Literature Review On Groundwater Pollution

CHAPTER TWO

LITERATURE REVIEW

2.1 INTRODUCTION

The exploitation of groundwater for man use started since ancient times. At first, people did not understand nature of groundwater occurrence properly; however, different methods of groundwater exploitation have been developed. Groundwater plays an important role in national development; hence, its management is of great importance. The demand for groundwater is increasing as the days go by due to a number of factors such as the relatively low cost of development, high population growth rate, high growth rate of industries, availability of groundwater at a needed place, relatively good natural quality etc.

In many developing countries many people dependent on groundwater for drinking, domestic

(1982) observed that the soil particles and rock materials in unconsolidated deposits are able to reduce pathogen numbers to acceptable levels as the contaminated water flows through them. Therefore, bacterial contamination occurs when the water table is so shallow or the contaminants get direct contact with the groundwater through the open well. This means that bacteriological contamination of groundwater in deep well are due to direct and localized factors such as poor sanitation around the well, discharge of industrial and domestic waste etc. (WHO 1996). A landfill is a particular piece of land used for the deposit of wastes materials. However, these waste materials in the landfill are potential sources of groundwater pollution (Everett, 1980; Foster et al., 1987). Therefore, proper landfills are planned, located, designed and constructed according to engineering specifications to avoid or reduced the negative impact on the environment and groundwater quality.

The negative impact of agricultural activities on groundwater quality is well established. Recharge by runoff from irrigation water into groundwater as well as leaching of agrochemicals cause serious groundwater contamination problems. The clearing of natural vegetation and ploughing up of virgin land for new cultivation also affect the groundwater quality. Irrigation is one of the major sources of salinity in the soil through which rainwater flows to the water table. The dissolution of these salts finally

Ayoko et al. (2007) observed that usually communities that depend on untreated groundwater for domestic and agricultural purposes are communities that lack adequate infrastructures to monitor water quality regularly and implement control strategies due to poverty. Chenini I and Khemiri S. (2009) noticed that the chemical composition of groundwater is controlled by many factors that include the composition of precipitation, mineralogy of the aquifers, climate, and topography. They concluded that the effect of the combination of these factors can create diverse water types that change in composition spatially and temporally. It is important to mention here that the interaction between groundwater and the host rock is affected by some physical parameters such as temperature, pH, etc. as they determine the rate of the interaction. According to Hem (1989), groundwater in igneous rocks is often lightly mineralized but characterised by high silica contents. The interaction between groundwater and the host material is essential when assessing impacts of anthropogenic activities on groundwater