International Conference on Frontiers of Environment, Energy and Bioscience (ICFEEB 2013) ISBN: 978-1-60595-133-1 Effects of Precipitations on Groundwater Salinization in Dar Es Salaam Coastal Plain (Tanzania) G. SAPPA, F. FERRANTI and G. LUCIANI ABSTRACT This paper deals with part of the first results of three years investigation activities, carried on in the Dar Es Salaam coastal plain (Tanzania) by the ACC-DAR project, a cofoundend research project, granted by the European Union, leaded by the Sapienza, University of Rome, in cooperation with Ardhi University of Dar Es Salaam, Here they are presented the effects of precipitations of groundwater salinization. As a matter of fact, in the last fifteen years the Dar Es Salaam coastal plan has been involved in a hard increasing of groundwater exploitation, due to population growing up, and, as a consequence of it, it has been registered a sensitive increasing in seawater intrusion, partly due also to climate change effect. The project, mentioned above, faced many aspects related to the adaptation to climate change by Dar Es Salaam people. In the framework of the project they were carried on 5 groundwater monitoring campaigns, involving about 80 boreholes spread all over Dar Es Salaam municipality. In the following they are presented the results of the elaboration of chemical analysis data, coming from two different monitoring campaigns, driven in June 2012 and in November 2012. The interpretation of these elaborations, carried on by the application of Stuyfzand classification method (6), let us to evidence that seawater intrusion on groundwater quality is affected by the precipitation rate of the area, which is strictly related to climatic conditions and their modifications INTRODUCTION The ACC Dar Project aims to improve the effectiveness of municipal initiatives for supporting coastal peri-urban populations in their efforts to adapt to Climate Change (CC) impacts, thus contributing to the implementation of the National Adaptation Programme of Action (NAPA) of the United Republic of Tanzania. As a matter of fact seawater intrusion and its evolution, during the years and related to seasonal variations of precipitation, is a very important factor affecting groundwater chemical composition. Groundwater chemical composition influences the different uses people can do with it (3). G. Sappa. DICEA – Department of Civil, Building and Environmental Engineering – Sapienza, University of Rome, Rome, Italy