Evaluation of Various Land Use Metrics for Enhancing Stream Water Quality Predictions

Water quality in streams is primarily affected by various land use practices. This study analyzes water quality data collected from the outlets of 113 watersheds across three South Atlantic states in the USA. The objective is to evaluate the relationship between different land use metrics and long-term stream water quality, specifically investigating whether incorporating the spatial proximity of various land uses to the stream and outlet can enhance predictions of stream water quality. To achieve this, four distinct metrics were utilized to assess their influence on stream water quality. The first metric, known as the Lumped method, assigns equal weight to all land uses. The second, the Inverse Distance Weights stream (IDWs), gives greater weight to land uses located closer to the stream. The third metric, the Inverse Distance Weights Outlet (IDWO), weights land uses according to their proximity to the watershed outlet. The final metric focuses on hydrologically sensitive areas (HSAs), which are areas within watersheds that generate the majority of runoff. The results indicated that the Lumped metric emphasizes the significance of forested lands, whereas the HSAs, IDWs, and IDWO metrics highlight the importance of the spatial distribution of agricultural and industrial lands within the watershed. These findings support the hypothesis that considering hotspot areas and their relative positions within the watershed can improve predictions of water quality. Overall, the incorporation of HSAs, IDWs, and IDWO metrics shows that not only is the extent of land use change within a watershed critical, but also the proximity of these land uses to a stream or outlet plays a significant role.