Impact Of Climate Change On Runoff In Typical Watershed Of Henan Province

Since the industrial revolution,the process of globalization has been accelerated and developed rapidly and deeply,which has triggered climate change on a global scale and attracted widespread attention worldwide.As one of the most direct factors affected by climate change,with the rise of temperature,the hydrological cycle and its flux will change,which can easily lead to extreme hydrological events.At the same time,water resources,as a national basic resources and social security strategic resources,plays a pivotal role in China.However,the diverse climate types,complex landforms and different regional development lead to the regional characteristics of water situation in China.Therefore,it is of great practical significance to carry out regional water resources assessment under the background of climate change.In this paper,a typical river basin in Henan Province was selected as the research object,and the temperature,precipitation and runoff data of typical river basin in Henan Province were collected to analyze the temporal and spatial evolution characteristics of meteorological elements and the runoff evolution trend of typical rivers in Henan Province in recent 40 years,and the relationship between precipitation and runoff was established.The BCC model data of CMIP6 were selected,and the grid data were coupled with the SWAT model and the RCCC-WBM model to simulate the hydrological process of typical basins in Henan Province,and the temperature,precipitation and water resources of typical basins in Henan Province were evaluated from 2021 to 2070.To judge the response of hydrometeorological elements in Henan Province under the background of climate change.The main results of this paper are as follows:(1)The results of the study on the evolution characteristics of meteorological elements show that the interannual variation of temperature in Henan Province presents a significant upward trend from 1972 to 2018,with the highest temperature rise in the Haihe River region and the lowest in the Yangtze River region.From1973 to 2016,the annual precipitation in Henan Province showed an insignificant upward trend,and the precipitation in the Huaihe River Region increased.In recent60 years,the annual average discharge of the main river basins in Henan Province showed a decreasing trend,and the monthly average discharge showed a significant decreasing trend.The results of the study on the relationship between precipitation and runoff suggest that with the increase of precipitation,human activities may have a greater impact on river runoff.(2)The sensitive parameters of SWAT model include 15 parameters such as base current regression coefficient,groundwater delay time and soil saturation conductivity,etc.The hydrological process simulation and the measured process fit well.The selected evaluation indexes Nash-Sutcliffe and relative errors are all within the qualified range,so the SWAT model has a good application in the research.The RCCC-WBM model adjusts the parameters manually by driving the model with the data of monthly mean precipitation,monthly mean temperature,monthly evaporation and monthly runoff.The results show that the index of periodic rate evaluation is within a reasonable range,and the degree of fitting between periodic rate evaluation and measured period is good.There is a certain gap between the verification period and measured period,which is considered to be caused by the change of the relationship between precipitation and runoff,which affects the consistency of hydrological series.(3)The prediction results of future temperature and precipitation under the BCC model with CMIP6 data show that the future temperature will show an increasing trend.In the future,the overall precipitation will not increase significantly,and there will be some differences in the variation range of precipitation under different emission scenarios.In most emission scenarios,the temperature rise in the north of Henan Province is larger,and there are regional differences in the increase of precipitation in the province under different emission scenarios.(4)In the future period of 2021-2070,the runoff of typical river basins in Henan Province will mainly increase,and the runoff may decrease under individual discharge scenarios.There are some differences in runoff trends under different models and different emission scenarios.Uncertainty is the main problem in climate change assessment.