Study On Water And Soil Resources Management In The Upper Reaches Of The Yellow River Based On The Concept Of Green Water Credit

Optimizing the allocation of water and soil resources is crucial for coordinating the upstream and downstream economic society and ensuring the sustainable development of water shortage basins.In large basins,there are significant differences in resource consumption,production costs,resource utilization efficiency,benefits,and environmental impacts between the upstream and downstream areas.In order to improve the efficiency and benefit of resource utilization in the whole basin and reduce the negative environmental impact,resource allocation should be tilted towards areas with high efficiency,benefits and low negative environmental impacts.To ensure regional equity,economic compensation should be provided from areas with high resource allocation to areas with low environmental impacts.This paper proposes a framework for optimizing the allocation and economic compensation of soil and water resources in large-scale watersheds based on the concept of green water credit,combined with hydrological models and cost-benefit analysis.It aims to optimize the allocation of soil and water resources in the upstream and downstream of the watershed,and promote the coordinated development of the upstream and downstream areas,as well as overall optimal development of the watershed.Taking the Yellow River Basin as an example,this paper selected Huangshui Basin in the upper reaches of the basin,and simulated five green water management measures,including terracing,contour tillage,stone line,land cover and conversion of farmland to forest above 15°using SWAT model.This study analyzed the changes in water quantity,sediment and water quality,conducted economic calculations of construction costs,economic benefits,and ecological benefits,and developed a green water credit scheme based on the actual situation of the basin.Furthermore,an evaluation index was constructed to evaluate the overall mechanism and discuss its extensibility and applicability.The main conclusions are as follows:(1)Green water management measures in Huangshui Basin can effectively increase blue water quantity,reduce sediment yield,and mitigate non-point source pollution.The average annual water production can be increased by 10.05×10~6m~3;groundwater supply can be increased by 8.32×10~6m~3,sediment transport can be reduced by 253,700t;total nitrogen and phosphorus can be reduced by 121.26t and 66.26t respectively.The average annual water yield of terraced field,stone line,land cover and farmland conversion to forest above 15°increased by 0.30～2.41%,the sediment yield decreased by 7.64～37.02%,the total nitrogen and total phosphorus in the drainage basin decreased by 4.09～19.66%and 10.09～56.43%,respectively.However,the green water management effect of contour cultivation was not significant.(2)Implementing green water management measures in the upper reaches of the Yellow River Basin brings about economic and ecological benefits to the entire basin.The benefit-cost ratio of all five green water management measures is greater than 1,indicating their potential for broader application in the upper reaches.The average green water management cost was 371.17 million yuan/a;the average upstream income was 147.19 million yuan/a;the average economic benefit was 508.73 million yuan/a;the average ecological benefit was 51.43million yuan/a,and the average benefit-cost ratio was 1.91.The benefit-cost ratio of the five green water management measures was all greater than 1,and the order in descending order was terraced field>stone line>farmland conversion to forest above 15°>stubble cover>contour planting.Among them,the benefit-cost ratio of terraced field was the highest(3.54).The benefit-cost ratio of contour tillage was the smallest,which was 1.22.From an economic perspective,all five management scenarios have positive effects on the overall development of the basin.(3)Considering the development situation of various regions in the Yellow River Basin,credit activities should be carried out in two stages in the form of vertical and horizontal credit.The main body of green water credit is the River Basin Green Water Credit Foundation and the four provinces in the middle and lower reaches.In the first stage,the river basin Green Water credit Foundation pays the cost of green water management measures to the upstream with vertical credit,and the average annual compensation fund is 3390 yuan/hectare.In the second stage,the four provinces in the middle and lower reaches share most of the payment pressure of the credit fund.The vertical compensation funds of the Green Water credit Foundation in the river basin decrease to 333.16 yuan/ha,and the four provinces in the middle and lower reaches pay the cost compensation and efficiency improvement benefits to the upstream in the form of horizontal credit,which is 4,340.35 yuan/ha.(4)Green water management and credit mechanisms in the Yellow River Basin can improve water resource utilization efficiency and reduce the development gap between the upstream and downstream areas to some extent.However,careful screening of management measures is necessary.The static unbalance difference of terraced field,stone line,stubble cover and conversion of farmland to forest above 15°was reduced by 44.90%,32.97%,31.91%and 47.27%,respectively,which can help narrow the development gap between upstream and downstream areas.However,equal-height tillage has shown to increase the level of imbalance,making it unsuitable for green water management and credit mechanisms.The green water management measures and economic compensation methods proposed in this paper can play a positive role in water and soil conservation and pollution reduction in the basin.While encouraging sustainable green water management behavior in the upper reaches,the water resources availability and economic benefits in the lower reaches can be improved to provide support for the high-quality sustainable development of the whole basin.