Application of SAR in mapping and monitoring wetlands

Vaibhav GuptaS3304216

Wetlands

SAR

Case Study

What are wetlands?

• It is an area of land whose soil is saturated with moisture either permanently or seasonally• Commonly called as marshes, swamps and bogs• Considered the most biologically diverse ecosystem• Unique characteristics of wetlands:WaterHydric soilHydrophytic vegetation

World wide distribution of wetlands

Prevent flooding

& erosion

Water purificati

on

Sediment trapping

& Nutrient removal

Climate change

Ground-water

recharge

Wildlife

What is SAR?

• Synthetic Aperture Radar- remote sensing technology

• Form of RADAR in which multiple radar images are processed to yield higher-resolution images

• Used to monitor natural disasters• Wide applications in mapping

environmental features

Low atmospheric attenuation•Microwave frequencies•Penetrate cloud, fog and haze

High resolution imagery•10 cm resolution

Sensitivity•Soil moisture & flooding•Vegetation differentiation

CASE STUDY: SPACE-BORNE SAR DATA FOR WETLAND MAPPING

Test the abilities of multi-frequency SAR data for wetland delineation & vegetation mapping

To evaluate the utility of the six band SIR-C data (L-HH, L-HV, L-VV, C-HH, C-HV, C-VV)

STUDY AREA

VEGETATION CLASSIFICATION & ACCURACY ASSESSMENTS

Maximum Likelihood Classifier (MLC)

Hierarchical Classifier (HC)

Rappahannock- MLCMRLC April October

Rappahannock

Mattaponi & Pamunkey

Rappahannock- HCMRLC April October

RESULTSL-HV was consistently the best band for

differentiation of woody and herbaceous

vegetation.

L-HH was the most useful band for differentiating forested wetland from upland forest in all cases except the

October Rappahannock Image. This is probably because most of the forested

wetland sites were not flooded in October on the Rappahannock.

CONCLUSIONMulti-band SAR data can be used to map wetlands with reasonable accuracy. Since MLC approach is simpler and available to a wide array of potential users, it would be the method of choice.

L-HV was determined to be the best band for discriminating forested wetland from upland forest, and C-HH was the best for discriminating emergent wetlands from agriculture.

The best method for vegetation mapping would probably be a synergistic approach between visible and SAR data.

Results also show the need for multi-polarization/multi-frequency SAR data for a complete wetland mapping and monitoring capability. HH polarization was found to be the most useful for detecting wetlands while L-band for discriminating flooded from non-flooded forests.

C band was best for discriminating emergent wetlands from agriculture and herbaceous uplands.

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THANK YOU

ANY QUESTIONS?