29 / 2023-12-21 06:11:12

Method for Forecasting Flood Risk in a Tropical Country. Case: Pao River Basin, Venezuela

forecasting method,flood risk,tropical country

In this study, a novel method for forecasting the flood risk is proposed called as CIHAM-UC-FFR in a tropical country. Study area is Pao river basin, Venezuela. The method is based on the rainfall-runoff process. CIHAM-UC-FFR method consists of three stages: 1) calibration and validation for the effective precipitation model, called CIHAM-UC-EP model, 2) calibration of forecasting models for components of CIHAM-UC-EP model, 3) proposed model for forecasting of gridded flood risk called CIHAM-UC-FR. The CIHAM-UC-EP model has a mathematical structure derived a conceptual model obtained by applying the principle of mass conservation combined with the adapted principle of Fick’s law. The CIHAM-UC-FR model is a stochastic equation based on the exceedance probability of the forecasted effective precipitation. Main purpose of CIHAM-UC-FFR method is to provide information to make decisions for contributing to prevent the consequences of flooding by protecting human beings and goods. Proposed method might be classified as an hybrid, which can be applied for obtaining lumped or distributed values in forecasted main variables of interest, estimated using models proposed for the effective precipitation (CIHAM-UC-EP) and flood risk (CIHAM-UC-FR) depending on availability of local information. In general, the CIHAM-UC-FFR method included various model categories for its components: 1) CIHAM-UC-EP (Event, conceptual/quasi-conceptual, lumped/distributed, measured/fitted parameters), 2) Precipitation (Event, distributed/lumped, empirical, stochastic, fitted parameter), 3) Parameters of CIHAM-UC EP (Event, lumped, empirical, stochastic, fitted parameter), 4) Probabilistic function for CIHAM-UC EP (Event, lumped/distributed, empirical, stochastic, fitted parameter), 5) CIHAM-UC-FR (Event, distributed, empirical, deterministic, fitted parameter). The advantages of applying the proposed method are based on: 1) the update of the calibration of equations due to it offers an easy incorporation of new information for making continuous recalibration of the components for CIHAM UC-EP model by using  time series of precipitation measured from rain gauges and time series of satellite images for the LULC factor, 2) the adaptability of the three parameters included in the CIHAM-UC-EP model to be derived using algorithms for mathematical adjustment or obtained from field measurements, which leads to CIHAM-UC-EP can be classified as a conceptual or quasi-conceptual model. Flow attenuation parameter (Af) might be obtained measuring infiltration rate for a determined flow length, expressed in m² h^-1.  The flow attenuation time (t) can be obtained from quasi-physically measured concentration time. Various scenarios are shown for a future time where the flood risk is progressively decreased as the expected life parameter of hydraulic structure is increased.