Watershed management dr.chandan

1. 1
Dr.Chandankeri G.G
Associate Professor
Dept. Of Civil Engineering
WATERSHED MANAGEMENT
1. Concept, objectives, planning and measures;
2. Integrated Watershed management (IWM)
a) Land use planning for watershed
management;
b) Water harvesting and recycling;
c) Food control and watershed management;
d) Socioeconomic aspects of watershed
management;
e) Watershed management practices
(rehabilitation, protection, improvement);
f) Watershed management approaches
(integration, community based watershed
management, old and new approaches) &
g) Emerging paradigms

2. WATERSHED MANAGEMENT - Concept
 Watershed is a drainage area on earth’s surface from which runoff, resulting from precipitation flows to
a single point into a larger stream / river / lake or the ocean.
The concept of watershed originates from surface hydrology where a river is assumed to be affected
primarily by its surface drainage area. I
In fact, both surface and subsurface hydrology define a river and the importance of subsurface hydrology
should not be overlooked. N
It is a land surface bounded by a divide which
contribute runoff to a common point.
Positive water accretion - precipitation and
negative accretion - evaporation.
There can be drainage laterally and vertically.
WSM involves management of the land surface & vegetation
- to conserve & utilize the water that falls on the watershed, &
- to conserve the soil for immediate & long term benefits to the farmer, his community and society.
Tanks & Ponds were constructed - to harvest water from the watershed, store and recycle it for crop use.
People were aware about the problem of sedimentation of these tanks & desilting operations.

3. WATERSHED MANAGEMENT - Concept
Practices such as bunding & other cultural operations to conserve soil moisture are prevalent
on dry lands, since long.
Watershed may be only few acres
Or hundreds of thousands sq.km .
All watersheds can be divided into
smaller and smaller sub-watersheds.
Watershed lands used for guarding water supply, flood effects and other hydrologic factors.
Soil conservation work on individual farms largely benefits these properties,
The greatest improvement in the control of water & sediment if it carried out on WSD basis.
As a natural unit, watershed reflects the interaction of soil, geology, water & vegetation by
providing a common end product runoff or stream flow
Conservation on one farm must also be related to that on the other farm
Need a systematic use of water from the top of each watershed to the bottom.

4. Watershed management is the process of creating
and implementing plans, programs, and projects to
sustain and enhance watershed functions that affect
the plant, animal, and human communities within a
watershed boundary.

5. WHAT WSM?
• Features of a watershed that agencies seek to manage
include water supply, water quality, drainage, storm water,
runoff, water rights, and the overall planning and utilization of
watersheds.
Watershed management - process of implementing land use practices &
water management practices to protect & improve quality of water & other natural
resources within a watershed.
Watershed management
• a way of looking at relationships
Between people, nature, land and water.
Watershed management
• aims at bringing about balance
between natural resources on one
land & society on the other.

6. THE NEED/IMPORTANCE FOR
WATERSHED MANAGEMENT
• Watershed management is necessary for the sustainable
protection of natural resources and environmental health.
• Watershed management, which recognizes the hydrologic
(water) cycle as the pathway that integrates
• physical,
• chemical and
• biological processes, is an important approach to achieving the goal of a
sustainable environment, and is the tool to implement an ecosystem-based
management strategy.

7. WSM – Objectives
WSM involves the wise use of all soil and water resources,
so as to provide a clean, uniform water supply
 The watershed aims , improving the standard of living of common man in the basin
• by increasing his earning capacity, by offering facilities such as electricity, water for irrigation,
• drinking water supply, freedom from fears of floods and droughts etc.
The overall objectives of watershed development programme include;
1. Recognizing of watershed as a proper unit for wise utilization and development of all lands.
2. The land should be treated in accordance with its peculiar need and by methods that will
control soil erosion, conserve water, encourage wild life, improve farm income and prevent
flood damage to agriculture lands.
3. Retardation and prevention of floods through small multi-purpose reservoirs and other
water impounding structures as the head water streams and in problem areas.
4. Provision for an abundant water supply for domestic, industrial and agricultural needs.
5. Control of organic, inorganic and soil pollution.
6. Broad expansion of recreational facilities, i.e. picnic and camping facilities with more lake
and stream suitable for boating, fishing or swimming.
7. Utilization of natural local resources for improving agriculture and allied occupation or
industries (small and cottage industries ) to improve socio-economic conditions of the local
residents.

