Class 10 Geography Chapter 3- Water Resources Notes

 

Class 10 Geography

Chapter 3- Water Resources

Notes

 

1. The Importance of Water

The Earth's surface is predominantly covered by water, with approximately three-fourths of its surface submerged in water. However, only a small fraction of this vast water resource is freshwater, suitable for various human activities and consumption. Water, being renewable, plays a crucial role in sustaining life on Earth.

2. Understanding Water Scarcity and the Imperative for Conservation

Water availability fluctuates both spatially and temporally, leading to the pressing issue of water scarcity. This scarcity is primarily attributed to over-exploitation, excessive usage, and unequal distribution among different social groups. Additionally, water resources face the risk of depletion due to the expansion of irrigated areas for dry-season agriculture. In some regions, water scarcity is exacerbated by poor water quality, further limiting its usability.

3. Urgency of Water Resource Conservation and Management

Conservation and effective management of water resources are essential for several reasons. Firstly, it is crucial for safeguarding public health by ensuring access to clean and safe drinking water. Secondly, conservation efforts are necessary to maintain food security, support livelihoods, and facilitate productive activities reliant on water resources. Lastly, conservation aids in preventing the degradation of natural ecosystems, preserving biodiversity, and ensuring ecological balance.

4. Multi-Purpose River Projects and the Role of Integrated Water Resources Management

Throughout history, humans have implemented various hydraulic structures to conserve water resources. These structures, including dams constructed using stone rubble, reservoirs, embankments, and irrigation canals, have contributed to the conservation of water. Modern dam construction continues this tradition, serving multiple purposes such as irrigation, hydropower generation, flood control, and recreational activities. However, their construction and operation have associated side effects that necessitate careful management through integrated water resources management.

5. Impacts and Side Effects of Dam Construction

Dams play a pivotal role in water conservation but are not without their drawbacks. Their construction and operation can disrupt natural river flows, leading to poor sediment flow and excessive sedimentation in reservoirs. This alteration of river ecosystems adversely affects aquatic life and habitats. Furthermore, dams fragment rivers, hindering the migration of aquatic fauna, especially spawning fish. The creation of reservoirs also submerges existing vegetation and soil, contributing to environmental degradation. Additionally, large-scale dam projects often face opposition from local communities due to displacement, loss of livelihoods, and restricted access to resources.

6. Case Study: Narmada Bachao Andolan

The Narmada Bachao Andolan (NBA) is a grassroots movement that emerged in response to the construction of the Sardar Sarovar Dam on the Narmada River in Gujarat. Initially focused on environmental concerns, particularly the submergence of trees and ecological damage, the movement has evolved to advocate for the rights of displaced communities. The NBA highlights the failures of large dam projects to achieve their intended goals and promotes alternative solutions like water harvesting systems rooted in ancient Indian traditions.

7. Rainwater Harvesting and Innovative Techniques

Rainwater harvesting is an environmentally friendly practice that involves the collection, storage, and utilization of rainwater for various purposes, mitigating the reliance on conventional water sources. This method offers a sustainable solution to water scarcity and plays a crucial role in water resource management worldwide.

A. Importance of Rainwater Harvesting

Rainwater harvesting is vital for addressing water scarcity issues, especially in regions where access to clean water is limited or unreliable. By harnessing rainwater, communities can reduce their dependency on groundwater and surface water sources, thus ensuring water security for domestic, agricultural, and industrial needs.

B. Techniques of Rainwater Harvesting

Various techniques are employed to harvest rainwater, tailored to the specific geographical and climatic conditions of different regions:

1. Diversion Channels in Hilly Areas: In mountainous regions prone to heavy rainfall, diversion channels such as 'guls' or 'kuls' are constructed to redirect rainwater runoff for agricultural irrigation. These channels help channelize rainwater away from slopes, preventing soil erosion and facilitating irrigation in terraced fields.
2. Rooftop Rainwater Harvesting in Dry States: In arid and semi-arid regions like Rajasthan, where water scarcity is a pressing issue, rooftop rainwater harvesting systems are widely adopted. Rainwater is collected from rooftops using gutters and stored in tanks or reservoirs for later use in household activities, livestock watering, and groundwater recharge.
3. Inundation Channels in Floodplains: In flood-prone areas like the plains of West Bengal, inundation channels are constructed to capture excess rainwater during monsoon floods. These channels help divert floodwater to agricultural fields, replenishing soil moisture and supporting crop growth during the dry season.
4. Rain-Fed Storage Structures in Arid Regions: In extremely arid regions, traditional rain-fed storage structures like Khadins and Johads are utilized to capture and store rainwater for agricultural purposes. These structures are designed to trap rainwater runoff, allowing it to percolate into the soil and recharge groundwater aquifers, thus sustaining agricultural production during dry spells.

C. Innovative Techniques: Bamboo Drip Irrigation

In addition to traditional rainwater harvesting methods, innovative techniques like bamboo drip irrigation are emerging as sustainable solutions for modern agricultural practices. Widely practiced in regions like Meghalaya, bamboo drip irrigation systems utilize bamboo pipes to transport rainwater from springs and streams to agricultural fields.

• Operation of Bamboo Drip Irrigation: Bamboo pipes, typically installed over hundreds of meters, transport rainwater collected from springs and streams to agricultural fields. The flow of water through the bamboo pipes is controlled by adjusting the pipe positions, allowing for precise water distribution to crops. At the field level, bamboo channels and diversion units are used to regulate water flow and deliver it directly to the plant roots.
• Benefits of Bamboo Drip Irrigation: Bamboo drip irrigation systems offer several advantages, including efficient water use, reduced soil erosion, and improved crop yields. By delivering water directly to the plant roots at a controlled rate, these systems optimize water distribution, minimize water wastage, and enhance crop productivity, particularly in areas with limited water availability.

