Explanation: Rooftop rainwater harvesting is a water conservation technique that involves collecting and storing rainwater from rooftops for later use. This method is particularly important in regions with low rainfall and high water scarcity, such as Western Rajasthan. The practice helps in conserving water and ensuring a sustainable water supply for domestic and agricultural purposes.
Western Rajasthan is a semi-arid to arid region with low rainfall and high water scarcity. The region faces significant challenges in water management due to its climatic conditions. The average annual rainfall in Western Rajasthan is less than 500 mm, which is insufficient to meet the water demands of the population and agriculture. As a result, rooftop rainwater harvesting has become a crucial water conservation technique in this area.
The practice of rooftop rainwater harvesting involves collecting rainwater from rooftops and storing it in tanks or underground reservoirs. The collected water can be used for various purposes, including drinking, cooking, washing, and irrigation. This method not only helps in conserving water but also reduces the burden on the existing water supply systems.
In contrast, Eastern Rajasthan, while part of Rajasthan, does not face the same level of water scarcity as Western Rajasthan. The eastern part of Rajasthan receives more rainfall, making rainwater harvesting less critical compared to the arid western region. Similarly, Western Tamil Nadu, although it does experience water scarcity, is not the primary region where rooftop rainwater harvesting is most practiced. The practice is more widespread in Western Rajasthan due to its arid climate and the need for sustainable water management.
Therefore, the correct answer is (A) Western Rajasthan, as it is the region where rooftop rainwater harvesting is chiefly practiced due to its climatic conditions and the need for sustainable water management.