Tanzania turns to Kimbiji Aquifer System as a new source of Water Supply
Setting drilling rig for drilling a monitoring borehole at Mkamba Primary School , Mwasonga village. Mkamba Primary School is one of the local institutions benefiting from the project.
The population of the city of Dar es Salaam in Tanzania is projected to grow from 6 million at present to more than 10 million by the year 2030 (World urbanization prospects, 2014). The rapid population growth and urbanization has placed a high demand on freshwater resources.
Until recently, most water for the city has been drawn from the Ruvu River, the single most important source of water for the city, involving significant operational costs. Prolonged droughts and deforestation have also adversely affected the runoff characteristics within the river basin. To meet the increasing water demand, Dar es Salam Water Supply and sanitation Authority (DAWASA) commenced a search for potential groundwater sites in the area. After drilling six deep wells of up to 610m at Kimbiji, Mpiji and Mpera, a deep, regional Neogene aquifer was discovered in the alluvial plain in the coastal area of Dar es Salam. These findings indicated that Kimbiji aquifer system could potentially be a future source of groundwater supply for the city and the surrounding communities.
Utilizing the Sub-grant funding made available by Global Environmental Facility and Cooperation in International Waters in Africa through the World Bank funding, the SADC Groundwater Management Institute (SADC-GMI) assisted the Government of the United Republic of Tanzania (Ministry of Water and Irrigation) to use the funding to further explore the Kimbiji Aquifer System as the potential source for water supply for Dar es Salam and surrounding areas.
The Groundwater Management in the Kimbiji Aquifer System project was formulated in order to assess alternative water sources, including groundwater resources in and around Dar es Salam through undertaking in-depth integrated qualitative and quantitative analysis of the Kimbiji Aquifer System to define its sustainable development and management. Ms Mwanamkuu Mwanyika, Principal Hydrogeologist at the Department of Water Resources Tanzania said the project will help the government to understand the nature and capacity of the Kimbiji aquifer in terms of quality and quantity. She also emphasized that the drilled monitoring wells will help control the abstraction rate of the boreholes drilled by the Dar es Salam Water Supply Authority to supply water to Dar es Salam Region. Sustainable groundwater resources management requires information on the behaviour of the aquifer before, and during the abstraction. This project will help to provide data to facilitate decision-making when the government is planning water resources for the City.
The Project will improve water supply in Dar es Salaam Region through monitoring of the quality, quantity and rate of abstractions.
Well development after a successful drilling of a monitoring borehole at Kigogo Fresh Primary School.
The project was developed to achieve the following objectives:
- To develop infrastructure for groundwater monitoring of Kimbiji Aquifer System
- To conduct ground and surface water monitoring and review field data in relation to the aquifer system’s response to large-scale pumping and potential hydraulic impacts on existing well owners, stream flows and wetland habitats in the project area
Currently, more than 1,800 shallow (mostly private) wells are used to augment local water supplies in the Dar es Salaam area. The majority of these wells are less than 100m deep, with greatly varying capacities and water qualities (JICA, 2005).
Through the Kimbiji Aquifer system project which was completed in 2020, 5 monitoring wells of 150m average depth were drilled in order to implement the environmental monitoring plan for the bigger Kimbiji Aquifer system project .
The project also installed groundwater monitoring data loggers, established groundwater abstraction register that included detailed survey of water users in and around the areas. Through the project, communities will also be able to access potable water for domestic and agricultural use, which will, in-turn improve livelihoods. The project will also help the City of Dar es Salam to meet the ever-increasing water demand due to population growth, industrialization and urbanization.
Wells were drilled in the following five sites recommended by groundwater investigation conducted prior to the drilling, and actual position of the drilling points were obtained from the geophysics report: Kibada Primary School (Kigamboni District), Mwasonga Mkamba Primary School (Ilala District); Mkuranga District Office (Mkuranga); Pugu Station (Temeke); Kigogo Fresh Primary School (Temeke).
The concrete deliverables coming out of the project are:
- The five drilled wells will help in accomplishing project objectives by collecting vitally important field data as intended and as specified by the environmental monitoring plan.
- The new installed infrastructure (monitoring wells) will provide the platform needed for monitoring of deep aquifer conditions, as detailed in the Aquifer Development Plan (ADP) report.
- The groundwater that was tested from the drilled exploration wells was found to be soft, slightly alkaline (mostly) and of a sodium-bicarbonate type.
- The laboratory results concluded that all of the samples from the exploration wells were of potable quality.
Ms. Mwanamkuu Mwanyika thanked SADC-MI, Global Environmental Facility, Cooperation in Internationals Waters in Africa, World Bank, and other partners for making this initiative a success. She assured cooperating partners in this project that the Tanzanian Government will ensure that they look after the infrastructure that has been put in place to assist the country. “Plans have been put in place to ensure that the project is sustainable beyond the funding period,” she concluded.
The drilling Team ready to start drilling a monitoring borehole at, Mkamba Primary School, in Mwasonga Village