The Research On Some Key Issues In Water Resources Planning Considering Uncertainty

At present, the water crisis, characterized by serious contradiction between supply and demand of water resources, severe pollution, waste of water and ecological degradation, has become a major constraint on social economic development. And the key to solving water crisis is to effectively enhance the efficiency of water resource utilization, and scientifically and properly plan and manage the limited water resources. In this paper, several core contents of the water resources planning (WRP) are discussed, such as water demand forecasting, crop area planning, water resources allocation, strategic environmental assessment for water resources planning, etc. The main research contents and results are as follows:(1) A combination model for annual water demand forecast.Water demand forecast is an essential ingredient of WRP. A combination of models including wavelet transform (WT) and kernel partial least squres-autoregressive moving average (KPLS-ARMA) is proposed to explore the nonstationarity of the annual water demand series, the nonlinear relationships between water demand series and its determinants, and the high correlations among those determinants, based on which a novel forecast model is proposed for annual water demand. First, WT is used to stabilize the water demand series which is decomposed into one low-frequency series and one or several high-frequency series. Then, KPLS model is applied to simulating the low-frequency series. ARMA model is constructed for each of high-frequency series. The combined models are applied to understanding the nonstationarity and forecast annual water demand of Dalian city. The results are then compared with those from other methods. It is shown that this method, which combines advanced statistical tools (such as WT and artificial intelligence) and traditional statistical models, provides the most accurate forecast of annual water demand in the city.(2) Crop area planning. The interval fuzzy multi-objective linear programming developed by Wu is extended to an interval two-phase fuzzy multi-objective linear programming to ensure the obtained solution is always efficient. Crop area planning is a vital part of water supply and demand analysis. Influenced by climatic and socioencomic factors, it exhibits some complex characteristics, such as multi-objective and uncertainty. The proposed method is introduced and applied to optimizing the cropping structure in Dalian City, in which parameter uncertainty is described as interval number and stipulation uncertainty as fuzzy relations. The results are compared with those from the un-renewed model. It is shown that the proposed model, which introduces multiple control variables to relex every objective and uncertainty constraint under different levels, can make better use of each constrained resource and provides a higher satisfactory level in searching for optimal solutions.(3) Water resources allocation. The task of contemporary water management is "managing variable and uncertain supplies to meet rapidly changing and uncertain demands". An inexact fuzzy chance-constrained stochastic muti-objective linear programming including fuzzy chance constrained, chance constrained and interval programming is proposed to deal with the fuzziness of water demand, the randomness of surface water availability, and the interval uncertainty of social economic paramaters, based on which a novel allocation model, with four objectives of economic, social, environmental and ecological benefit maximization, is proposed for water resources in Dalian city. The results suggest that the proposed method could incorporate more uncertain information and generate a set of interval solutions. These solutions are useful for analyzing the tradeoffs between system benefit and constrain-violation risks, and help decision makers select the optimal alterative according to their preferences.(4) Optimal selection of water resources allocation schemes. Water resources optimization decision is often a tradeoff among different decision-makers with conflicting benefits. In this paper, a multi-person multi-objective conflict decision model is introduced. First, the ideal bargaining solution is deduced by two-stage satisfying programming; then the final satisfying decision is chosen using fuzzy pattern recognition; finally, this model is applied to optimal selection of water resources allocation schemes in Dalian city. It is shown that this model, which is easy to solve, can balance the interests of all parties, and has a strong feasibiliy.(5) Application of index system of coordinated development assessment to strategic environmental assessment (SEA) of WRP. SEA of WRP, as an important component of WRP, can eliminate or reduce the negative environmental impacts caused by implementation of defective WRP. Considering the indices that describe regional economic development and the coordination of WRP system are often overlooked in index system of SEA of WRP, the system coordinated development theory is introduced and based on "state-relationship" framework the multi-layer index systems of the coordinated development assessment for WRP is constructed. Then, the evaluation model based on variable fuzzy set theory and variable weight principle is developed. This evaluation process is explained by taking Dalian City as an example. The results indicate that the proposed index systems can not only reflect the development level of each system, but also describe the coordinate degree between each system. Meanwhile, the proposed evaluation model can highlight some inferior indictors to the sheme and fully reflect problems in water resource planning.Finally, based on summarizing the full text, the existing problems in this study are pointed out, and the further research work is prospected.