HR: 11:25h
AN: B31G-05 INVITED     [PDF]
TI: Hydrological Impacts of Land Use Change in the Central Appalachian Mountains, U.S.: A Multi-Scale Analysis
AU: * Eshleman, K N
EM: eshleman@al.umces.edu
AF: University of Maryland Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, MD 21532 United States
AU: Negley, T L
EM: tnegley@eaest.com
AF: EA Science and Technology, 6731 Collamer Road, East Syracuse, NY 13157 United States
AU: Townsend, P A
EM: townsend@al.umces.edu
AF: University of Maryland Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, MD 21532 United States
AB: Quantifying, understanding, and predicting the hydrological impacts of land use changes and land management practices are important objectives of both the academic hydrologist and the civil engineer. Relationships between stormflow response and land use have been most readily observed at small spatial scales (e.g., hillslopes, small experimental watersheds), but have proved difficult to establish in larger basins where (1) high-resolution precipitation data are usually unavailable, (2) land use patterns are often exceedingly complex, and (3) land use changes are essentially uncontrolled. In the Central Appalachian Mountains of the U.S., conversion of forests to mined lands (through devegetation, excavation of overburden and coal deposits, and subsequent reclamation) is the dominant land use change presently occurring. In the Georges Creek basin in western Maryland, for example, the portion of the watershed classified as mined (including active, reclaimed, and abandoned surface mines) increased from 3.8 to 15.5% from 1962 to 1997; modest urbanization of the basin (2.4 to 4.7%) also occurred during this period. In 1999, we initiated a comparative field study to determine if surface coal-mining and subsequent land reclamation practices affect stormflow responses at multiple spatial scales: (1) plot, (2) small watershed, and (3) river basin scales. Results from the plot-scale experiments suggested that soil infiltration capacity is grossly reduced during mining and reclamation, apparently due to loss of forest litter and soil compaction by heavy machinery. At the small watershed ($<$25 ha) scale, a comparative analysis of a pair of gaged watersheds indicated that conventional methods of surface mining and reclamation can increase peak stormflow, total storm runoff, and storm runoff coefficient by about 250% relative to similar forested watersheds in the same region. Finally, frequency analysis of long-term runoff data from the larger, extensively-mined Georges Creek (area = 127 sq. km.) and predominantly-forested Savage River (area = 188 sq. km.) watersheds in western Maryland was unable to establish a comparable land use effect on stormflow response, due to inherent climatic variability. Such an effect was suggested, however, when high-resolution, gage-adjusted rainfall data generated from NEXRAD (NEXt generation weather RADar; WSR-88D) radars were employed for developing unit hydrographs for specific extreme events. Inadequacies in spatial rainfall estimation thus appear to be a major limiting factor in scaling changes in observed stormflow responses from small experimental watersheds to larger river basins undergoing extensive land use changes. We conclude that land use change effects in gaged river basins can be discerned if flood hydrographs are interpreted using accurate, areal precipitation data.
DE: 1821 Floods
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
SC: Biogeosciences [B]
MN: 2003 Fall Meeting