Analysis Of The Impact Of Strong Human Activities On Water Resources In The Luanhe River Basin

The variation of water cycle under the interference of strong human activities is one of the hot topics of current research,and it is also a difficult problem that needs to be solved urgently in hydrology.In the past three decades,the influence of human activities in the Luanhe River Basin has been increasing,the vegetation coverage in the basin has been increasing under the influence of ecological projects such as soil and water conservation,and the contradiction between water supply and demand driven by urbanization and agricultural irrigation has intensified.The development and utilization rate of water resources in the basin exceeds 86%.The sharp drop in surface runoff and seawater inflow has seriously affected the healthy and stable development of the regional economy.Based on this background,this paper focuses on the evolution of water resources under the influence of strong human activities,analyzes the change characteristics of hydrometeorological elements such as precipitation and runoff,and summarizes the changes in the underlying surface conditions of the basin and the development and utilization of water resources.Construct the Luan River Basin Distributed Water Cycle Model(Water Allocation and Cycle Model),simulate and evaluate the amount of water resources in the Luan River Basin and its changes in the past sixty years,and quantitatively analyze the changes in land use,vegetation coverage,and the impact of water resources development and utilization on water resources in the Luan River Basin.It also predicted and analyzed the evolution trend of water resources in the future,so as to provide scientific and technological support for the management and regulation of water resources in the basin and the sustainable development of the region.The main conclusions of this study are as follows:(1)The temporal and spatial variation characteristics of hydrometeorological elements such as precipitation,potential evapotranspiration,and runoff in the Luanhe River Basin were systematically analyzed.From 1956 to 2018,the precipitation in the Luanhe River Basin generally showed a downward trend.The average rainfall depth for many years was 537.4 mm.The spatial distribution of precipitation in the basin was uneven,showing a trend of increasing from northwest to southeast.The precipitation in the plain area was greater than that in the mountainous area..The overall potential evapotranspiration is on the rise.The average potential evapotranspiration for many years is 785.0 mm.The spatial distribution shows a trend of decreasing from northwest to southeast.The northern mountainous area is significantly larger than the southern plain area.The measured runoff in the Luanhe River Basin shows a significant downward trend.The runoff of each sub-basin is quite different,and the distribution is uneven during the year.The runoff during the flood season accounts for more than 60%of the annual runoff,and the spatial distribution shows a continuous increase from northwest to southeast.The runoff coefficient of 80%of the sub-watersheds in the basin shows a decreasing trend,and the runoff coefficient in the flood season is greater than that in the non-flood season.(2)Summarized and analyzed the changing laws and trends of land use,vegetation coverage,and water resources development and utilization in different subregions of the Luanhe River Basin.From the perspective of the whole basin,forest land is the largest,followed by cultivated land and grassland.From the perspective of sub-regions,the area changes are:mountain area,hilly area,plateau area,and plain area.In the past 20 years,the vegetation coverage in the Luanhe River Basin has shown an overall increasing trend,and the spatial distribution is characterized by "low in the northwest and southeast,and high in the central mountainous area".From the perspective of vegetation change trend,the vegetation coverage in the mountainous and hilly areas of the basin has been significantly improved,the plateau area is slightly improved,and most of the plain area is slightly degraded.The industrial and agricultural production in the basin has developed rapidly.The total designed irrigation area exceeds 2 million mu,the average annual water supply is 3.590 billion m3,and the annual average agricultural water consumption is 2.333 billion m3,accounting for 65.0%.(3)The Luanhe River Basin Distributed Water Cycle Model(WACM)was constructed to simulate and evaluate the precipitation,surface water,groundwater and total water resources in the basin from 1956 to 2018.The annual average precipitation in the Luanhe River Basin is 29.28 billion m3,showing a significant decreasing trend as a whole,of which 22.52 billion m3 in the mountainous area and 6.76 billion m3 in the plain area,the precipitation in the mountainous area is significantly greater than that in the plain area.The amount of surface water resources in the basin is 3.93 billion m3,showing a significant decline trend as a whole.Among them,the amount of surface water resources in the Luanhe mountainous area is 3.23 billion m3 and that in the plain area is 700 million m3.The amount of groundwater resources in the basin is 3.82 billion m3,showing a decreasing trend as a whole.Among them,the amount of groundwater in the Luanhe mountainous area is 2.93 billion m3 and that in the plain area is 890 million m3.The amount of water resources in the basin is 5.58 billion m3,showing an obvious decline trend.The total amount of water resources in the Luanhe mountainous area is 4.14 billion m3,and that in the plain area is 1.44 billion m3.The water resources in the mountainous area are larger than that in the plain area.(4)Based on the constructed distributed water cycle model,the impact of land use change,vegetation coverage change,and water resource development and utilization on the water resources in the Luan River Basin was quantitatively analyzed,and the evolution of water resources in the Luan River Basin under different scenarios in the future was simulated and predicted.trend.The results showed that:① Land use change aggravated the attenuation of water resources in the Luanhe River Basin,and the baseline scenario reduced the total water resources by 280 million m3 compared with the land use conditions in 2000.②The increase of vegetation coverage leads to the attenuation of water resources in the basin.The high coverage P2 scenario reduces the water resources by 550 million m3 compared to the P0 scenario.③Reducing the amount of agricultural irrigation water will significantly reduce the soil water content,and it will be less likely to run off and infiltrate to recharge groundwater after precipitation,thereby indirectly leading to a reduction in the amount of water resources.Compared with the baseline scenario,the amount of water resources in the basin under the C4 scenario decreased by 690 million m3.④Under the premise of maintaining the status quo of irrigation and groundwater burial depth,set up a comprehensive plan to predict the future water resources.The results show that under the three climatic conditions,the amount of water resources is the largest under the conditions of high urban and existing vegetation,and the smallest under the condition of medium urban and optimal vegetation.Among them,the maximum amount of water resources in the F10 scenario is 6.15 billion m3,the minimum in the F3 scenario is 5.18 billion m3,and the most probable scenario is the F8 water resource volume of 5.4 billion m3,a reduction of 280 million m3 compared with the baseline scenario.