDVI from high to low are deciduous broad-leaved forest,mixed forest,grassland,agricultural land,dense shrub,and evergreen coniferous forest.The monthly average maximum temperature is the dominant factor affecting the monthly NDVI change.The summer NDVI change has a strong correlation with the sunshine hours and precipitation,and the winter NDVI change has a high correlation with temperature.The correlation coefficients of temperature and precipitation with annual NDVI change are higher than that of the average light intensity change.On the annual scale,meteorological factors have more influence than human activities on vegetation changes.
Vegetation plays an important role in regulating hydrological processes and maintaining ecological balance in the basin.It is of great significance to analyze vegetation changes and their driving factors in the upper reaches of the Han River.This paper uses NDVI data of MODIS/Terra and Land Cover remote sensing data to analyze NDVI changes of different land use types in the upper reaches of the Han River,and combines meteorological data and DMSP light data to analyze the impacts of climate change and human activities on vegetation NDVI,in order to find out the dominant driving factors of vegetation index changes. The results show that,the NDVI in the upper reaches of the Han River increased from 2001 to 2017,averaging between 0.5 and 0.62.The inter-annual NDVI variation of the same land use type was not significant.The NDVI change trends of different land use types were basically the same.The vegetation types sorted by NDVI from high to low are deciduous broad-leaved forest,mixed forest,grassland,agricultural land,dense shrub,and evergreen coniferous forest.The monthly average maximum temperature is the dominant factor affecting the monthly NDVI change.The summer NDVI change has a strong correlation with the sunshine hours and precipitation,and the winter NDVI change has a high correlation with temperature.The correlation coefficients of temperature and precipitation with annual NDVI change are higher than that of the average light intensity change.On the annual scale,meteorological factors have more influence than human activities on vegetation changes.
2019, 17(4):149-155.
Abstract:
The precipitates in the dam corridor were mostly products of the interaction of groundwater with solid-phase media such as bedrock and concrete.The formation and evolution of the precipitates may have adverse effects on the safe operation of the dam.Before the reinforcement of Shimantan Reservoir,there were varieties of precipitates distributed in the corridor.In order to find out their material composition and analyze their source,we sampled and analyzed the precipitates and their nearby leakage water.X-ray diffraction and fluorescence spectroscopy were used to determine the mineral and chemical composition of the precipitates.Hydrochemical diagram and model calculation were used to study the chemical composition evolution of the leakage water.The results showed that the most widely distributed white precipitate had CaO and loss on ignition as its main chemical components,and calcite as its mineral component.It came from the dissolution and reprecipitation of cement stones in the dam body.Some black precipitates were mainly composed of MnO,and they originated from manganese cement in bedrock.The analysis results together with observation data such as uplift pressure can provide a scientific basis for the seepage reinforcement of the dam.
The precipitates in the dam corridor were mostly products of the interaction of groundwater with solid-phase media such as bedrock and concrete.The formation and evolution of the precipitates may have adverse effects on the safe operation of the dam.Before the reinforcement of Shimantan Reservoir,there were varieties of precipitates distributed in the corridor.In order to find out their material composition and analyze their source,we sampled and analyzed the precipitates and their nearby leakage water.X-ray diffraction and fluorescence spectroscopy were used to determine the mineral and chemical composition of the precipitates.Hydrochemical diagram and model calculation were used to study the chemical composition evolution of the leakage water.The results showed that the most widely distributed white precipitate had CaO and loss on ignition as its main chemical components,and calcite as its mineral component.It came from the dissolution and reprecipitation of cement stones in the dam body.Some black precipitates were mainly composed of MnO,and they originated from manganese cement in bedrock.The analysis results together with observation data such as uplift pressure can provide a scientific basis for the seepage reinforcement of the dam.
2019, 17(4):156-164.
Abstract:
The impacts of sunshine on thermal distribution of box-type aqueducts in high-altitude areas provide guidance for the design and construction of box-type aqueduct structures.The ANSYS is used in this study for a high-altitude box-type aqueduct,based on the heat conduction theory and the temperature boundary conditions of hydraulic aqueducts.The simulations of thermal distributions of the solar radiation show that the temperature of each wall is higher outside and lower inside with a quadratic distribution.The temperature stress of the wall is under expansion for the inner surface and under compression for the outer surface.The vertical maximum tensile stress appears on the inside of the top plate and the inside of the web.The maximum temperature compressive stress appears on the outside of the top plate and the web.The temperature stress on both inner and outer surfaces of each wall increases firstly and then decreases.Therefore,installation of temperature steel bars,lateral pre-stressing or surface heat insulation measures should be provided to improve the stress state of the aqueduct under the action of sunlight,and to make sure the safe operation of the structure,in the design and construction of the box aqueduct structure.
