Impacts Of Climate Change On Water Resources In Jing-Jin-Ji Region And Countermeasures

The Beijing-Tianjin-Hebei border is connected by water and veins,with sharing the continental monsoon climate.Due to the combined effect of the evolution of natural environment,climate change and human activities,regional water scarcity has become a huge obstacle to the coordinated and sustainable development of Beijing-Tianjin-Hebei region.This study will systematically analyze the water cycle and evolution of the Beijing-Tianjin-Hebei region,and thus to reveal the impact of climate change on the water resources of the Beijing-Tianjin-Hebei region,and to propose adaptive responses to water resources in this region.It will help deepen the understanding of the change of water cycle over Beijing-Tianjin-Hebei region in response to the climate change.Meanwhile,this study has important practical significance for the realization of ecological civilization construction of sustainable development of water resources in Beijing,Tianjin and Hebei.In this paper,the observed data of meteorology,hydrology and geology,NCEP/NCAR and ERA-40 reanalysis data and ESA CCI SM satellite remote sensing data wi th high spatial and temporal resolution are selected.Various mathematical statistics me thods,evaluation indicators,evaluation and prediction models are used to analyze the variation characteristics of precipitation and temperature in Beijing-Tianjin-Hebei region.Evapotranspiration(evapotranspiration)and soil moisture changes and their influencing factors reveal the evolution trend of water resources and water cycle in Beijing-Tianji n-Hebei region,and quantitatively assess the impact of climate change and human acti vities on water resources changes in Beijing-Tianjin-Hebei region.By using the Reg CM4 model,the present study predicts the recent variation of average air temperature and projecti on in the 21 st century with a RCP4.5 medium GHG emission.We also analyze the future cha nge of the surface water and the hidden resources by combining econometric mode.The adapt ive policies to future climate change are proposed.Major conclusions are as follows:(1)The temperature in the Beijing-Tianjin-Hebei region shows a significant upward trend in the past 56 years.A consistent upward trend can be observed over the three sub-regions.A sudden change of the temperature can be found in the early 1990 s.Different from the changes of the temperature,the precipitation shows weak downward trend.A significant sub-region difference can be observed.There is no obvious change in the northern Hebei Plateau,but the precipitation decline trend in the Jidong Plain is significant in the Beijing-Tianjin-Hebei region compared with other sub-regions.(2)The applicability of Pengman and Gaoqiao formulas in the Beijing-Tianjin-Hebei region is verified,and the phenomenon of “evaporation paradox” was found in this region.The evaporation and potential evaporation show a downward trend,while the real evaporation shows a weak upward trend.Especially after 2000,the upward trend is significant.These are consistent with the theory of evaporation complementation in previous studies.The real evaporation is positively correlated with surface water and groundwater,but is negatively correlated with temperature.(3)Analysis of the total amount of water vapor in the Beijing-Tianjin-Hebei region suggests a decreased trend in the past 56 years.Analysis of water vapor budget shows that the water vapor content is mainly concentrated below 700 h Pa in the middle and lower layers.The total water vapor budget is basically balanced and there is weak water vapor outflow.It is further found that the total amount of water vapor is the most abundant at 850-700 h Pa.Moreover,it is found that the net water vapor balance in summer is positive,and the water vapor balance is negative in spring,autumn and winter.(4)The surface water and groundwater resources in the Beijing-Tianjin-Hebei region show a decreasing trend in recent 56 years,and the reduction trend of surface water is particularly significant.It is further pointed out that both precipitation and temperature are the main factors affecting the changes of surface and groundwater resources in Beijing-Tianjin-Hebei.Quantitative analysis shows that the impact on the surface-groundwater resource change precipitation is more obvious,and the impact of human activities is greater than the impact of climate change.(5)The spatial distribution of soil moisture in Beijing-Tianjin-Hebei region is uneven,and there are obvious seasonal variations.The rising trend in summer is obvious,and the decreasing trend in winter is obvious.Soil moisture is negatively correlated with air temperature and evaporation,and positively correlated with precipitation.Precipitation is the main factor affecting soil moisture.(6)Projections indicate that the Beijing-Tianjin-Hebei region is facing the risk of warming and humidification.Annual,winter and summer average temperatures all showed a consistent upward trend.Especially the increase amplitude of temperature in summer is high as 1.2 ?.The annual average precipitation and summer precipitation in the Beijing-Tianjin-Hebei region showed an increasing trend,while the winter temperature shows an increased-decreased spatial distribution.Surface water resources in the Beijing-Tianjin-Hebei region show a weakening trend and an increased trend of groundwater resources are observed.