Urban Flood Vulnerability and Risk Mapping Using Integrated Multi-Parametric AHP and GIS: Methodological Overview and Case Study Assessment

Abstract

Abstract:This study aims at providing expertise for preparing public-based flood mapping and estimating flood risks in growing urban areas. To model and predict the magnitude of flood risk areas, an integrated Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) analysis techniques are used for the case of Eldoret Municipality in Kenya. The flood risk vulnerability mapping follows a multi-parametric approach and integrates some of the flooding causative factors such as rainfall distribution, elevation and slope, drainage network and density, land-use/land-cover and soil type. From the vulnerability mapping, urban flood risk index (UFRI) for the case study area, which is determined by the degree of vulnerability and exposure is also derived. The results are validated using flood depth measurements, with a minimum average difference of 0.01 m and a maximum average difference of 0.37 m in depth of observed flooding in the different flood prone areas. Similarly with respect to area extents, a maximum error of not more than 8% was observed in the highly vulnerable flood zones. In addition, the Consistency Ratio which shows an acceptable level of 0.09 was calculated and further validated the strength of the proposed approach.

Flood Potential Analysis (FPAN) using Geo-Spatial Data in Penampang area, Sabah

“…Low gradient slopes are highly vulnerable to flood occurrences compared to high gradient slopes. 38 In terms of slope gradient in the study area, the results suggest that 48.37% of the area can be categorized as 0o -5o, 28.45% as a 6o -15o, 22.41% as 16o -30o, 0.75% as 31o -60o and 0.01% in excess of 60o (Fig. 10 & Tab.…”

Physical Flood Vulnerability Mapping Applying Geospatial Techniques in Okazaki City, Aichi Prefecture, Japan

“…It can be derived directly from remote sensing data and it needs to be verified by survey [73][74][75]. Furthermore, the land use can represent the socioeconomic condition in a certain area [6,74]. The classification of land use is listed in Table 5.…”

“…The AHP pairwise have to be consistent with all pairwise comparisons. The AHP parameter for flooding was adapted from Ouma and Tateishi (2014) [6], and we modified by interviewing two hydrologists. Ouma et al formulated the parameter with 16 experts (four hydrologists, four engineers and eight end-users).…”

“…The flood vulnerability variables were determined by literature review; rainfall [1,6,18,[42][43][44][45][46]; drainage density [6,[47][48][49][50][51]; slope [16,18,44]; soil [6,52,53]; and land cover [44,[54][55][56].…”

Historic flood events in NE Romania (post-1990)

“…Processing techniques in GIS software allow local authorities to manage areas impacted by hazards, incorporate local knowledge and ensure community participation (Astite et al, 2015;Ireland, Volpi, & Petropoulos, 2015;Ouma & Tateishi, 2014;Sami, Mohsen, Afet, & Fouad, 2013).…”