abstract

Water resources refer to natural water bodies that can be directly utilized by human beings and can be continuously renewed. It mainly includes surface water and groundwater on land. It is a basic resource related to human survival and sustainable economic development. At present, the problem of water resources, especially the shortage of water resources, seriously restricts the economic development of China, which is one of the problems we must solve. Water resources are the most important resources for human production and life, but at present, the ecological environment has been seriously damaged and water pollution is serious. The protection of water resources and the treatment of water pollution have become the most concerned issues in modern society.

Risk refers to the combination of the possibility and consequences of a specific dangerous situation. Water shortage risk generally refers to the possibility of water shortage in regional water resources system and the losses caused by it due to the uncertainty of incoming water and water use under specific time and space environmental conditions. In recent years, the shortage of water resources in China, especially in the northern region, has become increasingly serious, and water resources have become a focus topic.

This paper uses the risk of water shortage in Beijing and the data of water shortage in Beijing to make a comprehensive evaluation. By establishing fuzzy probability model and entropy weight fuzzy comprehensive evaluation model, this paper analyzes the risk factors of water shortage in Beijing, and gives the solutions. The rapid growth of population, the rapid development of industry and agriculture and the deterioration of ecological environment have aggravated the shortage of water resources.

(1) fuzzy probability model: firstly, construct membership function to evaluate the fuzziness of water resources system; Secondly, the Logistic regression model is used to simulate and predict the risk probability of water shortage. Then, a water resources shortage risk assessment model based on fuzzy probability is established. Finally, the risk sensitive factors of water shortage are identified by discriminant analysis.

(2) Fuzzy comprehensive evaluation model of entropy weight: Aiming at the fuzziness and uncertainty of each index in water resources shortage risk evaluation, the entropy theory in information theory is applied to water resources shortage risk evaluation, and a fuzzy comprehensive evaluation model of water resources shortage risk based on entropy weight is established. Taking risk rate, vulnerability, recoverability, accident period and risk degree as risk evaluation indexes of regional water resources shortage, a comprehensive evaluation index system is established.

Using the data utility value reflected by information entropy to calculate the weight coefficient of evaluation index effectively solves the problem of difficult weight distribution and makes the determination of weight have a certain theoretical basis. The practical application results show that this method is simple, feasible, scientific and reliable, and the results are relatively objective and credible.

Keywords: water resources; Shortage risk; Fuzzy probability model; Fuzzy comprehensive evaluation model of entropy weight

Restatement 1 question

1. 1 background

In recent years, the shortage of water resources in China, especially in the northern region, has become increasingly serious, and water resources have become a focus topic. Take Beijing as an example. Beijing is one of the metropolises that are seriously short of water. The per capita water resource is less than 300m3, which is 1/8 of the national average and 1/30 of the world average. This is an area that is seriously short of water. The data listed in the attached table shows the water shortage in Beijing from 65,438+0,979 to 2000.

The shortage of water resources in Beijing has become the main factor affecting and restricting the social and economic development of the capital. The government has taken a series of measures, such as the construction of South-to-North Water Diversion Project, the establishment of sewage treatment plants and the adjustment of industrial structure. However, with the continuous development of climate change and economy and society, the risk of water shortage always exists. Therefore, it is necessary to identify the main factors of water resources risk, classify the harm level caused by risk, and take corresponding effective measures to avoid risks or reduce the harm caused by different risk factors, which is of great significance to the implementation of social and economic stability and sustainable development strategy.

1.2 problem

Firstly, this topic requires to evaluate and judge the main risk factors of water shortage risk in Beijing. Through the evaluation of water shortage risk factors, a mathematical model is established to comprehensively evaluate the water shortage risk in Beijing, and the risk level is divided. Regulating the main risk factors is of great significance for reducing the risk value and implementing the strategy of social and economic stability and sustainable development.

Secondly, after evaluating the water shortage risk in Beijing, the water shortage risk in the next two years is predicted, and the countermeasures to reduce the risk are put forward.

Finally, according to the evaluation results of water resources shortage in this paper, a suggestion report is written with the water administrative department of Beijing as the report object.

2 problem analysis

2. 1 water shortage risk assessment index

The shortage of water resources depends on the influence of water supply and water demand, both of which are random and uncertain. So the risk of water shortage is also random and uncertain. In risk assessment, we should fully consider the characteristics of risks and the complexity of water resources system, and consider a series of factors such as the probability of risk occurrence, the time of risk occurrence, the amount of loss caused by risk, the time of risk release, the distribution of water shortage and so on. Therefore, it is difficult to comprehensively describe and evaluate with a certain index, and it must be comprehensively considered from various indicators. The principle of evaluation index selection is:

(1) can reflect the water shortage risk in water shortage areas;

(2) It can reflect the degree of water shortage risk;

(3) It can reflect the carrying capacity of water resources system after water shortage risk occurs;

(4) Good representativeness, strong pertinence and easy quantification.

According to the above principles and references, the risk rate, vulnerability, recoverability, accident period and risk degree of water resources are selected as the evaluation indexes of water resources shortage risk in water resources system.

2.2 Beijing water shortage factors

(1) The uneven distribution of water resources in China is the main reason for the shortage of water resources in Beijing and North China.

(2) The rapid population growth and the rapid development of industry and agriculture in Beijing have aggravated the shortage of water resources.

(3) The ecological environment in North China has deteriorated and the frequency of drought has increased.

(4) Water pollution for residents' living, and the surface water resources have dropped sharply.

Three basic assumptions

(1) Assume that the data given in the question is basically true and valid;

(2) It is assumed that there will be no major natural disasters such as drought;

(3) Assume that the population flow in Beijing is normal;

(4) It is assumed that the South-to-North Water Transfer Project is operating normally;

4 symbol description

Symbolic meaning of serial number

1: V comment field

2.w The weight of each factor to the water shortage risk index

3.u evaluation object factor universe

4: x water shortage

5. Water demand

6. Water supply system

7: r fuzzy relation matrix

8. RMAX is the most satisfactory among different objects under the same evaluation index.

9.rmin is the most dissatisfied among different objects under the same evaluation index.

10: subjective weight of evaluation index I.