Equity-based optimisation of regional water pollutant discharge amount allocation: a case study in the Tai Lake Basin

Regional allowance allocation not only matters for regional economic efficiency but also for fairness between regions or companies. It is important to work out a fair and reasonable allocation method to achieve China's goal of the gross control of pollutant discharge. This research developed an equity-based optimisation for a regional water pollutant discharge allowance allocation method, which is based on the Gini coefficient of considering socio-economic and environmental factors. Taking the Tai Lake Basin in Jiangsu Province as an example, this paper optimised the present state of distribution on the basis of an assessment of fairness of the current discharge allowance allocation status. The optimised allowance allocation results of the Tai Lake Basin were distinct from other allocation methods, and reduced the inequity of regional allowance allocation. However, the stress of equity cannot give full consideration to both environmental and economic efficiency targets. Connecting the allocation of discharge targets with an emission trading system was proposed to address the shortcomings of the Gini coefficient based method.