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:
- 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.
- 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.
- 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.
- 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.
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