Climate Change Vulnerability Assessment and Adaptation Planning ...

3.0 Conducting a Vulnerability AssessmentCase study: Cameroon – low-technology water levelelevation surveyThrough one day of fieldwork, a transect acrossthe Douala Estuary mangrove area was surveyedfor elevation using the low-technology water leveltechnique (Figure 28 and Ajonina, 2011). The sitesselected (Figure 31) were at the seaward edge,including the eroding Kwelekwele Island (Figure 20;see case study in subsection 3.3).Results, shown in Table 15, indicate that the rangeof mangroves is from 6.75 to 75.4 cm, about a 70cm elevation bracket in a tidal range of 1.2 m. It isnormal for mangroves to occupy the upper half of thetidal range. Kwelekwele Island is about 35 cm lowerthan mangrove areas elsewhere in the estuary at theseaward edge, and this contributes to its vulnerability(Figure 20 and Table 12). Rhizophora racemosahas the broadest elevation range, about 6 to 54 cm,which would make it the most “climate-smart” speciesof those present. Laguncularia, in particular, andAvicennia have narrower elevation brackets, makingthem less able to tolerate rising sea levels.BolendoDouala EstuaryLEGENDRhizophoraMixed mangroveAvicenniaLandward forestSand spitVillagesElevation survey stationsReference StationEpakaStation 1 YoumeNStation 2Station 3Station 4Station 5Station 65000 metresMoukoukeStation 7Station 8By Michael HelmanFigure 31. Douala Estuary mangrove area showing elevation survey sites.Climate Change Vulnerability Assessment and Adaptation Planning for Mangrove Systems | 51