Floods of 18 and 19 November 2016 in Batouri (East Cameroon): Interpretation of the Hydro-Meteorological Parameters and Historical Context of the Post-Event Survey Episode.

Paulin Sainclair Kouassy Kalédjé,Alain Fouépé Takounjou,Mireille Zebsa,Jules-Rémy Ndam Ngoupayou,Joseph Mvondo Ondoa,Felaniaina Rakotondrabe

doi:10.1155/2019/3814962

Abstract

During the night of November 18 to 19, 2016, many stormy cells are not very mobile organized on the east of the southern plateau of Cameroon and dumped up to 260 mm of rain in 4 hours. Occurring on a relatively saturated soil, these rains caused strong floods of Kadey and Doumé. The floods were particularly damaging in the city of Batouri, where a subdivision was submerged by the Boumbé (tributary of the Sangha) with water heights in the houses reaching 1.75 m, despite the presence of a dam allowing clipping floods upstream of the basin. In this article, we present the results of the analysis of the postevent survey generated on this event with flow rates estimated on 15 sections of ungauged subbasins. These flows are then compared with those obtained from other recent postevent survey and those estimated by various regional estimations. The inventory of heavy rains around Batouri during the period 1970-2016 has led to the revision of current development standards in the region, which seem to underestimate rainfall and infrequent flows.

Highlights

The intense rains accompanied by flash floods are one of the characteristics of the Equatorial Guinean climate
The most impacted villages were from west to east: Sandae, Dogbwe, Batouri, Mongonam, Mboscoro, Kambele III, and Dem (Figure 1)
Rainfall accumulations of 260 mm in 4 hours have been achieved, and the specific flows are of the order of 10 to 20 m3/s/km2 or more. These flows are of the same order of magnitude or exceeded by those estimated during other recent Cameroonian REX in the forest and humid tropical regions (Congo Basin) on the one hand and on the other hand in several regions: MontpellierGrabels, Nimes, Var, and Lodeve (France); Bouar, Kagabandoro, and Bosangoua (Central Africa Republic); Kano, Adamawa, Taraba, Oyo, Delta Imo Lagos, and Edo (Federal Republic of Nigeria)

Summary

Introduction

The intense rains accompanied by flash floods are one of the characteristics of the Equatorial Guinean climate. The extension of urbanized areas in southeastern Cameroon has multiplied homes vulnerable to flooding [1,2,3]. The collection of data on flash floods is a crucial issue for the definition of flood zones and risk control in urban or periurban areas. The purpose of the REX analysis is to reconstruct the flows achieved during exceptional events from the flood leashes and the testimony of local residents. These operations have notably helped to reevaluate extreme flows in the Mediterranean and tropical zones, where values greater than 20 m3/s/km over a few km have frequently been observed [3, 7]

Methods

Results

Conclusion