Watershed management

Topic : Application of Remote Sensing in Watershed

Management and Desertification

ByRajashree Naik2014MSES0122ND Semister

1st yearDepartment of Environmental Science

Definition• A hydrological unit• Topographically delineated area drained by a

stream system, fromwhich runoff resulting from precipitation flow past from a point into single stream.

• Development is not confined just to agriculture lands but covers entirecatchment's area.

• Watershed approach links upstream anddownstream areas.

Watershed Development Approach- Integrated and multi-disciplinary approach.

- To suggest possible exploitation of resources within the limits of tolerance.

- Approach is Preventive, Progressive, Corrective & Curative.

• Objectives -• Conservation of Soil and Water• Improved ability of land to hold water• Maintaining adequate vegetative cover for controlling soilerosion• Rain water harvesting and ground water recharging.

• Benefits -• Promotes economic and social development of community• Employment generation and other income generation• Ecological balance

Components of Watershed

• Area• Drainage• Perimeter

• Watershed boundary• Length of the stream

Capability of Remote Sensing for Watershed Attributes Information

Attribute Attribute ParameterSize Area

Shape Geometric form, shape index, formfactor

PhysiographyMean elevation, av. Slope, relief& slope length

Drainage Drainage pattern & density, streamorder

Geology Rock types

Soil Texture, moisture, capability

Landuse Present , wasteland, surface water

Groundwater Potential

WATERSHED DEMARCATION AND SELECTION

Method: Separation of the major drainage area; principal drainagebasin and sub-basin; watershed

CATEGORIES DELINEATION SYSTEM

Region ………… 1.5-12 lakhs sq km

Basins ………… 0.3- 3.0 lakhs sq km

Catchment …………. 0.1 - 0.5 lakhs sq km

Sub catchment ……. 2000 - 10000 sq km

Watershed …………. 500 - 2000 sq km

Sub-watershed …….. 50 - 500 sq km

Mini Wateshed ……. 10 - 50 sq

km

Micro watershed …… 5 - 10 sq km

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Watershed Codification• Region : 4• Basin : E

• Catchment:5• Sub Catchment : A

• Watershed:6• Sub watershed : C• Mini watershed:2

• Micro watershed : a

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Indicators for Impact Assessment

Natural Resources Surface Runoff

Water Resource Development

Ground Water level/Yield

Change in Irrigated Area

Crop Diversity

Crop Yield

Crop intensity

Fodder Availability

Afforestation

Climate Change & Biodiversity

Land Use Change

Socio Economic

Employment Opportunity

Migration Status

Economic potential of Household Income

BPL Family

Animal Husbandry

Impact on Milk yield

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POINTS TO BE CONSIDERED BEFORE TAKING UP IMPACT STUDIES

1. SATELLITE IMAGES SHOULD BE OBTAINED ONLY AFTER CONSIDERABLE TIME AFTER IMPLEMENTATION( 6-10 YEARS)

2. CONDITIONS SHOULD BE SIMILAR FOR PRE AND POST TREATMENT RAINFALL- QUANTUM,DISTRIBUTION, ETC SOWING SEASON- EARLY/DELAY

3. AVAILABILTY OF SATELLITE DATA FOR REQUIRED DATES

4. RESOLUTION OF SATELLITE DATA-

SHOULD BE SAME FOR PRE AND POST

DESERTIFICATION• Assessment of current state of desertification• Analyses of land degradation processes• Selection of basic indicators of desertification• Mapping of degraded land and other related natural

resourses• Evaluating the impact of land use change and

rehabilitating measures taken• Monitoring and mapping is done

Example• River : Rogue River• State : Oregon• Country : United States• Watershed : Applegate river(tributary of Rogue)• Length:82mtr long• Study area:5,00,000acres• Analysis type : Multiscale Image analysis1. Valley segment scale:1:24,0002. Stream reach scale:1:12,000

Geospatial technology used• Landsat TM Satellite-30mtr pixel• Digital Elevation Model(DEM)-10mtr pixel (3-D representation-raster ; vector-obtained

through photogrametry;LIDAR)• Digital Orthophoto Quad(DOQ)-1mtr pixel computer generated picture; image displacement

removed , combines features of original photo and georeferenced map)

• Digital colour-infrared camera imagery-1ft pixel (thousands of pictures taken)

Digital Camera Imagery• DCIR :Infrared remote control(allows onscreen display• Camera System: Kodak DCS-420

Georegistered digital colored infrared camera imagery

overlaid on a DOQ and prepared for analysis

DEM derived stream work

Valley segment scale

• Used Arc/Info 7.2 AML Program• Valley segment scale:1:24,000• Hydrology info collected :Vegetation General description of upland and riparian vegetation

are appropriate at Valley-segment –assessment-scale

Made a database storing info about sereal stages, canopy closure and size etc..

Vegetation summaries generated to establish relationships between various data obtained

Result of Valley scale analysis by LANDSAT TM imagery

SUCCESSIONAL STAGES APPLEGATE ACRES

GRASS 1294

SHRUB 280

EARLY SERIAL 1695

LOW DENSITY FOREST 244

11 to 17 inch DBH 722

Stream Reach Scale• Stream reach scale:1:12,000• A single valley segment along the main stream was

selected• Required finer resolution and more detailed

information than valley segment scale• DCIR camera imagery provide such closeups

HYDROLOGYSpecial Hydrology application was developed using

combined manual $ computer assisted image processing

HYDROLOGY APPLICATION

DEEP

SHALLOW

VERYSHALLOW

MODERAT

E

SEDIMENT

BARS

• Stratified aquatic and terrestrial landscape using computer onscreen digitizing techniques

• Then performed an unsupervised classification on aquatic portion of digital camera imagery

• Labelled each resulting classes• Finally smoothed classification by using low

pass filters to minimise the occurrence of isolated pixels

Final hydrological map showing relative water depth with a ground photography

Manual Interpretation• Used ARC/TOOLS to view and delineate vegetation

polygons manually onscreen as GIS DATA LAYERS

• Assessed landscape vegetation at variety of scales to formulate MAP and eventually digitised individual vegetation patches no finer than 1:2000.

• This limited scale improved map unit consistency

• Eliminated the possibility of creating insignificantly small polygons

Computer assissted Interpretation• Resource Specialist also attempeted coputer assited

classification of vegetation for STREAM reach scale

• Though the resulting land over patterns generally matched features in the imagery,the vegetation type were mislabelled and this proved unreliable

Final vegetation map demonstrating polygon line precision with details

Deciduous -50%

Blackberry-40%

Dry Grass-10%

PROJECT COMPONENTS

REMOTE SENSING

DATA ACQUITION

IMAGE INTERPRE

TATION

DIGITAL IMAGE

PROCESSING

THANK YOU