| Water Saving Management Contract(WSMC)is a novel market-oriented business model,which can effectually allay the pressure of regional water crisis.However,the existing relevant water-use policies need to be readjusted after the implementation of WSMC,which makes the existing regional water resources planning unreasonable.Therefore,the regional water resources under WSMC need to be reallocated.Besides,benefit-sharing WSMC is one of the main operating modes of WSMC,in which the Water Service Company(WSCO)assumes most of the investment risk.Once the risk occurs,it will cause huge losses to WSCO.Therefore,how to rationally analyze the investment risk of the benefit-sharing WSMC project also needs to be solved.The main contributions of this dissertation are shown as follows:Firstly,an uncertain multi-objective programming(UMOP)model is formulated to rationally allocate the regional water resources under WSMC,taking into account the trade-offs among benefits of water consumption while satisfying the double control actions and water environment capacity constraints.In the model,the benefits of water consumption,the cost of water supply,and other parameters are considered as uncertain variables for the case of lacking sufficient data.Then,the model is transformed into the deterministic multi-objective model via inverse uncertainty distribution,which is worked out with the non-dominated sorting genetic algorithm-II(NSGA-II).The central area of Handan City in China is taken as a case study to confirm the feasibility of the model.The results showed that the condition of water shortage has improved dramatically.Secondly,combining with the contract specification,simulations of water-saving investment allocation and water-saving benefit distribution for both the water user and the WSCO are derived respectively using Geometric Brownian Motion.Then the investment risk assessment model,which set the probability of the water service company net present value is less than zero as the assessment index,is established with Monte Carlo simulation accordingly.The optimization models for contract period designing are developed respectively with the targets of maximizing the benefit of water service company and minimizing the investment risk of the WSMC project to obtain the optimal contract periods.Based on the above study,a case study is conducted to confirm the validity of models,with the results showing that the investment risk is 53.63%.Compared with the signed six-year contract period,the contract period of pursuing the maximized benefit of the WSCO is ten years and the contract period that favors investment risk minimization is seven years,which makes the investment risk reduced by 8.63% and 10.65%,respectively.Adjusted for the guaranteed annual water savings according to the positive correlation between the guaranteed annual water savings and water price,the investment risk is reduced by 23.77%.The investment risk rises in direct proportion to the initial investment,the user's benefit-sharing percentage,and the water service company's expected rate of return.The research on the water resources optimal allocation under WSMC of this paper enrich the research methods of water resources optimal allocation and broaden the research fields of WSMC,provide the theoretical basis for urban water resources planning and management;The research on the analysis of investment risk of benefit-sharing WSMC contributes to the decision-making of water service company on investing the benefit-sharing WSMC project and designing the contract period. |
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