Research On Driving Mechanism And Coupling Modeling Of Water Cycle In Strong Human Activity Area

The process of water cycle is the basis of regional water resources evolution.Water process for natural cycle includes precipitation,runoff,evaporation and other elements.In recent years,under the influence of global climate change and increasingly fierce human activities,the water cycle process is not only affected by natural factors,but also by human activities.The water cycle model is also moving towards the dual water cycle model of “natural-society”.China ranks first in the world in terms of population and is also the largest developing country in the world.Due to the growth of population and the high development of economy,China is one of the countries with the most prominent water resources problem in the world,and the per capita water resources amount is only about one fourth of the world average level.Jing-Jin-Ji district is the capital economic circle of China,including Beijing,Tianjin and Hebei Province.It is the political,economic and cultural center of China.At the same time,it is located in the Haihe River Basin,which is seriously short of water resources in China,and is also one of the areas with the strongest impact of human activities.The dualistic evolution of water cycle is particularly obvious in Beijing Tianjin Hebei region.Although the South-to-North Water Transfer Project has relieved the regional water pressure to a certain extent,there are still problems in the overall water security and spatial balance of the region.The problem of water resources in Jing-Jin-Ji district can be attributed to the imbalance of water cycle process.In order to ensure the sustainable development of the region,the regional water cycle process should be regulated.The basis of regional water resources regulation is to quantitatively analyze the water cycle flux and its change mechanism under the changing environment.At the same time,it is the key factor to accurately identify the driving factors in the evolution process of effluent circulation.In the process of social water cycle,the main driving factors at the social dimension mainly include population and economic factors,and the effects of these two kind of factors deviate from the gradient of natural water cycle process.For the natural water cycle process,water is a regional evolution from top to bottom,from high to low,while the process of human activities is to extract water resources from high places.Therefore,the establishment of the mathematical expression of the key process of the dual water cycle,analysis of the spatial and temporal status of regional water security and corresponding regulation can provide the corresponding basis for regional water resources management.In this study,the multi-year variation of water cycle in Jing-Jin-Ji district was analyzed,the method of trend test and cross wavelet transform were used to analyze the regional multi-year variation.Further,the coupling calculation method of dual water demand elevation in strong human activity area was explored and its rationality was analyzed.Aiming at the calculation of social water demand elevation,this study adopts the idea of energy conversion,which optimizes the problems of large spatial scale and lack of theoretical formula in the existing research to a certain extent.In this study,the idea of classical physics was used to calculate the spatial distribution of regional social elevation.On this basis,the method of comprehensive index method and Lorentz curve were used to analyze the water security and spatial equilibrium under the regional dual water cycle mode.Finally,taking 2035 as the target year,nonlinear programming was used in this study to control the water security and spatial balance in Jing-Jin-Ji district.The results show that the influence of climate factors on the macro performance of regional water cycle elements was not significant after 2000.On this basis,this study uses the theory of water demand field to construct the water demand pattern distribution map of Jing-Jin-Ji district from 2000 to 2015.The results showed that the water demand pattern of Jing-Jin-Ji district has changed significantly over the years,which was mainly reflected in the significant increase of water demand intensity in Beijing and Tianjin.At the same time,this study used a number of indicators of social development to construct the social development intensity map of Jing-Jin-Ji district from 2000 to 2015.Through comparative analysis,it can be seen that social and economic development is the driving factor of regional water demand change.Among them,in the early 20 th century,the acceleration of urbanization and the growth of urban population were the main driving forces to change the regional water demand pattern.However,in recent years,due to the slowdown of urbanization,the added value of the tertiary industry has become the main driving force of regional water demand pattern change.The spatial distribution of social water demand elevation based on energy conversion was reasonable,and the coupling of social water demand elevation and physical geography elevation was used for confluence calculation.The results showed that human activities had great impacts on regional confluence,and the results of coupling elevation confluence were closest to the actual situation,which better reflects the impact of human activities on regional water cycle.The results showed that the overall situation of water security in Jing-Jin-Ji district was well,but the spatial balance is poor.The water security and spatial balance of JingJin-Ji district could reach a good state after regulation.