Evaluating Hydrological Response to Forecasted Land-use Change

It is currently possible to measure landscape change over large areas and determine trends in environmental condition using advanced space-based technologies accompanied by geospatial analyses of the remotely sensed data. There are numerous earth-observing satellite platforms for mapping and monitoring land cover and land-cover change; however, the traditional workhorses have been the Landsat Multi-Spectral Scanner (MSS) and Thematic Mapper (TM) sensors. Landsat has had a long history of commercial availability (first launch July 1972), a well developed global archive, and has been widely used for land-cover change detection and monitoring. During the past two decades, important advances in the integration of remote imagery, computer processing, and spatial-analysis technologies have been used to develop landscape information that can be integrated within hydrologic models to determine long-term change and make predictive inferences about the future. This article presents two studies in which future land-use scenarios were examined relative to their impact on surface-water conditions, e.g. sediment yield and surface runoff, using hydrologic models associated with the Automated Geospatial Watershed Assessment (AGWA) tool. The base reference grid for land cover was modified in both study locations to reflect stakeholder preferences twenty to sixty years into the future and the consequences of landscape change were evaluated relative to the selected future scenarios. A third study utilized historical land-cover data to validate the approach and explore the uncertainty associated with scenario analysis. These studies provide examples of integrating modeling with advanced Earth-observing technology to produce information on trends and make plausible forecasts for the future from which to understand the impact of landscape change on ecological services.