| Beijing-Tianjin-Hebei region is an area with serious shortage of water resources,accounting for about 2.3% of China’s area,8% of China’s total population and 8.5% of China’s GDP,but its water resources are only about 0.7% of China’s.with the rapid development of Beijing-Tianjin-Hebei region,the problem of water resources is an urgent problem need to be solved.As a variable,water resources are affected by many factors,among which climate change is an important reason for the change of water resources.Based on the statistics of rainfall,temperature and evaporation in Beijing Tianjin Hebei region for65 consecutive years from 1956 to 2019,this study uses Mann Kendall,wavelet analysis and other methods to test the mutation and periodicity of climate change in Beijing-TianjinHebei region in recent 65 years.Combined with the characteristics of hydrological and geological conditions in Beijing-Tianjin-Hebei region,through parameter identification and verification,the surface underground physical distributed hydrological model of hill plain coupling is determined as the main simulation period from 2005 to 2019.Combined with the driving factors such as meteorology,boundary,reservoir regulation and storage and human activities in the water cycle in the study area,the construction of large-scale numerical model of surface groundwater coupling flow in Beijing-Tianjin-Hebei region is completed.According to the analytical results of "four water transformation",the important factors affecting the change of water resources in Beijing-Tianjin-Hebei region are attributed.Using the meteorological data simulated by the global climate system,the grid data of future climate change in the study area are extracted through downscaling processing,the regional climate change trend from 2020 to 2050 is analyzed,the boundary conditions of future climate evolution are determined,and the mountain plain prediction of surface groundwater water resources in the next 30 years.The main conclusions are as follows:(1)The matching degree between different climate models and the historical climate change trend of Beijing-Tianjin-Hebei was identified,and the consistency of historical and future change cycles of precipitation and temperature was verified.Beijing-Tianjin-Hebei region is greatly affected by human activities,coupled with a wide range of temperature control,regional climate change is obvious.It can be found from the comparative analysis of climate data between mountainous areas and plain areas in Beijing-Tianjin-Hebei that the annual average temperature in mountainous areas is about 5 °C lower than that in plain areas.However,in terms of rainfall,there is a big difference between mountainous areas and plain areas before 2000,and the maximum difference is 100 mm.After 2000,the gap continues to decrease,and gradually presents a similar trend of rainfall in the same latitude zone.This phenomenon also reflects the Beijing-Tianjin-Hebei in recent ten years to actively carry out ecological construction,plain water resources maintenance,returning farmland to forest and other measures have produced good results.(2)The influencing factors of water resources in Beijing-Tianjin-Hebei region are analyzed.For the inflow,due to the decrease of water production in the upstream area and the increase of water intake,the upstream inflow in the Beijing-Tianjin-Hebei plain area is attenuated.Long-term continuous over-exploitation of groundwater makes the groundwater resources in Beijing-Tianjin-Hebei plain area gradually depleted,groundwater level continues to decline,groundwater funnels are widely distributed,over-exploitation area is almost distributed in the whole plain area.Land use change,especially the increase in high water-consuming crops within cultivated land,directly affects the exploitation of groundwater and indirectly affects the dynamic evolution of groundwater resources.(3)An automatic connection method between MODCYCLE model and global climate model data is proposed,which expands the applicability of MODCYCLE model in future scenario prediction.Through the analysis of the future climate change trend in the study area,it is found that the spatial difference in the prediction of future temperature by various models is small.On the annual average,the increase of RCP8.5 scenario is greater than that of RCP4.5,indicating that radiation forcing has a great influence on temperature,and the spatial distribution of temperature in the study area has maintained a strong consistency with topography.(4)The effects of future climate change on the circulation and transformation of regional precipitation,soil water,surface water and groundwater systems were quantitatively studied.The change trend of ’ four water ’ transformation process in Beijing-Tianjin-Hebei region was predicted,and the future groundwater balance and water level dynamics in the plain area were evaluated.By comparing the shallow groundwater,it can be found that by2030,compared with the regional average annual precipitation of 533.1 mm from 1956 to2019,the average precipitation of multiple modes will increase by 2.06 %,and the funnel in the piedmont plain area will be significantly improved.By 2040,the average precipitation of multiple modes will increase by 2.32 %,and the groundwater funnel will be further alleviated.By 2050,the average precipitation of multiple modes will increase by 5.34 %.Based on this,the groundwater level in the Beijing-Tianjin-Hebei Plain will appear in some areas.By comparing the deep groundwater,it can be found.In 2030,the deep groundwater was recharged to some extent,but there was still a funnel at the sea entrance of Tianjin.By2040,the deep groundwater was further improved,which also shows that the precipitation has a certain lag on the regional deep groundwater recharge.By 2050,the deep groundwater again appeared a funnel.The reason is that although the precipitation increased between2040 and 2050,the groundwater recharge is still insufficient under high evaporation and agricultural exploitation.Figure [141] Table [18] Reference [183]... |
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