Analysis Of Water Resources Carrying Capacity Based On System Dynamics Model

With the continuous development of social economy and the improvement of people's living standard,the demand for water resources is put forward higher requirements.Therefore,the analysis of the carrying capacity of regional water resources is helpful to understand the water situation,and can provide a scientific basis for establishing reasonable strategies of water resources development and utilization.In the past period,the overproduction of groundwater in Shijiazhuang city was serious,and the contradiction between the shortage of water resources and the rapid growth of water demand further intensified the competitive use of water.The relationship between water supply and demand in Shijiazhuang city was becoming increasingly tense,and the competition between departments of water use is becoming more and more serious.On the other hand,due to insufficient judgment on the carrying capacity of water resources,the unreasonable utilization of water resources also leads to waste.In recent years,in order to curb the overdraft of groundwater,a series of measures of underground water pressure have been adopted in Shijiazhuang.At the same time,as the middle route of south-to-north water starting to supply water to Shijiazhuang,water supply structure has changed dramatically in the city.In order to scientifically evaluate the water resources carrying capacity in Shijiazhuang city at present and in the future,and provide scientific basis for adjusting the industrial structure and establishing reasonable policies for water resources development and utilization in Shijiazhuang city,the system model of water resources carrying capacity suitable for Shijiazhuang city is established by combining USES system dynamics with multi-index comprehensive evaluation method in this paper.In the solving period,Vensim6.0 software is adopted for analyzing the water system,domestic water demand system,the first industrial water demand system,the second industry and the third industry water demand system,ecological water demand system and sewage system in the system of carrying capacity of water resources in Shijiazhuang.Meanwhile,the indexes of the supply amount,population growth,urbanization rate,the second industrial added value growth rate,water requirement of the added value of ten thousand yuan,the added value of the tertiary industry,the second industry growth rate,net of farmland irrigation quota,ecological sewageirrigation,Sewage treatment rate and waste water return rate are taken as the decision variables to build the index system of water resources carrying capacity in Shijiazhuang city.In this paper,the water resources capacity in the planning years of 2020 and2030 under the scenarios of p=50% and p=75% is evaluated respectively by taking2015 as the current year in Shijiazhuang city.Meanwhile,four kinds of simulation schemes: current status continuation,water saving,industrial structure adjustment and comprehensive scheme are designed according to the economic,social and environmental status quo of Shijiazhuang city.The values of different decision-making variables in the four schemes are determined based on the requirements of the water-saving cities and the "13th Five-Year Plan" of Shijiazhuang,and the comprehensive planning of water resources,development and utilization of water resources and social economic development in different situation.Compared with the carrying capacity of regional water resources under different schemes,it is concluded that the comprehensive scheme is the optimal scheme.Based on the solution of the comprehensive scheme,it can be obtained that In 2020,Water resources can carry the secondary industry of 303.982 billion yuan and the tertiary industry of 433.079 million yuan,and agriculture irrigation area of 5.9055 million mu;In 2030,the value of the capacity will be 526.959 billion yuan and 1026.87 billion yuan for the secondary and tertiary industries individually,and agricultural irrigation area of 565.55 million mu.