Spatial Equilibrium Evaluation Of Water Resources Allocation In Erhai Irrigation Area Based On Gini Coefficient

Spatial equilibrium analysis of water resources allocation results is an important part of scientific water resources allocation work,and is an important tool to measure the spatial equilibrium of water resources.In order to evaluate the spatial equilibrium of the water resources allocation results in the Erhai Irrigation District of Yunnan Province,this paper relies on the existing water resources allocation results data and adopts the analysis method combining Lorenz curve and Gini coefficient.The Lorenz curves were calculated and the Gini coefficients were calculated,and finally,the spatial and temporal distribution of water resources in the Erhai Irrigation Area and its changing characteristics were quantitatively analysed.The imbalance index(I)was then used to analyse the imbalance between the total water resources and the economic and social development(water demand,population,industrial value added and irrigated area)of the 10 irrigation units in the Erhai irrigation area.The imbalance index values for each factor were obtained to reflect the match between water resources and socio-economic development indicators in each unit of the Erhai irrigation area.The results were compared with the Gini coefficient analysis.The results show that:(1)the spatial balance of water demand in each hydrological year is as follows: industrial water demand > urban domestic water demand > rural domestic water demand > agricultural irrigation water demand,the Gini coefficients of industrial and urban domestic water demand in the current year are 0.58 and 0.54 respectively,and in the planning year they drop to 0.38 and 0.50,so the balance of these two types of water demand has improved;the Gini coefficients of rural domestic water demand and agricultural irrigation water demand in the current year are 0.29 and 0.29 respectively.In the planning year,the total water demand decreases by 25.8%,of which water demand for agricultural irrigation decreases by 16.3%,water demand for urban living increases by 10.5%,industry increases by 5%,and water demand for rural living remains unchanged.The difference in spatial balance of water supply side in each hydrological year is as follows: current year: water supply from diversion and lifting project > water supply from groundwater project > water supply from water storage project > water supply from Erhai water lifting project;planning year: water supply from diversion and lifting project > water supply from external water transfer project > water supply from water storage project > water supply from Erhai water lifting project > water supply from agricultural receding water comprehensive utilization project,the Gini coefficient of each project in the current year is all greater than 0.4,the spatial balance of water supply is poor.In the planning year,except for the Gini coefficient of the water diversion project,the Gini coefficient of the other projects decreased slightly;in the planning year,the water supply from the water diversion project and the comprehensive use of agricultural water withdrawal project were included in the water supply plan,so that the water supply from the water diversion project and the water withdrawal project of the Erhai Sea decreased by 13.03% and 6.96% respectively compared with the current situation,while the water supply from the water storage project remained unchanged at about 29.5%.The water supply from the external water transfer and the comprehensive use of agricultural receding water projects is 8.1% and 12.5% of the total water supply respectively.In the planning year,the water supply pressure of each project is reduced,the water supply is more scientific and reasonable in the spatial scope,and the configuration of each water supply project reaches the optimal degree.(3)The analysis of the imbalance index shows that,except for the I-value of water resources and irrigated area,which increases in 2035,the I-values of water resources and water demand,total population,urban population,rural population and industrial value added all decrease,and this pattern of change is consistent with that of the Gini coefficient.The combination of the two indicates that the 2035 water resources allocation is effective,and to a certain extent the balance of water allocation in the irrigation area has been improved,reducing the contradiction between socio-economic development indicators and water resources replenishment,in line with sustainable development.The combination of the Gini coefficient,Lorenz curve and locational entropy can reveal the rationality and equilibrium of water resources allocation in large irrigation areas,while the imbalance index and Gini coefficient are consistent,and the two analysis methods can be verified to complement each other,further illustrating the scientific nature of the method chosen for the spatial equilibrium study and the rationality of the water resources allocation results.