56

CHAPTER – 3

STUDY AREAS AND DATASETS

3.1 STUDY AREAS:

The present study analyses airborne and spaceborne SAR data viz., DLR-

ESAR, ENVISAT-ASAR and ALOS-PALSAR with specific objectives of

vegetation classification and above ground biomass estimation in different

ecoregions of India. Thus, several spatial, phenological and physiognomic

factors were considered to select suitable forested sites. They are as follows.

1. Dry deciduous forests of Rajpipla, Gujarat.

2. Mixed moist deciduous forests of Achanakmar-Amarkantak Biosphere

Reserve, Bilaspur, Chattisgarh.

3. Moist Deciduous/Semi evergreen forests of Dandeli, Karnataka

The geographical location of study sites, climate, geology, major vegetation

types, biomass ranges and datasets used are discussed as follows:

3.1.1 Rajpipla, Gujarat

The airborne DLR-ESAR data and spaceborne ENVISAT-ASAR, ALOS-

PALSAR datasets were acquired for forest area of Rajpipla, located in

Aravalli Mountains in Bharuch, Gujarat, India (fig 3.1).

57

3.1.1.1 Geographical location: The study area forms part of

Shoolpaneshwar Wild life Sanctuary in Narmada district of Gujarat, India. It

is bounded in the north by the Narmada River and the Sardar sarovar, in

the west by Karjan River, Karjan reservoir and Tarav River. The central

coordinates of the area are 21°45’00” N and 73°45’00” E. The study area lies

between 21°42'36" N to 21°50'30" N latitude and 73°36'2" E to 73°50'31" E

longitudes.

3.1.1.2 Climate: The area has a typical monsoonal climate, with three

distinct seasons: summer from March - June, rainy from July - October and

Fig 3.1: Location map of study area: Rajpipla, Gujarat

KACHCHH

JAMNAGAR

SURAT

AMRELI

VADODARA

BHARUCH

ANANDRAJKOT

BHAVNAGAR

PATAN

JUNAGADH

DAHOD

BANAS KANTHA

AHMADABADSURENDRANAGAR KHEDA

SABAR KANTHAMAHESANA

VALSAD

NAVSARI

NARMADA

PANCHTALUKS

PORBANDAR

THE DANGS

GANDHINAGAR

RAJPIPLA

DEDIAPADA

AKKALKUVA

73°50'0"E

73°50'0"E

73°45'0"E

73°45'0"E

73°40'0"E

73°40'0"E

73°35'0"E

73°35'0"E

21°5

0'0"

N

21°5

0'0"

N

21°4

5'0"

N

21°4

5'0"

N

21°4

0'0"

N

58

winter from November-February. The temperature of the study area ranges

between a minimum of 10°C (average) in winter and to a maximum of 43°C

(average) in peak summer. Average rainfall of the area is about 1000 mm.

3.1.1.3 Terrain: Topography of the study area is highly varying with

gentle undulating plains to rugged hills. The area consists of moderately

hilly terrain comprising of height variation ranging from 607 ft to 1805 ft.

The hilly terrain with a continuum of small and high hillocks is a

characteristic feature of the area. The general slope of the area is towards

the west.

3.1.1.4 Forest types: The study area predominantly consists of Type

5A Tropical Dry Deciduous forest as classified by Champion and Seth

(1969).The predominant plant species in the study area is Teak with

patches of bamboo. Apart from bamboo, the study area is also dominated by

some other plant species viz., Haldu, Sadad, Amla, Khair, Harde, Amaltas,

mahuda, Tanach, Bor, Timru, Aritha, Karanj, bamboo etc. Dominant

species are Tectona grandis L. followed by Dendrocalamus strictus Nees.

Both species are homogenously distributed and occupy about 30% of the

study area. Tectona grandis, Bamboosa, Terminalia paniculata and

Cleistanthus, Butea monosperma are the dominant species in the study

area. Bushes have covered many areas, being relatively dense and up to 1 m

height or more. The biomass range and tree density are less in this area.

59

This study area is suitable for biomass analysis in C, L and P wavelength

bands. Studies on above ground biomass using different wavelength bands -

C, L and P, along with polarimetric analysis for vegetation characterization

was carried out in this study area.

3.1.2 Achanakmar - Amarkantak Biosphere Reserve, Bilaspur

The study area is located in Madhya Pradesh and Chhatisgarh states of

Central India. Spaceborne ENVISAT-ASAR and ALOS-PALSAR datasets were

acquired for this study area.