8. WSM - Objectives
• The overall objectives for the process are
divided into two types: Planning
Objectives and Implementation
Objectives.
• Planning Objectives are distinct,
specific, measurable statements that
reflect and define each goal. They are
designed to direct, track and measure
progress over the next several years of
preparing the Watershed Plan, but they
do not necessarily guide implementing
“on the ground” actions in the watershed.
By definition, Planning Objectives will be
one or several Implementation
Objectives.
• Implementation Objectives are also
distinct, measurable statements that
reflect the goals, but are meant to guide
ongoing implementation actions in the
watershed. The Implementation
Objectives will become part of the
Watershed Plan and can be used to
measure long-term progress.

9. WSM - Objectives
1) Ensure that the Watershed Management Initiative is a broad,
consensus-based process.
2. Ensure that necessary resources are provided for the
implementation of the Watershed Management Initiative.
3. Simplify compliance with regulatory requirements without
compromising environmental protection.
4. Balance the objectives of water supply management, habitat
protection, flood management and land use to protect and
enhance water quality.
5. Protect and/or restore streams, reservoirs, wetlands and the
bay for the benefit of fish, wildlife and human uses.
6. Develop an implementable Watershed Management Plan that
incorporates science and is continuously improved.

10. WATERSHED MANAGEMENT – Planning
Social and hydrologic factors are most important & largely determine the desired programme
can be carried out or not.
Central core of control in WSM is part of the hydrologic cycle (from the time of water is
received on the land until it leaves the area as stream flow or is returned to the atmosphere
No. of climatic factors effect movement of water - intensity, duration, type of precipitation,
air temp, wind velocity and humidity.
Hydrologic characters - infiltration capacity, moisture content, and other soil characters,
ex. Presence of permeable layer, substratum, texture etc. affect the movement of water in soil.
Similarly, runoff is affected by the length & steepness of slope, amount & type of vegetation,
stoniness etc.
All these factors affecting water movement cannot be changed through management, yet
some of the factors can be modified to achieve the aims of management.
Soil characters can be changed by mechanical means.
The effectiveness length and steepness of slope can be considerably changed by agronomic
and mechanical practices.

11. WATERSHED MANAGEMENT – Planning
The individual responsibilities of each department (hydrology, geology, engineering,
soil science, agronomy , economics) should be completely itemized in plan .
The plan should contain the following minimum details;
1. Description of watershed
a) Physical data
b) Economic data
2. Watershed problems
a) Flood water damage
b) Sediment damage
c) Erosion damage
d) Problems related to soil and water management
e) Problems related to crop management
3. Works of improvement to be installed
a) Land treatment measures
b) Structural measures
c) Crop management measures
4. Comparison of benefits and costs

12. WATERSHED MANAGEMENT – Measures
WSM measures classified into two broad categories – purpose and accomplishment
1. In terms of purpose : Includes land use and treatment measures which are effective
in increasing the infiltration rate and water holding capacity of the soil and preventing soil
erosion on watershed lands. They include all biological and mechanical methods of erosion
control, including water stabilizing measures, such as gully control structures or vegetation.
2. Method of accomplishments: Planned primarily for the management of water flow
after it has left the fields and farm water ways and reached the small branches and cracks.
- These measures include flood-water retarding structures, stream channel improvements
to increase carrying capacity and stabilize the beds &
banks, minor flood ways, sediment detention on basins
& similar measures.
- The primary benefits are
off-site or down stream, not at the place
where they are installed.
3. The aim in efficient management should be
selection of measures that could fit into the requirements of proper WSM.
Vegetative measures /
non-structural practices
i. Strip cropping
ii. Pasture farming
iii. Fertilizing the crop
iv. Grass land farming
Engineering / structural practices
i. Gully plugging
ii. Diversions
iii. Water ponds
iv. Reservoirs
v. Drainage works
vi. Flood protection structures
vii. Groundwater recharging
structures
viii. Terracing & bunding

13. LAND USE PLANNING FOR WSM
Comprehensive development of whole of the watershed in accordance with its potentialities
and capabilities for different landuse.
1. Planning deals with the total development of all kinds of resources of the watershed, namely,
land, water, climate, plant, animals, and man.
2. The ultimate aim is to improve the economic status of the inhabitants of the watershed.
3. Watersheds are complex in their characteristics and are rarely identical. Their response to development
depends upon the nature of resource available within the watershed boundaries.
4. Specific criteria and survey techniques need to be developed for selection of priority and responsive
watersheds for each individual programme.
The basic criteria for selection of watershed may be;
i. Intensity of the problem
ii. Prospects of correcting the problem
iii. Potential for overall development
iv. Availability of technology
v. Likely acceptability and participation by
the inhabitants and
vi. The infrastructure availability

