Salinity of Borehole Water in Arid and Semi-Arid Areas
Creators: name: Gloria Nyagaka
Publisher: name: Zenodo
Year: 2024

description: Salinity in boreholes has been a major concern in ASAL and coastal region of Kenya. Most partsEastern are dry and mostly Kitui County is Semi-arid and most of the boreholes drilled in this areaarefound to be saline. Groundwater resources is the only water supply in most parts of the countyespecially North and central Kitui.This report outlines approaches that were used to determine possible causes of salinity in boreholes,their levels, and finally recommend possible remedial measures that can be put in place. Severalapproaches were used in order to achieve objectives of this project.Data from boreholes spread over the entire project area were analyzed, discussed among colleagues andconclusions made over the results.The study area is covered by topographic map having an area of approximatelykm2 with a population of about people. The study area is accessible since there are several newlybuilt tarmac roads in the town and also through the main tarmac Kitui to Syongila where it branches tojoin Mombasa road and the other Thika road.Groundwater resource is the main source of water for both domestic and livestock since there are onlytwo major river traversing this vast area (Kalundu river and Mutendea River) which are highly polluted.The history of boreholes in kituiThe first borehole was made in 1950’s and was called the Kitui borehole which was 340ft deep.thepumped groundwater was of good quality and not saline., capacity of the pump was 23-36cubic metresper hour.The storage capacity of kitui aquifer was estimated to be 1000 Million cubic metres, monthlymaximum withdrawal estimation is 15,500 cubic metres. According to WatManSup Report no. 2 ofNovember 2006 by A van Loon and P. Droogers.Groundwater has become the main source of water in the modern world due to high population growthand high demand for water. Since surface water has been over-stretched, the importance ofgroundwater as a source of water for human consumption, agriculture and industrial purposes is inevery country. For the safety of groundwater users, tracing and identifying sources of pollution whichpose a contamination threat to subsurface waters is very vital. Groundwater is multidimensionalconcept and is characterized by location, occurrence over time, size, aquifer properties andaccessibility.Seasonal rivers are not reliable since most of them dry up immediately after the rain season.This is due to encroachment on catchment areas and destruction of natural forest for charcoal burning.Also climate variability has caused unreliable rainfall causing most of the seasonal rivers topermanently dry up.Climate variability due to global warming has contributed to decline of surface water resource in thestudy area.Demand on groundwater resources have increased in the recent past in the study area which has posed achallenge to Water Resources Managers in the region in meeting the Millennium development goalsand Vision 2030.Water is obtained through scooped holes from the beds of seasonal rivers and drilled boreholes duringdry seasons, sand dams store water which lasts few more weeks or months after rains stop.One of the major issues affecting this source in the study area is high salinity rate above WHO standardthreshold that render it unsuitable for human consumption and sometimes even for livestock use. Considering high costs of borehole drilling and scarcity of surface water resources in the study area,there is need to study causes of salinity in borehole and address remedial measures that can be put inplace to alleviate the problem.