Evaluation of Water Resources Carrying Capacity in Shandong Province Based on Fuzzy Comprehensive Evaluation

. Water resources carrying capacity is the maximum available water resources supporting by the social and economic development. Based on investigating and statisticing on the current situation of water resources in Shandong Province, this paper selects 13 factors including per capita water resources, water resources utilization, water supply modulus, rainfall, per capita GDP, population density, per capita water consumption, water consumption per million yuan, The water consumption of industrial output value, the agricultural output value of farmland, the irrigation rate of cultivated land, the water consumption rate of ecological environment and the forest coverage rate were used as the evaluation factors. Then,the fuzzy comprehensive evaluation model was used to analyze the water resources carrying capacity Force status evaluation. The results showed : The comprehensive evaluation results of water resources in Shandong Province were lower than 0.6 in 2001-2009 and higher than 0.6 in 2010-2015, which indicating that the water resources carrying capacity of Shandong Province has been improved.; In addition, most of the years a value of less than 0.6, individual years below 0.4, the interannual changes are relatively large, from that we can see the level of water resources is generally weak, the greater the interannual changes in Shandong Province.


Introduction
Water resources carrying capacity refers to the specific areas within the premise of a certain level of living production and the ecological function of water environment subsystem, through scientific and reasonable distribution measure, the maximum capacity to support the needs of the population, social, economic and ecological environment that the water supply can provide [1][2][3][4][5]. Shandong province is one of the northern water shortage regions. Based on Shandong province economic-socio-environment basic research date from 2001 to 2015, the application of fuzzy comprehensive evaluation model to evaluate the water resources carrying capacit, which aimed to provide a basis for the rational development and utilization of water resources in the leap-forward development of Shandong province.

Overview of Water Resources in the Study Area
Shandong province is located in the eastern seaboard of China, the northernmost end of east China area, there are three drainage areas of Yellow River, huai river and hai river. Precipitation is the main water resources in Shandong, and is greatly affected by rainfall. The Yellow River is the main external water source in Shandong, and the nansi lake is the largest lake in Shandong province. The average annual precipitation of the whole province is 679.5mm, and the yearly average total water resources is 30582 million m³; The per capita water resource is 344m³, less than 1/6 of the national average, and 1/25 of the world average, the third lowest per capita water resources in all provinces (cities and autonomous regions). According to the international water shortage standard, per capita water resource occupancy less than 500m³ would be considered as extreme water shortage area. While Shandong is only 344 m³ per capita, which shows that Shandong is in extreme water shortage.

The Construction of Fuzzy Comprehensive Evaluation Model
The fuzzy comprehensive evaluation method can provide an effective way for the research of regional water resources carrying capacity, the essence of this method is to affect the carrying capacity of water resources, on the basis of single factor evaluation, through comprehensive evaluation matrix expansion multi-factor comprehensive evaluation of water resources carrying capacity, thus it is concluded that the size of the water resources carrying capacity. In this paper, the fuzzy comprehensive evaluation model was applied to evaluate the overall water carrying capacity of Shandong province. According to the characteristics of regional water resources, referring to the analysis of supply and demand of water resources in the index system, on this basis, fully considered the differences between the stock of natural water resources assigned and the different way of development, and used the water resources supply and demand analysis index system of the national and Shandong province as the basis, the evaluation index was divided into three levels (table 1). In this paper, the carrying capacity of water resources was divided into 3 levels, and the 1 V level is excellent, which indicates that the water resources in this region still have a large carrying capacity, and the water resources supply is adequate. The 3 V level is poor, which indicates that water resources carrying capacity is to allow the lowest, it is difficult to develop in depth, has restricted the social economy and stable development; the 2 V level status is somewhere in between, which indicates that this region basically can adapt to the economic development of the basin water resources, water resources development and utilization to the larger size, but still has certain potential of development and utilization.

The Selection of Evaluation Factors, Classification and Grading
To better reflect the level of water resources carrying capacity, to take 1 point of numerical evaluation level: In the formula, a is the comprehensive evaluation value of water resources carrying capacity based on the comprehensive evaluation result matrix B .

The Calculation of the Evaluation Matrix
According to the actual value of each evaluation factor, the value of the subordinate function i  of the judging matrix was evaluated by comparing the classification index. Fuzzy processing was used to construct membership function to smooth transition between all levels. For the evaluation factors 1  , 2  and 3  •••••• the evaluation grade membership function was calculated as follows:

Calculation of Index Weight
First of all, according to the index level of the partition, referring to China's water resource evaluation standard, the "1-9" scale method commonly used in AHP [6][7][8], was adopted to construct the judgment data matrix. Secondly, according to the judgement matrix, used the mathematical matrix to calculate the importance of the indicator layer ( u ) relative to the principle layer ( A ), the importance of the criterion layer relative to the target layer ( O ), and then end up with a judgment matrix. Note that the water resources condition is the foundation of water resources carrying capacity, so water condition here than the social and economic condition and ecological environment condition more important, got 3:1:1. Finally, the weight of the indicator layer to the principle layer multiplied by the weight of the principle layer to the target layer, so the weight of the indicator layer to the target layer was obtained ( W ), and the weight calculation results can be gotten.

Calculation of Comprehensive Evaluation of Water Resources Comprehensive Capacity
According to the weight vector W and the judgment matrix R calculated above, the calculation formula for comprehensive evaluation result of the water carrying capacity is as follows:

Integrate Assessment of Water Resource Carry Capacity in Shandong Province
According to the evaluation index of carrying capacity of     significantly smaller than other years, again through the Shandong province water resources statistics showed that the groundwater resources in the past few years was lower than other years, and the carrying capacity of water resources in Shandong province were associated with groundwater reserves, namely once encountered drought years (dry year), groundwater can play the main water supply capacity.

Conclusion
This paper started from the characteristics of Shandong province economy-society-environmental composite system, comprehensive analyzed the main influencing factors of regional water resources carrying capacity as evaluation factors(to table 1), and the current status of water resources carrying capacity of Shandong province was evaluated by fuzzy comprehensive evaluation model. Results shown that the carrying capacity of water resources in Shandong province level gradually guaranteed, annual change gradually narrowed, but the contradiction between supply and demand of water resources is outstanding, the water shortage area is widely distributed, and in the later development should adhere to the open source throttling, pay equal attention to practical ability of to increase the supply capacity of water resources.