14. LAND USE PLANNING FOR WSM
5. Important characteristics for collecting information are size, shape, relief, drainage,
geology, soils, climate, surface conditions and land use, ground water, geographic location,
socio-economic conditions.
6. Once the problem is identified and objectives are defined, the priorities for a type of work in
the watershed can be fixed. For example;
a) In the catchment of a reservoir, an area yielding maximum silt load must be taken up first
b) In flood affected regions, area contributing maximum runoff need to be determined and
taken under the development programme.
c) In drought prone areas, it is important to determine the potentiality of different locations
for possibility of maximum water harvesting and demarcating the land based on its
capability of forest, pasture and agriculture.
d) The command areas need to be specified with cropping systems and response to
irrigation.
e) In salt affected soils, the reclamation programmes should be taken up on priority.
f) Areas affected with shifting cultivation & ravines need priority in order to prevent their

15. WATER HARVESTING & RECYCLING
 Major efforts in harvesting water
resources are through tanks or ponds (India)
 In 1876, there were more than 33,000 tanks in India
 The monsoon rains are high intensity short duration
storms inducing high runoff and flash floods.
 Surplus water stored in ponds and reservoirs and recycled for crop use.
 The use of farm ponds for ensuring two crops in arid and semi arid regions & are
quite effective in reducing flood hazards.
 Contour bunding routinely implemented in almost all parts of world
 In graded (150 cm) beds and furrows system developed by ICRISAT, centre for
cropped watershed, excess water is allowed to flow through small furrows to
grassed drainage ways and is then safely conducted to a tank or outlet.

16. WATER HARVESTING & RECYCLING
7 a) The velocity flow of water is controlled by the direction and slope of the furrows.
These beds and furrows provide considerable protection against soil erosion
throughout the year as they form a permanent land feature.
7 b) This system controls runoff and erosion and facilitates infiltration of water into the
soil uniformly over the watershed area. The system provides opportunity for
surface water collection in the tanks and groundwater recharge for wells, which
can then provide water year round for domestic use as well as supplemental
irrigation.

17. FLOOD CONTROL & WSM
1. A river or creek is in flood stage when its water flows over the banks and
covers the bottom land. This bottom land is called flood plain and its soil material, alluvium.
2. In WSM, more concerned with head water flood control, includes all measures that will
reduce flood flows in watersheds of small rivers and their tributaries.
3. The maximum size of the watershed for headwater area is about 1500 sq.km.
4. Headwater flood control measures are considerably different than downstream measures.
5. Headwater floods are typically flash floods of
short duration which occur rather frequently (2- 3 times in year).
6. Floods causes several types of losses and are categorized into 3 groups.
A) Direct losses – includes loss of property, crops, and land
which can be determined in monetary values
B) Indirect losses – Depreciated property, traffic delays and loss of income.
C) Intangible losses – community insecurity , health hazards and loss of life.
7. Damage to land is often un-noticed and therefore, not recorded in terms of monetary value.

18. FLOOD CONTROL & WSM
8. Soil erosion from uplands, sedimentation reservoirs, stream channels and flood plains and
pollution of water supply greatly affects the economy of the entire watershed.
9. Most floods occur due to natural causes as excessive rainfall and melting of snow.
Occasionally, tidal waves or hurricanes also cause flood.
10. Floods may also occur due to reservoir failures and such floods are often highly life
damaging but fortunately seldom these occur.
11. Depending upon their nature, floods are divided into two categories
Large area floods, which occur from storms of low intensity having a duration of few days to several weeks
Small area floods, which occur from storms of high intensity having a duration one day or less .
12. Generally, 85% floods occur under second category and such floods cause great damage to
agriculture land & sediment accumulation in rivers and reservoirs. These floods usually do
not produce high runoff on large streams but often causes serious local damage.
13. The large area floods cause greatest damage to metropolitan areas in addition to
considerable agriculture losses.
14. Flood flows are predicted from stream flow records, developed hydrographs, empirical
equations, meteorological data and previous high water marks.

19. FLOOD CONTROL & WSM
WATERSHED FLOOD CONTROL MEASURES
Two general classes;
1. Those that retard flow or reduce runoff by watershed treatments ,- flood control reservoirs
or underground storage
2. Those that increases the channel capacity to accelerate flow - includes channel
improvement , channel straightening and levees.
Measures that retard the flow or reduce runoff are economically and physically more desirable
due to the following reasons
I. They remove all viable evidences or danger of floods
II. They result in uniform flow in the streams thereby greater recharge of the groundwater and
more adequate water supply
III. They are the important step in the conservation of natural resources.
IV. They result higher crop yields, especially in areas with deficient irrigation water supply
V. These measures also result in reduction of sedimentation in lower tributaries.

