Abstract

Bathymetric survey and mapping are important procedures for monitoring temporal changes in hydrogeomorphic characteristics of lakes. This study is the first ever carried out on the lakes, and as such provides relevant baseline information for current use and future studies. The studied lakes (Gwakra, Geriyo, Pariya-Ribadu and Pariya) were purposively selected for the study on the basis of size and relevance. The bathymetric survey was conducted by sounding rod method. Preparation of the Bathymetric Maps involved the application of GIS procedures. Morphometric parameters of the lakes were determined from prepared maps by direct measurements and mathematical computations using appropriate formulae. Information derived from the prepared maps revealed that the lakes are characterized by gentle Basin Slope and almost uniform bottom morphologies with slight ruggedness. Maximum Lengths of the lakes ranged from 0.89 (Pariya) to 3.14 m (Geriyo), while Maximum Widths ranged from 0.34 (Pariya) to 1.52 m (Gwakra). The lakes were also found to be generally shallow with mean dry season depths ranging from 0.40 to 1.33 m and volumes ranging from 0.17 to 1.12 mcm. The lakes were characterized by low Indices of Basin Permanence (0.04 to 0.27), indicating senescence and dominance by littoral plants. Relative depths were also very low (0.07 to 0.42), indicating high propensity of water mixing and circulation of dissolved Oxygen adequate enough to support biological productivity. Thus, the lakes are recommended for substantial fish farming and livestock production in the area.  Proper management involving temporal morphological assessment of the lakes based on this study is also recommended for sustainable use.

Key words: Fluviatile lakes, hydrographic survey, bathymetric mapping, lake morphometric characteristics.