IRRIGATION AND WATER RESOURCES MANAGEMENT (CAT -1)

PART – A

1. Mention the usage patterns of water resources in the context of India

• Agriculture
• Domestic
• Industrial
• Hydropower
2. State the various resources of water mentioning its merits and demerits
Water resources may be classified into
Surface water:
Water available in the surface of the earth as an outcome of run off is called as
surface water
Merits:
• Easy to locate
• Does not require highly advanced machinery/ equipment to find its source
• Treatment of water will be simpler
Demerits:
• Easily contaminated
• Turbidity fluctuates with level of precipitation
• May freeze in winter
Ground water:
Water available below earth’s crust and not more than 2500 feet is considered
as ground water. Springs, wells are some of the examples of ground water
Merits:
• Will not be contaminated easily
• Quality will be stable throughout the year
• Bacterial content will be low
Demerits:
• Recovery of polluted water is not a easy job
• Operational cos is high
• Susceptible to long term contaminants
3. Differentiate retarding and detention reservoirs.

Detention Reservoirs Retarding Reservoirs

Stores excess floodwater and releases it Stores floodwater during rising flood
gradually after the flood. and releases it as flood recedes.
Equipped with large, gated spillways Ungated spillways and sluiceways,
and sluiceways for flexible operation. allowing automatic floodwater release.
More costly due to gates, lifting Lower costs, as no gates or lifting
equipment, and maintenance staff. equipment are required.
Exists, as human operation of gates can Eliminated, as no gates are present that
lead to errors or negligence. require manual operation.
 Water may be retained longer, Water is released in a few days, causing
potentially causing extended only temporary submersion.
submersion.

4. Define the term TMC and convert 200 TMC into Litres.

TMC Stands for Thousand Million Cubic. TMC is used as an acronym in Liquid
measurement unit to represent Thousand Million Cubic. Thousand Million Cubic (TMC) Feet
and is generally used to measure the amount of water stored in a reservoir. It’s also used to
gauge a dam’s intake and outflow. There are 28,316,846,592 liters in 1 TMC of water. This is
28316.85 million litres of water. 200 TMC will be equal to,
200 x 28316.85 = 56,63,370 litres

5. List out the demerits of irrigation.

• Due to excess application of water - Mosquito breeding – disease spread
• Areas already damp, cold – More dampness – erosion, leaching, salination
• Due to overirrigation and water table rise – results in rise of Ground water - may affect
the crops – causes efflorescence
PART – B
6. (i) What is the need for National Water Policy (NWP)? Discuss the salient features of NWP.

The objective of the National Water Policy is to take cognizance of the existing situation, to
propose a framework for creation of a system of laws and institutions and for a plan of action
with a unified national perspective.

SALIENT FEATURES:
• It introduces a proposal to levy tariff for all water uses, including irrigation if it exceeds
predetermined quota on a volumetric basis. In order to exercise this, a State water
Regulatory authority was established in every state, which will fix and regulate the
water rates. Responsibility of Tariff collection adjusting rates and water distribution
remains with the Water Users Association in states.
• The 2012 Policy also calls for a typically integrated perspective to govern the planning
and management of water resources. Such an attitude would consider local, regional,
and national contexts and be environmentally sound. As per the policy, water needs to
be managed as community resources under the State.
• This policy raised the debate of privatization of basic necessity like water which is
directly associated with life to the right. The policy was put into the public domain to
enlist the suggestions from a broad spectrum. The privatization of water started a new
debate in the country whether water should be charged or not.
• The arguments made for pro-privatisation of water is that excessive usages of water
irrigation and conservation of water can only be checked through tariff as water is a
limited natural resource?
• The excessive subsidy on electricity has led to the extreme exploitation of water for
irrigation in the green revolution. Privatized utility charges encourage investments,
bringing new technologies, improving services and water quality. The argument made
 against the privatization of water suggests that it does not serve the public and increases
the vulnerability of the poor.
• With growing urbanization and industrialisation, there is a growing demand for water
in cities. People with high purchasing power will have more access to water for
themselves, leaving behind the rural people.
• Water being the Basic element must not be privatized as it is a fundament for life and
health.

(ii) What are the challenges faced by water resources in India and suggest few strategies to manage?
Challenges:

• Seasonal and Spatial Variability: Uneven distribution of rainfall leads to floods and
droughts.

• Over-Exploitation: Excessive groundwater extraction has led to depletion and quality

issues.

• Pollution: Industrial discharge, agricultural runoff, and untreated sewage contaminate

water bodies.

• Climate Change: Altered precipitation patterns and melting glaciers impact water
availability.

• Inter-State Disputes: Disputes over water sharing among states.