20. FLOOD CONTROL & WSM
WATERSHED TREATMENT (WT)
The objective is to increase the water storage on
the surface and in the soil profile.
1. WT aim is to reduce flood runoff, controlling
erosion, increasing the amount of surface
storage and rate of infiltration and water
holding capacity of the soil.
2. Runoff retardation by land management and
soil type are largely dependent on vegetative
cover and favorable soil surface conditions.
3. Soil type affects runoff as much as 3 times
when compared between permeable and
heavy soils. Similar is the case with type and
density of vegetation.
4. Conservation practices, such as contouring,
strip cropping and terracing will reduce flood
peaks as well as total runoff from the small
to medium storms during the growing season.
5. Level or absorptive type terraces can have a
considerable effect on flood peaks of rather
large watersheds.
A Study conducted in the Sukhna lake, India
1. Catchmentt of 40 sq.km area showed that
2. 150 tonnes of sediment erosion per
hectare of the catchment.
3. About 50% of the total rainfall was lost as
runoff from the untreated hilly catchment.
4. Conservation practices including construction
of staggered contour trenches, check
dams and planting supplemented by debris
basin have reduced
5. Sediment from 80.5 tonnes /ha/yr to 3.0
tonnes /ha/yr from a hilly watershed of 20
ha within a period of 11 years.
6. The average runoff from the catchment has
come down to 10% of rainfall with 66%
reduction in peak discharge within 15 years.

21. FLOOD CONTROL & WSM
FLOOD CONTROL MEASURES
1. Small flood control reservoirs constructed in the head reaches have a salubrious
(healthy / clean) effect on minimizing damage down below. Water stored in such
reservoirs can be recycled for irrigation. It can also be used for town water supply,
power production, fish culture etc. The reservoir sides can be well developed for
recreational purposes.
2. Reservoirs for flood control reduce
flood peaks, but no flood volume.
3. The principal disadvantages of reservoir are that they
occupy some large land which remains flooded and that
the annual and initial costs are high.
UNDERGROUND STORAGE
Underground storage is accomplished by spreading the flow over a considerable area. In general,
this is applicable in arid regions. This is very effective in raising the groundwater table in the
watershed. In areas, where groundwater is considered as potential source of irrigation
water, this practice is very useful.

22. FLOOD CONTROL & WSM
CHANNEL IMPROVEMENT
1. It includes those measures that increase the channel capacity, such as enlarging
the cross sectional area of the channel and increasing the flow capacity.
2. Cross section of the channel can be increased either by deepening or widening the
channel or by removing trees and sandbars from the water course to increase the
channel effectiveness.
3. As evident from the manning’s equation, the velocity of flow can be increased by;
I. Removing debris and vegetation to reduce surface roughness
II. Widening or deepening the channel to increase the hydraulic radius and
III. by increasing the slope through deepening, straightening or lowering the water level
at the outlet.
CHANNEL STRAIGHTENING
1. Straightening of streams is to provide cutoffs. A cutoff is a natural or artificial
channel which shortens a meandering stream and the purpose is to increase flow
velocity, shorten channel length and decrease the length of levees. Sometimes the
length of the stream is shortened as much as one half the original length by
channel straightening.

23. FLOOD CONTROL & WSM
WATERSHED FLOOD CONTROL PREVENTIVE MAINTAINATNCE
1. Two classes of bank protection are ;
1. Those which retard the flow along banks and cause deposition and
2. Those which cover the banks and prevent erosion.
2. A common method of control to retard the flow along banks and
encourage soil deposition is to build retards extending into the
stream from the banks. Materials used include piles, trees, rocks,
and steel framing.
3. Grasses, shrubs and trees have been found effective vegetative control measures.
4. Mechanical measures to cover the stream bank include such devices as wood and
concrete mattresses, rock or stone, asphalt and sacked or monolithic structure.

24. SOCIO-ECONMIC ASPECTS OF WSM
1. A watershed is the natural unit for economic management and therefore, in its
management besides the Govt. view point, the view point of individuals and communities,
should also be considered.
2. The people have their needs, custom values, and, therefore, the measures taken for the
treatment of the watershed should have compatibility with the needs of the people.
3. Proper management of watershed, requires not only the knowledge and application of
scientific techniques, but also substantial investments of labour and capital whose returns
may be high in the long run and thus in compatible with the perspective of the farmer.
4. How to make the necessary investments and sacrifice is a socio-economic problem.
5. The most important economic aspect of WSM is to determine whether the investment
decisions on such programmes are rational (normal) . There are alternative techniques of
soil conservation , water harvesting, storage and conveyance of water, alternative cropping
patterns and technology packages for making optimum use of available water etc.
6. It is the job of the economist to evaluate these alternatives and suggest the efficient one.
7. Several techniques like benefit-cost analysis, interval rate return etc. are available for
evaluating such projects.

