The 24th IAHR-APD Congress (24th IAHR-APD Congress)

90 / 2024-01-07 07:43:05

Validation of Models for Predicting Rainfall-Runoff Process and Floodplain Delineation in Venezuelan Rivers. Cases: Cabriales River, Unare River, Urama River

validation,rainfall-runoff process,floodplain delineation

This work deals with the validation of models for predicting rainfall-runoff process and delineation of floodplains in Cabriales River-Pao River Basin (CR-PRB), Unare River Basin (URB), Urama River Basin (URRB), Venezuela. Under the financial support of National Fund of Science, Innovation and Technology (FONACIT, in Spanish), URB and CR-PRB were equipped with hydrometerological monitoring stations. In URB, two water level sensors models SEBA-PULS 20, manufactured by SEBA-HYDROMETRIE Company were installed on Clarines bridge (N09º57’07.8”, W65º10’12.83”) and Zaraza bridge (N09º20’40.7”, W65º18’40.5”), two rain gauges, RainWise model, placed on El Pueblito Water Reservoir  (N09º11’44.82”, W65º35’14.79”), Aragua de Barcelona Water Drinking Treatment Plant (N09º11’44.82”, W65º35’14.79”) and one weather station, Davis Instruments, El Cuji Water Reservoir into Unare River Basin (N09º26’00.05”, W65º13’04.09”). CR-PRB  was equipped with a water level sensors models SEBA-PULS 20, manufactured by SEBA-HYDROMETRIE Company installed on Fernando Peñalver Park bridge and a rain gauge, manufactured by TECNUM-ELECTRONICA, both placed on N10º11’58.42”, W68º00’8.82”. Flow capacity curves relating water depth against flow rate were generated for URB and CR-PRB. Rainfall was complemented with data measured in the hydrometeorological national network by National Institute of Meteorology and Hydrology. The models used were Clark unit hydrograph, Soil Conservation Service (SCS) unit hydrograph and the Snyder unit hydrograph. Software used were: ArcGIS 10.0, HEC-GEOHMS 1.0, HEC-HMS 3.5 and HEC-RAS 4.0. For the calibration phase, the Clark and Snyder unit hydrographs presented better adaptation to the outlet hydrographs of the study basins. For validation stage, error was smaller in the SCS unit hydrograph. In URB, the values of the design flows obtained with the simulation for return periods of 50 year resulted in high risk of flooding reflected in the floodplains, with values of up to 42.48% of coverage in inhabited areas. In URRB, results obtained indicated that for a flood with a return period of 10 years, the homes that would be affected would be those that are below the level of 35 meters above sea level; for 50 years, those that are below the level of 36 masl; and for 100 years, those that are below the level of 37 masl.