Study On Simulation Of Drought In A Region Based On SWAT Model

With the increasing of climate change and the frequency of extreme drought event on a worldwide scale,droughts have attracted the attention of environmentalists,ecologists,hydrologists,meteorologists,geologists and agricultural scientists.Jialu river basin is located in east-central of Henan province,which is one of the crucial production base of grain and cotton in Henan province.Drought disaster has been one of the main threats of food security in Jialu river basin where moderate and high drought occurred frequently.This paper took Jialu river basin as the research area and the relative soil moisture as the index,analyzing the time-space distribution regularities and periodic change of agricultural drought on the basis of the analysis about the factor of agriculture drought in Jialu river basin.At the same time,this paper have established SWAT model that simulated agricultural drought of Jialu river basin from 2009 to 2014,which based on the DEM data,landuse data,soil data and hydrometeorology data.In the end,this paper has verified the simulation effect of SWAT model through the comparision between the simulated and the measured value.This paper research results are as follows:(1)The agricultural drought in Jialu river basin has distinct seasonal nature and high frequency by the analysis about agricultural drought event in history basin show.Spring drought,summer drought and autumnal drought are the main drought types in Jialu river basin,with spring drought and summer drought occur frequently.There is significantly correlation in 0.05 confidence level between precipitation and relative soil moisture in 10-20 cm,which have indicated that relative soil moisture is an appropriate drought index to evaluate agricultural drought in Jialu river basin because that relative soil moisture not only fully reflect the precipitation of influence on the formation of the drought,but also expression the level of crop drought visually.(2)The interannual variation of relative soil moisture in Jialu river basin have put up a periodic variation about 9 years during early spring,the end of spring and the beginning of summer,mid-summer and autumn.There is a stable periodic signal and multi-scale period in upstream,while a single signal in downstream.The frequency of drought in early spring and drought in late spring or early summer was higher than that in middle summer and autumn.The frequency of drought in late spring or early summer is higher than that in early spring in upstream and downstream,and the frequency of drought in early spring was higher and more serious.There occurred spring-summer drought in upper and middle reach during 1992,1995,2000,which sustain for a long time and seriously.The drought in middle reach have sustain to autumn.(3)In Jialu river upstream,the frequency of drought in late spring or early summer is highest,followed by drought in early spring,the frequency of drought in autumn is lower than drought in early spring,and the frequency of drought in middle summer was minimum.In middle stream,the frequency of drought in early spring is highest,followed by drought in late spring or early summer the frequency of drought in middle summer is lower than drought in late spring or early summer,and the frequency of drought in autumn was minimum.In downstream,the frequency of drought in late spring or early summer is highest,followed by drought in early spring,there is a considerable frequency between drought in middle summer and drought in autumn,which was lower than the frequency of drought in early spring.(4)There have a good simulation result to relative soil moisture from 2009 to 2014 by agricultural drought prediction model based on SWAT model.The results of evaluation agricultural drought event were consistent with the history,which indicated that the prediction model can be applied to the prediction of agricultural drought in Jialu river basin.At the same time,the simulated and measured values of the relative soil moisture have consistent spatial distribution,and the simulated result show the regulation in greater detail.So SWAT model can be applied in the predition of agricultural drought in Jialu river basin.