3.1.2.1 Geographical location: The Achanakmar-Amarkantak

biosphere reserve lies between 22°24' to 22°35' N latitude and 81°34' to

80°55' E longitude, having an area of 3835 sq. km, covering parts of

Madhya Pradesh and Chhattisgarh States (fig 3.2). The study area is a

biosphere reserve (notified by the Government of India on 30th March 2005),

with Achanakmar Wildlife Sanctuary as the core area.

3.1.2.2 Climate: The biosphere area has a typical monsoonal climate,

with three distinct seasons, summer from March - June, rainy from July -

October and winter from November-February (EPCO, 2006). The average

annual rainfall of the area is about 1624 mm. Mean daily temperature

ranges from 10.9° C (in January) to 39.1° C (may).

3.1.2.3 Geology: The soils of the area are generally lateritic, alluvial

and black cotton type, derived from granite, gneisses and basalts (EPCO,

60

2006). The soil of the area varies greatly in physical and chemical properties

depending upon the parent rocks and topography is red laterite, nutrient

poor (lacking nitrogen and phosphorus) and characterized by excessive

amounts of iron oxide (EPCO, 2006).

3.1.2.4 Forest types: The forest is seasonally dry tropical with

Northern Tropical Moist deciduous forest predominating. The forest area of

the Achanakmar-Amarkantak biosphere reserve represents tropical

deciduous vegetation and can be classified into Northern Tropical Moist

Deciduous and Southern Dry Mixed Deciduous forests (EPCO, 2006;

Champion and Seth, 1968). Specifically, there are two dominant types

(Bremen et al., 1990) i.e. moist deciduous forest and Sal mixed forest.

BASTAR

RAIPUR

SURGUJA

DURG

DANTEWARA

BILASPUR

KOREA KORBA

KANKER

RAIGARH JASHPUR

RAJ NANDGAON DHAMTARI

MAHASAMUND KAWARDHA JANJGIR CHAMPA

MUNGELI

DINDORI

KOTA

PENDRA ROAD

PANDARIA

PUSHPRAJGARH

KOTATAKHATPUR 81°55'0"E

81°55'0"E

81°50'0"E

81°50'0"E

81°45'0"E

81°45'0"E

81°40'0"E

81°40'0"E

81°35'0"E

81°35'0"E

81°30'0"E

81°30'0"E

22°45'0"N 22°45'0"N

22°40'0"N 22°40'0"N

22°35'0"N 22°35'0"N

22°30'0"N22°30'0"N

22°25'0"N22°25'0"N

22°20'0"N22°20'0"N

Fig 3.2: Location map of study area: Achanakmar-Amarkantak Biosphere Reserve, Bilaspur, Chhattisgarh

61

Terminalia Paniculata and Shorea Robusta are the dominant species in the

study area, interspersed with teak plantations.

Vegetation classification using texture measures and interferometric

coherence, above ground biomass estimation using C-band ENVISAT-ASAR

and ALOS-PALSAR data studies were carried out in this study site.

3.1.3 Dandeli, Karnataka

This study area is located in parts of Western Ghats of Karnataka, India.

Spaceborne ENVISAT-ASAR and ALOS-PALSAR datasets were acquired for

the study area and analysed for vegetation classification using multi-sensor

fusion technique.

3.1.3.1 Geographic location: The study area covers parts of Haliyal

and Yellapur Forest divisions, Western Ghats of Karnataka, India (fig 3.3). It

is located from 14º40'15" to 15º21'30" N latitude and 74º16'34" to 75º21'34"

E longitude.

3.1.3.2 Geology: Geographically, it is a transitional zone between the

younger rocks of Deccan trap formation and the older crystalline rocks of

Archean shield of the Indian Peninsula. The soil on the exposed slopes and

broad valleys is loamy laterites with the pH values ranging from 5 to 5.8.

3.1.3.3 Climate: The area experiences southwest monsoon from mid

June to mid October. The mean annual rainfall is about 2500mm. The

mean monthly temperature ranges from 25 to 33ºC.

