| Due to the shortage of water resources in the arid inland areas of northwest China,which is characterized by the fragility of water resources system and the uneven distribution of water resources in time and space.The limited water resources have become the key factors that restrict the development of social economy and affect the ecological security.With the economic and social development and the further growth of water demand,the contradiction between the supply and demand of water resources and the security of water resources are increasingly prominent in the arid inland areas.The increasing human activities cause the imbalance of water resources,which leads to the threat of water shortage to the fragile ecosystem and the increasingly serious problems of ecological environment in the arid inland areas.With the future climate change and the aggravation of human activities,how the water resources of inland rivers will be and what kind of changes will happen become an important topic.Therefore,this paper takes Hexi inland area as the research area,using SWAT model and GM grey prediction model to explore the current situation and future trend of water supply and demand in the research area.Through the construction of water resources supply and demand balance model,the water resources supply,water demand and supply-demand relationship in Hexi inland area are quantitatively evaluated,and the spatial scale of sub-watershed is used to reveal its spatial and temporal distributioncharacteristics.On this basis,the change of water resources supply in the future is predicted by combining with the future climate scenario prediction,and the change of water resources demand under the future socio-economic development of the region is predicted at the same time.Then,the relationship between water resources supply and demand and the spatial pattern are analyzed in the study area during 2025?2055.In order to provide relevant reference for the rational utilization and allocation of regional water resources in the future,we put forward relevant measures and suggestions with the overall goal of water supply and demand balance based on the forecast results of future water supply and demand balance.The main conclusions are as follows:(1)The simulation of water supply in 2016 is about 80.74 × 10m3,and its spatial distribution shows a decreasing trend from south to north.The number of sub basins with water supply more than 100 ×106m3 is small,and they are mainly located in the Qilian Mountain Area in the upper reaches,which is the main flow producing area and the main contribution area of water resource supply in the whole region.The area of water supply with low value is mainly distributed in the north of Shule River Basin and the lower reaches of Heihe River Basin.According to the calculation of water demand of agriculture,industry,life,animal husbandry and ecology in Hexi inland area in 2016,the water demand is about 91.67 × 108m3.Agriculture and ecology are the sectors with large water demand,accounting for 78.1%and 14.75%respectively.In terms of spatial distribution of water demand,it can be seen that the high value areas are mainly concentrated in the middle reaches of Heihe,Shule and Shiyang river basins,which is highly related to the distribution of human production and life in each basin.(2)From the perspective of the time change of future water supply,the water supply under the climate scenarios of rcp4.5 and rcp8.5 will fluctuate in the range of 55.97 ×108m3?96.48×108m3 and 56.78×108m3?99.35×108m3 in 2025?2055,and will increase with the trend of 0.33 ×108m3 and 0.48×108m3 per year respectively.In terms of the distribution pattern of water supply in 2025?2055,the spatial distribution pattern of water resources supply is basically the same under the climate scenarios of rcp4.5 and rcp8.5.The high value areas are mainly concentrated in the upstream sub basins,while the low value areas are mainly distributed in the middle and downstream areas as water resources dissipation and the northern areas.From the perspective of time change of water demand from 2025 to 2055,the water demand will vary from 80.85×108m3 to 87.11×108m3,and will decrease by 0.21×108m3 every year.The water demand of agriculture will decrease with 0.56×108m3 per year,while water demand of industry,life,animal husbandry and ecology will increase with 18.12 ×106m3,6.12×106m3,6.32×106m3 and 4.68×106m3 respectively.From the perspective of future spatial distribution of water demand,the spatial distribution pattern of water demand is basically the same.The high value areas are mainly concentrated in the sub basins of the middle reaches where human activities are frequent,while the low value areas are mainly concentrated in the upper reaches where population distribution is rare and the lower sub basins where vegetation is sparse.(3)From the perspective of the time change of future water supply and demand balance,the FSI of scenario rcp4.5 and rcp8.5 will fluctuate between-0.197?0.04 and-0.216?0.06 respectively from 2025 to 2055,and the overall water resource will be in a state of shortage in the future.In terms of the change trend of water supply and demand in 2025?2055,the gap between supply and demand under the scenarios of rcp4.5 and rcp8.5 will gradually narrow by 0.12×108m3 and 0.27×108m3 per year respectively.The FSI under the scenarios of rcp4.5 and rcp8.5 will increase by 0.003 and 0.004 per year respectively,and the supply-demand situation of Hexi inland area will gradually improve in the future.In terms of the perspective of the spatial distribution of future water supply and demand balance,the spatial distribution of FSI in the region is relatively consistent in the future,with the overall spatial distribution characteristics of high in the South and low in the north.Among them,the positive area of FSI is mainly distributed in the upstream mountainous area,the negative area is mainly distributed in the middle and lower reaches of each basin,and the sub basins closely related to human activities and vegetation cover are seriously short of water resources and low security.(4)Based on the prediction results of water supply and demand in the future,each scheme can ensure that the domestic water consumption of residents can be met on the basis of achieving the balance of supply and demand water under the water resource allocation of different scenario schemes.According to the water allocation results of different scenarios,to ensure the future water consumption of agricultural and industrial production activities in the region will generate different degrees of ecological water occupation.Based on the future water demand of each department and the water supply under the future climate change,it is suggested to reduce the water demand of agriculture and industry while ensuring the ecological water consumption to the greatest extent,so that the water distribution of each department can reach more than 80%of the predicted water demand in the future.The suitable scenario schemes can ensure that the water distribution of each department is balanced and reasonable on the basis of realizing the future water supply and demand balance of the region,which can be a reference for the future water resources allocation in Hexi inland area. |
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