Assessment Of Surface Water Resources And Climatic-Ecological-hydrological Regionalization In Large-scale Areas

Under the influence of global changes and human activities,the imbalance and unsteady characteristics of the terrestrial water cycle have increased,which directly affects the amount and distribution of water resources.Changes in global surface water resources are directly related to the evolution of the natural environment and development of the social economy.The aim of this study is to carry out climatic-ecological-hydrological regionalization(CEHR)and surface water resources assessment in large-scale areas.Firstly,the climatic zones and climatic-ecological zones were regionalized in large-scale areas.Based on climatic-ecological regionalization,restoration and transplantation of water yield coefficients were carried out.On this basis,the surface water resources were assessed and the evolution was analyzed.Finally,based on climatic-ecological regionalization and surface water resources assessment,the CEHR was regionalized.The main contents and conclusions of this paper are as follows:(1)A basic database of key global indicators was constructed,and and climatic-ecological zones were regionalized in large-scale areas.First,a basic database related to global climate,ecology and hydrology was constructed.Data mining and assimilation technology was used to obtain global monthly rainfall and temperature data of 1 km×1 km grid from 1960 to 2016,1-4 level river network and water resources zones dataset,and multi-dimensional spatial-temporal topography and land cover dataset.Based on the Koppen climate classification criteria,climatic index was selected to regionalize the world into 13 climatic zones.On this basis,13 indicators related to the topography,vegetation characteristics and soil type were selected,and the unsupervised classification algorithm was used to regionalize the world into 229 climatic-ecological zones.The spatial and temporal distribution characteristics of climatic regionalization indicate that the climatic characteristics of eastern North America,southern Europe,northern Asia,and central Australia are more sensitive,and the climatic characteristics have changed significantly over many years.(2)The restoration and transplantation techniques of water yield coefficient were proposed,and the distribution characteristics of water yield coefficients in large-scale areas were revealed.A dataset of distributed population and global water withdrawal from 1960 to 2017 was produced.The population dataset contains 214 countries and 1805 provinces(or regions)and the water withdrawal dataset contains 214 countries and 616 provinces(or regions).In 2017,the global total water withdrawal is about 4.2 trillion m3,and the total water withdrawal in all continents is increasing significantly.Based on climatic-ecological regionalization,through the restoration of water yield coefficient(WYC)and parameter transplantation,the water resources assessment parameters in ungauged regions were obtained.The comparison of the parameter transfer methods shows that the combined method of coupling space proximity and physical similarity can effectively improve the accuracy of parameter transfer.The analysis of the spatiotemporal changes of the WYC shows that the regions with large water yield coefficients are mainly distributed in southwest China,the west coast of North America,the Amazon basin of South America,and northern Europe.In addition,from 1960 to 2016,the WYC in parts of North China and Southwest China,northern North America,and central Africa showed a decreasing trend.(3)The evolution of surface water resources in large-scale areas in the past 60 years was revealed,and its nonstationary characteristics were analyzed.Based on the WYC,the assessment of surface water resources was carried out for 60,564 level-4 water resources regions worldwide.The verification of the calculation results by the data of the China Water Resources Bulletin,relevant research data of the continents,and per capita surface water resources data of 72 countries shows that the results fit well,and the WYC method can accurately estimate surface water resources in large-scale areas.From 1960 to 2016,the multi-year average of the total global surface water resources was approximately 41.058 trillion m3.In addition,there are both significant decreasing trends of surface water resources in North America and Africa,and the global total surface water resources have a significant decreasing trend.Meanwhile,the surface water resources of Africa,North America,South America,and Oceania have significant nonstationary characteristics,while the nonstationary characteristics of surface water resources in Asia and Europe is insignificant.(4)The CEHR was regionalized in large-scale areas,and the development and utilization characteristics of global water resources were analyzed.Based on the climatic-ecological regionalization,the characteristics of water yield and water resources development and utilization are selected as the indexes to regionalize the CEHR in large-scale areas,and the world was regionalized into 2561 zones.In addition,the global water resources development and utilization characteristics were analyzed,and the results shows that the surface water resources development and utilization rates in Asia,Africa,Europe,North America,South America,and Oceania were approximately 19.4%,6.5%,11.7%,10.5%,2.1%,and 1.6%,respectively.In the past 60 years,the surface water resources development and utilization rates in Asia,Africa,South America and Oceania has been increasing,which have shown a trend of first increase and then decrease in Europe and North America.Meanwhile,from 1960 to 2017,the water consumption per 10,000 dollars of GDP decreased from 42400m3 to 493.8m3 in China,but there is great water saving potential compared with developed countries such as the United Kingdom,France,and the United States.The main innovations of this study are reflected in three aspects:(1)For basic data,based on the distributed computing and multi-model interpolation method,a dataset of global meteorological,land cover,vegetation,soil and hydrological monitoring were integrated.A dataset of global river networks and corresponding water resources zones divisions and a dataset of distributed global population and water withdrawal were integrated and produced.(2)For the theory and technology,the regionalization index,criteria and methods of large-scale regional climatic zones,climatic-ecological zones,and climatic-ecological-hydrological zones were constructed.The optimal parameter transfer method for ungauged regions and the method of surface water resources assessment and nonstationary analysis in large-scale areas were proposed.(3)For the application and achievement,the global climatic zones,climatic-ecological zones and climatic-ecological-hydrological zones were regionalized,and the distribution characteristics of the regionalization were analyzed.The parameters for global surface water resources assessment of level-4 water resources zones were obtained.The global surface water resources assessment and nonstationary analysis were carried out,and the global water resources development and utilization characteristics were analyzed.