Hydrogeology of a weathered fractured aquifer system near Gitega, Burundi | Hydrogéologie d’un système aquifère fracturé altéré près de Gitega, Burundi Hidrogeología de un sistema acuífero fracturado alterado cerca de Gitega, Burundi 布隆迪Gitega附近风化断裂含水层系统的水文地质状况 Hidrogeologia de um sistema aquífero fraturado por intemperismo próximo a Gitega, Burundi
2019
Vassolo, Sara | Neukum, Christoph | Tiberghien, Christian | Heckmann, Matthias | Hahne, Kai | Baranyikwa, Désiré
The domestic water supply of Burundi is mainly based on some 25,000 springs that provide water through gravity systems. These systems have their natural limitation and cannot respond to future domestic water needs caused by the enormous annual population growth. An estimate of the quantity and quality of groundwater resources in the crystalline and metamorphic hard-rock environment, with strongly variable weathering features, is a prerequisite to ensure future water supply from groundwater resources. The hydrogeology of the Nyanzari aquifer system, which is used for the water supply of the city of Gitega in central Burundi, has been investigated with the aim of understanding aquifer characteristics. Results indicate that weathering of the metamorphic basement rocks has led to the development of two-staged aquifers: a deeper fractured aquifer in the saprock, covered by a shallow saprolite aquifer. This shallow aquifer is fed directly by precipitation and discharges at numerous small overflow springs along the valley edges. In general, the discharge of the springs shows seasonal variation patterns with maxima shortly after the rainy season similar to those of the hydraulic heads measured in the saprock aquifer. Groundwater management in the Nyanzari wellfield is partly unsustainable since abstraction is temporarily higher than recharge, even if, so far, periods of over-abstraction have been compensated by later rainy seasons. The lessons learned concerning the behaviour of the strongly weathered fractured aquifer system in Nyanzari will help to develop and manage comparable groundwater resources in Burundi.
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