Estimating land use characteristics for hydrologic models

Many hydrologic models, including both linked process simulation models and unit hydrograph models, require estimates of land use characteristics (e.g., percentage of impervious area) for calibration. Past investigations have demonstrated that reliable estimates of land use can be obtained by aerial photograph sampling analyses. Even when aerial photographs are available, however, it is an expensive and time‐consuming process to measure land use characteristics. Prediction equations that are derived from data characterized by high variability in the land use characteristics appear to be a reliable alternative to aerial photograph sampling analyses. In addition to being less expensive and time consuming the prediction equation approach can be used in generating land use estimates for future land use configurations. The prediction equations derived herein require demographic characteristics (e.g., population density and housing density) that can be obtained from census summaries or projections compiled by planning agencies and thus could be used with hydrologic models to estimate the impact of future development alternatives.