TC Burundi: Management and Protection of Groundwater Resources

Report of the project:

• Burundi - Management and Protection of Groundwater resources

Hydrological map of Burundi

Background:
Burundi is a small country of 27,834 km² located in the centre of Africa. According to the 2008 census, the population sums up to 8.04 million persons. The country is mainly conformed by a high plateau with variable altitude (from 772 m.a.s.l at the Tanganyika Lake to 2,670 m.a.s.l. at mount Heha). It has an equatorial climate with mean annual temperatures that vary according to the altitude between 23 °C to 17 °C. The mean precipitation is 1277 mm with two rainy seasons (February to May and September to November) and two dry seasons (June to August and December to January).

Presently the domestic water supply is based on the about 25,000 springs with different discharge rates that provide water through local gravity systems. However, these systems have their natural limitation and cannot respond to future higher domestic water needs caused by the enormous population growth (around 3 %). Therefore, there is an urgent need for the country to estimate the quantity and quality of groundwater resources, if future water demand is to be covered.

Project areas

The Project:
The project "Management and Protection of Groundwater Resources" is a bilateral cooperation project of the Burundian Ministère de l’Eau, l’Environnement, l’Aménagement du Territoire et de Urbanisme (MEEATU) and the German Federal Institute for Geosciences and Natural Resources (BGR). The direct project partner is the Institut Géographique du Burundi (IGEBU) located in Gitega. The project is integrated in the Programme Sectoriel Eau (ProSecEau), a national water and sanitation programme financed by the German Federal Ministry for Economic Cooperation and Development (BMZ) that includes the Gesellschaft für Internationale Zusammenarbeit (GIZ) and KfW as further operative and financing organisations.

Aim of the BGR project is the quantification and protection of groundwater resources. The technical activities take place in various intervention zones, each with a different goal, as follows:

• Kirundo: estimation of the groundwater resources in the granite aquifer in the province of Kirundo
• Gitega: delineation of protection zones for the city water supply system
• Rumonge: definition of the quality and quantitative potential of local groundwater resources. The project supports the implementation of an Integrated Water Resources Management (IWRM) approach in this pilot zone

Kirundo region

Technical results:
Kirundo study area: This region is characterized by a gentle hilly surface of rounded hills. There is absolute absence of rivers, but numerous valleys are flooded by groundwater conforming large lakes. Drinking water access is far from been adequate and there is an urgent need for construction of new water points in the form of tube wells. At present water provision in the area takes place either from rough surface water from the lakes or from some scattered shallow wells or new tube wells drilled in the period 2012-2013 that unfortunately present very high concentrations of iron, manganese, ammonium and fluoride. Therefore, investigations are needed in order to find regions with good groundwater potential and quality.

The project performed a basic hydrogeological study that involved analysis of satellite images combined with surface geophysics (transient electromagnetic and tomography). The investigations led to the sitting of 5 points that have been drilled in the last months. Drilling results show the presence of some 90 m of weathered granite on the top of the fresh granite. The performed pumping tests lead to transmissivity values of 4x10^-4 m²/s, indicating promising groundwater potential for the weathered granite in the area. Additionally, the groundwater quality complies with the World Health Organization (WHO) standards, although the fluoride concentration is at the limit (1.5 mg/L).

Gitega study area: Gitega is the second large city in Burundi after the capital Bujumbura. The population counts for about 23,000 habitants (estimation 2012). The area is characterized by quartzite/schist hills intercalated by relatively narrow valleys covered by layers of clay product of decomposed schist. The "Régie de Production et de Distribution d’Eau et d’Électricité" (REGIDESO) is in charge of the water supply for the city. It is a centralized system fed, at present, by 12 boreholes distributed in three wellfields and numerous springs located to the east and southeast of the city.

Distribution of springs at Birohe

The project started investigating the bacteriological composition of the extracted water from both wells and springs. As expected, the wells are bacteria-free, but springs do present bacterial pollution as the result of direct pollution from human activities. There is thus a need for definition of protection zones, especially for springs. Periodical measurement of E-Coli bacteria at Birohe, to the east of Gitega, showed very different results depending on the source. While springs C26 and C119 are free of E-Coli, C25 has shown E-Coli in half of the measurements. Springs C115 and C116 do not have bacteria in 11 % of the measurements, while C117 and C118 are E-Coli free in 17 % of the measurements.

