Beyond Flood Hazard Maps: Detailed Flood Characterization With Remote Sensing, Gis and 2d Modelling

Abstract

ABSTRACT:Flooding is considered to be one of the most destructive among many natural disasters such that understanding floods and assessing the risks associated to it are becoming more important nowadays. In the Philippines, Remote Sensing (RS) and Geographic Information System (GIS) are two main technologies used in the nationwide modelling and mapping of flood hazards. Although the currently available high resolution flood hazard maps have become very valuable, their use for flood preparedness and mitigation can be maximized by enhancing the layers of information these maps portrays. In this paper, we present an approach based on RS, GIS and two-dimensional (2D) flood modelling to generate new flood layers (in addition to the usual flood depths and hazard layers) that are also very useful in flood disaster management such as flood arrival times, flood velocities, flood duration, flood recession times, and the percentage within a given flood event period a particular location is inundated. The availability of these new layers of flood information are crucial for better decision making before, during, and after occurrence of a flood disaster. The generation of these new flood characteristic layers is illustrated using the Cabadbaran River Basin in Mindanao, Philippines as case study area. It is envisioned that these detailed maps can be considered as additional inputs in flood disaster risk reduction and management in the Philippines.

Flood hazard assessment and the role of citizen science

“…Furthermore, discharge, velocity, and water level recorded in situ are important because they represent the initial or the boundary condition and they are used for model calibration and validation (Büchele et al, 2006). Second, the topographic information is the key information in many hydrological models (Santillan, Marqueso, Makinano-Santillan, & Serviano, 2016;Werren, Reynard, Lane, & Balin, 2016), allowing the watershed delineation and the extraction of topographyrelated parameters such as slope and flow directions (Tarboton, Schreuders, Watson, & Baker, 2009). Third, the land use is used as input for hydrological modelling and influences significantly the runoff (Knebl, Yang, Hutchison, & Maidment, 2005).…”

“…As ground data are either scarce (e.g., in many countries of Africa, Komi et al, 2017), or declining (e.g., in the pan-Arctic region, Lins, 2008), and therefore time series incomplete, hydrological modelling is a useful tool to understand main processes involved in flood scenarios and to obtain outputs for flood hazard mapping such as the water depth, the flood extent, the flow velocity, and the duration of inundation (Néelz & Pender, 2010;Néelz & Pender, 2013;Santillan et al, 2016). With computational technology progress, modelling can be achieved in 1D (Brunner, 2016), 2D (Moulinec et al, 2011), or 3D (Prakash, Rothauge, & Cleary, 2014).…”

Quantitative flood hazard assessment methods: A review

“…On an international level, there exist many examples of flood mapping for purposes of flood risk management (de Moel et al, 2009; Klijn et al, 2008). Among these, the U.S. National Flood Insurance Program (NFIP, 2021; Luke et al, 2018); the French Flood Risk Prevention Plan (Decree 2019‐715, 2019; Guillier, 2017); the Flood Risk Management Plan of the Rhine, Germany (ICPR, 2021); the Danube Flood Risk Management Plan (ICPDR, 2021); the plan PLUIES (Flood prevention and control and effects of floods on victims) in Wallonia, Belgium (PLUIES, 2003); the DREAM and UP DREAM programs in the Philippines (Santillan et al, 2016; UP DREAM, 2016); the recent update of hazard and flood risk maps for several thousand kilometres of river courses and coastal sectors in Spain (Olcina‐Cantos & Díez‐Herrero, 2021). The EU Floods Directive (European Council, 2007) requires member states to produce flood hazard and risk maps as a preparatory step to the development of flood risk management plans (de Moel et al, 2009).…”

GIS-Based Flood Hazard Mapping in Itang District of the Gambella Region, Ethiopia

“…Over the last two decades, remote sensing has played an increasing role in water resource management (Dewan et al 2007;Winsemius et al 2013;Mina and Ying 2015). Geographic Information System (GIS) is also used extensively to model surface water and flood damage assessment (Opolot 2013;Santillan et al 2016;Rimba et al 2017;Ogato et al 2020). The Hydrologic Engineering Center's River Analysis System (HEC-RAS) model developed by the U.S. Army Corps of Engineers (USACE) is generally used for investigating flooding and flood-related hazards worldwide (Smith and Ward 1998;U.S.Corps of Engineers 2002;Merz et al 2004;Brunner 2016;Azouagh et al 2018).…”