Attribution Analysis Of Runoff Variation In Typical Basin Of Haihe River Basin Based On SWAT Model

The impact of climate change and human activities on the environment has always been a research keypoint and research hotspot for hydrological workers.In recent years,under the combined influence of climate change and human activities,many river basins in the world have experienced more serious reduction trends.However,different scholars have different classification methods for the study of the contribution of the two to runoff under different watershed conditions.Compared with qualitative and general analysis,quantitative and detailed analysis can get valuable conclusions,and it can also provide corresponding basis for policy designation and subsequent environmental and resource work.The system clarifies and quantifies the impact of climate change and human activities on watershed runoff changes.It has important scientific significance for studying the water cycle,water ecology and rational development and utilization of water resources in the basin,and it also has a certain social and economic green sustainable development.In order to systematically and comprehensively analyze the impacts of climate change and human activities on runoff,this paper selects the Haihe River Basin as the research area,and choose the upper reaches of the Zhanghe River,which is significantly affected by human activities,and Luanhe river basin,which is not affected by human activities.The mutation points of runoff in the two basins were tested by the sequence mutation test method,and the impact assessment model of runoff variation was established based on the results of the mutation test and the mean flow.At the same time,based on meteorological data,land use data,soil data and other basic data,the SWAT model of the two research areas was established,and the model used to simulate the natural runoff of the two basins.After a series of research and analysis,the main results of this paper are as follows:(1)With the long series of historical data,the SWAT model was used to simulate the natural runoff in the two research areas for nearly 60 years,and SWAT-CUP was used to select the parameters suitable for the two basins,and finally the model calibration and verification work was completed.(2)Based on the SWAT model and the corresponding impact assessment model of runoff variation attribution analysis,the contribution rates of climate change and human activities to runoff in the two basins were calculated.The results show that The runoff changes in the upper reaches of the Weihe River in the past 60 years are mainly affected by human activities.Under the full sequence conditions,the contribution rate of human activities is 59%,while in the years of dry and dry years,the contribution rate of human activities is higher,the rate rise to 65%;runoff changes in the upper reaches of the Weihe River are mainly affected by climate change,and their contribution rate is 89%.Simultaneously comparing simulated runoff with measured runoff,the SWAT model is sensitive to short-term and large-scale changes in precipitation data input.(3)According to the results of the two-basin impact assessment model,the climatic factors and human activity factors of the two basins were analyzed separately.It was found that the variability of the upper reaches of the Weihe River with human activities as the dominant factor appeared in the same time as the channel water flow.The time when the variability of the Weihe River Basin,which is the main factor,is consistent with the time of the rainstorm.This result verifies the results of the impact assessment model and supplements the results of the impact assessment model from two aspects.(4)By comparing the upper reaches of the Weihe River with climate change as the main factor and the upstream of the Weihe River,which is mainly affected by human activities,it can be found that under the influence of single factor of climate change,the stability of runoff in the two study areas is better than before.There is not much change,but if it is affected by human activities,the upper reaches of the Weihe River show a trend of relatively dramatic changes and a high degree of dispersion of runoff.In the year of normal and dry years,the actual runoff is simulated.There is a significant reduction in natural runoff.It shows that the impact of human activities on the runoff process is more severe,showing obvious nonstationary characteristics.