Introduction of flood insurance and flood hazard map in Kota Bahru, Malaysia

<p>Flood hazard maps are essential for development and assessment of flood risk management strategies. Conventionally, flood hazard assessment is based on deterministic approach which involves deriving inundation maps considering hydrologic and hydraulic models. A flood hydrograph corresponding to a specified return period is derived using a hydrologic model, which is then routed through flood plain of the study area to estimate water surface elevations and inundation extent with the aid of a hydraulic model. A more informative way of representing flood risk is through probabilistic hazard maps, which additionally provide information on the uncertainty associated with the extent of inundation. To arrive at a probabilistic flood hazard map, several flood hydrographs are generated, representing possible scenarios for flood events over a long period of time (e.g., 500 to 1000 years). Each of those hydrographs is routed through the flood plain and probability of inundation for all locations in the plain is estimated to derive the probabilistic flood hazard map. For gauged catchments, historical streamflow and/or rainfall data may be used to determine design flood hydrographs and the corresponding hazard maps using various strategies. In the case of ungauged catchments, however, there is a dearth of procedures for prediction of flood hazard maps. To address this, a novel multivariate regional frequency analysis (MRFA) approach is proposed. It involves (i) use of a newly proposed clustering methodology for regionalization of catchments, which accounts for uncertainty arising from ambiguity in choice of various potential clustering algorithms (which differ in underlying clustering strategies) and their initialization, (ii) fitting of a multivariate extremes model to information pooled from catchments in homogeneous region to generate synthetic flood hydrographs at ungauged target location(s), and (iii) routing of the hydrographs through the flood plain using LISFLOOD-FP model to derive probabilistic flood hazard map. The MRFA approach is designed to predict flood hydrograph related characteristics (peak flow, volume and duration of flood) at target locations in ungauged basins by considering watershed related characteristics as predictor/explanatory variables. An advantage of the proposed approach is its ability to account for uncertainty in catchment regionalization and dependency between all the flood hydrograph related characteristics reliably. Thus, the synthetic flood hydrographs generated in river basins appear more realistic depicting the observed dependence structure among flood hydrograph characteristics. The approach alleviates several uncertainties found in conventional methods (based on conceptual, probabilistic or geomorphological approaches) which affect estimation of flood hazard. Potential of the proposed approach is demonstrated through a case study on catchments in Mahanadi river basin of India, which extends over 141,600 km<sup>2</sup> and is frequently prone to floods. Comparison is shown between flood hazard map obtained based on true at-site data and that derived based on the proposed MRFA approach by considering the respective sites to be pseudo-ungauged. Coefficient of correlation and root mean squared error considered for performance evaluation indicated that the proposed approach is promising.</p>

Download Full-text

THE SAFETY-BEHAVIOR-INDICATIVE FLOOD HAZARD MAP

Journal of Japan Society of Civil Engineers Ser D3 (Infrastructure Planning and Management) ◽

10.2208/jscejipm.67.528 ◽

2011 ◽

Vol 67 (4) ◽

pp. 528-541

Author(s):

Toshitaka KATADA ◽

Yasushi OIKAWA ◽

Makoto KODAMA

Keyword(s):

Flood Hazard ◽

Hazard Map ◽

Safety Behavior ◽

Flood Hazard Map

Download Full-text

Analysis of Hydro-Morphometric of Flash Flood Hazard Map of Wadi Gharandal Basin, Southwestern Sinai Area, Egypt, Using GIS and RS

Bulletin de la Société de Géographie d'Egypte ◽

10.21608/bsge.2018.90307 ◽

2018 ◽

Vol 91 (1) ◽

pp. 67-87

Author(s):

Mohamed Abd El-Aziz

Keyword(s):

Flash Flood ◽

Flood Hazard ◽

Hazard Map ◽

Flood Hazard Map ◽

Gis And Rs ◽

Southwestern Sinai

Download Full-text

Going beyond the Flood Insurance Rate Map: insights from flood hazard map co-production

10.5194/nhess-2017-384 ◽

2017 ◽

Author(s):

Adam Luke ◽

Brett F. Sanders ◽

Kristen Goodrich ◽

David L. Feldman ◽

Danielle Boudreau ◽

...

Keyword(s):

Flood Hazard ◽

End Users ◽

User Preferences ◽

Flood Insurance ◽

Hazard Map ◽

Flood Hazards ◽

Hazard Maps ◽

Baseline Hazard ◽

Flood Maps ◽

Flood Hazard Maps

Abstract. Flood hazard mapping in the United States (US) is deeply tied to the National Flood Insurance Program (NFIP). Consequently, publicly available flood maps provide essential information for insurance purposes, but do not necessarily provide relevant information for non-insurance aspects of flood risk management (FRM) such as public education and emergency planning. Recent calls for flood hazard maps that support a wider variety of FRM tasks highlight the need to deepen our understanding about the factors that make flood maps useful and understandable for local end-users. In this study, social scientists and engineers explore opportunities for improving the utility and relevance of flood hazard maps through the co-production of maps responsive to end-users' FRM needs. Specifically, two-dimensional flood modeling produced a set of baseline hazard maps for stakeholders of the Tijuana River Valley, US, and Los Laureles Canyon in Tijuana, Mexico. Focus groups with natural resource managers, city planners, emergency managers, academia, non-profit, and community leaders refined the baseline hazard maps by triggering additional modeling scenarios and map revisions. Several important end-user preferences emerged, such as (1) legends that frame flood intensity both qualitatively and quantitatively, and (2) flood scenario descriptions that report flood magnitude in terms of rainfall, streamflow, and its relation to an historic event. Regarding desired hazard map content, end-users' requests revealed general consistency with mapping needs reported in European studies and guidelines published in Australia. However, requested map content that is not commonly produced included: (1) standing water depths following the flood, (2) the erosive potential of flowing water, and (3) pluvial flood hazards, or flooding caused directly by rainfall. We conclude that the relevance and utility of commonly produced flood hazard maps can be most improved by illustrating pluvial flood hazards and by using concrete reference points to describe flooding scenarios rather than exceedance probabilities or frequencies.

Download Full-text