Hi everyone, on my research today am going to look on how the occurrence of underground water can be affected in various way like;
- Precipitation and evaporation in the area.
This are the major factors which influence the occurrence of underground water. If the precipitation is high and evaporation is low ,then more water is likely to enter the ground into the saturated zone. Consequently,the water table in areas with heavy or high precipitation is generally high or nearer to the surface.in drier areas where evaporation is likely to be high, the water table is usually low except in deep valleys where it may be nearer to the surface.
- Porosity of rocks.
It refers to the ability of bedrocks to absorb variable quantities of water in response to the force of gravity. This ability to absorb water depends on the number size and shapes of spaces within the rock. Thus rocks with large spaces like gravel, sand and limestone have high propensity of water to percolate through them.
- Permeability of rocks.
Like porosity, the degree of permeability of a rock plays a key role in the occurrence of underground water. Permeability refers to the ease at which water can move underground. It primarily depends on the molecular attraction, which acting mainly through surface tension tends to retard the movement of water. It is influenced by the size of particles. The smaller the particles, the larger the surface area and the greater the volume of water that can be held by surface tension. For instance, the surface area of clay particles in a given volume of gravel, thus making the permeability of gravel much greater, while the porosity of the two materials are the same.
- slope .
The nature of slope has great influence on the rate of water percolation into the ground. Generally, the rate of percolation on steep slopes is low because most water forms surface runoff. In gentle slopes like plateaus or plains, water percolation rate is high because the flat nature of the landscape allows water to move slowly thus giving adequate time for infiltration.
- Vegetation cover.
generally , percolation of water underground is high on surface which are covered with vegetation because water is held for substantial length of time. Areas with little or no vegetation on the other hand have low percolation rate because most of the water forms run-off.
- Level of saturation in the ground.
Dry ground absorbs a lot of water , however , as the air spaces fill up, the rate of infiltration is reduced. The drier the ground, the higher of the rate of infiltration.
- Water loss through evapotranspiration.
When the atmosphere has a low moisture content, it encourages a high rate of evapotranspiration, this in turn reduces the amount of water that could have infiltrated the ground. Therefore the higher the evapotranspiration, the lower the infiltration. The existence of underground water makes it possible for the following to occur;
- Wells and
- Artesian basin and artesian wells.