state and explain the various sources of water for class 10
Answers
Answer:
Types of Water Resources
Explanation:
Water sources can be classified as protected or unprotected. Protected sources are covered by stonework, concrete or other materials that prevent the entry of physical, chemical and biological contaminants.
Drinking water ladder.
The situation in Ethiopia
Figure 3.2 shows estimated trends in drinking water coverage in Ethiopia. Each of the columns shows the percentage of drinking water that is supplied by surface water, other unimproved sources, piped supply and other improved sources, for the years 1990 to 2012.
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Figure 3.2 The change in drinking water sources in Ethiopia between 1990 and 2012 for urban (left), rural (centre) and total populations (right). (Data from JMP, 2014).
Look at Figure 3.2 and calculate the percentages of water supplied from improved water sources to urban populations and to rural populations in Ethiopia in 2012.
Reveal answer
One reason for the low coverage of rural premises is that the rural population is dispersed, and therefore difficult to serve easily. In urban areas, people live closer together and populations are more concentrated in given areas; therefore pipes can be laid more easily (and with less expense) to cover a large population.
Deep wells or boreholes
These are wells that have been sunk with drilling machines designed for constructing water extraction boreholes (Figure 3.8). These machines are able to penetrate through harder material that cannot be tackled by hand digging and can therefore pass through at least one impermeable layer of rock to a productive aquifer underneath. They typically obtain water from depths ranging from 30 to 60 m, but large urban supply boreholes can be much deeper than this.
Drilling rig for a borehole.
A borehole.
At the surface, different types of pump may be used including hand pumps like the one in Figure 3.6. For larger boreholes in urban areas electric or diesel-powered pumps would be used.
Springs
Groundwater may emerge above ground as a spring. This happens in locations where the water table reaches the surface, or where the boundary between a permeable layer of underground rock and an impermeable layer reaches the ground surface, as shown in Figure 3.3. Springs are normally found at the foot of mountains and hills, in lower slopes of valleys, and near the banks of major rivers.
Spring source protection
Whether the spring originates from shallow or deep rock layers, animals should be excluded from the surrounding area by a stock-proof fence. Springs should be protected from flooding and surface water pollution by constructing a deep diversion ditch above and around the spring. The ditch should be constructed so that it collects surface water running towards the spring and carries or diverts it away. It needs to be deep enough to carry all surface water away, even in a heavy rainstorm.
Small springs are typically protected by a ‘spring box’ (Figure 3.10), which is constructed of brick, masonry or concrete, and is built around the spring so that water flows directly out of the box into a pipe or cistern, without being exposed to outside pollution such as run-off, bird droppings and animals.
A spring box.
Protected spring providing water for Bahir Dar. The concrete slab on the left covers and protects the source of the water.
Surface waters
The quality and quantity of surface water varies from one place to another and over time, due to factors such as geology, climate and surrounding land use.
Rainwater can be collected in several ways:
Groundwater reserves
Glaciers
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