Students of Cumberland High School singing a version of Gyptian's 'Serious Time' during the official handing-over ceremony of two additional classrooms at the rear of the school on Friday, December 2, 2005. - Anthony Minott Photo

THIS WEEK I will share with you sections of another question based on underground water.

It is Question Three from the June 1996 paper.

(a) Study the diagram in Figure 1 below, which shows an artesian basin then answer the following questions:

(See diagram below)

(i) Which well ­ A, B, or C ­ will contain water all year round? (1 mk)

(ii) Which well will never contain water? (1 mk)

(iii) Name the source of water in the aquifer. (1 mk)

(b) (i) Name two sources of underground water other than the one shown in the diagram above. (2 mks)

(ii) Explain two ways in which underground water may be polluted. (6 mks)

Here is the expected response to the question:

(a) (i) Well A will contain water all year round.

(ii) Well C will never contain water.

(iii) The rain is the source of water in the aquifer.

(b) (i) Two sources of underground water other than the one shown in the diagram above include any of the following - spring; hot springs; geysers.

(ii) Some ways in which underground water may be polluted were shared in the last lesson. Included on the list were:

• Untreated domestic sewage seeping underground.
• Industrial waste materials finding their way into underground water supplies.
• Chemicals used in agricultural activities - herbicides, pesticides, fungicides and fertilisers - seeping into underground water.

In addition to these are:

• Spills from oil pipelines
• Over pumping: fresh water lenses are undertaken by salty water. If these wells are over-pumped, the salty water is drawn towards the surface and pollutes the aquifer.

Let me now look at a section of another objective which expects you to be able to describe and explain the occurrence of springs. Two questions you may want to ask are - what is a spring, and how do springs occur?

The information in response to these questions comes from the text Morphology And Landscape by Harry Robinson.

A spring may be defined as a natural outflow of water from the ground, the point of emergence of groundwater. The rate of flow is variable: It may gush out forcibly, flow strongly, or seep out gently. The flow, moreover, is likely to vary seasonally. Springs are often classified as permanent if they have a continuous flow, or intermittent, if they dry up temporarily. Spring water may vary in its physical and chemical character: It may be cold or warm, soft or hard, mineralised or non-mineralised.

HOW DO SPRINGS OCCUR?

Springs result from variations in the rocks and structure of the crust. Neither the land surface nor the geology of the crust is uniform. Topographic variations, differences in rock type and geological accidents produce conditions conducive to spring formation. Broadly, however, the occurrence of springs depends upon three factors or conditions:

(i) the shape of the land surface.
(ii) the position of the water table.
(iii) the character and relationship of the rocks.

Springs are of numerous and varying origins, but mostly they are related to the arrangement of previous and impervious strata and to geological structures such as folding, faulting, jointing, etc.

In the next lesson, I will share with you information on the different types of springs.