Continuous hydrologic modeling study with the hydrologic modeling system

The development of model parametrization methodologies using geographic information systems is becoming increasingly important in hydrologic modeling applications, especially given the continued trend of comprehensive and readily available geospatial databases. This paper discusses the development of parametrization and calibration methodologies for the 12-parameter soil moisture accounting (SMA) algorithm recently added to the Hydrologic Modeling System (HMS) program by the Hydrologic Engineering Center (HEC). The U.S. Army Corps of Engineers, Nashville District, is considering HMS as a tool for continuous hydrologic simulation in the Cumberland River basin. The study demonstrates that parameters for a complex soil moisture accounting model can be derived from publicly available geographic information system (GIS) databases and that the use of seasonal or multiparameter sets improves model performance. Only one of the seven parameters estimated using GIS databases was varied during model calibration. Parameter values after model calibration, including four parameters estimated using historic streamlow records, deviated from estimated values by an average of 37%. Model performance indicates that the developed parametrization and calibration methodologies work well when applied to the test watershed and should be applicable to other watersheds in the Cumberland River basin.