Cross-section of the Birohe area

To be able to reduce the bacterial pollution of springs at Birohe, the project has proposed the installation of protection zones. To start with, tracer tests aimed to estimate the flow velocity were performed at two springs using common salt (NaCl) as tracer material. The geological situation of the area is characterized by a hilly arch composed of quartzite intercalated by layers of schist with a surface gradient of 19 %. The valley at the bottom is composed of clay of at least 5 m of thickness. This geological set-up that leads to the appearance of springs is typical for about 80 % of the country.

The tracer results show a high groundwater flow velocity (1 m/h) that explains the susceptibility of the springs to pollution. Further, the project has drilled three observation wells in order to control the largest wellfield in the area. These sites were located by means of remote sensing and surface geophysics. Drilling results have confirmed the excellent potential of the zone (transmissivity = 3x10^-3 m²/s to 8x10^-3 m²/s) as well as the good groundwater quality that meets the WHO standards.

Distribution of E-Coli in Rumonge area

Rumonge study area: The third study area was selected to comply with the ProSecEau programme that plans to install an IWRM pilot project in the region. The area is characterized by a mix of quartzite/schist hills and granite hills with abrupt slope to the east and a flat plain of lake sediments to the west along the border of the Tanganyika Lake. Bacteriological analyses have shown that 75 % of the samples from springs and 33 % of the samples from surface water are free of E-Coli bacteria.

The city of Rumonge is mainly supplied by two wells located at the shore of the Tanganyika Lake that pump groundwater from the sedimentation plain. Both show very high concentrations of iron (> 10 mg/L) and need treatment before supply. The project has drilled five boreholes at different locations in the plain aimed to search for a better site where iron is not a hazard. Drilling results have confirmed the very good potential of the area (transmissivity = 3x10^-3 m²/s) and have shown that iron appears to be spread all over the area, although concentrations are lower at the border of the plain towards the mountains.

Literature:

Technical reports

• BLÜMEL, M. (2015): Improvement of IT Infrastructure and Data Management Systems at the Geographic Institute of Burundi (IGEBU). – Technical Report No. 5 of the project "Management and Protection of Groundwater Resources in Burundi", prepared by IGEBU & BGR: 32 p., 32 fig.; Hannover. (PDF, 3 MB)
• BRAC, F., MAZURU, A., KREKELER, T., TIBERGHIEN, C. & VASSOLO, S. (2018): Essais de traçage dans les sources Kagoti I et Ruhero II, Gitega. - Rapport Technique No 11 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 39 p., 30 fig., 8 tab.; Gitega - Hanovre. (PDF, 6 MB)
• HAHNE, K. (2014): Lineament Mapping for the Localisation of High Groundwater Potential Using Remote Sensing. - Technical Report No. 4 of the project "Management and Protection of Groundwater Resources in Burundi", prepared by IGEBU & BGR: 52 p., 53 fig., 2 tab.; Hannover. (PDF, 9 MB)
• HECKMANN, M., VASSOLO, S. & TIBERGHIEN, C. (2016): Groundwater Vulnerability Map (COP) for the Nyanzari Catchment, Gitega, Burundi. – Technical Report No. 7 of the project "Management and Protection of Groundwater Resources in Burundi", prepared by IGEBU & BGR: 96 p., 33 fig., 14 tab.; Hannover. (PDF, 6 MB)
• MIBURO, D. & TIBERGHIEN, C. (2019): Rapport sur les pompages d’essai du forage Aquavie Liquid. - Rapport Technique No 14 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 11 p., 7 fig., 1 tab., 2 ann.; Gitega. (PDF, 6 MB)
• MIBURO, D. & TIBERGHIEN, C. (2019): Rapport des travaux de réhabilitation du forage F8 Cewe. - Rapport Technique No 17 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 17 p., 26 ann.; Gitega. (PDF, 9 MB)
• NDAYITWAYEKO, F., TIBERGHIEN, C. & NDGAIJIMANA, G. (2019): Note technique pour la remise en marche à pleine capacité du système AEP de Bugabira. - Rapport Technique No 15 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 18 p., 3 fig., 7 tab., 10 ann.; Gitega. (PDF, 3 MB)
• NIJIMBERE, R., RUGERINYANGE, D., TIBERGHIEN, C., NEUKUM, C. & VASSOLO, S. (2018): Synthèse des études techniques préalables à la définition des périmètres de protection des captages d’eau potable de la ville de Gitega. - Rapport Technique No 10 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 46 p., 41 fig., 7 tab., 9 ann.; Hanovre. (PDF, 11 MB)
• NOELL, U. (2016): Report on the Geophysical Measurements to Support the Technical Cooperation Project in Burundi. – Technical Report No. 6 of the project "Management and Protection of Groundwater Resources in Burundi", prepared by IGEBU & BGR: 103 p., 28 fig., 4 tab.; Berlin. (PDF, 12 MB)
• PFUNT, H., TIBERGHIEN, C. & VASSOLO, S. (2016): Numerical Groundwater Model for the Nyanzare Well Field at the Town of Gitega, Burundi. – Technical Report No. 8 of the project "Management and Protection of Groundwater Resources in Burundi", prepared by IGEBU & BGR: 46 p., 18 fig., 4 tab.; Hannover. (PDF, 2 MB)
• RYUMEKO, M. & TIBERGHIEN, C. (2018): Rapport de supervision pour la construction des forages effectués à Gihanga. - Rapport Technique No 12 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 35 p., 19 fig., 2 tab., 7 ann.; Gitega. (PDF, 5 MB)
• TIBERGHIEN, C. & BARANYIKWA, D. (2018): Estimation des volumes d’eau prélevables de l’aquifère cristallin du champ captant de Gitega et de sa recharge. - Rapport Technique No 9 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 33 p., 8 fig., 6 tab., 10 ann.; Gitega. (PDF, 4 MB)
• TIBERGHIEN, C., BARANYIKWA, D., VASSOLO, S. & VALLEY, S. (2015): Étude sur le potentiel en eaux souterraines de la plaine de Rumonge - Rapport Technique No 3 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 40 p., 32 fig., 11 tab., 15 ann.; Hanovre. (PDF, 7 MB)
• TIBERGHIEN, C., NAHIMANA, N., BARANYIKWA, D., VALLEY, S. & VASSOLO, S. (2014): Présentation des captages d’eau potable de la ville de Gitega et évaluation de leurs qualités chimiques et bactériologiques en vue de la définition des périmètres de protection. - Rapport Technique No 2 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 42 p., 28 fig., 16 tab., 9 ann.; Hanovre. (PDF, 5 MB)
• VASSOLO, S. (2014): Guide National de Détermination des Périmètres de Protection des Captages d’Eau destinée à la Consommation Humaine: Annexe au Décret N°100/189 du 25 août 2014 portant modalités de détermination et d’instauration des périmètres de protection des captages d’eau destinés à la consommation humaine. - Rapport Technique de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 24 p., 11 fig., 2 tab., 6 ann.; Gitega. (PDF, 3 MB)
• VASSOLO, S. & KREKELER, T. (2013): Essais de traçage dans le bassin versant de Birohe, Gitega. - Rapport Technique No 1 de projet "Gestion et Protection des Ressources en Eau Souterraine au Burundi", elaboré par IGEBU et BGR: 13 p., 12 fig., 2 tab.; Hanovre. (PDF, 3 MB)
• VASSOLO, S. & KREKELER, T. (2013): Tracer Tests at Birohe Water Catchment, Gitega. - Technical Report No. 1 of the project "Management and Protection of Groundwater Resources in Burundi", prepared by IGEBU & BGR: 14 p., 12 fig., 2 tab.; Hannover. (PDF, 3 MB)

Map

• HECKMANN, M., TIBERGHIEN, C. & VASSOLO, S. (2017): Groundwater Vulnerability Map for the Nyanzari wellfield, Gitega, Burundi. – Prepared by IGEBU & BGR; Hannover. (PDF, 5 MB)