62

BIJAPUR

TUMKUR

RAICHUR

GULBARGA

BELGAUM

KOLAR

BELLARY

SHIMOGA

BIDAR

HASSAN

MYSORE

KOPPAL

UTTAR KANNADHAVERI

GADAG

UDUPI

BAGALKOT

MANDYA

CHITRADURGA

CHIKMAGALUR

DAVANGERE

KODAGU

DHARWAD

CHAMRAJNAGAR

BANGALORE RURALDAKSHIN KANNAD BANGALORE URBAN

SUPA

YELLAPURMUNDGOD

HALIYALKALGHATGI

KARWAR

SIRSIANKOLA

75°0'0"E

75°0'0"E

74°55'0"E

74°55'0"E

74°50'0"E

74°50'0"E

74°45'0"E

74°45'0"E

74°40'0"E

74°40'0"E

74°35'0"E

74°35'0"E

74°30'0"E

74°30'0"E

74°25'0"E

74°25'0"E

15°1

0'0"

N

15°5

'0"N

15°5

'0"N

15°0

'0"N

15°0

'0"N

14°5

5'0"

N

14°5

5'0"

N

14°5

0'0"

N

14°5

0'0"

N

3.1.3.4 Forest types: Native vegetation is evergreen/semi-evergreen

type and has a continuum to secondary/moist deciduous types in lower

rainfall tracts to the east (Pascal, 1986). The test site area is characterised

by a complex mosaic of vegetation and land cover types. Almost 75 % of the

study area is covered by forest. Typical tropical evergreen and semi-

evergreen rainforests dominate the natural vegetation. Forest types in the

study area were classified as tropical wet semi evergreen and tropical moist

and dry deciduous forest types (Champion and Seth, 1968). Tectona

Fig 3.3: Location map of study area: Dandeli, Karnataka

63

grandis, Xylia xylocarpa, Lagerstroemia lanceolata, Terminalia alata,

Terminalia paniculata, Dillenia pentagyna are the dominant tree species and

under-story is represented by Psychotria dalzelli, Eupatorium odoratum,

Wagatea spicata and Ziziphus spp.

Field inventory and Phytosociological data analysis of the ground truth

collected in the study areas are discussed in Chapter-7 of above ground

biomass estimation.

3.2 DATA SETS USED IN THE PRESENT STUDY:

Airborne DLR-ESAR data was acquired for Rajpipla study site; ENVISAT-

ASAR and ALOS-PALSAR data was acquired for all the three study areas

namely Rajpipla, Bilaspur and Dandeli. Additionally, IRS P6 LISS-III and

LISS-IV data acquired for all the three study areas were used as reference

datasets, table 3.1.

3.2.1 Airborne DLR-ESAR data

The DLR-ESAR is a multi-frequency and multi-polarimetric airborne

Experimental Synthetic Aperture Radar with 4.5m spatial resolution and a

pixel size of 1.2 m. The data were collected in X, C, L and P-bands. The X

band data was acquired in two polarizations HH and VV. The DLR-ESAR

data was acquired on 2nd October 2004 for Rajpipla study area. Multi-look

geocoded data of C, L and P-bands in HH, HV, VV and VH polarizations

were generated from Single Look Complex (SLC) data (table 3.2).

64

Table 3.1: Details of satellite datasets used for different study areas

Study Area Satellite Date Polarization 28th Nov 2005 VV/VH 19th Dec 2005 HH/VV 25th Sep 2006 HH/VV

ENVISAT-ASAR

30th 0ct 2006 HH/VV ALOS-PALSAR 10th Feb 2007 HH LISS-III 11th Jan 2004 -

Dandeli, Karnataka

LISS-IV 16th Dec 2005 - 24th Sep 2006 HH/VV ENVISAT-ASAR

29th 0ct 2006 HH/VV ALOS-PALSAR 04th Oct 2006 HH LISS-III 20th Jan 2006 -

Bilaspur, Chattisgarh

LISS-IV 22nd Feb 2006 - DLR-ESAR - X, C, L & P-bands

2nd Oct 2004 HH, HV, VH & VV

23rd Sep 2006 HH/VV ENVISAT-ASAR

28th 0ct 2006 HH/VV ALOS-PALSAR 11th June 2007 HH/HV

Rajpipla, Gujarat

LISS-IV 12th Nov 2005 -

The depression angle for C-band and L-band was 350 and standard

images were processed with 8 look processing and the depression angle for

P-band was 400 with 4 look processing. Each image pixel was encoded as 16

bit signed integer.

Variations in backscatter were observed in different wavelength bands

and different polarizations. The study area is covered in 3 segments in X, C

and L-bands and 6 segments in P-band, respectively.

