Some Features
of Wetlands of Rajasthan:-
(According to "National
Wetland Atlas of Rajasthan Wetlands Atlas Published in August, 2010 by Space
Applications Centre (ISRO), Ahmedabad)-
What are Wetlands-
Wetlands
are one of the crucial natural resources. Wetlands are areas of land that are
either temporarily or permanently covered by water. This means that a wetland
is neither truly aquatic nor terrestrial; it is possible that wetlands can be
both at the same time depending on seasonal variability. Thus, wetlands exhibit
enormous diversity according to their genesis, geographical location, water
regime and chemistry, dominant plants and soil or sediment characteristics. Because
of their transitional nature, the boundaries of wetlands are often difficult to
define. Wetlands do, however, share a few attributes common to all forms. Of
these, hydrological structure (the dynamics of water supply, throughput,
storage and loss) is most fundamental to the nature of a wetland system. It is
the presence of water for a significant period of time which is principally
responsible for the development of a wetland.
Classifications-
One
of the first widely used classifications systems, devised by Cowardin et al,
1979, was associated to its hydrological, ecological and geological
aspects, such as:
- Marine (coastal wetlands including rock shores and coral reefs,
- Estuarine (including deltas, tidal marshes, and mangrove swamps),
- Lacustarine (lakes), riverine (along rivers and streams),
- Palustarine ('marshy'- marshes, swamps and bogs).
Given
these characteristics, wetlands support a large variety of plant and animal
species adapted to fluctuating water levels, making the wetlands of critical
ecological significance.
Utility of wetlands-
Utility wise, wetlands directly and indirectly support millions of people in providing services such as-
Utility wise, wetlands directly and indirectly support millions of people in providing services such as-
- Food, fiber and raw materials,
- Storm and flood control,
- Clean water supply,
- Scenic beauty and
- Educational and recreational benefits.
The
Millennium Ecosystem Assessment estimates conservatively that wetlands cover
seven percent of the earth’s surface and deliver 45% of the world’s natural
productivity and ecosystem services of which the benefits are estimated at $20
trillion a year (Source: www.MAweb.org).
Wetland Classification System-
1. Inland
Wetlands-
(i) Natural Inland Wetlands-
1.
Lakes
2.
Ox-Bow Lakes/ Cut-Off Meanders
3.
High altitude Wetlands
4.
Riverine Wetlands
5.
Waterlogged
6.
River/stream
(ii) Man-made
Inland Wetlands-
1.
Reservoirs/ Barrages
2.
Tanks/Ponds
3.
Waterlogged
4.
Salt pans
2. Coastal Wetlands-
(i) Natural
Coastal Wetlands-
1.
Lagoons
2.
Creeks
3.
Sand/Beach
4.
Intertidal mud flats
5.
Salt Marsh
6.
Mangroves
7.
Coral Reefs
(ii) Man-made
Coastal Wetlands-
1.
Salt pans
2.
Aquaculture ponds
Definitions of wetland categories used-
For ease of understanding, definitions of wetland
categories and their typical appearance on satellite imagery is given below:
(i) Natural Inland Wetlands-
1. Lakes:- Larger bodies of standing water occupying distinct basins (Reid et al,
1976). These wetlands occur in natural depressions and normally fed by
streams/rivers.
2. Ox-bow lakes/ Cut off meanders:- A meandering stream may erode the outside shores of its
broad bends, and in time the loops may become cut-off, leaving basins. The
resulting shallow crescent-shaped lakes are called oxbow lakes.
3. High Altitude lakes:- These lakes occur in the Himalayan region. Landscapes
around high lakes are characterized by hilly topography. Otherwise they
resemble lakes in the plain areas. For keeping uniformity in the delineation of
these lakes contour line of 3000 m above msl will be taken as reference and all
lakes above this contour line will be classified as high altitude lakes.
4. Riverine Wetlands:- Along the major rivers, especially in plains water
accumulates leading to formation of marshes and swamp. Swamps are ‘Wetland
dominated by trees or shrubs’ (U.S. Definition). In Europe, a forested fen (a
peat accumulating wetland that has no significant inflows or outflows and
supports acidophilic mosses, particularly Sphagnum) could be called a swamp.
5. Marsh:- A frequently or continually inundated wetland characterized by emergent
herbaceous vegetation adapted to saturated soil conditions. In European
terminology a marsh has a mineral soil substrate and does not accumulate peat
(Mitsch and Gosselink, 1986).
