Multi-Scenario Simulation Of Water And Land Resources Allocation Scheme In Guanzhong-Tianshui Economic Region Based On GIS

Water and land resources are the material basis for human survival and development,with the development of science and technology and social economy,the degree of human utilization of water and land resources has continued to deepen,and the pressure of population growth on water and land resources is increasing,causing various ecological and environmental problems.The No.1 document of the Chinese Central Government in 2011 pointed out that“water is the source of life,the key to production,and the foundation of ecology”,the“13th Five-Year Plan”also proposes to adhere to the strictest system of cultivated land protection,stick to the red line of cultivated land,promote land remediation,and promote the coordinated development of green agriculture and urban and rural areas.Therefore,the comprehensive utilization and optimal allocation of land and water resources is one of the important issues that need to be solved urgently for China's national development.The study takes the Guanzhong-Tianshui Economic Region as the research object based on the GIS and RS technologies,and uses the weather data of the main meteorological sites,remote sensing image,DEM and socio-economic data of the study area as the research data.The paper choose the water and land carrying capacity(WCC and LCC)and the water and land carrying index(WCCI and LCCI)models to evaluation the spatial and temporal differences of water and soil resources carrying capacity in the study area from 2006 to 2015 firstly;and then using the Autoregressive Integrated Moving Average Model(ARIMA)and Neural Network Model(BP)to predict the socio-economic water consumption in the research area in 2020 and2025,the CA-Markov model is used to simulate the spatial distribution of land use in the study area in 2020 and 2025.Basised on the grey linear programming(GLP)method,the study uses the land resource type as the decision variable,take the maximize sum of ecological and economic benefits as the objective function,and take the different water supply and demand scenarios as constraints,an eco-oriented multi-objective scenario comprehensive allocation scheme for water and land resources was established which is based on different water resources abundances(low flow year,middle flow year,abundant flow year)and different ecological water demand levels.The research has important practical significance for realizing the efficient use of regional water and soil resources,and is conducive to promoting the development of the western region and the economic development of the“Belt and Road”.The research results can provide scientific reference for relevant departments to carry out land resource remediation and formulate water resources optimization scheduling scheme.The main conclusions are as follows:(1)The carrying capacity of water and soil resources is different in spatial and temporalThe water and soil resources carrying capacity of Guanzhong-Tianshui Economic Region is at different levels of overload or critical overload.On the spatial scale,the urban areas with overloaded land resources are Yangling District,Xi'an City,Shangluo City,Tongchuan City and Tianshui City.Human-grain balance areas are Baoji City,Weinan City and Xianyang City,and there is no grain surplus area;the water resources carrying capacity is overload in all regions,and there is an imbalance problem between water resources and land resources in different regions.On the time scale,from 2006-2010 to 2011-2015,land resources carrying capacity is deteriorated in the cities of Xi'an,Xianyang,Baoji,Weinan,Shangluo and Yangling,land resources carrying capacity is improved in the cities of Tianshui and Tongchuan,during this period,the number of serious overloading cities increased by 2,the obvious overloading cities decreased by 3,there are three new critical overloading cities added,and the balance surplus cities decreased by 2;from 2006-2010 to 2011-2015,water resources carrying capacity is deteriorated except for Xianyang,from critical overload to overload,and the water resources carrying capacity of other areas is improved,maintaining the original bearing capacity level,which belongs to the water overload area.(2)The use of water and land resources is changes greatly in spatial and temporalThe study uses a combination of singular value decomposition(SVD),Autoregressive Integrated Moving Average Model(ARIMA)and Neural Network Model(BP)to predict the socio-economic water requirements of the study area in 2020 and 2025:which is 6.171 billion m~3 and 6.252 billion m~3 in 2020 and 2025 respectively.The socio-economic water demand is increasing with time.Which is increased by 0.51 billion m3 in 2025 compared to 2015,with an average annual growth rate of 0.87%.The overall trend of land use change in Guanzhong-Tianshui Economic Region is as follows:arable land,grassland,and unused land are gradually reduced;forest land,construction land,and water areas have gradually increased;The changes of arable land,forest land,grassland and construction land are more significant.From 2015 to2025,the area of cultivated land decreased by 3,825.80km~2,it should be strictly controlled he loss of cultivated land resources in the future;the area of grassland decreased by 2,759.35km~2,which mainly converted into construction land and forest land;the unused land area decreased slightly;the forest area increased by 3727.73 km~2,mainly distributed in the Chinese national Ziwuling Forest Reserve,the Chinese national-level Liupanshan Forest Reserve,and the Chinese provincial Qinling-Guanshan Forest Reserve.The construction land increased by2130.06km~2,mainly due to the development of regional urbanization;The water area increased slightly,which is related to the implementation of regional water diversion projects and the construction of artificial reservoirs.(3)The scenario simulation projects of land and water resources allocation exixts diversity and probability in different planning yearsBased on different water supply models and different water demand levels,the study obtained 21 schemes of water and land resource allocation,of which 11 are available.Under the current year,the low-allocation scheme and the medium-allocation scheme have available solutions,the water supply situation under the high-allocation scheme cannot meet the ecological environment demand of the land resource system.It can be estimated that in yare of2020,the water resources supply situation of the study area in abundant flow year can meet the different ecological environment water demand level of the land resource system,which indicates the low,medium and high allocation project all can be realized at the abundant year;in middle flow year,the water supply situation can meet the minimum ecological water demand level of the land resource system but can not meet the higher level of ecological water demand,which indicates that just the low-allocation scheme can be realized at the middle year;in low flow year,the water resources supply situation can not meet the ecological environment needs of the land resource system,which indicates that there is no allocation scheme can be realized at the low year.It can be estimated that in yare of 2025,the water resources supply situation of the study area in in abundant flow year can meet the different ecological environment water demand level of the land resource system,which indicates the low,medium and high allocation project all can be realized at the abundant year;while in the year of middle flow and low flow,the water resources supply situation can just meet the minimum ecological water demand level of the land resources system,but still can not meet the higher level of ecological water demand,which indicates that only the low-allocation scheme can be realized at the middle and low year.The characteristics and innovations of the research are as follows:(1)The study uses a combination of singular value decomposition(SVD),Autoregressive Integrated Moving Average Model(ARIMA)and Neural Network Model(BP)to predict the socio-economic water requirements of the study area in 2020 and 2025 and achieved ideal prediction results,providing basic data for optimal allocation of soil and water resources.(2)The paper discusses the diversity and probability of the multi-scenario simulation of water and land resources optimal allocation scheme in the simulation of abundant flow year,middle flow year,low flow year,and different levels of ecological water needs of the land resources system,at the same time,CA-Markov model is used to simulate the spatial distribution of land use,which fully reflects the characteristics of multi-scenario simulation and spatial-temporal scale synthesis.