Runoff Simulation Of The Watershed From Lancun To Erba Station Of Fen River Based On SWAT Model

Based on the current problems of water resources and water environment,this thesis takes the future comprehensive management of water resources as the starting point to carry out the research of runoff simulation as well as runoff response under climate change in the study area.Firstly,the database of land use,soil,meteorology and hydrology in the study area is constructed,and SWAT model is localized.Then,parameter sensitivity analysis,calibration and verification are carried out by using SUFI-2 algorithm in SWAT-CUP program,and then the applicability of the model is evaluated.Finally,based on scenario driven technology,the impact of temperature and precipitation changes on the runoff in the basin is analyzed.The main conclusions of this study are as follows:(1)Based on GIS platform,DEM,land use and soil distribution map are processed and transformed;the database of soil properties and meteorological hydrological database of the study area was successfully constructed;the study area runoff simulation was realized based on SWAT model localization construction,and the study area was divided into 31 subbasins and 421 Hydrological Response Units(HRUs).(2)By using SWAT-CUP program parameter sensitivity analysis tool,it is determined that the main sensitive parameters of runoff simulation in the study area include SOL?K(..)(saturated hydraulic conductivity),CN2(SCS Runoff Curve Number),ESCO(soil evaporation compensation coefficient),ALPHA?BF(groundwater recession constant number),CH?N2(manning roughness coefficient of main channel),etc.(3)Then the year 2002 was selected as the model preheating period,the years from 2003 to 2011 were selected as the model calibration period,and from 2012 to 2015 were as the validation period,for which the parameters of the model were calibrated and validated.It implies that SWAT model has good applicability in runoff simulation in the study area.The accuracy evaluation indexes R2,NSE and Re are 0.76,0.74 and-11.3% respectively for the calibration period,and for validation period is 0.85,0.81 and-8.0% respectively.All indexes meet the standards above class B.However,from the perspective of simulation process,some peak simulation results before 2009 are not good enough,which maybe related to the upstream reservoir drainage in March,resulting in large fluctuation of water flow process from January to March.(4)Climate change scenarios are set based on precipitation and temperature change.Then the response degree of runoff was analyzed by driving the calibrated and validated SWAT model with climate change scenarios.The results show that: Within the calculated temperature range(-2 ? ? 2 ?),there is a negative correlation between the temperature change and the runoff change,i.e.the temperature increases cause the corresponding runoff decreases.With the increase of the temperature range,the rate of runoff decrease slows down and the temperature effect weakens;Within the calculated rainfall variation range(-10% ? 10%),there is a positive correlation between precipitation change and runoff change,i.e.precipitation increases,cause the corresponding runoff increases.With the increase of rainfall amplitude,the increase rate of runoff increases,and the effect of precipitation increases;Runoff is more sensitive to precipitation varies ±10% than to temperature varies ±2?.