• Water Scarcity: Chronic water shortages, particularly in summer

• Groundwater Depletion: Over-extraction leading to declining water tables.

Strategies:

• Integrated Water Resource Management (IWRM): Coordinated development and

management of water, land, and related resources.

• Watershed Management: Conservation and management of the entire watershed to

sustain water resources.

• Rainwater Harvesting: Collecting and storing rainwater for reuse.

• River Linking Projects: Proposed projects to transfer water from surplus to deficit
areas.

• Groundwater Regulation: Laws and policies to control groundwater extraction.

• Cauvery Management Board: Established to manage the sharing of Cauvery waters.

• Desalination Plants: Plants near Chennai to convert seawater to drinking water.

• Tank Rehabilitation: Reviving traditional tank systems for water storage.

• Micro-Irrigation: Promoting drip and sprinkler irrigation to conserve water.
7. (i) Define the term, Drought. Discuss the management strategies to prevent the ill effects of
droughts.

Drought has many definitions, it originates from a deficiency of precipitation over an

extended period of time, usually a season or more.This deficiency results in a water shortage
for some activity, group, or environmental sector.It can have a substantial impact on the
ecosystem and agriculture of the affected region and harm to the local economy.
Some of the methods to mitigate the adversities of drought are:
1.Creation of surface storage - creating reservoirs by building dams, big and small, and
diversion canals – to supply water wherever and in whatever amounts desired.
2.Equitable distribution -A rotational system of supply of water if strictly implemented will
not only meet the ends of equity but will also economize use of water.
3.Maintenance of irrigation system - proper fund allocation
4.Better irrigation practice - Leveling of the fields so that water gets more evenly distributed
can greatly improve the performance.
5.Watershed development - Construction of structures, like check dams, Nalla bunding,
contour bunds, Gully plugging, percolation tanks, development of rainwater harvesting and
construction of wells etc.
6.Integrating small reservoirs with major reservoirs - very important that minor schemes
are integrated with the canal systems of major reservoirs.
7.Transfer of water from water excess basins to water-deficit basins - A permanent long
term solution to drought problem may be found in the basic principles of transfer of water from
surplus river basins to areas of deficit.
8.Cropping Pattern - Proper selection of crops for drought affected area
9.Alternative land use models for water sustainability

(ii) With neat sketch explain the storage capacity and water levels of reservoir.
LEVELS OF RESERVOIR
1. FRL (Full Reservoir Level)

• Storage level corresponding to the storage – both inactive and active storage + flood
storage

• Highest reservoir level without spillway discharge

 2. DSL (Dead Storage Level)

• Below the level, there are no outlets to drain the water in the reservoir by gravity
3. MDDL (Minimum Drawdown Level)

• Level below which the reservoir will not be drawn down so as to maintain a minimum
head required in power projects

4. MWL (Maximum Water Level)

• Level likely to be attained during the passage of the design flood

• Highest reservoir or flood level

• Depends upon the specified initial reservoir level and the spillway gate operation rule
STORAGE LEVELS:

1. LIVE STORAGE

• Between full supply level and the invert level of the lowest discharge outlet

• Volume of water available at any time between the dead storage level and full reservoir
level

2. DEAD STORAGE

• Total storage level below the invert level of the lowest discharge outlet from the
reservoir

• Contains sedimentation

3. OUTLET SURCHARGE / FLOOD STORAGE

• Between full reservoir level and the maximum water level – during peak floods

4. BUFFER STORAGE

• The space located just above the dead storage level up to minimum drawdown level

• Release of water from this level during dry conditions prevails for essential
requirements only

8. (i) Explain the factors affecting duty and recommend the methods used to improve duty in
irrigation.
Factors affecting the duty.

• Methods and system of irrigation

a. Perennial irrigation
b. Flow irrigation
c. Lift irrigation
• Method of cultivation
• Type of the crop
 • Base period of the crop
• Soil and Subsoil of the irrigation field
• Quality of water
• Climatic conditions of the Area
Methods used to improve duty in irrigation

• Suitable method of applying water to the crops should be used

• Proper land ploughing and levelling before sowing the crop
• Lined canals which reduces seepage and percolation
• Good quality of water
• Crop rotation and frequent cultivation

(ii) Derive the relationship between Duty, Delta and Base period and hence find the
delta of the rice crop when base period is 120 days, and the duty is 1400 hectares

Relation between duty, delta and base period

Where D = duty in hectares/cumecs

B = Base period in days

Δ = Delta in metre (total depth of water supplied)

Given: D = 1400 hectares/cumecs

B = 120 days
To find: Δ = ?

Formula used:

Solution:

1400 = (8.64 * 120) / Δ

Δ = 0.74m = 74 cm