| Habahe County of Xinjiang is a typical cold and arid climate in the north continental temperate zone,with little rainfall,large evaporation and abundant transit surface water resources.However,due to the large terrain drop and straight river channel,the utilization rate of water resources is low.The inefficient use of water resources has become the main limiting factor for ecological restoration of economic development in this region.From 1980 to 2020,due to global climate change and rapid expansion of cultivated land,water resources extraction in Habahe County increased rapidly,and the spatio-temporal distribution of water resources changed greatly,resulting in water resources shortage,misallocation and wetland ecosystem degradation in Ketohai Wetland.Therefore,the local government is actively exploring the reuse project of wetland water replenishment and agricultural water reclamation.However,due to the lack of monitoring means and scientific guidance,the water replenishment effect is not obvious,and it still cannot effectively prevent the degradation of wetland and the reduction of biodiversity.This study sorted out the characteristics of climate change,the construction and development of water conservancy and agriculture in Habahe County in the past 40 years,combined with the water supply and water demand of Ketohai Wetland,and concluded that:(1)In the past 40 years,the replenishment water obtained by natural means such as rainfall and snow melt water has decreased,agricultural water has seriously crowded out wetland ecological water,river channel interception has increased,wetland has been in a state of water shortage for a long time,wetland ecosystem has gradually degraded,and forest coverage has decreased.(2)Around 2000,the construction of water conservancy and irrigation facilities was basically completed,and cultivated land rapidly increased from 20,700 hectares to 43,400 hectares.Agricultural water consumption increased,accounting for 98% of the county’s water consumption,and agricultural water return increased significantly.In terms of water resources replenishment,the proportion of agricultural water loss increased from 17.89% to23.53%,and the impact of human activities on the wetland became more and more severe.(3)The ecological water of the wetland is constantly crowded out,and there is a gap of110 million cubic meters between the water supplement and the water demand of the wetland.Human intervention is needed to increase the retention capacity of the wetland to surface runoff and improve the utilization rate of water resources.Therefore,in order to improve the utilization rate of water resources and the water storage capacity of wetlands,this study proposed a wetland water replenishment and restoration strategy based on micro-terrain transformation.Through the identification and transformation of wetland micro-topography,using fewer engineering measures,water blocking dikes of different heights are set at the dumping points of depressions to increase the storage volume of depressions in wetlands,improve the utilization rate of rainwater in natural ditches and agricultural backwater in drains,extend the retention time of surface runoff in wetlands,increase the surface area of wetlands and groundwater infiltration recharge.Improve the utilization rate of water resources to achieve the purpose of wetland water replenishment and wetland ecosystem restoration.In this paper,the digital elevation model is used to identify eight depression areas which can be used for water storage and micro-topographic transformation in the study area.The total area is 537.62 hectares and the water storage capacity is 8,064,300 cubic meters.The surface area and water storage capacity increased to 1084.03 hectares and 13.4845 million cubic meters,and 21,01.37 hectares and 23.9913 million cubic meters,respectively,through micro-topographic transformation of 0.5 meters and 1 meter,respectively.The surface area increased by 102%and 291%,and the water storage capacity increased by 67% and 197%.It fills up 14.3% of the water resource gap of the wetland,alleviates the water shortage of the wetland to a certain extent at a low cost,curbs the degradation of the wetland ecosystem,prolonging the retention time of surface runoff in the wetland,and provides ideas and schemes for future wetland restoration projects.In general,the surface water resources in Habahe County are relatively abundant compared with the overall level of the arid area in Northwest China.However,due to the overall steep longitudinal slope and straight river course,the transit flow of rivers is large but the ability to retain water is poor,and the utilization efficiency of water resources is low.At the same time,wetland in arid area is highly sensitive to water resources distribution and human activities,so it is required that wetland restoration and water replenishment engineering measures should reduce the impact on wetland as much as possible,improve the utilization efficiency of ecological water with less manual intervention,make full use of water resources during agricultural backwater,reservoir emptying and flood discharge periods,achieve multi-objective composite utilization of water resources and improve the utilization rate of water resources.Wetland water replenishing capacity and restoration strategy based on micro-topographic transformation significantly improves the water storage area and water storage capacity of wetland with less manual intervention and engineering amount,effectively increases the retention capacity of wetland to surface runoff,and then restores wetland area,improves wetland habitat,restores wetland ecosystem,and enhances the resilience of wetland under extreme climate.It provides ideas and basis for the increasingly strict requirements of ecological civilization construction and wetland restoration and water replenishment projects. |
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