Evaluation of Geology and Hydrogeology of the Water Leakage in Hammam-Grouz Dam, Algeria

Water has been known since antiquity as the catalyst and survival of mankind. Therefore, hydraulic structures have been constructed to resolve various hydraulic problems which are exposed, such as pollution, eutrophication, accelerated siltation, intense evaporation, and water leakage. In Algeria, the problem of water leaks has appeared in many dams, among them the Hammam Grouz dam in the north-east of the country. Indeed, hydro-technical work is considered the most threatened in the country by this thorny problem. During the period between 1984-1987, there was a lack of suitable sites for dam construction in this area, which led the services concerned to build this infrastructure in a cluse composed of limestone (Cenomanian) moderately karstic, which is characterized by dissolutions concentrated along the joints. This site was consolidated and sealed during the construction of the dyke dam that allows its exploitation before a real test. However, it should be noted that the water level rose above the normal reservoir level for the first time on January 26, 2003, showing that this site can no longer withstand the strong pressure forces caused by the coastline water. In fact, significant water leaks have appeared in the lower gallery and at the downstream foot of the right bank. The following variation of water leaks over time can be observed to have a convergence of stability of the level of the water level in the bowl to levels not exceeding 718 m, which is the equivalent of less than 1/3 of the original storage capacity of the dam. The appearance of significant water leaks at the Hammam Grouz dam as soon as the spill was first discharged indicated that the sealing works carried out during the construction of the dyke had either lost their effectiveness or weren't perfect. The settlement works were carried out today at the level of the basin and the banks of this hydraulic infrastructure. Despite having minimized the flow of the resurgences that appeared downstream of the dike, they did not solve the problem definitively. This may result in the appearance of a place where water is leaking. Indeed, during the hydrological year 2007/2008, the appearance of a vortex in November 2007 within the lake rendered the dam of Hammam Grouz useless because it was empty during the first three months of the year 2008, in addition to the water loss that threatened them. This phenomenon floods the lower gallery of the dyke with each rise of the level of water beyond a limit threshold. Hence, it is impossible to perform some monitoring related to stability control. The harmful effects of the problem of water leakage, the stability of the dike and the quantity of water stored, especially with water scarcity in this semi-arid region, require treatment of this phenomenon. The most adapted techniques are those that use sealing materials. Having the same characteristics as the places to be waterproofed and which adapt sufficiently to their geological formations, the allocation of sealing works to a highly qualified co-contractor is of great importance in order to provide satisfactory sealing results to make them watertight in order to operate them properly.

Doi: 10.28991/HEF-2021-02-03-08

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