Research On The Conjunctive Operation Of Surface Water And Groundwater For Ecological Stability In The Desert Oasis Of The Heihe River Basin

In the past hundred years,climate change and human activities have had a great impact on water resources.The sharp increase in global water demand and the shortage of water resources have formed a sharp contradiction.The frequency of extreme water events has gradually increased,and the ecological environment has continued to deteriorate.As one of the effective means to solve these problems,optimal operation of water resource has carried out many studies,but there are few studies on the conjunctive operation of vegetation restoration and agricultural water use,surface water and groundwater(groundwater level)in the basin where desert oasis is located.The research on the conjunctive operation of surface water and groundwater in Heihe River basin not only enriches the relevant research results of the conjunctive operation of surface water and groundwater,but also has practical significance for the restoration of ecological environment in Heihe River Basin,and provides a reference for the ecological improvement of oasis in the Inland River Basin in Northwest China.This paper takes the typical basin of the inland river basin in northwest China-the middle and lower reaches of the eastern sub-water system of the Heihe River Basin(upper reaches is a hilly area,and the degree of water resources development and utilization is low)as the research area.Based on multi-year(monthly)sequence data such as runoff elements,socio-economic,water supply,remote sensing images of Heihe River Basin,groundwater depth of Heihe River Basin,etc.,in-depth analysis of water resources development and utilization status and existing problems,Carrying out water supply and demand forecasting and proposing a new model of conjunctive operation of surface water and groundwater for ecological stability;using methods such as water balance principles,multi-objective planning,genetic algorithms,and large-scale system decomposition and coordination theory to construct water balance models and conjunctive operation of surface water and groundwater models.The model proposes a conjunctive operation scheme for ecologically stable surface water and groundwater in the desert oasis of the Heihe River Basin.The main conclusions are as follows:1.The main problems in the current water resources development and utilization in the Heihe River Basin are:lack of water resources,high development and utilization intensity,deterioration of the ecological environment,unreasonable water use structure,large impacts of water conservancy projects,insufficient management efforts,and imperfect management mechanism systems.2.Combined with the area and coverage,groundwater level,social and economic development,etc.,under the conditions of limited water resources and certain water-saving measures,the future supply and demand of water in the study area is initially predicted.According to relevant planning and literature,the water supply in the study area is determined.The water demand is 2.46 billion m3;the water demand in 2035 is 2.925 billion m3,of which the agricultural,industrial,domestic,and ecological water requirements are 1.308 billion m3,159 million m3,139 million m3,and 1.319 billion m3 respectively(the amount of water required for the vegetation in Ejin Oasis 674 million m3),the preliminary balance analysis of water resources showed a water shortage of 465 million m3;water demand in 2050 was 3.046 billion m3,of which agricultural,industrial,domestic,and ecological water requirements were 1.226 billion m3,184 million m3,and 172 million m3,respectively.1.464 billion m3(including Ejina Oasis vegetation water demand is 754 million m3),the preliminary balance analysis of water resources shows that the water shortage is 586 million m3,the research area has a contradiction between supply and demand,and the water shortage is large.Problems such as water shortage and ecological restoration.3.The discharge volume of Yingluoxia,Caotanzhuang,Heihe Bridge,Zhengyixia and other sections of the Heihe River Basin has been systematically analyzed.In general,the Heihe River Basin has entered a period of abundant water in the past ten years,and the discharge volume has increased significantly.On this basis,using the hydrological,meteorological,water supply and other data of the middle reaches of the Heihe River Basin from 2000 to 2016,a water balance model of the middle reaches of the Heihe River Basin was established,and the parameters were calibrated using the least square method and genetic algorithm 0.8.The water balance model of the middle reaches of the Heihe River Basin with an NSE coefficient of 0.59.The model can well describe the response relationship between surface water and groundwater,and the relationship between the inflow of Yingluoxia and the discharge of Zhengxia Gorge.4.Incorporating the midstream water balance model,an ecological stability-oriented surface water and groundwater conjunctive operation model was established in the study area.The preliminary water supply and demand balance analysis showed that the study area had a large amount of water shortage,so the model adhered to the principle of supply and demand and coordinated ecology and industry.Water,agriculture,domestic and other water resources,under limited water resources,use sufficient water-saving measures and industrial structure adjustment measures to achieve ecological restoration,maximize the efficiency and benefits of water resources,meet the development scale of various industries,and achieve sustainable water resources The overall goal of utilization is solved by model calculation,and a conjunctive operation scheme for ecologically stable surface water and groundwater in the desert oasis of the Heihe River Basin is proposed.After optimization and control,the total water distribution in the study area in 2035 is 2.449 billion m3,of which the surface water distribution is 1.82 billion m3,the groundwater distribution is 629 million m3,and the agricultural,industrial,domestic and ecological water distribution is 831 million m3 and 159 million m3,139 million m3,1.32 billion m3;the total water distribution in 2050 is 2.46 billion m3,of which the surface water distribution is 1.82 billion m3,the groundwater distribution is 640 million m3,and the agricultural,industrial,domestic,and ecological water distribution are respectively 653 million m3,184 million m3,172 million m3,1.451 billion m3;the proportion of industrial benefits within the economic system gradually increased,the economic benefits of the research area gradually increased,and the area of natural oasis in the downstream desert oasis area continued to expand,which could basically be restored to the target year Level to achieve ecological stability in the desert oasis area.