An adaptive modeling and monitoring approach to describe the hydrologic behavior of small catchments

An adaptive combination of field mapping, simple hydrologic monitoring, and hydrologic modeling was used to describe the hydrologic behavior of two zero-order catchments: one undeveloped forest, the other suburban. Field mapping was used to delineate hydrologic process zones and provide guidance for the location of monitoring stations. Hydrologic monitoring included continuous streamflow and precipitation, as well as limited piezometer information. The hydrologic model was developed in conjunction with the measurement program to assure that the level of model detail was consistent with the level of field measurements used for model input and testing. At the start of the work it was anticipated that saturation overland flow would drive peak discharge in the forested catchment and Horton overland flow from impervious surfaces would dominate storm runoff in the suburban catchment. Instead, subsurface flow was found to dominate both annual and peak discharge in the forested site, and discharge from lawns and other pervious areas accounted for roughly 60% of annual and storm runoff from the suburban catchment. The adaptive combination of modeling and measurements was essential to elucidate the various components of flow production and flow paths in these catchments.