Résumé
This report presents an integrated dynamic simulation model that represents wetland functioning. The model can be used for analysing trade-offs between the provision of ecosystem services and ecosystem integrity and resulting land use changes in the Ga-Mampa wetland in the Limpopo basin in South Africa. The purpose of the analysis is to generate knowledge that can assist decision-makers and local communities in managing wetland ecosystems in a sustainable manner. The model was developed using the STELLA platform and comprises seven interactive sectors namely: hydrology (itself sub-divided into three sub-sectors: natural wetland, cultivated wetland and irrigation scheme), crop production, crop economics, irrigation management, natural resources use, land use change decision, and community well-being. These sectors are inter- linked and changes in one sector impact on other sectors through feedback loops between sectors. Key parameters in the model are community demand for food, demand for income, and biophysical drivers (soils, rainfall, groundwater and surface flows). Taking into account these factors, the local community makes choices about uses of different categories of land and water resources available to them (irrigation scheme and wetland). These activities impact on the wetland functioning, which in turn influences economic returns of wetland related activities and ultimately livelihoods. The report describes each sector in details, including a presentation of input data and results of calibration. The model is intended to be used to simulate several management options in the valley under various localised scenarios of global changes.