Analysis The Characteristics Of Drought And Flood In Karst Area Of Southwest China Based On SWAT Model

The frequent occurrence of drought and flood in karst areas of Southwest China has seriously affected the development of social harmony and stability.In this paper,the Daotian river basin in Bijie City of Guizhou Province is selected as the research area.Based on the distributed hydrological model,the characteristics of drought and flood under land use change and climate change are explored from the basin scale.Construction of distributed hydrological model and drought and flood evaluation model in the study area.The hydrological response under different scenarios in the study area was analyzed based on the change of hydrological factors(export flow,evapotranspiration,soil water content,etc.).Based on Palmer index,the evaluation model of drought and flood in the study area was established,the temporal and spatial distribution characteristics of drought and flood events were clarified,and the impact of human activities and climate change on drought and flood in the study area was revealed..Through this study,it is expected to provide scientific research basis for the prevention and control of drought and flood disasters and rocky desertification,and create green mountains and waters in karst areas in Southwest China,which is of great significance for the prevention and control of drought and flood disasters in karst basins and make the sustainable development of society.The main research contents and achievements are as follows:(1)In view of the influence of underground river on SWAT model watershed division in karst area,this study determines the location and flow direction of underground river in the study area on the basis of full geological survey and field tracer test by conceptualizing the underground river in SWAT model by modifying DEM,which improves the applicability of SWAT Model in karst area.At the same time,the Swat distributed hydrological model suitable for the study area is established based on the improved method.(2)This study analyzed the change of land use and historical climate characteristics of the study area in three periods,and set up 8 land use scenarios and 10 climate scenarios.The results show that the grassland types are decreasing,but the hydrological response caused by land use change under human activities is not obvious.The trend of precipitation decrease and temperature increase is obvious in this area.The monthly change of hydrological response caused by precipitation change is not obvious as it caused by temperature change.(3)The characteristics of drought and flood in the study area are based on the analysis of drought and flood index.Based on Palmer index,the drought and flood evaluation model suitable for Daotian River basin was constructed.The results show that spring drought and summer drought are easy to occur,and flood is easy to occur in June.The central part of the study area is easy to drought,while the western part is easy to humid.From 1995 to 2005,the change of drought and flood index caused by human activities was less than 0.04,and the decrease of drought and flood index caused by climate change was 0.21 to 0.29,which shows climate change was the main reason for the change of drought and flood index in the study area.