25. SOCIO-ECONMIC ASPECTS OF WSM
To study the economic feasibility of WSM and safeguard the individual
benefits of the beneficiaries as well as the social benefits, the
following have to be taken into consideration;
1. Social objectives and interests of general public as custodian of natural
resources.
2. Development of backward areas
3. Growth of ancillary / additional industries
4. Channelization of income of agriculture sector productive use
5. Production of wages consumer goods
6. Encouragement of co-operative objectives
7. Generalization of employment

26. WATERSHED MANAGEMENT PRACTICES
In order to achieve the solution of different objectives selected for WSM, it is
necessary to follow the following steps ;
1. Rehabilitation phase: In this phase, treatments measures are applied to
the critical areas for the recognized problems , so that these critical areas
can be restored to the pre-deterioration stage. All biological and
engineering measures are implemented to all types of land falling under
watershed.
2. Protection phase: The general health of watershed is taken care off and its
normal working is also ensured and protection of watershed against all
those factors which cause deterioration is carried out in this phase of
management phase.
3. Improvement phase: The overall improvement made during the
management of watershed are evaluated for all the lands covered. In
addition , attention is also given to make improvement on agriculture
land, forest land, forage / hunt protection , pasture land and socio-
economic status of the people.

27. WSM APPROCHAES
Integration of Scientific Information & Societal Values: Watershed
management decisions should be based on sound scientific information, both in
terms of identifying problems and selecting options for addressing those
problems.
Proponents of community-based watershed management maintain that involving local
stakeholders results in more locally relevant solutions that take into account each
community's unique social, economic, and environmental conditions and values.
Stakeholder participation is also thought to create a sense of local ownership of identified
problems and solutions, thus ensuring long-term support for resulting management plans.
Community-based watershed management - approach
to water resource protection that enables individuals,
groups, and institutions with a stake in management
outcomes (often called stakeholders) to participate in
identifying & addressing local issues that affect or are
affected by watershed functions.
Social Aspects: watershed management and its
contribution towards optimal utilization of natural
resources thereby accruing greater and sustainable
benefits to mankind.

28. WSM APPROCHAES
Characteristics of Community Based Watershed Management
Changing Roles & Relationships: As local communities participate more actively in
watershed management, roles & relationships of resource managers &
stakeholders will change. Community-based watershed management recognizes
that all stakeholders have a critical role to play in the management planning
process.
Whole-System Perspective: Watershed management is not a single strategy, but is a
general approach to water resource protection that recognizes the
interconnectedness of all the physical and biological components of the
landscape, including human communities.
Whole-System Perspective: A community-based approach considers not only the
physical characteristics of a watershed, but it also takes into account the social &
economic factors associated with watershed issues. The goal of community-based
watershed management is to protect and restore watershed functions while
considering the variety of social and economic benefits of those functions.

29. WSM APPROCHAES
Adaptive Management Style: Addressing environmental, social, and economic issues
at the watershed scale is complex, and often there is a high level of uncertainty
regarding the outcomes of management decisions.

30. WSM APPROCHAES
Challenges Associated With Community Based Watershed Management
Watersheds may cover thousands of acres of public & privately owned land.
Developing a basic understanding of how human activities affect watershed functions
is a major undertaking.
Some key stakeholders may lack the time, motivation, skills, or resources to
participate effectively throughout the management planning process.
Resource management professionals may be reluctant to give up their role as experts
and to share authority with lay persons regarding resource management issues.
Conflicts between stakeholders over management goals and the means to
accomplishing those goals are inevitable, and resource management professionals are
often ill-prepared to facilitate constructive dialogue to resolve these conflicts.
Community-based approaches require time and resources to generate interest and to
build relationships between stakeholders.
Funding agencies and stakeholders may grow impatient with the lack of observable
outcomes.

31. WSM APPROACHES
OLD AND NEW APPROACHES

32. EMERGING PARADIGMS
Rural development over the past 20 years has been marked by a gradual
shift from the intervention-based method to an approach promoting
rural people’s involvement in their own development so that more
attention could be paid to the people’s requirements, problems on the
ground could be better understood & groups concerned could be helped
to improve their situation.
Direct Intervention Method Vs Participatory Method