Combining a hydrological model with ecological planning for optimal placement of water-sensitive solutions

Newer water management approaches aim to better utilize runoff by treating it as a resource rather than a nuisance and by promoting a more holistic handling of runoff. These approaches use nature-based green infrastructure solutions to increase infiltration and detain water. Identifying optimal placement for these solutions is challenging due to multiple and sometimes competing objectives. Here, we propose a methodology to help planners and stakeholders maximize the benefits of flood mitigation projects by identifying opportunities for sustainable development. Most studies examine placement decisions based on metrics obtained from hydrological models. However, solely depending on hydrological indicators, without accounting for social and ecological indicators, might bias the placement decisions. We propose combining hydrological and land-use planning models. We used the revised version of the Soil and Water Assessment Tool (SWAT) known as SWAT+ to simulate existing hydrological conditions and the results as initial input for the conservation decision support software MARXAN. We added data on endangered species and distance from the human population as ecological and social indicators. This addition shifted the selected areas and provided a more complete view of runoff management than only hydrological indicators. Furthermore, we show that coupling SWAT+ and MARXAN can effectively balance hydrological concerns with ecological and social factors.