Sustainable natural resource management requires inputs from both the natural and the social sciences. Since social and natural systems are inter-related and inter-dependent, it is essential that these data can be integrated within a given analysis, which requires that they are temporally and spatially compatible. However, existing environmental and socio-economic monitoring networks tend to observe, collect and report socio-economic and biophysical data separately; with the result that much of these data are spatially and temporally incompatible and therefore add to the complexity of objective and consistent trade-off analyses. This paper presents an approach for overcoming spatial incompatibilities between socio-economic and biophysical data; based on a meta-modelling approach using Geographical Information Systems, the geo-spatial analysis platform, and an application of a water-use simulation model. Keywords: Water allocation decision making, Geographical Information Systems, GIS, Meta-modelling, Data integration, Spatial analysis, River basins, Inkomati water management area, Environmental modelling, Biophysical data, Socio-economic data.