Groundwater development and management across Marsabit, Isiolo, Garissa and Wajir Counties in Kenya, and the Jubbada Hoose (Lower Juba) Region in Somalia.
The Merti Aquifer lies east of Kenya and extends south-west into Somalia's Jubbada Hoose region, covering approximately 73,713 km². The area of interest stretches from Sericho, Modogashe, Habaswein, Merti, Fafi, Dadaab and Liboi through to Goobweyn and Afmadow in Somalia, broadly following the Ewaso Ng'iro / Lagh Dera drainage axis.
The study area is a gently eastward-sloping plain covered by mostly ephemeral drainage channels and scarce vegetation. The western fringe is bounded by the slopes of Mt. Kenya and Mt. Marsabit (over 1,500 m amsl), descending to about 400 m amsl near the Somali border. Rainfall is below 300 mm/year across most of the arid and semi-arid zone, with evaporation exceeding rainfall for most of the year.
| Year | 2019 | 2026 | 2030 | 2035 | 2040 | 2045 |
|---|---|---|---|---|---|---|
| Projected population (Kenya side) | 818,390 | 1,006,620 | 1,132,447 | 1,313,639 | 1,523,821 | 1,767,633 |
The Merti basin is a sub-catchment of the Juba-Shebelle catchment, drained mainly by ephemeral laghas flowing south-east. The aquifer is hosted in semi-consolidated sedimentary formations — friable to semi-consolidated gravel, grit, sand, silt and clay in lenticular beds — and is confined, roughly 64 m thick, typically encountered at 110-180 m below ground level (bgl), though depths vary and the full lateral extent remains unspecified due to sparse borehole data, especially on the Somali side.
Groundwater is generally struck at 105-150 m bgl. In low-lying areas the saline interface can appear as shallow as 150 m bgl, while in higher-elevation zones it lies deeper than 350 m bgl. The aquifer's central axis, following the approximate course of the Ewaso Ng'iro / Lagh Dera, yields the best water quality and quantity and is the aquifer's main recharge pathway.
Key concern: several existing boreholes (e.g. Dhobley, Hoosingow) are pumped at high yields for up to 24 hours a day, penetrating the fresh-saline transition zone and pushing EC above 3,000 µS/cm. The report recommends more, shallower boreholes pumped at lower yields over longer hours — spaced to balance abstraction and recharge and prevent further up-coning and salinization.
Ten priority projects — five per country — combine drinking-water supply and water-buffering technologies. Buffering infrastructure also supplies livestock, since boreholes are prioritized for human consumption.
Monitoring & production, 1.5 km spacing
Buffering along Lagh Dera tributaries
Cascading dams on sandy laghas
Haffir-type, rehabilitated or new
Auxiliary abstraction, near-surface
Liboi (Kenya) and Dhobley (Somalia) — the main cross-border towns along the aquifer — were selected for the transboundary pilot phase, combining borehole supply with water-buffering dams and pans.
| Site | Main infrastructure | Target population | Est. demand |
|---|---|---|---|
| Dhobley 1 (Somalia) | 3 boreholes (2 production, 1 monitoring) | ~22,000 | 660 m³/day |
| Dhobley 2 (Somalia) | 2 earth dams | Buffering for pastoralists & communities | |
| Dhobley 3 (Somalia) | 2 water pans (Haffir dams) | Buffering for pastoralists & communities | |
| Liboi 1 (Kenya) | 3 boreholes (2 production, 1 monitoring) | ~1,203 | 36 m³/day |
| Liboi 2 (Kenya) | 2 earth dams | Livestock demand ≈ 117 m³/day | |
| Site | Main infrastructure | Target population | Est. demand |
|---|---|---|---|
| Hoosingow 1 & 2 (Somalia) | Water pan rehab + 2 boreholes (rehab) + 1 monitoring borehole | ~4,500 | 135 m³/day |
| Modogashe — KE 1.3 | 4 cascading sub-surface dams + infiltration galleries | ~2,309 | 69 m³/day (+ 371 m³/day livestock) |
| Gurufa — KE 2 | 3 boreholes (2 production, 1 monitoring), piped to Modogashe | ~2,309 (served via Modogashe) | 69 m³/day |
| Shantabaq — KE 7 | 2 boreholes (1 production, 1 monitoring) | ~377 | 11 m³/day |
A further set of alternative projects (Tabda, Bilis Qooqani, Arbajahan, Habaswein, Abakore, Goreale, Ademasajida, Eldera, Barkuke) is listed for second-priority feasibility, pending additional investigation.
Water quality at recommended sites was screened against salinity, taste/odour, colour, electrical conductivity, chemical integrity and the absence of aggressive substances. Zones with elevated fluoride concentrations — visible on the potential map above — were specifically avoided for drinking-water supply siting, and the report flags them as a persistent constraint on the aquifer's central axis.
Recharge to the Merti Aquifer is driven primarily by the Ewaso Ng'iro river system, whose sandy bed provides substantial storage capacity. Hydrogeological parameterisation places the aquifer in the permeable zone of the Merti beds, with moderate specific capacity and transmissivity.
A proposed Merti Aquifer Management Committee (MAMCo), bringing together hydrogeologists, engineers and socio-economists from both riparian states, would set the planning vision and oversee development. A Merti Catchment Technical Secretariat would coordinate MAMCo and its ministerial representatives.
Recommended joint measures include a bilateral MoU, community empowerment and education, O&M capacity building, cross-border knowledge exchange, systematic monitoring of abstraction and infrastructure, and shared data dissemination through a common database.
Cumulative estimated cost, all phases: USD 18,308,385.
| Client | Financed by | Report No. | Date | Consultant |
|---|---|---|---|---|
| IGAD | The World Bank Group | 20/2022 | June 2022 | Earth Water Ltd, Acacia Water & HydroRift |
Prepared under the Horn of Africa Groundwater Initiative (HoA-GWI), implemented by IGAD through the Water Unit at the IGAD Secretariat in Djibouti, in partnership with government representatives from Kenya and Somalia. This Volume I synthesises the priority and alternative proposed projects; Volume II presents the detailed engineering designs and drawings.