The impacts of sunshine on thermal distribution of box-type aqueducts in high-altitude areas provide guidance for the design and construction of box-type aqueduct structures.The ANSYS is used in this study for a high-altitude box-type aqueduct,based on the heat conduction theory and the temperature boundary conditions of hydraulic aqueducts.The simulations of thermal distributions of the solar radiation show that the temperature of each wall is higher outside and lower inside with a quadratic distribution.The temperature stress of the wall is under expansion for the inner surface and under compression for the outer surface.The vertical maximum tensile stress appears on the inside of the top plate and the inside of the web.The maximum temperature compressive stress appears on the outside of the top plate and the web.The temperature stress on both inner and outer surfaces of each wall increases firstly and then decreases.Therefore,installation of temperature steel bars,lateral pre-stressing or surface heat insulation measures should be provided to improve the stress state of the aqueduct under the action of sunlight,and to make sure the safe operation of the structure,in the design and construction of the box aqueduct structure.
2019, 17(4):165-171.
Abstract:
The dam of Chaiping Hydropower Station is located close to the riverbed curve and has relatively poor geological conditions.The energy dissipation mode for the dam is surface flow energy dissipation,which complicates the discharge flow state of the hydropower station.The downstream riverbed suffers from violent erosion.Therefore,it is necessary to carry out overall hydraulic model test of the hydropower station to prove that the hydropower station design can meet the engineering operation requirements.This study found that the main stream of the discharge flow from the spillway dam is biased to the right bank,and has seriously eroded the riverbed on the right bank downstream the hydropower station.This affects the stability of the dam and the safe operation of the project.It is necessary to optimize the shape of the hydropower station.In this study,we increased the angle of the right guide wall of the hydropower station,extended the left pier of the left side of the spillway dam,and removed the left guide wall of the overflow dam,so as to force the main stream of the discharge flow to the middle of the channel.The optimization scheme can abate the erosion of the downstream riverbed,reduce the impact of riverbed erosion on the overall stability of the dam,meet the operational requirements of the hydropower project,and provide design reference for similar projects.
The dam of Chaiping Hydropower Station is located close to the riverbed curve and has relatively poor geological conditions.The energy dissipation mode for the dam is surface flow energy dissipation,which complicates the discharge flow state of the hydropower station.The downstream riverbed suffers from violent erosion.Therefore,it is necessary to carry out overall hydraulic model test of the hydropower station to prove that the hydropower station design can meet the engineering operation requirements.This study found that the main stream of the discharge flow from the spillway dam is biased to the right bank,and has seriously eroded the riverbed on the right bank downstream the hydropower station.This affects the stability of the dam and the safe operation of the project.It is necessary to optimize the shape of the hydropower station.In this study,we increased the angle of the right guide wall of the hydropower station,extended the left pier of the left side of the spillway dam,and removed the left guide wall of the overflow dam,so as to force the main stream of the discharge flow to the middle of the channel.The optimization scheme can abate the erosion of the downstream riverbed,reduce the impact of riverbed erosion on the overall stability of the dam,meet the operational requirements of the hydropower project,and provide design reference for similar projects.
2019, 17(4):172-177.
Abstract:
The conventional laboratory triaxial tests are carried out to study strength and deformation characteristics of cement-modified expansive soil by taking medium/weak expansive soil in Simashan as object of the study and cement as modified material.The results show that the plastic limit of expansive soil can be increased and the plastic limit index and free expansion rate can be reduced by cement modification.The triaxial stressstrain curve of cement-modified expansive soil presents three segments of elasticity,non-linear strengthening and stress softening.With the increase in confining pressure,the softening type gradually develops to hardening type.Both peak strength and residual strength increase with the increase in confining pressure.The specimens are in shear failure mode,and the shear failure angle conforms to the calculated value of MohrCoulomb theory.
