Study On Stochastic Simulation Of Water Supply And Demand And Evolution Characteristics In The Luhun Irrigation District

Luhun irrigation district,which is a key irrigation district in Henan province of China,has made outstanding contributions to the water security,economic development and social stability of Henan province.In recent years,with the acceleration of economic and social development,the contradiction between water supply and demand has increased dramatically in Luhun irrigation district.In order to avoid the occurrence of uneven drought and flood in irrigation district as far as possible,it is of great significance to clearly understand whether the supply and demand of water resources in irrigation districts match perfectly.However,due to the uncertainty of water supply and demand situation and the limitation of the available historical time series in irrigation districts,how to effectively capture the correlation and evolution law hidden behind the uncertainty of hydrological factors is challenging to the traditional hydrological certainty theory.In this paper,a stochastic simulation model of water supply and demand under different water supply conditions is constructed.The characteristics of state evolution of water supply and demand in irrigation districts are explored.The main contents and achievements of the research are as follows:（1）Correlation coefficients was used to explore the contemporaneity and short-term dependence of water supply and demand variables characterizing natural rainfall and man-made irrigation in the irrigation district based on historical annual rainfall,ET₀ and man-made irrigation water.Based on Copula function and Markov method,a two-dimensional Monte-Carlo stochastic simulation model with both temporal and contemporaneous dependence relationship is proposed.It has been verified that original probability and statistical characteristics are well kept in the simulated time series under the two water supply conditions.（2）Based on the stochastic simulation data,the Copula function was used to construct the risk model of water resource shortage in irrigation areas,and the joint probability and conditional probability of water shortage risk under different water supply conditions were calculated.Compared with the result based on the historical data,the risk of water resource shortage obtained by stochastic simulation is slightly higher,so it can provide more conservative guidance for water resource planning in irrigation districts.（3）Markov method was used to construct joint state transition matrix under different water supply conditions in the irrigation district based on stochastic simulation data,and the evolution characteristics of water supply and demand state under natural rainfall and artificial irrigation conditions were analyzed.Therefore,simulated data to some extent compensate the state transition analysis of the historical data due to the insufficient sequence length.By comparing the transfer probability of univariate water supply or water demand,it can be concluded that it is more practical to study the evolution law based on the joint variable of water supply and demand.Based on this analysis,effective countermeasures are put forward to deal with the imbalance between water supply and demand in the irrigation district in the future.