Soil map Groundwater vulnerability Contamination hazards 82 6000 82 7000 82 8000 82 9000 82 6000 82 7000 82 8000 82 9000 GPGroundwater ES - Managem entand Protection

M 21000 21000 21000 21000 MapNo.1 G i t e g a u 96 96 96 96 tw e M n Mut iz u t G i t e g a w G i t e g a w e e n n z z i i B i r o h e B i r o h e

Somali Quarter

Rango 1 & 2 RIG Roadcut Pz Birohe Pz Birohe

Vyinkona Quarry

Vyinkona 20000 20000 20000 20000 96 96 96 96

.N.R 8

Nyanzare 4 Nyabututsi 2

Nyabututsi 1 ibu Core 1-7 Oc Rugari Nyanzare Quarry Groundwater Vulnerability Map hira 1 & 2 abu Ny and thematic maps Core 8 Nyanzariwellfield

Betaniya 19000 19000 19000 19000 96 96 96 96 Gitega, S. Kazibaziba V S.Kazibaziba V

InstitutGéographique du Burundi (IGEBU), Gitega,République du Burundi in collaborationin with: FederalInstitute for Geosciences and Natural Resources (BGR ), S. Kazibaziba S.Kazibaziba Hannover,Federal Republic ofGermany

2017 CamLithic bic / Leptosol Umbrisol(hum clayic) ic, soilprofiles N y a n z a r i Cam bicLeptosol Ferralic / Cam bisol P isoplinthicPlinthosol studysites N y a n z a r i FerralicCam bisol P etroplinthicPlinthosol

Ferralsol (Anthraquic)Gleysol R.N. 8 R.N. 8 (Umbric)Ferralsol Groundwater vulnerability of the Nyanzari wellfield, Gitega Benetereziyan Benetereziyan Groundwatervulnerability isa qualitative measure of theprotection capacity of the overlying layers (O) Sisters Sisters Soil depth Soil texture Pz Itankoma Pz Itankoma the likelihood of groundwater contam ination. It whiletak inginto account am ountand intensity of 18000 18000 18000 Wellfield 18000 sum m arizesthe intrinsic physical characteristics of precipitation the(P), m edium for contam inant 96 Wellfield 96 96 96 the unsaturated z one to facilitate or retard transport. M M G i t e g a u G i t e g a u tw tw contam inant transport from the surface to the e e n n z z F7.3 F7.3 i i F7 groundwater reservoir. V ulnerability or the The Nyanzari wellfield southeastF7, of Gitega, F7 F7.5 F7.17 F7.5 F7.17 F7.12 F7.12 groundwaterprotection capability of the unsaturated providesof 2/3 the drinking water for the growing F7.8 F7.8 z one is controlled by the properties and the provincecapital. Deep soils and thick weathering Pz 02 F2 Pz 02 F2 thick nesses of its different com partments: soil, layersprovide a generally good protection of the F7 Pz 01 F7 Pz 01 F7.15 F7.15 lithologicallayers and weathering zones. groundwater reservoir. However, num erous lineam entsmapped by rem otesensing techniques Pz 03 F4 Pz 03 F4 F8 F8 majorA risk for groundwater contam inationis rapid m ay facilitate rapid infiltration and groundwater infiltration and preferential flow along zones of contam inationvia preferential flowpaths. structuralweak nesssuch as faults and lineam ents. P otential contam ination sources of the Nyanzari yabuhira yabuhira The magnitude of such preferential flow further wellfieldare the 1) Gitega petroleum reservoir, 2) N N dependsonthe infiltration characteristics of the soil, latrinepits and spreading urbanization, cattle 3)

.N.R 8 .N.R 8 therelief and land use type. farms,uncontrolled 4) waste dum psandreduction 5) S. Nyanzari S.Nyanzari ofprotective soil functions by clay extraction for TheGroundwater Vulnerability Map of the Nyanzari constructionpurposes.

cibu ibu watershed adapts the COP approach (Zwahlen TheGroundwater Vulnerability Map isapowerful tool O Oc 2003, Vías2003, et originally al,2006), developed for forregional and urban planning to preserve the hira hira abu abu Ny Ny carbonate(karst) environments. The COP -method quality of drinking water in the development of assessesthe risk of concentrated flow bypassing (C) Gitega. 17000 17000 17000 17000 96 96 96 96 Authors: Heck mTiberghien ann M., Vassolo C., S. Sources: Geographical Coordinate System: Topographic Map: GitegaIGN/IGEBU,(SA-36-XIII-1c), 1:50,000, 1981 WGS Datum (World84 Geodetic : System ) Geological Map: DigitalGeological BR Map, 1:100,000, GM, 2011 P rojection:UTM 35S Transv.(Univ. Mercator) Elevation: FitConseil (funded by PPEU, CDRproject, 2013) Lineaments: S urveyby Hahne GP& ES,BGR 2013 , Soils: S urveyby Heck m annGP& ES,BGR 5/2015 , deepm) (>1.5 clay loam intermediatem) (0.5-1.5 clayloam loam ysand References: shallowm) (<0.5 sandyclay loam sandyloam Heck mTiberghien ann M., Vassolo C., 'Groundwater (2016): S. Vulnerability Map (COP for the ) Nyanzari catchm ent,Gitega, Burundi',GP ESRapport BGRN° 7, /IGEBU. VAndreo íasPerlesJ., B., Carrasco M., Vadillo F., Jiménez 'ProposedI., (2006): P. Method for Groundwater Vulnerability MappingCarbonatein (karstic) Aquifers: The COP Method’. Hydrogeology Journal912–25. (6): 14 Erosion & deposition Ferricrete distribution Z wahlen‘Vulnerability (2003): F. and Risk Mapping for the Protection ofCarbonate (Karst) Aquifers Final Report’. COS T ActionLuxem 620. bourg:European Cooperation thein Field ofScientific and Technical Research.

