Research of Runoff Variation Impacted by Hydraulic Projects in Fengman Basin
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Abstract:
There are many hydraulic projects in the Fengman Basin. The hydraulic projects, especially the poorly manually controlled and small to medium sized water conservancy projects, can affect the rainfall-runoff conditions in the basin. The original hydrological forecasting model failed to take into account this effect and therefore resulted in decreased prediction accuracy, which can affect the implementation of normal hydrological forecasting work and the performance of flood control and profiting effect of the reservoir in the basin. Based on the previous studies, the measured hydraulic project operation data and the American land resources satellite Landsat TM/ETM+ data were used to analyze the storage and release characteristics of hydraulic project during the flood. The results showed that the initial storage condition, phase of flood season, and precipitation are the three main factors affecting the storage and release characteristics of hydraulic project. The storage and release characteristics included that (1) flood detention ratio is smaller during the flood season and bigger during the flood recession period; (2) the bigger the initial storage is, the smaller the flood detention ratio is. If the initial storage is similar, the flood detention ratio during the flood recession period is bigger than that at the begining of flood season; and (3) the later the flood during the flood recession period occurs, the bigger the flood detention ratio is. The obtained storage and release characteristics were applied to adjust the flood forecasting in the Fengman Basin. , which showed that the forecasting error decreased from 146.6% to 8.6% for the flood on September 14, 1996 and from 31.8% to 10.1% for the flood on August 26, 2006 after the adjustment. Consequently, the obtained storage and release characteristics were useful and can improve the forecasting accuracy of runoff in the Fengman Basin.