65

3.2.2 Space-borne ENVISAT-ASAR:

Environmental Satellite (ENVISAT) was launched by the European Space

Agency in 2002 with an Advanced Synthetic Aperture Radar (ASAR) sensor

operating at C-Band with a centre frequency of 5.3 G Hz. ENVISAT-ASAR is

capable of transmitting the data in single and dual channels with Precision

(PRI) viz., ground range calibrated amplitude data and Single look complex

Parameter Multilook Geocoded Polarimetry

Bands X C L P L P

Wave length (cm) 3.12 5.6 23.06 85.65 23.06 85.65

Central frequency

(GHz) 9.6 5.3 1.3 0.35 0.35 0.68

Slant range sample

spacing (m) 2.49 2.49 2.49 2.49 2.49 2.49

Azimuth range

sample spacing (m) 0.35 0.35 0.35 0.35 0.35 0.35

Range pixel spacing

(m) 1.28 1.28 1.28 1.28 1.28 1.28

Azimuth pixel

spacing (m) 1.40 1.40 1.40 1.40 1.40 1.40

Radar Altitude (km) 3.6 3.6 3.6 3.6 3.6 3.6

Depression angle

(degrees) 35 35 35 40 35 40

No. of looks 8 8 8 4 8 4

App pixel size (m) 2.5x2.5 2.5x2.5 2.5x2.5 2.5x2.5 2.5x2.5 2.5x2.5

Table 3.2: Details of air-borne DLR-ESAR data in different wavelength bands for Rajpipla study area

66

(SLC) acquisition modes. In dual mode, the sensor could be operated in

different alternating polarization modes viz., HH+HV, VV+VH and HH+VV.

The data can be acquired in any of the selected beam positions (IS2–IS7)

depending on the incidence angle ranges, in image mode, alternate

polarization mode and wide swath mode. The data acquired for present

study was alternate polarization mode. The resolutions, incidence angle

ranges in different modes are given in specifications below.

This is the first satellite which increased capability in terms of coverage,

range of incidence angles, polarization, and modes of operation.

3.2.2.1 ENVISAT-ASAR Specifications

Agency European Space Agency

Frequency C-band

Polarization HH or VV or HH/HV or VV/VH

Ground Resolution 15 to 1000 m

Acquisition Modes Strip map (Image), Alternating Polarization

mode, ScanSAR (Wide Swath, Globe)

Swath 100 to 405 km

Repeat cycle 35 days

Launch 2001.

3.2.2.2 Acquired ASAR datasets: The acquired datasets for Rajpipla

and Dandeli study area were in alternating polarization IS2 mode viz.,

67

(HH/VV, incidence angle ranges from 19.20 to 26.70) with a swath of 105km

in descending node. For Bilaspur study area, the acquired datasets are in

alternating polarization IS3 mode viz., (HH/VV, incidence angle ranges from

26.00 to 31.40) with a swath of 105km in descending node.

Amplitude (Precision image format) data and repeat pass single look

complex (SLC) data for interferometry were acquired for the three study

areas for vegetation classification and above ground biomass estimation.

3.2.3 Space borne ALOS-PALSAR:

Advanced Land Observing Satellite (ALOS) was launched on 24 Jan 2006

by JAXA (Japan Aerospace Exploration Agency) with an L-band sensor

named Phased Array L-band Synthetic Aperture Radar (PALSAR).

The Phased Array L-band Synthetic Aperture Radar (PALSAR) is an active

microwave sensor operating in L-band frequency. The centre frequency of

the PALSAR is 1.24 GHz. L-band PALSAR data is useful in acquiring

vegetation information, distinguishing features on the ground, classification

of land use, etc.

PALSAR works in following 3 observation modes: Fine mode, ScanSAR

mode and Polarimetric mode.

68

3.2.3.1 ALOS-PALSAR Specifications

Agency Japan Aerospace Exploration Agency

Frequency L-band

Polarization Single Pol, Dual Pol, Full Pol

Acquisition Modes Stripmap (Fine) and ScanSAR

Ground Resolution 7 to 100 m

Swath 20 to 350 km

Repeat Cycle 44 days

Launch 2006

As the polarimetric data is not available over Indian regions, fine mode

data of PALSAR is selected for the study sites for the above ground biomass

estimation.

3.2.3.2 Acquired PALSAR datasets: The acquired datasets of ALOS-

PALSAR for Dandeli and Bilaspur study areas were in fine mode, single

polarization (HH) data with off nadir angle of 34.30 and 41.50 respectively.

Dual polarized HH/HV fine mode data with off nadir angle 34.30 was

acquired for Rajpipla study site.

Corresponding optical data viz., LISS-III, LISS-IV, CARTOSAT-1 for

Rajpipla were also acquired for ground truth collection and comparative

analysis with SAR data. The ESAR, ASAR and PALSAR datasets acquired

were converted to ground range, calibrated and preprocessed to derive the

specific objectives as explained in next chapters.