The document covers watershed analysis and planning using GIS, detailing the definition, components, and methodologies for watershed delineation. It emphasizes the role of GIS in enhancing watershed modeling techniques and the benefits of effective watershed management for resource conservation and agricultural productivity. The analysis involves various steps, such as DEM acquisition, flow direction assessment, and the establishment of stream networks, along with factors influencing the accuracy of these analyses.

1. College of forestry
Assignment on
‘watershed Analysis And Planning Using
GIS’
Submitted by Submitted to
VISHAL (16055)
DIKSHA DEV (16064)
SHAHRUKH BEG(16060)
Surbhi Jayara (16067)
Dr. Deepa Rawat

2. _INDEX_
1. Watershed Analysis; Introduction and Definition
2. Components of watershed.
3. Delineation of watershed.
4. Steps involved in watershed delineation.
5. Factors influencing watershed analysis
6. Application of watershed analysis.
7. Benefits derived from watershed methodology.

3. Watershed ;
 A watershed is an area of land that
feeds all the water running under it and
draining off of it into a body of water . It
combines with other watersheds to form
a network of rivers and streams that
progressively drain into larger water areas.

5. Watershed Analysis:
Watershed analysis refers to the process of
using DEM and raster data operations to
delineate watersheds and to derive features
such as stream ,stream networks ,catchment
areas , basin etc.

6. Traditionally, the use of geographic
information systems for watershed management
Projects has been limited to a supporting role in
Mapping and related to engineering activities-not
often serving as a driving resource in the
analytical process .
Watershed studies conducted using a GIS
Platform have demonstrated that the spatial
analysis capabilities of GIS hold the key to improv
-ed watershed modeling techniques .This approac
-h allowed for the establishment of more accurate ,
Efficient and high – quality products.

7. In watershed analysis using GIS, the
data is gathered in a variety of formats
including spatial data ,non-spatial data
and digital remote sensing data ….
Effective data analysis requires
incorporation of both spatial and non-
spatial entities that may change in time.

8. Objectives of Watershed;
 1. Production of food, fodder, fuel.
 2 Pollution control
 3. Over exploitation of resources should be minimized
 4. Water storage, flood control, checking sedimentation.
 5. Wild life preservation
 6. Erosion control and prevention of soil, degradation and
conservation of soil and water.
 7. Employment generation through industrial development dairy
fishery production.
 8. Recharging of ground water to provide regular water supply
for consumption and industry as well as irrigation.

9. Components of watershed:
Broadly a watershed have five
components ;
*Watershed Boundary
*Subbasin
*Drainage divides
*Stream networks
*Outlets

12. Delineation Of Watershed;
Delineation of watershed can be divided
into two types;
: Area based method
: Point based method

14. Steps involved in delineation of
watershed;
When delineating watersheds or defining stream
networks, we proceed through a series of steps,which are ;
1. DEM acquisition-:
The first input required for watershed analysis is
DEM. In a DEM , each cell of raster GIS layer has a value
corresponding to its elevation .
DEM data files contain the elevation of the terrain over a
specified area ,usually at a fixed grid interval over the “bare
earth”.

16. _FILL_
Fill sinks in a surface raster to remove
small imperfection -s in a data. A filled
DEM or elevation raster is a void of
depression. A common method to
remove depression is to increase its
cell value to the lowest overflo
-w point out of the sink .This results in
flat surface.

17. Flow Direction;
A flow direction raster shows the
direction water will
flow out of each cell of a filled elevation raster .
A widely used method for deriving flow direction
is the D8method ,used by Arc GIS.
D8 method produces good results in the
zone of convergent flows and along well
defined valleys.


18. Flow Accumulation_
A flow accumulation raster tabulates
for each cell the no. of cells that will flow to it.
The tabulation is based on the flow direction
raster.

19. 5. STREAM NETWORK;
 Stream network can be derived from
a flow accumulation raster .
The derivation is based on threshold
accumulation value.
Threshold values between 100 to 500 cells
seem to best capture the stream network in
the area.

20. 6.STREAM LINKS;
Assigning a unique value and
associating with flow direction to each
section of stream network is a step to derive
stream links.

21. 7. Area -wide watersheds;
Inputs required for area-
wide watersheds delineation are
flow direction raster and stream
network raster.
A denser stream network
will have more but smaller
watersheds.

22. 8. Point-Based Watersheds;
 Delineation of individual watershed
-s based on point of intersection [ pour point ] foll
-ows the same steps as for delineation of Area-
wide watersheds .
Point based watersheds delineation
Is based on the point of interest . This point of
interest may be stream gauge stations or dams.

23. Factor Influencing Watershed Analysis ;
 There are two main factors which
effects watershed analysis, these are as
follows;
1. DEM; A 30m DEM likely to be too coarse to
provide detailed topographic features for
geomorphic and hydrologic modeling.
2. Algorithm ; Choice of algorithm is also an
important factor in watershed analysis.

24. Application of watershed analysis ;
Watershed analysis is used for the
management and planning of natural resources .
1. To provide necessary inputs for hydrological
modeling .
2. Flood prediction modeling and snow-melt
run-off models etc.
3. Watershed analysis provides catchment bound
-aries but also hydrological parameters useful for
Management programs .

25. Benefits derived from Watershed Metodology ;
1. The crop yield has increased by in dry land
farming.
2. The soil loss due to erosion was brought down..
3. Large extents of barren hill slopes were covered
by vegetation .
4. Large tracts of marginal lands brought under dry
land horticulture.
5. Development of Agro-Horti and Agro-Forestry
systems.

26. 6. Water -resources were harvested through nala
bunds , farm - ponds gully embankments.
7. Regeneration of grasslands for more fodder
and grass.
8. The income of farmers increased considerab
-ly.