Hydrological Feasibility of Dams in Libya: An Assessment of Evaporation Losses

Abstract

   Dams are among the most important engineering structures used since ancient times and upon which great civilizations were built. They are constructed to protect cities from the risk of floods and to store water for use in various sectors depending on the volume of water collected and the topography of the area. Approximately 40% of the world’s agricultural lands are irrigated using water stored behind dams, and hydropower accounts for 19% of global electricity production and 85% of renewable electricity generation. This paper aims to examine the feasibility of the dams constructed in Libya and assess whether they have achieved the objectives for which they were built, as well as to review the challenges that have hindered the optimal utilization of these dams. Given the enormous volumes of water lost annually from dam reservoirs through evaporation, this study focused on estimating evaporation losses from the main dams—Wadi Al-Majnin Dam, Wadi Kaam Dam, and Wadi Ghan Dam—considered the largest in terms of stored water volumes. Wadi Al-Qattara Dam was excluded from the analysis due to the unavailability of data in the software used (GLEV). For this purpose, the Global Lake Evaporation Volume (GLEV) model was applied to calculate the monthly evaporation from these dams during the period 1985–2018. Monthly evaporation rates ranged from 15,000 m³ during the colder months to 329,000 m³ in some of the hotter months. The results revealed that water losses from dam reservoirs through evaporation are extremely high due to the prevailing climatic conditions, which significantly increase evaporation rates. This situation necessitates reconsidering the feasibility of constructing large storage dams. The study concludes with a set of proposals and recommendations to maximize the benefits derived from these dams.