6. Waterlogged:- Said of an area in which water stands near, at, or above
the land surface, so that the roots of all plants except hydrophytes are
drowned and the plants die (Margarate et al, 1974). Floods or unlined
canal seepage and other irrigation network may cause water logging.
7. River/stream:- Rivers are linear water features of the landscape.
Rivers that are wider than the mapping unit will be mapped as polygons. Its
importance arises from the fact that many stretches of the rivers in
Indo-Gangetic Plains and peninsular India are declared important national and
international wetlands (Ex. The river Ganga between Brajghat and Garh
Mukteshwar, is a Ramsar site, Ranganthattu on the Cavery river is a bird sanctuary
etc.).
(ii) Man-made Inland Wetlands-
- Reservoir- A pond or lake built for the storage of water, usually by the construction of a dam across a river (Margarate et al, 1974).
- Barrage- Dykes are constructed in the plain areas over rivers for creating Irrigation/water facilities. Such water storage areas develop into wetlands (Harike Barrage on Satluj – a Ramsar site, Okhla barrage on the Yamuna etc. – a bird sanctuary).
- Tanks/Ponds- A term used in Ceylon and the drier parts of Peninsular India for an artificial pond, pool or lake formed by building a mud wall across the valley of a small stream to retain the monsoon (Margarate et al, 1974). Ponds Generally, suggest a small, quiet body of standing water, usually shallow enough to permit the growth of rooted plants from one shore to another (Reid et al, 1976). In this category Industrial ponds/mining pools mainly comprising Abandoned Quarries are also included (Quarry is defined as "An open or surface working or excavation for the extraction of stone, ore, coal, gravel or minerals." In such pits water accumulate (McGraw Hill Encyclopaedia of Environmental Sciences, 1974), Ash pond/Cooling pond (The water body created for discharging effluents in industry, especially in thermal power plants (Encyclopaedic Directory of Environment, 1988) and Cooling pond: An artificial lake used for the natural cooling of condenser-cooling water serving a conventional power station (Encyclopaedic Directory of Environment, 1988). These ponds can be of any shape and size.
- Waterlogged- Man-made activities like canals cause water logging in adjacent areas due to seepage especially when canals are unlined. Such areas can be identified on the images along canal network.
- Salt pans- Inland salt pans in India occur in Rajasthan (Sambhar lake). These are shallow rectangular man-made depressions in which saline water is accumulated for drying in the sun for making salt.
(iii) Natural Coastal Wetlands-
- Lagoons/Backwaters:- Such coastal bodies of water, partly separated from the sea by barrier beaches or bass of marine origin, are more properly termed lagoons. As a rule, lagoons are elongate and lie parallel to the shoreline. They are usually characteristic of, but not restricted to, shores of emergence. Lagoons are generally shallower and more saline than typical estuaries (Reid et al, 1976).
Backwater:- A creek, arm of
the sea or series of connected lagoons, usually parallel to the coast,
separated from the sea by a narrow strip of land but communicating with it
through barred outlets (Margarate et al, 1974).
- Creek:- A notable physiographic feature of salt marshes, especially low marshes. These creeks develop as do rivers "with minor irregularities sooner or later causing the water to be deflected into definite channels" (Mitsch and Gosselink, 1986). Creeks will be delineated, however, their area will not be estimated.
- Sand/Beach:- Beach is an un-vegetated part of the shoreline formed of loose material, usually sand that extends from the upper berm (a ridge or ridges on the backshore of the beach, formed by the deposit of material by wave action, that marks the upper limit of ordinary high tides and wave wash to low water mark(Clark,1977).Beach comprising rocky material is called rocky beach.
- Intertidal mudflats:- Most unvegetated areas that are alternately exposed and inundated by the falling and rising of the tide. They may be mudflats or sand flats depending on the coarseness of the material of which they are made (Clark, 1977).
- Salt Marsh:- Natural or semi-natural halophytic grassland and dwarf brushwood on the alluvial sediments bordering saline water bodies whose water level fluctuates either tidally or non- tidally (Mitsch and Gosselink, 1986).
- Mangroves:- The mangrove swamp is an association of halophytic trees, shrubs, and other plants growing in brackish to saline tidal waters of tropical and sub-tropical coastlines (Mitsch and Gosselink, 1986).
