rainwater harvesting

Water resources in India are broadly categorized into:

1. Surface Water Resources: Comprising about 70% of usable water, including rivers, lakes, and ponds. 
2. Groundwater Resources: Stored in underground aquifers.

When it rains, some water flows over land (runoff), and some seeps down into the ground. This underground water that gets stored between rocks and soil is called groundwater. But it doesn’t float around randomly underground — it collects in a special place called an aquifer.

What is an Aquifer?

• Aquifer = An underground layer of rock or soil that holds water.
• These rocks have tiny spaces (pores) where water gets stored, like a sponge — these are called permeable rocks.

Types of Aquifers

1. Confined Aquifer

• Water is trapped between two hard, impermeable layers (like sandwich filling).
• Since it’s trapped, it builds pressure — it can’t move freely or rise up on its own.
• Need deep boring to extract water.

2. Unconfined Aquifer

• Has impermeable rock only at the bottom. The top layer is open — water enters easily from rain, rivers, etc.
• It can be accessed with shallow dug wells or tube wells.

Aquifers are hidden heroes of India’s water system. If we understand them and protect them, they can keep serving us for generations.

The Tubewell Revolution has transformed Indian agriculture, with about 60% of irrigation now dependent on wells and tube wells. The states of Punjab, Haryana, Rajasthan, Uttar Pradesh, Gujarat, and Tamil Nadu have particularly high groundwater extraction rates.

Causes of Groundwater Depletion

1. Discharge Factors:

1. Intensive groundwater extraction for irrigation and other uses.

2. Low Recharge Factors:

1. Climate change is causing erratic rainfall and droughts.
2. Loss of vegetation reduces infiltration and recharge.
3. Faulty urban planning with inadequate provisions for groundwater recharge (e.g., concrete surfaces blocking infiltration).

3. Other Contributing Factors:

1. Climate change is leading to unpredictable monsoons and droughts.
2. Cultivation of water-intensive crops, such as sugarcane and rice.
3. Rising sea levels are causing saltwater intrusion in coastal aquifers.

Government Initiatives for Groundwater Conservation

1. National Water Policy 2012: Framework for unified water management laws and institutions.
2. Jal Shakti Abhiyan (2019): Focuses on improving groundwater availability in 256 water-stressed districts.
3. Central Ground Water Board (CGWB): Monitors groundwater and promotes scientific management.
4. Pradhan Mantri Krishi Sinchai Yojana (PMKSY): Aims to enhance irrigation efficiency and reduce water wastage.
5. Atal Bhujal Yojana: Community-led groundwater management through convergence of central and state schemes.
6. MGNREGA: Implements water conservation activities in rural areas.
7. Environment (Protection) Act, 1986: Provides a legal framework for groundwater protection.
8. Jaldoot App: Launched by the Ministries of Rural Development and Panchayati Raj, this app facilitates village-level groundwater monitoring by Gram Rojgar Sahayaks, measuring water levels twice annually (pre- and post-monsoon).

Apart from the alarming depletion of groundwater levels, the quality of groundwater in India is also deteriorating due to pollution:

• Fluoride contamination is widespread in regions such as the northern plains, Telangana, and Golconda, leading to fluorosis —a disease that causes tooth decay and bone damage.
• Arsenic contamination is serious in areas like Uttar Pradesh, Bihar, and West Bengal (notably Malda, Murshidabad, Burdwan, Asansol), primarily due to untreated discharge from leather and other industries.
• Nitrate levels have increased nationwide because of excessive use of nitrogenous fertilizers like urea, contaminating groundwater and posing health risks.

Rainwater Harvesting is the process of collecting and storing rainwater for direct use or for replenishing groundwater.

Benefits

• Increases water availability
• Checks the declining groundwater table
• Reduces community dependence on groundwater for daily needs
• Saves energy by reducing the need for groundwater pumping

Traditional Rainwater Harvesting Methods in India

India has a rich history of rainwater harvesting dating back over 4000 years, with diverse regional techniques such as:

• Rajasthan: Kund or Tanka (underground covered tanks)
• Himachal Pradesh: Kul and Kuhi
• Maharashtra: Bhandaras
• Tamil Nadu: Eri
• Andhra Pradesh: Cheruvu

Watershed Management means protecting and managing all the water and land within a watershed so that rainwater is not wasted, groundwater gets recharged, soil stays in place, and people benefit.

It focuses on:

1. Storing more rainwater where it falls
2. Reducing water runoff that causes floods and soil erosion
3. Recharging groundwater by letting water slowly soak into the ground
4. Improving farming, increasing incomes, and reducing migration

Simple Techniques Used

• 🛑 Check dams – small earthen dams to slow water flow and recharge groundwater
• 🌱 Afforestation – tree planting to hold soil and reduce erosion
• 🌿 Vegetative cover – helps trap rainwater and improve soil health
• 🏞️ Avoiding large concrete dams – to maintain natural river flow and ecosystem balance

Scheme: Jal Sadhana

• It was previously called the Integrated Watershed Management Programme or IWMP
• Features:
  1. Plans made with full community participation
  2. Old ponds and dams are cleaned before the monsoon
  1. Each farm is ensured water
  1. Focuses on both drought and flood prevention
  2. Uses satellite images and mobile apps (like Drishti) to monitor progress