Hydrological Simulation In Shang Dong River Basin Of Arid Area Based On SWAT Model

Affected by climate change and human activities,the characteristics of water resources in the basin have changed significantly,especially in recent years,the development and utilization of river basins have increased year by year,which has made the hydrological process difficult to capture and brought adverse effects to the water resources management department of the basin.It is of great significance and practical value to use scientific and reasonable methods to predict the future water resources of the basin and reveal the characteristics of future water resources evolution.This paper takes the Shang dong river basin of the arid desert steppe in central Inner Mongolia as the research object,firstly,the trend,mutation and periodic test of the climatic factors of the basin are carried out.;on this basis,we construct the distributed SWAT model of the Shang dong river basin to simulate the hydrological process.Finally,the temporal and spatial characteristics of future water resources in the basin are predicted by developing 24 reasonable climate change scenarios and 7 land use/vegetation cover scenarios.The main research results obtained in this paper are as follows;1.The average annual temperature increase in the Shang dong river basin between 1959 and 2017 was 0.38?/10a,the temperature sequence has changed suddenly in 1990,and the temperature shows a quasi-four-time oscillation of alternating cold-warm in the time series of 12a?32a.The annual precipitation increase is 7.60mm/10a,and the precipitation shows a quasi-four-time oscillation of wet-dry alternating in the time series of 12a?32a.2.The sensitivity of the model parameters was analyzed by the LH-OAT hypercube sampling method in SWAT-CUP software.The results show that different model parameters have significant effects on runoff simulation.In general,the parameters that are more sensitive to the model simulation of hydrological processes are:SCS runoff curve number(CN2),soil saturated water content(SOL_BD),base flow Alpha factor,soil evaporation compensation coefficient,main channel Manning coefficient Groundwater delay time,water level threshold of recurrent flow in shallow aquifer,groundwater re-evaporation coefficient,effective permeability coefficient of tributary alluvium,soil saturated permeability coefficient.3.The periodicity and verification period of the model are 2010-2014 and 2015-2016,respectively.The Nash-Sutclife efficiency coefficient(NSE)is used as the objective function,and the three evaluation indexes of NSE,R2 and RE are used as model evaluation indicators,which evaluated the simulated flow value and the measured flow.The results show that the simulated and measured values of runoff in the periodic and verification periods are well fitted.The NSE of the periodic and verification periods are greater than 0.60,and the correlation coefficients are 0.72 and 0.65,respectively,and the relative errors are less than 10%,which means the SWAT model of Shang dong river basin can simulate the hydrological process of the basin well and then assess the water resources of the basin.4.Based on the above-mentioned consistency analysis results,the temporal and spatial characteristics of future hydrological elements in the basin are predicted by setting the future 24 climate change scenarios in the Shang dong river basin.The results show that hydrological factors(ET,soil water content and surface runoff)are significantly changed by precipitation scenarios.In general,hydrological factors are positively correlated with precipitation.At the same time,ET has a positive correlation with temperature,and there is no evidence of ET paradox.Surface runoff,soil water content and temperature are negatively correlated.In addition,the results also show that precipitation is the main cause of changes in hydrological factors,and the temperature influence is small.Spatially,the western and southern regions of the basin are affected by climate scenarios,and the runoff changes significantly,the area with relatively large annual average runoff change in the sub-basin is "inverted L-shaped".ET and soil water content in the central and southern regions have a greater impact,showing an inverted small font.5.Seven scenarios of land use/vegetation cover change were used to assess the response of water resources to land use change in the future.The results show that the response of different hydrological factors to land use change varies significantly in time.Generally speaking,runoff is positively and negatively correlated with construction land and grassland,but positively and negatively correlated with ET and soil moisture respectively.Meanwhile,the change of hydrological factors caused by land use change is much smaller than that of climate scenarios;Spatially,the changes of hydrological elements are closely related to the transformation of land use/cover types.The hydrological factors changed significantly in the areas greatly affected by land use type change,but the change was not significant,and even the local area had no change.