Rainwater harvesting, through a variety of traditional and innovative techniques, plays a crucial role in sustainable water management. By harnessing nature's bounty, communities can alleviate water scarcity, enhance agricultural productivity, and promote environmental sustainability. As the world grapples with water scarcity challenges, the adoption of rainwater harvesting practices is essential for ensuring water security and resilience in the face of climate change.

8. Why is there scarcity of water in India?

The scarcity of water in India is primarily due to a combination of natural factors and human activities that contribute to the imbalance between water supply and demand. Some key reasons for water scarcity in India include:

a)    Uneven Distribution of Rainfall: India's monsoon climate results in uneven distribution of rainfall across different regions and seasons. While some areas receive heavy rainfall during the monsoon season, others experience prolonged dry spells, leading to water scarcity.

b)    Over-Exploitation of Groundwater: Rapid urbanization, industrialization, and agricultural activities have led to the over-exploitation of groundwater resources in many parts of India. Excessive withdrawal of groundwater for irrigation, domestic, and industrial purposes has resulted in declining water tables and depletion of aquifers.

c)    Pollution of Water Sources: Pollution of rivers, lakes, and groundwater sources due to industrial discharge, untreated sewage, agricultural runoff, and improper waste disposal has contaminated water bodies, rendering them unsuitable for drinking and other purposes. Water pollution exacerbates water scarcity by reducing the availability of clean water for various uses.

d)    Inefficient Water Management: Inefficient water management practices, including inefficient irrigation techniques, outdated infrastructure, and inadequate water storage facilities, contribute to water wastage and inefficiency in water use. Inefficient water management exacerbates water scarcity by failing to optimize water resources and meet growing water demand.

e)    Climate Change: Climate change exacerbates water scarcity in India by altering rainfall patterns, increasing the frequency and intensity of droughts and floods, and melting glaciers in the Himalayan region. These climate-related impacts disrupt water availability and exacerbate water stress in many parts of the country.

f)     Population Growth and Urbanization: Rapid population growth and urbanization increase the demand for water for domestic, industrial, and municipal purposes. The growing population exerts pressure on existing water resources, leading to increased competition for limited water supplies and exacerbating water scarcity in urban and peri-urban areas.

g)    Inter-State Water Disputes: Inter-state water disputes over shared river basins, such as the disputes over the Cauvery, Krishna, and Godavari rivers, further exacerbate water scarcity by impeding water-sharing agreements and hindering equitable distribution of water resources among neighboring states

9. Some important rain water harvesting techniques in different states of India.

a)    Rooftop Rainwater Harvesting (RRWH) in Rajasthan:

                      i.        Rajasthan, being a predominantly arid state, heavily relies on rainwater harvesting techniques like RRWH.

                    ii.        RRWH involves capturing rainwater from rooftops and directing it into storage tanks or recharge pits for later use or groundwater recharge.

                   iii.        This technique helps in supplementing water supply during dry periods and reduces dependency on groundwater sources.

b)   Johads and Khadins in Rajasthan and Gujarat:

                      i.        Johads and Khadins are traditional rainwater harvesting structures widely used in the arid regions of Rajasthan and parts of Gujarat.

                    ii.        Johads are small earthen dams constructed across seasonal streams or nullahs to collect rainwater runoff during the monsoon season.

                   iii.        Khadins are traditional embankments built across slopes to capture rainwater and recharge groundwater aquifers.

                   iv.        These structures help in enhancing groundwater recharge and improving water availability for agriculture and domestic use.

c)    Bamboo Drip Irrigation in Meghalaya:

                      i.        Meghalaya, characterized by high rainfall, utilizes innovative rainwater harvesting techniques like bamboo drip irrigation.

                    ii.        Bamboo drip irrigation involves the use of bamboo pipes to channel rainwater from springs and streams to agricultural fields.

                   iii.        The bamboo pipes control the flow of water, delivering it directly to the roots of plants at a slow and steady rate, thus reducing water wastage and improving crop yields.

d)   Inundation Channels in West Bengal:

                      i.        West Bengal, with its extensive floodplains, utilizes inundation channels for rainwater harvesting and flood management.

                    ii.        Inundation channels are shallow depressions or canals constructed along the floodplains to capture excess rainwater and store it for later use in agriculture.

                   iii.        These channels help in reducing flood damage, recharging groundwater, and providing water for irrigation during the dry season.

e)    Check Dams in Maharashtra and Karnataka:

                      i.        Maharashtra and Karnataka employ check dams as a rainwater harvesting technique to conserve water and recharge groundwater.

                    ii.        Check dams are small dams constructed across seasonal streams or rivers to impound rainwater runoff and allow it to percolate into the ground.

                   iii.        These dams help in recharging groundwater aquifers, preventing soil erosion, and improving water availability for agriculture and drinking purposes.

f)     Tankas in Rajasthan and Gujarat:

                      i.        Tankas, also known as underground water tanks, are traditional rainwater harvesting structures used in Rajasthan and Gujarat.

                    ii.        Tankas are cylindrical underground tanks constructed to capture and store rainwater from rooftops for domestic use.

                   iii.        They help in storing rainwater during the monsoon season and providing a reliable source of water for household needs during dry periods.