Comprehensive Evaluation Of Water Environment Carrying Capacity In Chengdu From 2011 To 2015

Water is the source of life.With the acceleration of industrialization and urbanization,problems such as water shortage and continuous deterioration of water environment have become increasingly prominent.Although Sichuan is located in the southwest and rich in water resources,as a political,economic and cultural center of Sichuan,the contradiction between supply and demand of water resources still exists with the continuous growth of population and economy.Based on the demand of water quality and total water resources,this paper mainly studies the variation characteristics of water environment carrying capacity in Chengdu,and the research results can provide decision support for the scientific formulation of water environment management methods in Chengdu.Based on DPSIRM model,this paper makes a comprehensive evaluation of the carrying capacity of water environment in Chengdu.The research contents include:1.Study on evaluation index system of water environment carrying capacityDPSIRM framework model was used to construct the evaluation index system of water environmental carrying capacity.The weight of each index was calculated by using the coefficient of variation method.Through weight analysis,the first eight indexes that had a great impact on the carrying capacity of water environment in Chengdu were:（1）the discharge intensity of wastewater per unit of GDP（0.115）;（2）Water consumption of ten thousand yuan of industrial added value（0.113）;（3）fertilizer application intensity per unit of GDP（0.088）;（4）BOD（0.079）;（5）sewage treatment capacity（0.076）;（6）surface water resources（0.072）;（7）DO（0.063）;（8）domestic water intensity per unit of GDP（0.06）.2.Comprehensive evaluation of water environmental carrying capacityThe carrying capacity of water environment in Chengdu has been improved as a whole,and the evaluation level has been raised from the unsafe level in 2011 to the safe level in 2015.Driving force subsystem evaluation:the evaluation value of per capita regional GDP increased from 0.037 in 2011 to 0.056 in 2015,and the evaluation value of population density and urbanization rate remained around 0.007 and 0.003 respectively in the past five years,indicating that economic development is the main reason for promoting the development of water environment in Chengdu.Pressure subsystem evaluation:per unit of GDP of industrial wastewater emissions intensity value growth in 2015 to 8.58 times in 2011,the added value of ten thousand yuan of industrial water use value in five years has been more than 0.073,per unit of GDP fertilizer strength growth evaluation index from 0.043 in 2011 to 0.075 in 2015,shows that industry and agriculture are the main factors of Chengdu city water environment pressure.State subsystem evaluation:COD_Mn evaluation remained around 0.026 for 5 years,indicating that the effect of COD_Mn on water environment was small.BOD value fluctuated between0.057 and 0.071 within 5 years,while DO value fluctuated between 0.034 and 0.053,indicating that water quality in Chengdu city was unstable.Influence subsystem evaluation:the evaluation value of surface water resources decreased from 0.055 in 2011 to 0.016 in 2015.The evaluation value of groundwater resources and the evaluation value of per capita water resources kept fluctuating around 0.013 and 0.015respectively,indicating that the capacity of water resources carrying human production and life is decreasing in Chengdu city.Response subsystem evaluation:the intensity evaluation value of domestic water per unit of GDP increased from 0.019 in 2011 to 0.052 in 2015,and the capacity evaluation value of sewage treatment in sewage treatment plants increased from 0.014 in 2011 to 0.067 in 2015,indicating a significant improvement in the sewage treatment capacity of Chengdu.Management subsystem evaluation:the evaluation value of green land area in built-up area of Chengdu increased from 0.014 in 2011 to 0.028 in 2015,indicating that the green area of built-up area of Chengdu increased constantly.The evaluation value of the tertiary industry as a share of GDP is relatively low,which shows that the development of the tertiary industry has a weak impact on the water environment carrying capacity of Chengdu.