Overview
This lecture covers India's water resources, highlighting water scarcity, causes, conservation methods, multi-purpose river projects, traditional and modern rainwater harvesting, and irrigation systems.
Water Scarcity and Causes
- Only a small proportion of Earth's water is freshwater, mainly from runoff and groundwater.
- Water is a renewable resource due to the hydrological cycle, but many areas face water scarcity.
- Water scarcity is caused by increasing demand, over-exploitation, and unequal access.
- High population and food production needs increase water use, worsening scarcity.
- Urbanization and industrialization exert growing pressure on freshwater sources.
- Pollution also causes scarcity when water is available but not fit for use.
Water Conservation and Management
- Conservation and sustainable management are essential to ensure food security and public health.
- Over-exploitation and mismanagement can cause ecological crises and resource depletion.
- Government initiatives like the Jal Jeevan Mission and Atal Bhujal Yojana aim to improve rural water supply and promote conservation.
Multi-Purpose River Projects
- Dams store water for irrigation, hydropower, domestic and industrial uses, flood control, and recreation.
- Multi-purpose projects integrate development but can cause environmental harm (sediment disruption, habitat loss, floods).
- Examples: Bhakra Nangal and Hirakud projects, Sardar Sarovar Dam.
- Inter-state river disputes arise over water sharing, e.g., Krishna-Godavari dispute.
Rainwater Harvesting
- Traditional systems include diversion channels (guls/kuls), rooftop harvesting, inundation channels, khadins, johads, and tankas.
- Rooftop rainwater harvesting is now compulsory in Tamil Nadu and common in Shillong and Gendathur.
- Rainwater harvesting provides a reliable water source, especially during dry periods.
- Modern adaptations involve rooftop collection, filtration, and groundwater recharge.
Bamboo Drip Irrigation System
- In Meghalaya, bamboo pipes transport spring water to fields, minimizing wastage and watering plants directly.
- The system uses gravity and precise placement to regulate flow.
Key Terms & Definitions
- Hydrological Cycle — continuous movement of water on, above, and below Earth's surface.
- Water Scarcity — lack of sufficient available water resources to meet regional demands.
- Multi-purpose Project — dam or river development serving several functions (irrigation, power, water supply, etc.).
- Rainwater Harvesting — collection and storage of rainwater for reuse before it runs off.
- Tankas — underground tanks collecting and storing rainwater, especially in Rajasthan.
- Bamboo Drip Irrigation — traditional method using bamboo pipes to deliver water directly to crop roots.
Action Items / Next Steps
- Write a short proposal on how to conserve water in daily life.
- Research and report on a traditional dam or irrigation method.
- List inter-state water disputes in India.
- Collect information on how industries pollute water resources.
- Find and describe rainwater harvesting systems in your locality.