Water Resource Management And Risk Regulation In Irrigation Districts Under Changing Water Supply And Demand

At present,China is in a new stage of social development,raising the requirements for sustainable development in various fields.In the new period,the demand for food is increasing and the problem of water shortage is becoming more and more serious,so solving the problem of water shortage is a basic priority for the sustainable development of irrigation areas.On the one hand,optimizing the allocation of limited irrigation water in large irrigation areas to improve the efficiency of water resources utilization and avoid the risk loss caused by water shortage,and on the other hand,using the operation mechanism of water rights market in small scale to promote the efficient flow of water rights and establish a complete water allocation and distribution mechanism is an effective means to guarantee water security,food security and promote the sustainable development of irrigation areas.In this paper,we take the typical irrigation areas on the Sanjiang Plain and the Songnen Plain in Heilongjiang Province as the study area,and consider the risk losses under different levels of water supply and demand encounters for large scale irrigation areas.In addition,a risk-adjusted large-scale irrigation district water allocation scheme is used to allocate secondary water rights to the lower distribution system.A sustainable integrated water price is also developed,and the Changgang irrigation district water market is used to drive the efficient flow and rational allocation of water rights,and a complete multi-scale water allocation mechanism is constructed through the combination of the two.The main research contents and conclusions are as follows.(1)Parameter estimation and line optimization for runoff and ET0 in the Jinxi irrigation area of the Three Rivers Plain,and the optimal linkage function are preferred to calculate the probability of combined supply and demand water abundance and depletion encounters.The probability of the same flat water year is 28.79%,the frequency of synchronous encounter is 31.49%,and the frequency of asynchronous encounter is 68.51%.Based on the probability of water supply and demand encounter,a water allocation risk control model based on the change of water supply and demand was constructed.The model takes into account the uncertainty of water supply and demand,the risk loss of extreme conditions and the uncertainty of several hydrological parameters to enhance the stability of the optimal water resources allocation system.The model considers the maximum economic benefits of the irrigation district while providing recourse for water shortages that fail to meet established targets.As the decision maker’s requirement for risk aversion increases,the risk loss of the system increases from RMB 104 million to RMB 114 million,and the system benefit decreases from RMB 1.518 billion to RMB 1.508 billion.As the probability of violation increases,the optimal water allocation increases from 510.7 to 554.65 million m3,the system gain increases from RMB 1.395 billion to RMB 1.575 billion,and the risk loss decreases from RMB 127 million to RMB 107 million.A variety of irrigation scenarios were derived by weighing the system gains and expected losses under different scenarios.(2)A sustainability evaluation index system for irrigation water in the irrigation district was constructed,and ecological priority indicators were added to the index system,including green water footprint,blue water footprint,gray water footprint,carbon footprint,and water quality.The comprehensive evaluation results were 0.080,0.065,0.065,0.102,0.066,0.108,0.108,0.101,0.113,0.101,0.090.The comprehensive evaluation results for the four water identification zones were0.0702,0.0849,0.0917,0.0859,reflecting the relative degree of sustainable development in each identification area.This is used as the water price coefficient combined with the true value of water resources to obtain the water rights trading price.(3)A two-layer water rights allocation model driven by water rights trading is constructed.The model is based on the Stackelberg-Nash-Cournot equilibrium model to build a decision framework for water rights allocation between the irrigation district administration and managers of different water identification zones,which effectively solves the complex problems in the initial allocation and reallocation of water rights.The application of the model in the Changgang Irrigation District of the Songnen Plain showed that the water rights allocation results were able to uncover a water rights market of up to 366.81 thousand m~3 of water rights available for transfer and facilitate water rights trading of up to 309.47 thousand m~3 compared to the current brutal water allocation model.areas with water rights savings profited from water rights trading of up to 29.23 thousand m~3.This demonstrates the huge potential of the water rights trading market.The standardization of the water rights market can both enhance the economic benefits of irrigation areas and promote the establishment of a water crisis awareness among water users.Its model of water rights allocation can provide an important reference for the construction of water rights markets in irrigation areas.