The Integrated Catchments model of Phosphorus dynamics (INCA-P), a new approach for multiple source assessment in heterogeneous river systems: model structure and equations

摘要

Anew model has been developed for assessing the effects of multiple sources ofphosphorus on the water quality and aquatic ecology in heterogeneous riversystems. The Integrated Catchments model for Phosphorus (INCA-P) is aprocess-based, mass balance model that simulates the phosphorus dynamics in boththe plant/soil system and the stream. The model simulates the spatial variationsin phosphorus export from different land use types within a river system using asemi-distributed representation, thereby accounting for the impacts of differentland management practices, such as organic and inorganic fertiliser andwastewater applications. The land phase of INCA-P includes a simplifiedrepresentation of direct runoff, soilwater and groundwater flows, and the soilprocesses that involve phosphorus. In addition, the model includes a multi-reachin-stream component that routes water down the main river channel. It simulatesOrganic and Inorganic Phosphorus concentrations in the land phase, and TotalPhosphorus (dissolved plus particulate phosphorus) concentrations in thein-stream phase. In-stream Soluble Reactive Phosphorus concentrations aredetermined from the Total Phosphorus concentrations and the macrophyte, epiphyteand algal biomasses are simulated also. This paper describes the model structureand equations, the limitations and the potential utility of the approach. style="line-height: 20px;">Keywords: modelling, water quality, phosphorus, soluble reactive phosphorus, basin management