Study on Causes of Runoff Variation Based on Hydrological Simulation——Taking Sanchuanhe River Casin as a Case Study

SIMHYD rainfall runoff model was firstly calibrated with natural hydro-meteorological data in Sanchuanhe River Basin.And then,the model was used to extrapolate natural runoff period affected by human activities.Finally,the causes of runoff variation in Sanchuanhe River Basin were analyzed with hydrological simulation method.And results show that SIMHYD rainfall runoff model has good simulation result for monthly discharge in Houdacheng hydrometric station.Absolute runoff reductions affected by human activities and climate change have shown increasing trends.On average,70.1% and 29.9% of total runoff reduction were caused by soil and water conservation measures and change in meteorological factors.Human activities are main causes of runoff reduction in Sanchuanhe River Basin.