Simulation Study Of Runoff In Beijing-Tianjin-Hebei Region Based On The SWAT Model

The development of human society and economy is accompanied by an increase in demand for water resources,which makes the contradiction between water supply and demand increasingly prominent.In order to resolve this contradiction,better management and full use of water resources,and sustainable use of water resources,the use of hydrological models to simulate and describe the water cycle of the basin through mathematical methods,and to understand its temporal and spatial changes,has important practical significance.The distributed hydrological model has become a research hotspot since it was proposed,and it is of great significance to study the rational allocation of water resources and the laws of water resources changes.SWAT model,as a representative of distributed hydrological model,is widely used in river basin runoff,pollutant simulation,and analysis of underlying scenario changes.The Beijing-Tianjin-Hebei region has an important strategic position in the development of our country,but with the long-term and rapid development of the regional economy,the issue of its water resources use has become increasingly prominent.Problems in the use of water resources not only restrict the development of the Beijing-Tianjin-Hebei region,but are also not conducive to the protection of the regional ecological environment.In response to the above problems,hydrological simulations and watershed scenarios are set up in the Beijing-Tianjin-Hebei region.The causes of the problems are fully analyzed,and solutions to the problems are proposed from the perspective of hydrological simulations.Suggestions are made for more reasonable development and utilization of water resources to promote better regional development.This article takes the Beijing-Tianjin-Hebei region as the research object and uses the SWAT model as a research tool.It has extensively collected the basic data of the study area and constructed a basic database of the research area to simulate the runoff in the Beijing-Tianjin-Hebei area.The changes in water resources management measures were explored,which laid the foundation for further development of water quality simulation,coupled surface and underground simulation,and basin management measures.It also provides support for the construction of a comprehensive simulation forecast system for the"Sanshui"in the Beijing-Tianjin-Hebei region.1.This research builds a complete basic database system of SWAT model in Beijing-Tianjin-Hebei area.The database includes digital elevation,soil,land use,meteorological and hydrological aspects.There are 3 sets of DEM raster data,6 sets of land use raster data in different periods,1 set of soil raster data,3 sets of meteorological data of different scales,and digital research area water system,river network,irrigation area,lake bank,hydrological station and other hydrology data.It provides basic support for subsequent research.2.This study selected typical areas of the Chaobai River Basin and Dongyang River Basin,and evaluated the applicability of SWAT model precipitation input data in the temperate East Asian monsoon climate zone where the study area is located.The results show that the model rate supported by the CMADS precipitation data of the Chaohe River tributary of the Chaobai River without reservoir control is regularly R2=0.64,NSE=0.64,and the verification period R2=0.61,NSE=0.58,which meets the evaluation criteria for the SWAT model simulation effect.The CMADS precipitation data is applicable under the scenario of no-reservoir-controlled watershed in the temperate East Asian monsoon climate zone;in the Chaobaihe Reservoir controlling the tributary Baihe system,the model supported by the CMADS precipitation data has regular rates of R2=0.89,NSE=0.87,and the validation period model R2=0.61,NSE=0.61;CMADS precipitation data supported by the Dongyanghe Reservoir control basin model rate regularly R2=0.84,NSE=0.78,verification period R2=0.87,NSE=0.85,CMADS precipitation data has a very high temperature in the reservoir control basin of the temperate East Asian monsoon climate zone.Good applicability.CMADS precipitation data can be used to build hydrological models of the basin affected by human activities in the temperate East Asian monsoon climate zone,as the basis for subsequent analysis of human activities and scenario changes.3.This study builds a SWAT model in the Beijing-Tianjin-Hebei region.The model area of the study area is 22.2×10~4 km2,including a total of 242 sub-basins and 1459 hydrological response units.The model includes a total of 7 water inlets and 12 water outlets.Based on the constructed model,the runoff in the study area was simulated.According to the available data,the Shexian County,the new tide barrier,Ningchegu,Chaigoubao East,Zhongtangmei,Linqing Hydrological Station were analyzed to analyze the contents of each station.The watershed runoff sensitivity parameters were calibrated and the results were fitted and verified.During the entire simulation period,the monthly runoff simulation results of Shexian Hydrological Station were R2=0.81,NSE=0.75;the monthly runoff results of Xintiozha Hydrological Station were R2=0.81,NSE=0.78;and the monthly runoff results of Ningchegu Hydrological Station were R2=0.82,NSE=0.81;Monthly runoff simulation results of Linqing Hydrological Station R2=0.92,NSE=0.90;Monthly runoff results of Zhongtang Mei Hydrological Station R2=0.63,NSE=0.63;Monthly runoff simulation results of Chaigoubao Hydrological Station R2=0.85,NSE=0.85.The model as a whole has a good simulation effect.4.Based on the above research,the Chaobai River Basin was selected as a typical research area to study the response to runoff and sediment yield under historical land use changes and different land use change scenarios.The results show that with the historical change of land use in the basin,the runoff and sediment yield in the basin have increased.Comparing the results of runoff and sediment yield under different scenarios,increasing the forest land area is conducive to water conservation and soil and water conservation,while the increase in cultivated land area is It will aggravate water and soil loss in the watershed,which is not conducive to ecological protection and restoration.The Yongding River Basin was selected as a typical research area,and the feasibility of restoring“with water”in the downstream under the scenario of changes in water resources management measures was studied.The results show that through the effective allocation of water resources in the upstream,it is possible to achieve“water”in the downstream reach of about 70 km,which provides a reference for the formulation of water resources management measures.5.Summarize the existing conclusions and results of this research,analyze existing problems and deficiencies,and put forward prospects for further research in order to obtain more practical application values.