Research On Ecosystem Health Evaluation Of Qingshui River Basin Based On Vegetation Ecological Water Demand

An important task of Ningxia Hui Autonomous Region in the new era is to protect the ecological health of the watershed as well as to achieve high-quality development.The ecological environment of the watershed is becoming more and more prominent under the constant disturbance of external pressure,and factors such as climate change and human interference have led to a gradual deterioration of the ecological health quality of the watershed.This requires a systematic analysis and targeted management of watershed ecological problems.The evaluation of watershed ecosystem health is the key to the scientific understanding of watershed ecological health and the sustainable development of watershed ecological health.Therefore,this paper is based on the idea of "problem identificationproblem analysis-problem solving" to evaluate the ecosystem health of the Qingshui River basin,which has important theoretical and practical significance for the overall planning and management of the basin,as well as water pollution prevention and ecological environmental protection.In this paper,we combine theory and practice to study the ecological water demand and vegetation ecological water demand in the Qingshui River basin,and evaluate the ecosystem health of the Qingshui River basin with the ecological water demand of vegetation as the main index.The main research results are as follows:(1)In this paper,the Tennant method and frequency curve method were used to calculate the ecological water demand in the river channel of the Qingshui River in order to determine its ecological baseflow and ecological water demand,taking into account the actual situation of the Qingshui River basin.In the calculation process,a control section appropriate to the evaluated river section was selected,the inlet control section of the Qingshui River--Quanyanshan section,and the data from this section were used for the calculation,and finally the ecological base flow and the ecological water demand in the river channel were determined through comparative analysis.(2)Combined with GIS and other technical means,the ecological water demand and ecological water deficit of vegetation in the Qingshui River basin in 2000,2010 and 2020 were calculated by using the Penman-Monteith model with each administrative district as the study unit according to the basin scale,and the change characteristics of ecological water demand of vegetation in the Qingshui River basin were analyzed in time and space.The results showed that the ecological water demand of vegetation in general showed a steady increase during the study period;meanwhile,the ecological water deficit in the study area was mostly negative,indicating that the vegetation in the study area was in a long-term water deficit,and the ecological water deficit in general showed a trend of increasing from south to north due to the wet and rainy climate in the southern mountainous region and the low rainfall and drought in the central arid region.(3)Combining the actual characteristics of the Qingshui River basin with the principles of the basin health evaluation index system,we screened out the indicators that can reflect the health status of the basin,combined with the Pressure-State-Response(PSR)model to build a comprehensive evaluation index system covering these three levels,and used the comprehensive evaluation index method to evaluate the ecological health of the basin.Based on the comprehensive ecosystem health index,the watershed ecosystem health criteria were classified into five levels:sick,generally sick,subhealthy,healthier and healthy.The index was also used to express the health status of each evaluation unit and the basin as a whole,and the health status of the Qingshui River basin was analyzed.The results show that the ecological environment quality of the Qingshui River Basin has changed significantly from "generally sick" to "subhealthy" from 2000 to 2020,and in general,the ecological environment of the Qingshui River Basin has been significantly improved and has good prospects for development.