hydrology model

Hydrologic Modeling of Land Processes in Puerto Rico Using Remotely Sensed Data

Hydrologic Modeling of Land Processes in Puerto Rico Using Remotely Sensed Data
Cruise, J. F.; Miller, R. L.
Journal of the American Water Resources Association, vol. 30, Issue 3, p.419-428

Abstract: 
An integrated, multi-disciplinary effort to model land processes affecting Mayaguez Bay in western Puerto Rico is described. A modeling strategy was developed to take advantage of remotely sensed data. The spatial, interannual, and seasonal variability of sediment discharges to the bay were also evaluated. Classified images of remotely sensed data revealed the spatial distribution and quantities of land use classes in the region and aided in the discretization of the watershed into homogeneous regions. These regions were modeled using a geomorphic modeling technique based upon spatially averaged parameters. Simulation results from the modeling effort compared favorably with observations at two locations within the watershed. Results showed that runoff and sediment loads from the area exhibit a marked seasonal trend and that deforested areas located in the foothill regions of the watershed contribute a disproportionate share of the sediment load to the bay. In years when rainfall distributions are uniformly distributed over the area, the sediment yields may be up to 100 percent higher than years when the rainfall is concentrated in the heavily forested mountainous regions.

The Use of a Distributed Hydrologic Model to Predict Dynamic Landslide Susceptibility for a Humid Basin in Puerto Rico

Abstract: 
This thesis describes the use of a distributed hydrology model in conjunction with a Factor of Safety (FS) algorithm to predict dynamic landslide susceptibility for a humid basin in Puerto Rico. The Mameyes basin, located in the Luquillo Experimental Forest in Puerto Rico, was selected for modeling based on the rich ensemble of soil, vegetation, topographical, meteorological and historic landslide data available. The basin was parameterized into the TIN-based Real-time Integrated Basin Simulator (tRIBS) with particular emphasis on vegetation parameters for broadleaf evergreen trees in tropical climates. The basin was forced with precipitation data that included a synthesized rainfall event likely to result in a landslide based on rainfall intensity-duration thresholds. The basin’s response was assessed mainly in terms of soil moisture and values of selected vegetation parameters, which served as the dynamic inputs into the FS algorithm. An off-line FS algorithm was developed and tested using typical values for parameters encountered in the Mameyes basin. Sensitivity analyses indicated that slope angle, soil cohesion and soil moisture were the most sensitive parameters in this FS algorithm. When the tRIBS / FS Algorithm combination was employed over the entire basin, landslides were indicated in 48 out of 13,169 modeled locations. The spatial distribution of landslides compared favorably to a static landslide susceptibility map developed in previous work by Lepore et al. (2008b) while the temporal distribution of landslides was correlated with rainfall events. Landslides were predicted over a range of slope angle values, including on relatively gentle slopes where the modeled soil moisture drove the instability. The results demonstrate that the tRIBS/FS algorithm combination developed in this work is able to capture the key dynamics associated with slope stability, specifically the interactions between the slope angle and the soil moisture state.
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