考虑风险价值的不确定性水资源优化配置

保障区域农业用水的可持续发展,对水资源进行优化配置至关重要。由于粮食主产区水资源配置过程中存在许多不确定性因素,在追求最小用水成本时,也存在着较大的风险,因此该文以三江平原涵盖的七台河、佳木斯、双鸭山、鹤岗和鸡西5个重要粮食主产区为研究区域,以区间两阶段随机规划模型为基础,引入风险偏好,构建地表水和地下水优化配置模型。结果表明,双鸭山和鸡西的配水过程中地表水缺水量很大,主要开采利用地下水;佳木斯作为粮食生产面积较大的行政区,需要外来水进行补给;七台河和鹤岗的种植面积较小,综合考虑引水成本和粮食收益,引用较少的外来水来降低成本;最后得出不同来水水平下,各种风险偏好下水资源优化配置的最小成本的变化规律,即在低来水水平下,用水成本从344.2×108~355.4×108元增加到411.5×108~430.7×108元;在高来水水平下,总用水成本从422.5×108~435.3×108元降低到351.7×108~365.3×108元;在中来水水平时,总用水成本则呈现出先增加后减少的规律。该模型兼有区间两阶段和风险价值模型的特点,综合衡量成本和风险,可有效节约用水成本,并能增强水资源系统规避风险的能力,并以佳木斯2014年实际用水为例,计算得到相对误差在15%以内,较为真实地反映水资源优化配置过程中的不确定性和风险性,为提高水资源利用效率和区域水资源规划管理提供依据。

Allocation optimization of water resources based on uncertainty stochastic programming model considering risk value

Abstract: To ensure the sustainable water development of regional agricultural and improve the use efficiency of water, it is very important to optimize the allocation of water resources. There are many uncertain factors in the process of the water resources allocation in the food production areas with the change of the system environment in China, and in the pursuit of the minimum cost, there are also many uncertain risks. Choosing the 5 important agricultural regions, i.e. Qitaihe, Jiamusi, Shuangyashan, Hegang and Jixi located on the Sanjiang Plain as the study area, by using the method of interval two-stage stochastic programming method and introducing the risk appetite, the surface water and groundwater joint scheduling is established under the condition of water resources optimal allocation, and the water deficit and the optimal configuration of water law for each administrative region are analyzed. The results show that the surface water is much deficient in Shuangyashan and Jixi during the water distribution process, where the mainly exploited is the groundwater; for Jiamusi, which is an administrative region with larger grain production area, the water demand is bigger, and the external water supply is more; for Qitaihe and Hegang where the planting areas are lesser, considering the cost of water diversion and grain yield, the less external water is needed to pilot to reduce the cost. The calculation results show that the changing rules of water deficit and the optimal allocation of water under different administrative region and different water level are as follows: Qitaihe and Jixi have small change under different water level, Jiamusi and Shuangyashan have great change under different water level, and the minimum cost of water under the optimal allocation is [736.12, 843.40]×108 yuan. At last, the paper analyzes the minimum cost of optimal allocation of water resources under different probability of water level and different risk preference scenario on Sanjiang Plain. Because under the low water level, it is easy to cause the high demand for water resource system, and an increased level of risk aversion can be instead of water cost increase, the cost of water shortage will be increased to meet the basic requirements of crops, which changes from [344.2,355.4]×108 to [411.5,430.7]×108 yuan; at a high level of the water, the increase of the level of risk aversion can reduce the cost which caused by the loss of oversupply, and thus reduce the total cost of water from [422.5,435.3]×108 to [351.7,365.3]×108 yuan; in the middle level, it is between low and high water level. This model conjoins the advantages of the interval of two-stage stochastic programming and the characteristics of the risk value model. In the joint allocation of water resources, the model comprehensively considers the cost and risk, effectively saves water cost, and enhances the ability of water resources system to avoid risk. The model makes up for the deficiency of the traditional interval two-stage stochastic programming method, introduces the risk preference of decision makers to find the minimum cost of water resources' optimal allocation scheme under the condition of uncertainty, avoids concentrating the risk loss in a certain region, and facilitates reasonable water resource allocation for policymakers in different administrative regions on the Sanjiang Plain. The water allocation in different region and different time realizes the dynamic distribution of multi-water source irrigation system. This model can ensure the need of crop grow when the irrigation water resources are rationally configured in the growing period of the crop, and effectively avoids the waste of water resources, as well as improves the efficiency of irrigation water, which is of great significance for sustainable use of water resources. The research improves the utilization efficiency of water resources and provides the basis for the planning of regional water management, which can more truly reflect the uncertainty for optimization allocation of water resources.