Application Of Carrying Capacity & Pollution Load Allocation Simulation Model (Cc Plus Plas) In Implementation Of Pollution Control Red Line In Water Functional Zones

China' s 2011 No. 1 policy document on Accelerating Water Conservancy Reform and Development emphasises the implementation of the strict water resources management policy of the "three red lines". Under the pollution load control red line (the 3rd line) concept each water function zone (WFZ) (control section) of a river must be managed so that it meets defined water quality targets by defined dates through control of discharges from cities and industry. A Carrying Capacity and Pollution Load Allocation Simulation model (CC + PLAS) has been developed to support implementation of this policy. The CC + PLAS model calculates the carrying capacity (amount of pollutions that can be added to each WFZ and still meet targets) and calculates the pollution load allocations (load of pollutants permitted from each discharge point). The current Chinese concept for calculating carrying capacity only operates under fixed, and rather unrealistic, scenarios. CC + PLAS integrates the basic Chinese approach with European concepts of river basin water quality modelling which take account of various factors impacting river water quality. For example, CC + PLAS can calculate the river carrying capacity under different flows and different seasonal conditions and use monitored data about actual river water quality to estimate the quantity and impact of all pollution sources and processes. It can then be used to forecast future water quality trends brought by social economic development as well as improvements from the application of various pollution reduction strategies with estimates of the likely water quality in comparison to WFZ targets. In this way it facilitates the river need oriented pollution management to help authorities to plan how to achieve their targets of compliance with WFZ targets by 2015, 2020 and 2030. The CC + PLAS model provides a scientific and convenient tool to water resources protection and river basin planning. In this paper pilot applications of the model in the middle reaches of the Yellow River are described.