Call edition 2012

A new edition of the Prize of the Belgian Development Cooperation has been launched. This call is open until March 31st, 2011. You can read in the regulations whether you comply with the criteria for participation.

I would like to submit my application

Hydrogeological and hydrogeochemical investigation of a coastal aquifer in Dar-es-Salaam, Tanzania

Ibrahimu Chikira MJEMAH researcher laureate
ichikira@yahoo.com

°1971 Tanzania
Bachelor of Environmental Engineering, University of Dar-es-Salaam, Tanzania, 2000

Hydrogeological and hydrogeochemical investigation of a coastal aquifer in Dar-es-Salaam, Tanzania

We are often told these days that the coming decades will see a significant shortage of drinking water worldwide, the worst victims of which will be the population of developing countries. This study, of high developmental relevance, examines the issue of drinking water in the former Tanzanian capital Dar-es-Salaam, with a current population of approximately 3 million still being the largest urban centre in the country.
The aims of the study are fourfold: firstly, to investigate the structure and the dynamics of groundwater reserves; secondly, to chart the movements of groundwater; thirdly to describe groundwater quality on the basis of hydrogeological and hydrogeochemical processes and the limiting conditions of the coastal aquifer; and fourthly, to create a mathematical model for simulation of regional groundwater flows in the area under study.
Despite the lack of scientific publications in ISI-rated (International Standards Institute) peer-reviewed journals, the high scientific quality of the work is clear. The award-winner carried out numerous pump tests, flow measurements, water level measurements, and so forth, in difficult conditions, and charted the results in a clear fashion. His work is not only thoroughly scientific, but also socially relevant for future groundwater and surface water policy in Tanzania.
The laureate concluded, among other things, that groundwater replenishment of the two sorts of aquifers (an unconfined and a semi-confined aquifer) is done by rainfall both through the faults in the study area (regional) and through the sandy nature of the surface sediment in the coastal plain (local). This is estimated at 122 mm per year. The results also indicate that the aquifer contributes to the flow of the rivers Mzinga, Kizinga and Msimbazi, so that they remain water-bearing during the dry season, albeit as a result of different lithological conditions. Groundwater extraction in the area studied is estimated at 8.79 million m³/year. Dr Mjemah also calculated that outflow to the rivers accounts for 28964 m³/day, and outflow to the sea for 81368 m³/day.
The analysis of groundwater quality produced signs of deterioration due to pollution from point sources, in particular the wastewater of inhabitants (household drainage, septic tanks, dug latrines, etc.), and to some extent urban agriculture, with manure and artificial fertilizers. There was a high concentration of nitrate and sulphate and the dominant water type in both types of aquifer is NaCl, while in unpolluted shallow wells the CaHC03 water type was dominant.
The award-winner ends by presenting his recommendations, both for future research (e.g. concerning comparison with unpolluted sites) and for social action (focusing attention on possible problems of aquifer overexploitation).
This study certainly merits the Development Co-operation Prize and scientific and social valorisation of the results will hopefully be swift, for instance through scientific publications and implementation of the findings in local policy.

Dattari Mjemah, hongera sana kwa kazi hii.
 

report: Prof. Farid Dahdouh-Guebas, Biocomplexity Research Focus, Laboratory of Plant Science and Nature Management, Vrije Universiteit Brussel, Belgium, and Department of Biology of Organisms, Université Libre de Bruxelles, Belgium