Water quality change and habitat potential in riparian ecosystems

Riparian ecosystems play a vital role in providing ecosystem services that include habitat support and protection of water quality. This study assessed the role of riparian ecosystems along the lateral and longitudinal dimensions of the watershed system. A reach-scale assessment, spatial analysis using GIS, and a dynamic simulation of interactions were used to evaluate riparian dynamics in the Westfield River Watershed of Massachusetts. Riparian and riverine characteristics (slope, soils, and flow regime), disturbance regimes (land use and bank impairment), bird habitat suitability, available niches for wildlife, and vegetation biomass were found to vary along the longitudinal dimension of the watershed. Habitat potential (suitability to sustain a species) declined in general (trend) with riparian distance and a maximum potential was observed at an intermediate level. Dynamic simulation was performed using the STELLA model to quantify interactions between different reaches, land conditions, and land use to quantify soil loss (RUSLE equation) and spatial accumulation. Simulations showed a spatial influence in sediment transfer and loading into the stream. Policy simulations on land use in specific riparian locations showed a significant impact of urbanization on the water quality of the river. Significant reductions in soil loss (3%–48% decrease, depending on the spatial location of the practice) could be achieved through implementation of Best Management Practices (BMPs). Optimal placement of BMPs and conservation efforts in the riparian zone could be used to protect habitat potential and water quality of the watershed.