Evaluation of Regional Water Resources

Abstract

To evaluate the regional water resources carrying capacity according to the importance of each related factor,we establish a model and sort out indicators that can characterize the ability of a region to provide clean water for its population. The water deficient ratio and utilization ratio of water resources are selected as the final evaluation indexes, which are of great practical value. We use the fuzzy membership function method, combined with the principal component analysis to construct a multi-index comprehensive evaluation index system. Introduction Water scarcity may lead to drought. Humans historically have suffered a lot from drought, which happens more frequently than other disasters. For example, in 1921 in Soviet Union over 5 million people perished from starvation due to drought, and in 2006, Sichuan, China, experienced its worst drought in modern times with nearly 8 million people and over 7 million cattle facing water shortages[1]. These droughts are closely related to rainfall. By searching the information, we found that, besides human activities, water scarcity also results from its geographical location, altitude, distance from the major river systems, and the vegetation coverage, etc. These factors will then affect the precipitation, snowfall and evaporation. Instead of using water immoderately until the drought, a good understanding of the water resources carrying capacity will be of great significance. Evaluation Model of Water Resources Carrying Capacity First, we establish the equation according to the balance between supply and demand of water resources. Then, we use the principal component analysis(PCA) to determine the weight of each parameter affecting the total water demand. And finally we develop the fuzzy comprehensive evaluation model to analyze the influence of each parameter on the water supply capacity. The assumptions of the model are as follows: Assuming that there are no accidents, such as large-scale infectious disease, war, natural disasters and so on. Assuming that the industrial structure of the industrial and agricultural industries will not be changed for the policy. Assuming that the total discharge of sewage in the region will not exceed a certain limit in the year of our study. No consideration is given to the loss of water from the surface and ground water. The runoff of the area is not less than the minimum base flow rate of the river, so that the area can meet the requirement of ecological water consumption. First, we establish the equation according to the balance between supply and demand of water resources: The model parameters and their meaning are shown in Table 1: 2nd Workshop on Advanced Research and Technology in Industry Applications (WARTIA 2016) © 2016. The authors Published by Atlantis Press 682 Table 1 Model parameters Parameter Meaning Parameter Meaning total W Regional water resources including those that are unavailable other E A I P W W W W W , , , , water resources for residential, industrial, agricultural, ecologic and other purposes D S W W , Water supply; water demand WDR Water deficient ratio R W Return flow P Regional population T W Water volume transferred from other regions S Agricultural irrigation area W Amount of surface water and groundwater R Regional gross industrial production α Utilization ratio of water resources A I P C C C , , Water consumption per unit of population, irrigation and industrial production R T S W W W W + + = (1) other E A I P D W W W W W W + + + + = (2) D S D S D W W W W W WDR − = − = 1 (3) total S W W = α (4) Obviously, when the regional water supply is less than the demand( D S W W WDR ), this shows that the regional clean water cannot support such a society on this scale. But if we increase water volume transferred from other regions and/or decrease water demand by saving water,WDR will reduce. On the contrary, that is D S W W ≥ , 0 ≤ WDR ,this shows that the regional water resources can afford such a scale of society. Water supply and demand are in good condition. Utilization ratio of water resources is the ratio of regional water supply and the total amount of water resources including those that are unavailable. It reflects the utilization of water resources. We divide water resources into three levels by utilization ratio: % 30 α : The society is in water-saving pattern,water health is deteriorated. Secondly, we use principal component analysis to determine the weights: The principal component analysis method is a statistical analysis method to change the original multiple variables into a few comprehensive indexes. It makes the contribution of each index to the overall system as the weight. We make the analysis through SPSS. The evaluation system is divided into three layers: target layer, criterion layer and index layer. Indicators are shown in the Table 2: Table 2 Each indicator in the evaluation system Target layer Criterion layer Index layer Water supply index Regional water resources Surface water and groundwater Regional policy Water transferred from other regions Utilization ratio of water resources Water pollution Return flow Water demand index Resident life Urban population Annual water consumption per person in cities Rural population Annual water consumption per person in rural areas Economic development Agricultural irrigation area Water consumption per unit of irrigation Gross industrial production Water consumption per unit of industrial production Ecological condition Ecological water demand Analysis steps are as follows: