Research OG Water System Connectivity In Inner Flow Area

The water system is the main carrier of water resources and is highly susceptible to climate change and human activities,maintaining its connectivity is critical to the health of the river ecosystem.This paper takes the arid and semi-arid regions of China as the research object,and is divided into 7 sub-regions: Inner Mongolia Inner Flow Area,Hexi Corridor-Alxa Inner Flow Area,Qaidam Inner Flow Area,Junggar Inner Flow Area,Ili River Inner Flow Area,Tarim Inner Flow Area,Qiangtang Plateau Inner Flow Area,based on reservoirs,dams,roads,cities,population,precipitation,air temperature,vegetation and soil,etc.,nine indicators including nighttime light index,population density,standardized precipitation index,standardized precipitation evapotranspiration index,vegetation index and soil moisture,etc.,are selected.Using these indexes build a water system connectivity evaluation index system,and which evaluate the water system connectivity in the inner flow area from three aspects: vertical,horizontal and comprehensive connectivity,the main results are as follows:(1)The influence degree of reservoirs and dams on the water system connectivity in each sub-inner flow area is in the following order: Junggar inner flow area > Tarim inner flow area > Hexi Corridor-Alxa inner flow area > Inner Mongolia inner flow area > Yili river inner flow area >Qaidam Inner Flow Area>Qiangtang Plateau Inner Flow Area.The influence degree of roads on the water system connectivity in each sub-inner flow area is in the following order: Tarim inner flow area > Junggar inner flow area > Hexi Corridor-Alxa inner flow area > Inner Mongolia inner flow area > Qiangtang plateau inner flow area > Qaidam inner flow area Flow Area>Ili River Inner Flow Area.Urban construction,population density and air temperature are increasing and soil moisture is decreasing,which are not conducive to the water system connectivity.While the increase of precipitation and the improvement of vegetation are all conducive to the water system connection.(2)The average longitudinal connectivity index of the water system in the inner flow area is 86.266,and the evaluation result of the longitudinal connectivity of the water system is “general”.There are 9641 reaches with good longitudinal connectivity of the water system,accounting for 6.315%,and 138612 reaches with general longitudinal connectivity,accounting for90.791%,and 4419 reaches with poor longitudinal connectivity,accounting for 2.894%.The average longitudinal connectivity index of the rivers represented by the inner flow area is 75.178,and the overall longitudinal connectivity of the water system is “general”;the reaches with poor longitudinal connectivity of the water system are mainly distributed near the dam,indicating that the dam has a greater impact on the longitudinal connectivity of the water system.(3)The average horizontal connectivity index of the water system in the inner flow area is 84.108,and the evaluation result of the horizontal connectivity of the water system is “general”.There are 120 reaches with good lateral connectivity of the water system,accounting for 0.079%,and148,277 reaches with general lateral connectivity,accounting for 97.121%,and 4,275 reaches with poor horizontal connectivity,accounting for 2.8%.The average horizontal connectivity index of the rivers represented by the inner flow area is 86.193,and the overall horizontal connectivity of the water system is “general”;the reaches with poor horizontal connectivity of the water system are mainly distributed near the reservoir,indicating that the reservoir has a greater impact on the lateral connectivity of the water system.(4)The average comprehensive connectivity index of the water system in the inner flow area is 83.886,and the evaluation result of the comprehensive water system connectivity is “general”.There are 108 reaches with good comprehensive connectivity of the river system,accounting for 0.071%,and 148952 reaches with general comprehensive connectivity,accounting for 97.563%,and 3612 reaches with poor comprehensive connectivity,accounting for 2.366%? The average comprehensive connectivity index of the rivers represented by the inner flow area is 73.503,and the overall comprehensive connectivity of the water system is “general”;the reaches with poor comprehensive connectivity of the water system are mainly distributed near dams and reservoirs,indicating that dams and reservoirs have a greater impact on the comprehensive connectivity of the water system.