- Coral reefs:- Consolidated living colonies of microscopic organisms found in warm tropical waters. The term coral reef, or organic reef is applied to the rock- like reefs built-up of living things, principally corals. They consist of accumulations of calcareous deposits of corals and corraline algae with the intervening space connected with sand, which consists largely of shells of foraminefera. Present reefs are living associations growing on this accumulation of past (Clark, 1977).
(iv) Man-made Coastal Wetlands-
1. Salt pans: An undrained usually small and shallow rectangular, man-made depression or
hollow in which saline water accumulates and evaporates leaving a salt deposit
(Margarate et al, 1974). Salt pans are square or rectangular in shape.
2. Aquaculture ponds: Aquaculture is defined as "The breeding and rearing
of fresh-water or marine fish in captivity. Fish farming or ranching". The
water bodies used for the above are called aquaculture ponds (Encyclopaedic
Directory of Environment, 1988). Aquaculture ponds are geometrical in shape
usually square or rectangular.
Wetlands of Rajasthan:-
Area estimates of various wetland categories for
Rajasthan have been carried out using GIS layers of wetland boundary,
water-spread, aquatic vegetation and turbidity. Total 12625 wetlands have been
mapped at 1:50,000 scale in the state. In addition, 34123 small wetlands (<
2.25 ha) have also been identified. Total wetland area estimated is 782314 ha
that is around 2.29 per cent of the geographic area (see Table). Rivers/
streams contributed 39.95% to the total wetland area. The reservoir/barrages
with 190600 ha (24.36% area) is the second major wetland category. Area under
Tanks/ponds is 151027 ha (19.31%). Graphical distribution of wetland type is
shown in Figure 10. Open water spread is more during in Post-monsoon (368129
ha) than during Pre-monsoon (158696 ha). Aquatic vegetation is slightly more
during Pre-monsoon (5166 ha) than in Post-monsoon (4102 ha). The qualitative
turbidity of water is low in both the seasons.
Area
estimates of wetlands in Rajasthan-
Sr. No
|
Wetland Category
|
Number of Wetlands
|
Total Wetland Area in ha
|
% of wetland area
|
Open Water
|
|||||
Post-monsoon Area in ha
|
Pre-monsoon Area in ha
|
|||||||||
(i) Natural Inland Wetlands -
|
||||||||||
1
|
Lakes/Ponds
|
65
|
38269
|
4.89
|
28122
|
21711
|
||||
2
|
Waterlogged
|
61
|
16856
|
2.15
|
12933
|
5091
|
||||
3
|
River/Stream
|
648
|
312570
|
39.95
|
52080
|
28021
|
||||
(ii) Man-made Inland Wetlands -
|
||||||||||
1
|
Reservoirs/Barrages
|
979
|
190600
|
24.36
|
165938
|
71546
|
||||
2
|
Tanks/Ponds
|
10731
|
151027
|
19.31
|
100594
|
18659
|
||||
3
|
Waterlogged
|
101
|
7636
|
0.98
|
4423
|
1284
|
||||
4
|
Salt pans
|
39
|
12283
|
1.57
|
4030
|
2433
|
||||
Total - Inland
|
12624
|
729241
|
93.22
|
368120
|
148745
|
|||||
2. Coastal Wetlands - Natural
|
||||||||||
1
|
Intertidal
mud flats
|
1
|
18950
|
2.42
|
9
|
9951
|
||||
Total - Coastal
|
1
|
18950
|
2.42
|
9
|
9951
|
|||||
Sub-Total
|
12625
|
748191
|
95.64
|
368129
|
158696
|
|||||
Wetlands (<2.25 ha), mainly Tanks
|
34123
|
34123
|
4.36
|
-
|
-
|
|||||
Total
|
46748
|
782314
|
100.00
|
368129
|
158696
|
|||||
District-wise
wetland statistics of Rajasthan-
(Source- NATIONAL
WETLAND ATLAS of RAJASTHAN made by Space Applications centre, Indian Space
Research Organisation- ISRO, Ahmedabad–380 015)
Sr. No.
