Hydrology and Hydraulics Structures

Landslide protection and drainage system

Task

Executive design of works aimed at protecting and draining two landslides in Calabar,

Design

Detailed design
Client

LCROSS RIVER STATE - Nigeria (NR)

Opere finalizzate al sistema di protezione e drenaggio di due frane presenti a Calabar in Nigeria

The project

The executive project, drawn up by GIT and GCOS Universal Ltd., relates to works aimed at the ‘Protection and drainage system for two landslides in Calabar – CCECC and CICC sites’.

Geodetic surveys of landslide-prone areas have revealed that both movements are characterised by the same mechanism; both phenomena may have originated along an existing watershed affected downstream by flooding from the Calabar River.

Following a flood, the river water levels flooded the areas surrounding the riverbed; subsequently, as the levels dropped, the return of the water to the channel triggered regressive erosion which, having been underestimated for years, caused it to recede by several hundred metres.

The following measures have been planned for both landslides:

Filling with compacted soil (and blocks of quarry material upstream of the sill (dam control) at the CCECC site and overall reprofiling of the lower part of the slope.
Hydraulic works for treating water on slopes, through the implementation of a drainage network
Revegetation of the surface layer of the soil through naturalistic engineering measures.