TITLE:
Evolution of Dam Lakes in the Kayanga/Geba Basin: Contribution of Remote Sensing and GIS
AUTHORS:
Saly Sambou, Rene Ndimag Diouf, Birane Cisse, Ibrahima Diouf, Joseph Sarr, Honore Dacosta
KEYWORDS:
Dam Lakes, Remote Sensing, GIS, Watershed, Kayanga/Geba
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.12,
December
31,
2021
ABSTRACT: The Confluent and Niandouba dams were built in 1984 and 1997 respectively
to better control water resources, increase agricultural production and promote
local development. This article studies their evolution on the Kayanga/Geba
River, a transboundary river between Guinea, Senegal and Guinea-Bissau, from
its impoundment to the present day. The topographic characteristics analysed
through the DTMs (Digital Terrain Models) show a flat shape for the Confluent
Dam Lake and long plateaus for the Niandouba Dam Lake. The cross-sections present
a variety of morphologies ranging from wide U-shaped valleys with sinuous
bottoms to deep V-shaped valleys. The homogenisation and reconstruction of
missing values were carried out using the regional vector method. The application of Pettitt’s statistical test
on annual rainfall (1932-2019) indicates breaks of stationarity in 1967 or
1969. The post-breakage deficits range from 11.4% to 19.4%. The segmentation
method corroborates the results of the Pettitt test. The variations of the
surface area of the Confluent and Niandouba water bodies are linked to
rainfall, evaporation and withdrawals for different uses. Their monitoring
would allow for better management of available water resources but also
for good planning of off-season crops.