|
District
|
Geographic Area*
(sq. km)
|
Wetland Area
(ha)
|
% of total Wetland Area
|
% of district Geographic Area
|
1
|
Ganganagar
|
7984
|
1708
|
0.22
|
0.21
|
2
|
Hanumangarh
|
12645
|
6549
|
0.84
|
0.52
|
3
|
Bikaner
|
27244
|
2666
|
0.34
|
0.10
|
4
|
Churu
|
16830
|
1368
|
0.17
|
0.08
|
5
|
Jhunjhunun
|
5928
|
5319
|
0.68
|
0.90
|
6
|
Alwar
|
8380
|
12774
|
1.63
|
1.52
|
7
|
Bharatpur
|
5066
|
10415
|
1.33
|
2.06
|
8
|
Dhaulpur
|
3084
|
9370
|
1.2
|
3.04
|
9
|
Karauli
|
5530
|
10042
|
1.28
|
1.82
|
10
|
Sawai Madhopur
|
4500
|
22606
|
2.89
|
5.02
|
11
|
Dausa
|
3429
|
11720
|
1.5
|
3.42
|
12
|
Jaipur
|
11152
|
41352
|
5.29
|
3.71
|
13
|
Sikar
|
7732
|
5388
|
0.69
|
0.70
|
14
|
Nagaur
|
17718
|
30876
|
3.95
|
1.74
|
15
|
Jodhpur
|
22850
|
17032
|
2.18
|
0.75
|
16
|
Jaisalmer
|
38401
|
24876
|
3.18
|
0.65
|
17
|
Barmer
|
28387
|
44638
|
5.71
|
1.57
|
18
|
Jalore
|
10640
|
54440
|
6.96
|
5.12
|
19
|
Sirohi
|
5136
|
19259
|
2.46
|
3.75
|
20
|
Pali
|
12387
|
50304
|
6.43
|
4.06
|
21
|
Ajmer
|
8481
|
32167
|
4.11
|
3.79
|
22
|
Tonk
|
7194
|
46875
|
5.99
|
6.52
|
23
|
Bundi
|
5550
|
21238
|
2.71
|
3.83
|
24
|
Bhilwara
|
10455
|
72563
|
9.27
|
6.94
|
25
|
Rajsamand
|
3853
|
20435
|
2.61
|
5.30
|
26
|
Udaipur
|
13430
|
42292
|
5.41
|
3.15
|
27
|
Dungarpur
|
3770
|
21278
|
2.72
|
5.64
|
28
|
Banswara
|
5037
|
32468
|
4.15
|
6.45
|
29
|
Chittaurgarh
|
10856
|
55537
|
7.1
|
5.12
|
30
|
Kota
|
5446
|
16316
|
2.09
|
3.00
|
31
|
Baran
|
6955
|
22602
|
2.89
|
3.25
|
32
|
Jhalawar
|
6219
|
15911
|
2.03
|
2.56
|
33
|
Pratapgarh*
|
*
|
*
|
*
|
*
|
Total
|
342269
|
782384
|
100
|
2.29
|
District-wise wetland statistics of Rajasthan in descending order-
Sr. No.
|
District
|
Wetland Area (ha)
|
1
|
Bhilwara
|
72563
|
2
|
Chittaurgarh
|
55537
|
3
|
Jalore
|
54440
|
4
|
Pali
|
50304
|
5
|
Tonk
|
46875
|
6
|
Barmer
|
44638
|
7
|
Udaipur
|
42292
|
8
|
Jaipur
|
41352
|
9
|
Banswara
|
32468
|
10
|
Ajmer
|
32167
|
11
|
Nagaur
|
30876
|
12
|
Jaisalmer
|
24876
|
13
|
Sawai Madhopur
|
22606
|
14
|
Baran
|
22602
|
15
|
Dungarpur
|
21278
|
16
|
Bundi
|
21238
|
17
|
Rajsamand
|
20435
|
18
|
Sirohi
|
19259
|
19
|
Jodhpur
|
17032
|
20
|
Kota
|
16316
|
21
|
Jhalawar
|
15911
|
22
|
Alwar
|
12774
|
23
|
Dausa
|
11720
|
24
|
Bharatpur
|
10415
|
25
|
Karauli
|
10042
|
26
|
Dhaulpur
|
9370
|
27
|
Hanumangarh
|
6549
|
28
|
Sikar
|
5388
|
29
|
Jhunjhunun
|
5319
|
30
|
Bikaner
|
2666
|
31
|
Ganganagar
|
1708
|
32
|
Churu
|
1368
|
33
|
Pratapgarh*
|
*
|
Graphical Representation-
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