| Water is not only a material resource for maintaining life and sustainable development of ecosystem,but also an important strategic resource for the development of human society and economy.With the rapid development of society and economy,the contradiction between water for social and economic development and water for maintaining healthy ecosystems has become more and more prominent and the situation of predatory exploitation of water resources has occurred from time to time,resulting in the deterioration of regional ecological environment.It is of great significance to study the hierarchical requirement of regional ecological water requirement for ensuring the harmonious and sustainable development of regional ecological environment and human society.Based on the status quo of ecological environment in Beijing-Tianjin-Hebei region,this paper puts forward the concept of hierarchical ecological water requirements,which can be divided into minimum water requirements,suitable water requirements and ideal water requirements according to the variation characteristics of ecological water requirements in different years and at different levels.The connotation of different levels of ecological water requirement was expounded.In terms of specific calculation objects,the integrated calculation of ecological water requirement in Beijing-Tianjin-Hebei region was carried out from three aspects of river course,reservoir,lake and wetland,which fully reflect the water requirement of different water ecosystems and effectively represent the total ecological water requirement in Beijing-Tianjin-Hebei region.Based on Google satellite images and 91 weitu,we measured the length and width of 40 main rivers and primary tributaries in the whole Beijing-Tianjin-Hebei region,extracted the water surface area of 62 reservoirs,lakes and wetlands,and analyzed the water exchange relationship among different water requirements.The main river network map of Beijing-Tianjin-Hebei region was drawn,which effectively solved the problem that it was difficult to obtain a large amount of basic data for the calculation of ecological water requirements in Beijing-Tianjin-Hebei region.In the specific calculation,the functional method of river ecological water requirements calculation is used to calculate the river ecological water requirements in different levels.The minimum,suitable and ideal ecological water requirements in Beijing-Tianjin-Hebei region is 3.418 billion m3,4.520 billion m3 and 5.827 billion m3,respectively.The ecological water requirements of reservoirs and lakes in Beijing-Tianjin-Hebei region was calculated by using the functional method of wetland ecological water requirements.It is calculated that the total ecological water requirements of reservoirs in Beijing-Tianjin-Hebei region is 397 million m3,and the minimum,suitable and ideal ecological water requirements of main lakes and wetlands are 500 million m3,703 million m3 and 1.109 billion m3 respectively.Based on the river ecological water requirements,wetland ecological water requirements and river wetland repeated ecological water requirements under different water requirements levels,the minimum,suitable and ideal ecological water requirements in Beijing-Tianjin-Hebei were calculated as 4.281 billion m3 and 5.437 billion m3,7.001 billion m3,respectively.Then the index was obtained by introducing the ecological water requirements rate,the minimum ecological water requirements rate of Beijing-Tianjin-Hebei is 39%,the suitable ecological water requirements rate is 49%,and the ideal ecological water requirements rate is 63%.That is,under the conditions of meeting the minimum,suitable and ideal ecological water requirements,the total local ecological water requirements account for about 40%,50%,and 60%of the total surface water resources respectively.The research conclusions can provide a reference threshold for the estimation of regional ecological water requirements in northern urban agglomerations. |
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