International Waters learning Exchange & Resource Network

Conjunctive surface groundwater management Pilot Designs

09 Oct 2024 | by f.vilar-denardi@unesco.org
Enhancing conjunctive management of surface and groundwater resources in selected Transboundary aquifers: Case study for selected shared groundwater bodies in the Nile Basin.

The Nile Basin Initiative is currently implementing the project entitled “Enhancing conjunctive management of surface and groundwater resources in selected Transboundary aquifers: Case study for selected shared groundwater bodies in the Nile Basin”. This project aims at fostering the more effective utilization and protection of three selected shared aquifers in the selected sub-basins in the Eastern Nile and the Nile Equatorial Lakes region through further improving the understanding of the available groundwater resources and demonstrating ‘conjunctive management that optimizes the joint use of surface and groundwater. 

National and International consultants were recruited to conduct pilot project designs for conjunctive management of surface and groundwater. The pilot designs were developed through deep and continuous engagements with stakeholders along the three transboundary aquifers to enhance ownership and promote sector – sector/national and regional cooperation. 

The consultation meetings followed extensive field visits and ground measures used to generate and develop reasonable project designs. The stakeholder’s consultation meetings were planned to support the consultants’ continuous engagement with the national experts in the basin for the enhancement of the design’s development and the integration of the pilot designs in the national and sub-basin water resources future development plans.

Following a through ground investigations and consultations meetings, the selection was set on the type of conjunctive use of water resources approach. The pilot project technology (MAR) managed aquifer recharge was recommended by most Nile Basin countries and the shared aquifer diagnostics analysis report (SADA report). The technology was to be ascertained by field investigations and ground measures to generate the most reasonable and most effective design.

Two designs of MAR technology were developed by consultants (Fig1& Fig2), verified by national experts and modified to adjust to the current social needs and international standards on drinking water supply following the SDG 6 for water and sanitation. 

The MAR structure in Kagera region (Fig1) was proposed to provide potable water to the small communities within the vicinity of the aquifer area. The intervention involves the construction of a subsurface high permeability ditch for the collection and storage of groundwater in sufficient quantities to meet the domestic water demand of targeted communities. The structure will be designed to serve about 500 persons (20-30 m3/day). The proposed structure will be oriented within the native aquifer in a normal direction to the natural flow gradient and with an adequate dimension to ensure sufficient yield over a wide range of hydrologic conditions.  The subsurface structure will also function as a storage reservoir below the ground.  A groundwater monitoring network comprised of 40 wells was designed to cover the full extent of the Kagera aquifer.  The wells will be fitted with multiparameter probes to measure the water level as well as selected water quality parameters.

Water tables vary considerably in the Mount Elgon aquifer, typically from 10 to 70 meters, depending on distance from the main riverine recharge source and extent of local extraction. With per capita water demand expected to double over the next 15–20 years, combined with population increases, water supplies are under increasing pressure. A Managed aquifer recharge structure (MAR)(Fig2) is intended to take advantage of water supplies available during the rainy seasons when river flows are up to 15 times greater than in the dry season, and artificially augments recharge to increase underground water supplies for future use. The MAR intervention at Mount Elgon area, can help stabilize or raise groundwater levels, improving the availability of primary water supply for potable uses and making water supplies more secure.  The MAR induced infiltration technology for Mount Elgon region will be constructed by check dam sites, supplied by injection borehole, solar pumps, above ground intake well, piezometers and treatment plants. 

For Gedaref Adegrat shared aquifer area a regional monitoring system was designed(Fig3). The monitoring system was generated using a multi criterion analysis for three major parameters including, 1) availability of ground- surface water 2) environmental aspects3) socio economic aspects, among various sub criterion including accessibility to motor roads, urban dwellings, power supply, etc… the final lay out of the monitoring network was represented using a suitability map showing potential sites for monitoring. The design recommended twelve sites in Sudan and eleven sites in Ethiopia using solar pumps and online/offline motorized sensors for reading water levels and other water quality parameters.

MAR technology is not a newly introduced technique in Africa and the Nile Basin region, the technology has been in use for generations. The knowledge regarding the improved MAR technology will provide opportunities for improved water supply that will have positive impacts on health and economic performance at all levels of community, but to fully satisfy the unmet water demand, that will require further investment in surface groundwater investigations, share of knowledge and best practice.  Water quality is of paramount importance, and use of recharge protection zones, managed extraction points, education, water quality monitoring and appropriate technologies will be important to achieve potable water at the household level.  

Fig. 1 MAR structure Kagera region (Burundi, Rwanda, Tanzania& Uganda)

Fig. 2 MAR structure Mount Elgon region (Kenya&Uganda)

Fig.3 Regional Groundwater Monitoring suitable sites, Gedaref- Adegrat region (Ethiopia & Sudan)

About the project: The Nile Basin Initiative (NBI) is a regional intergovernmental partnership that seeks to develop the River Nile in a cooperative manner, share substantial socio-economic benefits and promote regional peace and security. It was launched on 22nd February 1999 by Ministers in charge of Water Affairs in the riparian countries namely Burundi, DR Congo, Egypt, Ethiopia, Kenya, Rwanda, South Sudan, The Sudan, Tanzania, and Uganda. Eritrea participates as an observer. NBI provides riparian countries with the first and only all- inclusive regional platform for multi stakeholder dialogue, information sharing as well as joint planning and management of water and related resources in the Nile Basin.