M M G i t e g a u G i t e g a u tw tw e e n n z z i i

RWANDA 16000 16000 16000 16000 96 96 96 96 0 500 1.000 m 0 500 1.000 m D.R. 82 6000 82 7000 82 8000 82 9000 82 6000 82 7000 82 8000 82 9000 CONGO B U R U N D I

0° COP groundwater vulnerability index TheCOP Groundwater Vulnerability Map highlights areas where the groundwater resource is at risk Industries Urbanization Infrastructure Vulnerability after clay extraction becauseof noor only low protection by the unsaturated zone. Zones of high to very high vulnerability Gitega .N.R 8 .N.R 8 veryhigh vulnerability (0-0.5) lowvulnerability (2-4) petroleumtank quartzitemining settlem ent2006 university highvulnerability ifprotective (0.5-1) soil cover isrem oved requireprecautionary protection measures. High vulnerability exists areasin ofhigh groundwater levels highvulnerability (0.5-1) verylow vulnerability (4-15) (valleybottom lower s, slopes) and along lineam entsthat indicate zones ofpossible structural weak ness coffeeprocessing constructionquarry settlem ent2014 hospital Clay extraction for construction increases groundwater vulnerability.

u u andconcentrated, preferential infiltration. R estrictionof clay extraction is necessary to safeguard the protection cib cib m oderatevulnerability (1-2) cattlehusbandry footballstadium O O functionofthe soil. uhira uhira yab yab N N Wells Springs Hydrology Vegetation cover & topography T A N Z A N I ANIZ A T piez om eter spring(REGIDESO) streamnetwork forestplantation agriculture m ajorroad well spring(local use) NyanzariBirohe& catchm entareas openforest escarpment track COP = C x O x P well(disused) spring(disused) assum edsubsurface catchm entarea with grassland contourline footpath possibleinflux from the Bikinga watershed Gitega: Nyanzari wellfield 82 4000 82 6000 82 8000 83 0000 83 2000 83 4000

deposition m assive-vermiform(petropl.) deposition(likely) plateauferricretes C: Risk of concentration of flow O: Protection by overlying layers P: Precipitation (reduction of protection)

erosion(moderate) softplinthite (locally) 22000 22000 96 96 M M M erosion(strong) reworked,dispersed concretions u u u t t t G i t e g a w G i t e g a w G i t e g a w reworked,pack edpisolithic e e e G i t n n n e g a pack ed,pisolithic z z z i i i iroh potentialsubsurface distribution offerricretes B e C e

20000 B n 20000 96 ir e 96 oh - e C M Geology Faults and lineaments ushasha - o M R Nyakibingo u u n M M g G i t e g a u G i t e g a u M t a tw tw a u e e tw n n A r z z anz e i n i i y a i ri n N - z

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82 4000 82 6000 82 8000 83 0000 83 2000 83 4000 Betaniya Water sources

wellwell / disused Nyanzaristudy area Bikinga piez om eter build-upareas Nyanzari Geological formation Lithology Faults Lineaments veryhigh risk (0.0-0.2) lowrisk (0.6-0.8) verylow (1) high(4-8) verylow (0.9-1.0) high(0.6) spring(REGIDESO) spring(local use) Elevation [m asl] V yanda(schist) granite faults m ajorvalley low(2) veryhigh (8-15) low(0.8) veryhigh (0.4-0.5) Nyanzari watersheds highrisk (0.2-0.4) verylow risk (0.8-1) spring(disused) 1500-1600 1800-1900 V yanda(metaquartzites) quartzite faults(uncertain) tributaryvalley m oderaterisk (0.4-0.6) m oderate(2-4) m oderate(0.7) 1600-1700 >1900 NyanzariWatersheds Kiryam a(schist) schist faults(extrap.) veryfiedby fieldwork hydrogeol.transect 1700-1800 P ossiblesubsurface catchm ent Nyabikere schist& S P OTimages only TheCFactor quantifies the risk of concentration of flow TheO Factor describes the protective function of the TheP Factor sum m arizesthe quantity and the intensity Granitesalk alines quartzite unclassified andrapid infiltration along preferential pathways (here overlyinglayers and the effectiveness of the unsaturated of precipitation; the transport m edium that carries Map Notice / Disclaimer fissuresand fractures) thus bypassing the protective z oneto protect the groundwater resource. Param eters contam inantsfrom the surface through the unsaturated Thismap is based on different sources of information. Use of this map is subject to the user’s risk Institut . Géographique du Burundi and Inclination (fromGeological Mapfield / obs.) FederalInstitute for Geosciences and Natural Resources give nowarranty as tothe quality or accuracy ofthe information supplied nor accept functionof the unsaturated overlying layers. Param eters consideredinclude texture and thick nessof the soil layer z one into the aquifer.A hom ogeneous precipitation anyliability respectin ofloss, dam age,injury or other occurrences, however caused. / bedding controlling enhanced infiltration are the distance to aswell as lithology, thick nessand fracturation of the regimewith rainfall am ountsaround 1200 mm /aand / foliation lineam entsmand (10 m100buffers), land cover types weatheringand lithological layers. m oderateintensities result ainsingle category within the ©Institut Géographique du Burundi (IGEBU),République du Burundi FederalInstitute for Geosciences and Natural Resources (BGRFederal ), Republic ofGermany studyarea: low reduction ofprotection. GitegaHannover, / 2017