CBSE Class 10 Social Science Water Resources NCERT Solutions

Water scarcity is determined by more than just rainfall. It depends on the availability of usable water relative to demand. Here's the classification:

(a) Not suffering from water scarcity: High rainfall generally implies abundant water resources, assuming the water is accessible and not excessively polluted.

(b) Suffering from water scarcity: A large population increases the demand for water. Even with high rainfall, the per capita availability of usable water can be insufficient to meet the needs of a dense population.

(c) Suffering from water scarcity: If the water, despite high rainfall, is heavily polluted, it becomes unusable for drinking, agriculture, and industry, leading to scarcity of clean water.

(d) Not suffering from water scarcity: Low rainfall might suggest scarcity, but a low population means the demand for water is also low, potentially balancing the availability.

Multi-purpose river projects are designed to serve various needs. Let's examine the given statements:

(a) Favourable: These projects often involve building dams and canals that can divert water to arid or drought-prone regions, thus alleviating water scarcity.

(b) Favourable: By controlling the release of water from dams, these projects can manage river flow and prevent excessive flooding downstream.

(c) Unfavourable: This statement describes a significant negative social impact. The construction of large dams often submerges vast areas of land, displacing communities and disrupting their traditional livelihoods. This is a criticism, not an argument in favour.

(d) Favourable: Many multi-purpose projects include hydroelectric power plants that generate electricity, which is essential for industrial development and domestic use.

Therefore, the statement that is NOT an argument in favour is (c).

Let's correct the inaccuracies in the given statements:

(a) Incorrect statement: Multiplying urban centres with large and dense populations and urban lifestyles have caused the over exploitation of water resources.

Correction: Rapid urbanization and changing lifestyles increase water demand significantly, often leading to over-exploitation and scarcity, rather than proper utilization.

(b) Incorrect statement: Regulating and damming of rivers affect their natural flow and causes the sediment to settle at the bottom of the reservoir.

Correction: Dams alter the river's natural flow regime and trap sediments, preventing them from reaching downstream areas, which can have ecological consequences.

(c) Incorrect statement: In Gujarat, the Sabarmati basin farmers were agitated when higher priority was given to water supply in urban areas, particularly during droughts.

Correction: During droughts, when water is scarce, farmers in the Sabarmati basin (Gujarat) did express agitation because urban areas were prioritized for water supply over agricultural needs.

(d) Incorrect statement: Today in Rajasthan, the practice of rooftop rainwater harvesting is on the decline due to the Rajasthan canal.

Correction: While the Rajasthan Canal has increased water availability in some areas, the practice of rooftop rainwater harvesting, especially in arid regions like Rajasthan, is crucial and has historically been important, though its popularity might fluctuate with perceived availability.

Water is considered a renewable resource because it is continuously replenished through the Earth's natural processes, primarily the hydrological cycle. Here's how it works:

1. Evaporation: Water from oceans, rivers, lakes, and even soil evaporates into the atmosphere as water vapour.

2. Transpiration: Plants also release water vapour into the atmosphere through transpiration.

3. Condensation: This water vapour rises, cools, and condenses to form clouds.

4. Precipitation: When the water droplets in clouds become heavy enough, they fall back to the Earth as rain, snow, sleet, or hail.

This precipitation replenishes surface water bodies (rivers, lakes) and groundwater. Even water that flows into the sea eventually participates in this cycle again. Thus, the total volume of freshwater is constantly recycled, making it a renewable resource, provided it is not over-exploited or excessively polluted.