Event Title

Using GSSHA hydrologic modeling for the flood early warning system of the Esteli River, Nicaragua

Presenter Information

Fidel Perez
Jim Nelson

Location

Eccles Conference Center

Event Website

http://water.usu.edu

Start Date

1-4-2014 5:40 PM

End Date

1-4-2014 6:00 PM

Description

A spatially-distributed, physically-based GSSHA, hydrologic model has been developed to improve an existing early flood warning system of the towns Estelí and Condega that are upstream and downstream respectively in the Estelí river watershed in Nicaragua. For the sake of thoroughness, the results of the GSSHA model are compared with lumped HMS and quasi-distributed ModClark models for actual and design storms, and for the rainfall of Hurricane Mitch in 1998. The model is first used to assess the effectiveness of the set of locations of the monitoring sites by estimating the response time of the sub-basins. The threshold values for rainfall and river stage are redefined by examination of generated hydrographs and flood maps. Varying grid sizes for this watershed with total surface area of over 1,300 km2 are evaluated by comparing computational time which is critical in operational flood forecasting centers. Finally a set of models with multi-resolution 2D grids is developed to take into account the difference in terrain relief between the surrounding steep terrain in the mountainous areas and the much flatter slopes of the urban areas. A larger or regional model covers the entire watershed, and there are two smaller inset models with higher resolutions grids to represent areas in both of the cities. The overland flow and stream boundary conditions from the regional, coarse-resolution model are transferred to the local-area, higher-resolution models, a procedure here recommended in model coupling for real time flood warning operations that allows for a better prediction of flow depth in the inundated urban areas.

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Apr 1st, 5:40 PM Apr 1st, 6:00 PM

Using GSSHA hydrologic modeling for the flood early warning system of the Esteli River, Nicaragua

Eccles Conference Center

A spatially-distributed, physically-based GSSHA, hydrologic model has been developed to improve an existing early flood warning system of the towns Estelí and Condega that are upstream and downstream respectively in the Estelí river watershed in Nicaragua. For the sake of thoroughness, the results of the GSSHA model are compared with lumped HMS and quasi-distributed ModClark models for actual and design storms, and for the rainfall of Hurricane Mitch in 1998. The model is first used to assess the effectiveness of the set of locations of the monitoring sites by estimating the response time of the sub-basins. The threshold values for rainfall and river stage are redefined by examination of generated hydrographs and flood maps. Varying grid sizes for this watershed with total surface area of over 1,300 km2 are evaluated by comparing computational time which is critical in operational flood forecasting centers. Finally a set of models with multi-resolution 2D grids is developed to take into account the difference in terrain relief between the surrounding steep terrain in the mountainous areas and the much flatter slopes of the urban areas. A larger or regional model covers the entire watershed, and there are two smaller inset models with higher resolutions grids to represent areas in both of the cities. The overland flow and stream boundary conditions from the regional, coarse-resolution model are transferred to the local-area, higher-resolution models, a procedure here recommended in model coupling for real time flood warning operations that allows for a better prediction of flow depth in the inundated urban areas.

http://digitalcommons.usu.edu/runoff/2014/2014Abstracts/3