Evaluation Of Water Scarcity In China Considering Inter-basin Water Transfer

In order to alleviate the regional water scarcity,a large number of inter-basin water transfer projects have been built,are under construction and are planned to be built,but there are few researches on the impact of inter-basin water transfer projects on water scarcity in China.This paper collects water transfer projects across secondary basins in China,and uses index evaluation method to quantify the impact of water transfer projects on water scarcity in the historical period(2003-2016)in secondary basins.At the same time,the multi-model ensemble median value of the corrected water availability and water demand was used to calculate the water scarcity in China in the future period under 10 SSP-RCPs scenarios,and to explore the influence of the inter-basin water transfer projects under climate change in the future(2017-2099),and provide decision-making support for regional water resources planning and management in China under future climate change.The main research results are as follows:(1)Using water scarcity indicator,population-weighted water scarcity indicator,and inequality coefficient,the impacts of inter-basin water transfer projects in historical periods are studied at secondary basins,primary basins,and national scales.The conclusions are as follows:By 2016,the designed annual water transfer volume of the inter-basin water transfer project reaches 48.5 billion m~3,involving 43 secondary basins,only 3 of which change the water scarcity level,and the rest only changed the size of the scarcity indicator,and the water scarcity in 25 basins is alleviated.About 80%of the population is affected by water transfer,and more than 50%of the population(726 million)benefit from water transfer projects,but372 million people have increased water scarcity.The water transfer projects reduce the inequality coefficient from 0.64 to 0.60.(2)The quantile mapping algorithm considering trend retention and linear scaling method are used to correct the water availability data under multiple GCM-GGHMs models and agricultural irrigation water use data under GCM-GGCMs models under RCP2.6 and RCP6.0 scenarios,respectively.The latter is combined with the industrial,domestic and ecological water demand under SSP1-5 scenario to obtain the total water demand,and then the water scarcity indicator under the 10 SSP-RCPs scenarios are obtained and their trends are analyzed.The results show that:the total water availability in the country have a slight increase under the two RCPs scenarios,and the increase trend in the north is more significant than that in the south;under the 10 SSP-RCPs scenarios,water demand increases in most basins,but decreases mainly in north China,especially in northeast region;the spatial distribution of water scarcity level in the future period is similar to the historical period,and the water scarcity in the north is much greater than that in the south.Compared with the historical period,the water scarcity in most basins will increase in the future period,but the aggravation degree will decrease with the time(except SSP3-RCPs scenario).(3)Using the same indicators as in the historical period,the impact of inter-basin water transfer projects in the future period is studied,and finds that the impact of inter-basin water transfer projects increases obviously with time.The specific conclusions are as follows:Taking into account the water transfer projects under construction and planning,the inter-basin water transfer involves 60 secondary basins,with a designed water transfer volume of 80.3 billion m~3.Under 10 SSP-RCPs scenarios,the water transfer projects change the water scarcity level in 7-14 basins.Taking the SSP1-RCP2.6 scenario as an example,the water transfer affects 93.2%of the national population,and more than 62%of the population benefits.In the future,the short-term,mid-term and long-term water transfer projects will reduce the inequality coefficient by 0.043,0.050 and 0.057,respectively.