Evaluation Of Water Resources Carrying Capacity Of The Yellow River Basin Based On Load Balance

Most of the Yellow River Basin is located in arid and semi-arid areas,and water shortages are serious.The problems caused by rapid development of social economy accompanying by agricultural pollution,water shortage,rapid growth in industrial water demand,low water use efficiency,and deterioration of ecological environment have been alleviated,but the water use conflict in the Yellow River Basin is still prominent.Water pollution,ecosystem degradation and other issues cannot be ignored.Quantitative evaluation of water resources carrying capacity in the basin can provide a theoretical basis for effective regulation of water resources,improvement of water resources carrying capacity and elimination of water resources overload areas,in order to achieve the goal of harmony between human and water.On the basis of summarizing and analyzing the concept and connotation of water resources carrying capacity evaluation,this paper made full sense of the new connotation of water resources carrying capacity,established the “quantity-quality-watershed-flow”four-dimensional water resources carrying capacity evaluation index system,and determined the indicator evaluation criteria.The combination of contact entropy model and EFAST weight algorithm was used to evaluate the water resources carrying capacity.The spatial and temporal variation characteristics of water resources carrying capacity were analyzed.The key indexes which make the system vulnerable was identified by the set pair subtractive situation.Control measures for water resources carrying capacity based on load balancing were proposed through the load equilibrium formula,which make water resources carrying capacity reach the state of not overload or critical overload.Taking the Yellow River Basin as an example,the spatial distribution of water resources carrying capacity in the Yellow River Basin in 2010 and 2015 were analyzed.And the changes of water resources carrying capacity in each province from 2007 to 2016 were evaluated.Then the paper proposed a regulation scheme of water resources carrying capacity in the Yellow River Basin based on load balancing after forecasting the water resources carrying capacity in 2020.The main findings are as follows:(1)The paper formulated a four-dimensional water resources carrying capacity index system for the “quantity-quality-watershed-flow” in the Yellow River Basin.Seven indicators including per capita water resources,precipitation,per capita domestic water consumption,Groundwater exploitation coefficient,water consumption per 10,000 yuan of agriculturaloutput value,water consumption per 10,000 yuan of industrial added value and ecological environment water use rate were selected in the water quantity dimension.Three indicators including water quality compliance rate,per capita ammonia nitrogen emission and per capita COD emission were selected in the water quality dimension.Watershed rate and the wetland retention rate were included in the watershed dimension.The water flow dimension contain the river network density,the minimum three-day flow rate ratio,the flow reversal times and the vertical connectivity.(2)The comprehensive evaluation results of water resources carrying capacity of the Yellow River Basin in 2010 and 2015 indicate that the water resources carrying capacity in most cities of Qinghai and Gannan province are not overloaded or critically overloaded,while the remaining cities are still in the state of overload or severe overload.Even the water resources carrying capacity of the Ningxia Hui Autonomous Region and the Inner Mongolia Autonomous Region are all overloaded or severely overloaded.It is urgent to adjust the water resources allocation plans for the cities in the region and formulate a water resources allocation plan for load balance.(3)The water resources carrying capacity of the Yellow River Basin increased slowly in2007-2016.The water resources carrying capacity of Qinghai province kept in a critical overload state and the remaining provinces were overloaded for many years.The evaluation results of load balance in the Yellow River Basin are basically consistent with the water resources carrying capacity score.The vulnerability indexes of water resources carrying capacity in the Yellow River Basin diagnosed by the subtractive set were mainly the per capita water resources and the per capita pollutant emissions.The low water efficiency of agriculture and industry was also one of the factors causing low water resources carrying capacity in the middle and upper reaches of the Yellow River.(4)The water resources carrying capacity of the Yellow River Basin in 2020 was forecasted.The results found that with the current planning scheme,except Qinghai province keep a critical overload state because a high carrying capacity and a low load.the water resources carrying capacity of the Yellow River Basin provinces will be overloaded,Ningxia and Shandong province will be at a serious overload level,and Shanxi province will be very close to a serious overload level.After formulating the regulation and control plan for water resources carrying capacity,the water resources carrying capacity of Qinghai province has risen from critical overload to loadable,and the water resources carrying capacity of Gansu,Inner Mongolia,Shaanxi and Henan provinces has risen from overload to critical overload.In Ningxia,Shanxi and Shandong,due to the extreme water shortage,the water resourcescarrying capacity will be risen from the serious overload to the overload level.The fundamental ways to improve the water resources carrying capacity of the Yellow River Basin are to save water,increase water supply,and reduce pollutant emissions.The regulatory measures vary from province to province.