13 / 2023-12-16 04:52:12

Method for Flood Risk Prediction in Pao River Basin, Venezuela

flood risk,pediction method,tropical basins

This study proposes a method for flood risk estimation in Pao river basin, Venezuela. The novelty consists of linking the effective rain with the exceedance probability on the occurrence of the effective rain and weather events during the service life of the hydraulic structure that would be designed to mitigate the flood risk. Two dynamic factors were included, which were the precipitation and the land use and land cover (LULC), monitored using sensors of precipitation data in real time, as well as multispectral images produced by remote sensing technology installed in Landsat satellite group, respectively. Precipitation was acquired in digital format from the website of the National Institute of Meteorology and Hydrology, Venezuela. The information was recorded every five minutes. Records of rain in each of the 25 selected gauging stations were accumulated on a monthly scale. An arrays of monthly precipitation time series were created for the months from May until October within the rainy season from two periods 1980-2000 and 2015-2018. ArcGIS 10.0 computational tool was used to transform tabular records to a layer of points that represented the geographical location of precipitation measurement stations inside and outside of Pao River basin. Geostatistical spatial tool was used to apply the Ordinary Kriging method and thus, generate the maps of monthly precipitation. The application of geostatistical techniques required to comply: a. Exploratory Analysis, b. Structural Analysis, c. Predictions. Six stages were included: 1) estimation of precipitation map, 2) estimation of water storage map in the soil, 3) estimation of the effective precipitation map, 4) generation of effective precipitation classification map, 5) estimation of exceedance probability map of effective precipitation, 6) estimation of hydrological risk map.  Results were validated through the principal components (PC) technique, PC was applied to flood risk maps for the time series 1980-2000. PC was also applied to the updated time series 2015-2018 of flood risk map. Change detection technique based on difference of PC N° 1 in the Pao river basin was applied, obtaining that flood risk did not change the occurrence of spatial pattern in a significant way. This result can be explained because of that the pattern found in the period 1980-2000 corresponded to the spatio-temporal distribution observed in the period 2015-2018, validating the method proposed and the areas committed in the extreme occurrence of the flood risk.