The conventional laboratory triaxial tests are carried out to study strength and deformation characteristics of cement-modified expansive soil by taking medium/weak expansive soil in Simashan as object of the study and cement as modified material.The results show that the plastic limit of expansive soil can be increased and the plastic limit index and free expansion rate can be reduced by cement modification.The triaxial stressstrain curve of cement-modified expansive soil presents three segments of elasticity,non-linear strengthening and stress softening.With the increase in confining pressure,the softening type gradually develops to hardening type.Both peak strength and residual strength increase with the increase in confining pressure.The specimens are in shear failure mode,and the shear failure angle conforms to the calculated value of MohrCoulomb theory.
2019, 17(4):178-184.
Abstract:
Agricultural water-saving zoning is the premise of regional agricultural planning.In view of the shortage of water resources in Hebei Province,rational agricultural water-saving zoning is an effective means to improve the efficiency of irrigation water use and agricultural production.In this paper,we selected eight indexes including irrigation water demand index,farmland productivity potential,net primary productivity of crops,soil type,utilization of groundwater,topography,population,and GDP,and we built a water-saving zoning model of Hebei Province through the spatial analysis function of ArcGIS and principal component analysis.According to the model,149 counties/districts in Hebei Province are classified into 3 types:urgent,important,and deferred areas for agricultural wate-saving.According to the characteristics of each region type,we pointed out their existing problems and put forward suggestions for future development.
Agricultural water-saving zoning is the premise of regional agricultural planning.In view of the shortage of water resources in Hebei Province,rational agricultural water-saving zoning is an effective means to improve the efficiency of irrigation water use and agricultural production.In this paper,we selected eight indexes including irrigation water demand index,farmland productivity potential,net primary productivity of crops,soil type,utilization of groundwater,topography,population,and GDP,and we built a water-saving zoning model of Hebei Province through the spatial analysis function of ArcGIS and principal component analysis.According to the model,149 counties/districts in Hebei Province are classified into 3 types:urgent,important,and deferred areas for agricultural wate-saving.According to the characteristics of each region type,we pointed out their existing problems and put forward suggestions for future development.
2019, 17(4):185-192.
Abstract:
In order to study the performance of the full-flow pump (motor-pump),we used the CFD software to simulate the three-dimensional flow of the motor-pump model system,and analyzed the internal flow state and overall performance of the motor-pump.The results showed that in all working conditions,the front guide vane inlet flow rate uniformity of the motor-pump is above 97%,and the uniformity of the impeller inlet flow rate is above 91%.The uniformity is enough to ensure pump performance.The hydraulic loss of the inlet flare tube and the front guide vane is low,while that of the back guide vane and the outlet flare tube is relatively high.The outlet velocity of the outlet flare tube is unevenly distributed with a poor flow state.The maximum efficiency of the system is 69.47%,and the head is 4.855 m when the flow rate is 290 L/s.In all working conditions,the head of the motor-pump system is smaller than the head of the contrasting axial-flow pump system,and the former′s efficiency is lower than the latter′s.The shaft power consumed by the motor-pump system is more than that consumed by the contrasting axial-flow pump system.The motor-pump has short pipelines,large outlet flow velocity,insufficient diffusion,and large hydraulic loss.These are the main reasons why the motor-pump system has low efficiency.
In order to study the performance of the full-flow pump (motor-pump),we used the CFD software to simulate the three-dimensional flow of the motor-pump model system,and analyzed the internal flow state and overall performance of the motor-pump.The results showed that in all working conditions,the front guide vane inlet flow rate uniformity of the motor-pump is above 97%,and the uniformity of the impeller inlet flow rate is above 91%.The uniformity is enough to ensure pump performance.The hydraulic loss of the inlet flare tube and the front guide vane is low,while that of the back guide vane and the outlet flare tube is relatively high.The outlet velocity of the outlet flare tube is unevenly distributed with a poor flow state.The maximum efficiency of the system is 69.47%,and the head is 4.855 m when the flow rate is 290 L/s.In all working conditions,the head of the motor-pump system is smaller than the head of the contrasting axial-flow pump system,and the former′s efficiency is lower than the latter′s.The shaft power consumed by the motor-pump system is more than that consumed by the contrasting axial-flow pump system.The motor-pump has short pipelines,large outlet flow velocity,insufficient diffusion,and large hydraulic loss.These are the main reasons why the motor-pump system has low efficiency.
2019, 17(4):193-201.
