How Advances in GIS Improve Watershed Master Planning

Harris County is a natural flood prone region subject to a high degree of flood damage and risk. Due to the combination of flat terrain, impervious clay soils and subtropical annual rainfall average exceeding 48 inches, Houston has earned the moniker "The Bayou City". Regular flooding from the great flood of 1929 to Tropical Storm Allison in 2001 have caused significant flood related damages to the City of Houston, resulting in both economic and human losses. To combat the continued flood related losses, the State of Texas established the Harris County Flood Control District (HCFCD) in 1937, with the prime responsibility of overseeing the streams, rivers and bayous for residential and agricultural beneficial uses. As Harris County developed, increasingly complex watershed management issues developed, and HCFCD's role expanded to include cooperation with the US Army Corps of Engineers to complete watershed master plan studies and implement regional flood control and flood relief projects. As technology develops, traditional hydraulic and hydrologic methodologies are incorporated into geographic information systems (GIS), creating a more useful tool to both manage and develop planning tools to address watershed development issues. While GIS integrated watershed concepts are still maturing, many regulatory agencies, such as the HCFCD, are beginning to reap the benefits of GIS as a means to manage, update and track watershed development status and the hydrologic (flooding) aspects of that development. This paper describes the efficiency realized by utilizing GIS to manage several digital data sources and hydrology and hydraulics applications in the watershed master planning process.