水环境承载力约束下的城市经济规模量化研究

论文提出了以地区生产总值(GDP) 表征的水环境承载力定量计算模型,以扬州市为例,选取COD作为污染控制因子,进行实例计算。通过对模型参数的灵敏度分析,确定不同参数影响程度,找出影响水环境承载力的主要制约因子;采用区间估计理论,评估模型计算结果的可靠性;提出对于确定的经济发展目标,排放强度控制线模型。结果表明,考虑污染减排政策干预的因素,扬州市目标年水环境承载力(以GDP 表征) 可达8 372×10⁸元,在90%的置信度水平上,其置信区间为7 881×10⁸~9 030×10⁸元;在总量控制目标确定的条件下,水环境承载力主要制约因子为污染物排放强度和第三产业比例;如果该区域经济目标定为5 070×10⁸元,则单位工业增加值COD排放强度不得大于0.69 kg/10⁴元。

A Quantitative Study of Urban Economic Scale Constrained by Water Environmental Carrying Capacity

Environmental carrying capacity is an important constraint to regional sustainable development. It is the thresholds of the population size and economic scale that make the system of a regional environment support. In this article, a new method is proposed to study the threshold of urban economic scale constrained by water environmental carrying capacity. Regional water environmental carrying capacity can be quantitatively represented by the value of Gross Domestic Product (GDP), if the population size can be predictable in this region. This new method is primarily based on the Water Environmental Threshold Value Model, which is proposed for the first time in this article, as well as some statistical techniques. In this mathematical model, the threshold value of GDP constrained by water environmental carrying capacity at a regional level is a function of five independent variables: G=(P + C)×k_I + 0.1W_I]/k_I×(1-R_T)], where G denotes the threshold value of GDP at a regional level, P is the value-added in primary, C is the value-added in construction, W_I is the goal of the total amount control of industrial pollutants, R_T is the proportion of the tertiary industry in GDP, and k_I is the amount of pollutant emissions per 104 yuan of industrial value-added. The statistical methods applied here include regression analysis, which is used for the computation of the parameters P, C, W_I, R_T, k_I, and interval estimation, which is used for the analysis of the sensitivity and reliability of the model. Yangzhou City is taken as a case to compute the economic scale constrained by the water environmental carrying capacity in 2015. COD is chosen as a total amount control factor (COD≤56845 t/a). The values of P, C, W_I, R_T, and k_I are 229.02×10⁸ yuan, 228.45×10⁸ yuan, 18132 t, 39%, and 0.39 (1.38) kg/10⁴ yuan per unit of industrial value-added, respectively. The result of computation indicates that: 1) Taking into account the continuity of the policy of pollutant reduction (k_I=0.39), the annual water environmental carrying capacity of Yangzhou City can achieve 8372×10⁸ yuan in GDP, with a confidence level of 90% and a confidence interval of 7881×10⁸ to 9030×10⁸ yuan; 2) without considering the pollutant emission reduction policy (k_I =1.38), the annual GDP at the regional level can reach only 2904×10⁸ yuan; 3) When the total amount control goal is determined, the main limiting factors of economic growth are the pollutant emission intensity and the proportion of the tertiary industry. If the regional economic growth target touches 5070×10⁸ yuan, then the COD emission intensity should be controlled to below 0.69 kg/10⁴ yuan per unit of industrial value-added.