DAR ES SALAAM AQUIFER PART 1

General Introduction
Groundwater is one of the major sources to of water supply in Dar Es salaam, Tanzania. However, population growth, increasing urbanization, industrialization and tourism, and climatic changes have caused an intensive exploitation of groundwater resources leading the aquifers become more vulnerable to seawater intrusion. The aim of this study is to examine the variations of groundwater aquifers their distribution and water quality evaluation for drinking and irrigation purposes. Physical and chemical data come from the analysis of groundwater samples, collected from 28 wells, used for the evaluation of water quality parameters, during a year of monitoring. the role of seawater intrusion, evaporation process and anthropogenic pollution (i.e. high NO3 levels due to industrial activities), were observed as the major factors that influenced the water chemistry, and hence the water quality. The high salinity and the groundwater level depletion create serious problems for current use of water supplies as well as future exploitation.
This project is aimed at improving the knowledge about the groundwater aquifer in Dar Es Salaam Region. In order to provide a series of enhanced methodologies for improving municipal activities in the water management sector, it was investigated the evolution of groundwater quality and availability in the principal coastal aquifer of Dar es Salaam has undergone a considerable population growth, with a consequent increase of the urban areas, soil consumption and increased demand for water, which, given the scarcity of surface water resources, is largely satisfied by withdrawing the groundwater. Access to clean water is a major problem for Dar es Salaam, since only one third of the households received piped water available at their dwelling. The rate of groundwater extraction is expected to grow due to growing rate of demographic expansion. More specifically, project activities will enhance the capacities of Dar's municipalities by increasing their understanding of adaptation practices, and by developing methodologies for integrating adaptation activities into strategies and plans for Urban Development and Environment Management in unplanned and underserviced coastal settlements. In order to provide a series of enhanced methodologies for improving municipal activities related to issues in the water management sector, the specific environmental phenomenon of seawater intrusion was investigated. This phenomenon is already contributing  and will increasingly contribute as climatic change progresses   to the degradation of those natural resources on which a large part of Dar Es Salaam’s peri-urban livelihoods depend. Through the implementation of various analytical methods, tailored to the available set of climatic and hydro geological data (both historical and current data), the climatic and Anthropogenic drivers and the temporal evolution of the phenomenon were studied.
The work will account for the aquifer characterization, sedimentation process as well as give an aiding scope to the government and the water distribution companies during the water distribution project. 

Observation of Dar Es Salaam aquifers their characteristics geological properties as well as their accessibility to groundwater. By using the borehole data provided and review of different literature concerning groundwater in Dar Es Salaam region the project will come up with types of aquifers available in Dar es salaam, their characteristics and geological influence on groundwater properties. The borehole data provided includes those of borehole logging, water struck depth, yield capacity of wells and water quality in terms of salt intrusion.
From these borehole data the results were as follows:
Classification of groundwater based on struck depth of water into shallow wells, medium to deep wells and deep wells. Shallow wells are the wells on which the struck depth is less than 20m, medium to deep wells are the one in which the struck depth ranges from 20m to 40m and deep wells are the ones in which the struck depth ranging from 40m to 60m according to our given data.
The groundwater quality has been described from the effect on salt intrusion on the groundwater from sea water. It was observed that the wells which were drilled in areas nearby the ocean
Have salty taste compared to those further from the ocean.
In characterization of an aquifer from the borehole logs above the groundwater system in the study area can be divided in two aquifers, a semi-confined and an unconfined aquifer, separated by a clay aquitard. However, a second clay layer can be identified within the semi-confined aquifer.  Both aquifers and the aquitard are located in the sediments of Pleistocene to Recent age.
Underlying these sediments are the clay-bound sands of the Mio-Pliocene, ranging to 800 m
in thickness. Because of the low permeability and great thickness of this formation, the top of
the Mio-Pliocene can be considered as the base of the groundwater reservoir (Mjemah et al.,
2009). A third aquifer can locally be identified, a coral reef limestone aquifer, also of
Quaternary age. It is found mainly on Msasani Peninsula and along the coast, laterally
connecting with or underlying the unconfined sand aquifer.
Due to inadequate data most of the results obtained are based on few data which cannot well describe the overall hydrology of  Dar Es Salaam hence more data should be gathered so as to provide more accurate results.