HR: 1400h
AN: H33B-14    [Abstracts]
TI: Land use as a Parameter of Distributed Hydrological Modeling at the CATIE Farm, Turrialba, Costa Rica.
AU: Toohey, R
EM: ryantoohey@uidaho.edu
AF: Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), GIS Laboratory 7170 Sede Central, Turrialba, Costa Rica
AU: Toohey, R
EM: ryantoohey@uidaho.edu
AF: Environmental Science Program University of Idaho, Morril Hall 216 P.O. Box 443006, Moscow, ID 83844-3006, United States
AU: * Boll, J
EM: jboll@uidaho.edu
AF: Deparment of Biological and Agricultural Engineering University of Idaho, P.O. Box 440904, Moscow, ID 83844-0904, United States
AU: Brooks, E
EM: broo2789@uidaho.edu
AF: Deparment of Biological and Agricultural Engineering University of Idaho, P.O. Box 440904, Moscow, ID 83844-0904, United States
AU: Jones, J
EM: jjones@catie.ac.cr
AF: Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), GIS Laboratory 7170 Sede Central, Turrialba, Costa Rica
AB: As distributed hydrological models continue to develop, their amount of spatial detail requires the evaluation of a larger set of variables. Deforestation is often cited as a principal cause of changing hydrological regimes in the tropics. However, many studies debate the exact mechanism of change. Also, much of the tropics have been permanently deforested for agricultural expansion. Therefore, in this study we instrumented fields (1-6 ha) of four common land uses (forest, coffee agroforestry, sugar cane, and pasture) with meteorological stations, soil moisture probes, and H-flumes. Additional field measurements have shown differences in bulk density, saturated hydraulic conductivity, and soil moisture dynamics between land uses. Hydrograph analysis suggests that the pasture site responds differently to rainfall than the other land uses. Runoff from the pasture site results in higher intensity, greater volume, and shorter duration runoff events than the other land uses. However, the other land uses respond more frequently with lower maximum event intensities, lower volumes and longer durations. In the forest and coffee sites, soil moisture dynamics suggest the importance of lateral preferential flow paths due to root influenced soil structure for runoff response. Therefore, while vertical Ksat values may be greater at all sites than most rainfall intensities, lateral Ksat values may differ significantly between sites. Field measurements and the distributed physically based Soil Moisture Routing (SMR) model are being used test hypotheses, and direct further field research. These results will prove important to understand hydrological connectivity in fragmented landscapes, and the potential recovery of hydrological services within a typical humid tropical environment.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 1838 Infiltration
DE: 1847 Modeling
DE: 1850 Overland flow
SC: Hydrology [H]
MN: 2007 Joint Assembly