Extreme Event-based Rainfall-runoff Simulation Utilizing GIS Techniques in Irawan Watershed, Palawan, Philippines

River flow assessments and ecologically sustainable water management plans are now possible due to the advancement of sophisticated computer models. The US Army Corps of Engineers developed the HEC-HMS model, which can be used for various hydrological simulations. Rainfall-runoff modeling aids in estimating peak flows, which is critical for water resource management planning. On December 18, 2017, a heavy rainfall event in the ungauged Irawan basin in Puerto Princesa City, Palawan, Philippines, was simulated to determine the peak flow and amount of water. The current research aims to construct a rainfall-runoff simulation model. A specific hyetograph is used to make the hydrographs for the basin. This study utilizes ArcGIS and QGIS, which perform the geospatial analysis and provide the HEC-HMS model's hydrologic modeling inputs. The hydrological parameters were determined using soil type, land use, and land cover maps. Incorporating SCS loss, Clark unit hydrograph, and Muskingum flow routing, HEC-HMS was employed in the rainfall-runoff simulation. Rainfall data corresponding to the recorded streamflow was used to calibrate and validate the parameters. Several performance metrics, including Nash-Sutcliffe efficiency (NSE) and Percentage Bias (PBIAS), were utilized to evaluate the overall effectiveness of the system. An effective decision-making and warning system can be implemented using the developed model. Doi: 10.28991/CEJ-2023-09-01-017 Full Text: PD

Simulation of Runoff and Flood Inundation in Kosi River Basin using Hydrological models, ANN, Remote Sensing and GIS

Floods are probably the most recurring, widespread, disastrous and frequent natural hazards of the world. India is one of the worst flood-affected countries. In India the Himalayan Rivers account for maximum flood damage in the country. The problem of flood in the state of Bihar is well known and every year it becomes a recurring problem to the entire region. The plains of north Bihar are some of the most susceptible areas in India, prone to flooding. Flood forecasting & flood warning, flood hazard mapping and flood risk zoning are quite effective non-structural procedures in managing floods that decreases the risks and disasters floods may cause. In view of this an attempt has been made in the present work to simulate runoff and flood inundation for Kosi River Basin in Bihar, India. This study introduces about the parameterization of hydrologic and hydraulic modelling for simulation of runoff and flood inundated area mapping. Time series analysis of hydrological data has been done to look for the rainfall and runoff behaviour in Kosi Basin and their cross-correlation. SRTM-DEM of 90m resolution is used to generate the various maps (DEM) of Kosi Basin. Hydrological and hydraulic models HEC-HMS, HEC-RAS, SCS-CN in addition to ANN models are used for runoff and floodplain inundation modelling. Results indicated that for Kosi catchment, the empirical runoff prediction approach (ANN technique), in spite of requiring much less data, predicted daily runoff values more accurately than semi-distributed conceptual runoff prediction approach (SCS-CN method). The flood inundation simulation for the Kosi River floodplain is carried out using HEC-RAS 1-D hydrodynamic model indicates promising results. Further, linear/non- linear regression models were developed to estimate the flood inundation area provides best results

Modelling flash flood using LiDAR and high resolution satellite imagery: a case study of West Creek, Toowoomba

Australia is one of the most heavily exposed countries in the world to different natural hazards, such as floods. In December 2010 and January 2011, large areas of the south and central Queensland were affected by flooding. On Monday 10th January 2011 heavy rains continued from 12:30 pm to 2:00 pm in the City of Toowoomba catchment area. Flash flooding occurred suddenly and unexpectedly making it difficult to prevent or predict before it occurred. This led to a rise in water levels in streets and roads, disrupting traffic and causing loss of life and properties. To reduce the effect of flood disasters and minimize the damages, flood inundation maps can be used to determine the locations of threat. This research used an integration of the HEC-Hydrologic Modelling System (HEC-HMS), HEC-River Analysis System (HEC-RAS) with Geographic Information Systems (GIS) to develop an improved model of the West Creek flood extent and flood event in the city of Toowoomba. The flood extent and depth in the different flow conditions of the West Creek channel was described in this study. The Hydrologic model (HEC-HMS) was used for 15 minutes time series data to create the flow rate at West Creek catchment from 12:00 pm to 4:00 pm. HEC-RAS with HEC-GeoRAS extension in ArcGIS was applied to simulate the flash flood in West Creek from Spring Street to Long Street. Digital Elevation Model (DEM) derived from high density LiDAR data and land cover data extracted from high resolution remote sensing imagery were used to model the flood inundation in the study area. The HEC-GeoRAS extension was used to prepare data sets for the stream centreline, banks, flow paths and cross-sections for import to the HEC-RAS hydraulic model. The downstream boundary conditions were defined in HEC-RAS. The hydrological results from HEC-HMS showed the maximum discharge value of West Creek Catchment at different periods of time. These results were comparable with Toowoomba Regional Council Report (TRCR). The flood inundation maps showed the maximum flood width and depth of West Creek Channel (starting from Spring Street and ending at Long Street) at 1:00 pm to 3:00 pm, which was greater than any previous floods in Toowoomba. The validation between the modelled flood extent at peak time and flood extent in the Nearmap aerial photo showed a high degree of correlation. Therefore, the model can provide a sound basis on which to analyse similar scenarios