High Resolution Bathymetric and Satellite mapping of Gubi Dam Bauchi State, Nigeria

Abstract

There is a global concern about the rate of depletion of water reservoirs due to increase in demand and stagnation of supply amid population increase and climate change. Therefore, understanding and managing dams through strategic planning and sustainable-related policies is necessary. The objective of this paper is to examine the current condition of Gubi Dam and change pattern in relation to causes of the change. The dam was sampled using acoustic side-scan sonar and mapped the bathymetry to compute volume and capacity using Trapezoidal, Simpson’s Rule and Simpson’s 3/8 Rule. Results show astonishing similarity between the three methods, although overestimation in volume with over 1x105m3 was observed with Simpson’s Rule. Landsat 8 OLI/TIRS was used to corroborate these findings. Water surface area shows continuous decline from 2014-2020. The surface area shows similarity to the overall terrestrial surface temperature computed, indicating some level of evaporation. However, recent change in government policy in agricultural has pushed most inhabitants around Gubi Dam and its recharging rivers and streams back to farming. Irrigated farming during the dry season, hence increased usage of Gubi Dam and affected recharge from the rivers. Rural-urban migration to Bauchi metropolis could also increase water usage because the city depends solely on the dam. Annual bathymetric mapping, provision of gauge rainfall data and fixing of water level measurements at both the dam and the recharging rivers and streams are suggested. Sustainability measures relating to core environmental values, issues and threats be examined to guide research and policy thrust.

Keywords: Acoustic, Side Scan Sonar, Bathymetry, Landsat 8, Water Surface, Volume