Abstract:
In order to explore the water and sediment processes at the Shizuishan hydrologic station in the Yellow River and to provide information for the Haibowan reservoir management,nonlinear statistical techniques were used to investigate the water and sediment changes from 1951 to 2016.The results showed that the temporal distributions of water and sediment at the Shizuishan station was uneven,and the changes during the 1960s were larger.Both annual runoff and annual sediment discharges showed statistically significant decreasing trends,which had a positive continuity and lasted for about 8 and 10 years.The step-changes of streamflow and sediment discharge occurred in 1986 and 1968,respectively,and the main reason for these changes was the coustruction of large reservoirs in the upper reaches of the Yellow River.Both reservoirs had significant impacts on streamflow and sediment discharge,and the streamflow discharge was always below 2 000m3/s after the operations of these two reservoirs.The intraannual and interannual distributions of streamflow and sediment discharges were also tended to be even.The relationship between water and sediment was re-adjusted in different periods,although its adjustment magnitude was minor.The average annual sediment concentration and average incoming sediment coefficient were significantly lower after the operation of Liujiaxia reservoir,but remained almost the same after the operations of Long and Liu reservoirs.
In order to explore the water and sediment processes at the Shizuishan hydrologic station in the Yellow River and to provide information for the Haibowan reservoir management,nonlinear statistical techniques were used to investigate the water and sediment changes from 1951 to 2016.The results showed that the temporal distributions of water and sediment at the Shizuishan station was uneven,and the changes during the 1960s were larger.Both annual runoff and annual sediment discharges showed statistically significant decreasing trends,which had a positive continuity and lasted for about 8 and 10 years.The step-changes of streamflow and sediment discharge occurred in 1986 and 1968,respectively,and the main reason for these changes was the coustruction of large reservoirs in the upper reaches of the Yellow River.Both reservoirs had significant impacts on streamflow and sediment discharge,and the streamflow discharge was always below 2 000m3/s after the operations of these two reservoirs.The intraannual and interannual distributions of streamflow and sediment discharges were also tended to be even.The relationship between water and sediment was re-adjusted in different periods,although its adjustment magnitude was minor.The average annual sediment concentration and average incoming sediment coefficient were significantly lower after the operation of Liujiaxia reservoir,but remained almost the same after the operations of Long and Liu reservoirs.
2019, 17(4):202-208.
Abstract:
In order to evaluate the water conservation function of economic forests in Taihang Mountains of Hebei Province,we selected five kinds of economic forests (apple,walnut,cherry,chestnut and apricot) planted on terraces and studied the waterholding characteristics and benefits of litter and soil in the forests by indoor immersion method and cuttingring method.Then we analyzed their hydrological effects.The results showed that:The accumulative volume of the litter was as follows:walnut (8.28 t/hm2)>chestnut (7.11 t/hm2)>apple (4.07 t/hm2)>cherry (3.69 t/hm2)>apricot (3.42 t/hm2).Chestnut forest litter had the largest water holding capacity (17.07 t/hm2).There was a logarithmic relationship between the water holding capacity and water holding time of the litter,and a power function relationship between water holding rate and water holding time.The effective interception capacity of litter was the largest in chestnut forest (14.37 t/hm2).Soil bulk density increased with depth.The average soil bulk density of the five economic forests ranged from 1.40 to 1.52 g/cm3.The average maximum water holding capacity of soil in the five economic forests ranged from 856.01 to 946.41 t/hm2.The sequence from low to high was:apple
In order to evaluate the water conservation function of economic forests in Taihang Mountains of Hebei Province,we selected five kinds of economic forests (apple,walnut,cherry,chestnut and apricot) planted on terraces and studied the waterholding characteristics and benefits of litter and soil in the forests by indoor immersion method and cuttingring method.Then we analyzed their hydrological effects.The results showed that:The accumulative volume of the litter was as follows:walnut (8.28 t/hm2)>chestnut (7.11 t/hm2)>apple (4.07 t/hm2)>cherry (3.69 t/hm2)>apricot (3.42 t/hm2).Chestnut forest litter had the largest water holding capacity (17.07 t/hm2).There was a logarithmic relationship between the water holding capacity and water holding time of the litter,and a power function relationship between water holding rate and water holding time.The effective interception capacity of litter was the largest in chestnut forest (14.37 t/hm2).Soil bulk density increased with depth.The average soil bulk density of the five economic forests ranged from 1.40 to 1.52 g/cm3.The average maximum water holding capacity of soil in the five economic forests ranged from 856.01 to 946.41 t/hm2.The sequence from low to high was:apple
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