JOURNAL OF CRITICAL REVIEWS

ISSN- 2394-5125 VOL 7, ISSUE 18, 2020 GEO-PHYSICAL CHARACTERISTICS OF WETLAND RESOURCES IN DISTRICT,

Banashree Saikia1, D. Sahariah2

Research Scholar and Professor Department of Geography, Gauhati University

E-mail:[email protected]

Received: 14 March 2020 Revised and Accepted: 8 July 2020

ABSTRACT : This study is an attempt to identify the distribution of wetland resources and also investigate their origination, morphology and hydrological characteristics in floodplain region of , Assam. These wetland resources are popularly known as beels and besides swamps and marshes commonly known as doba, hola, jalah, pitoni and doloni among the local people of the district. The wetlands found in the district as various types and sizes cover an area of 9849.40 hectares accounting for 2.48% of the total geographical area of the district. It is identified that 65.63% of total wetlands are riverine origin and 34.37% constitute as waterlogged and man-made type. The fluvio-geomorphic process, soil texture and climatic condition as well as man-made factors have governed the existing wetland pattern in the district.

KEYWORDS: Wetland, Distribution and origin, Morphology, Hydrology

I. INTRODUCTION

Wetlands in geo-physical environment locate mainly interface between truly terrestrial and aquatic surfaces (Mitch and Gosselink, 1993), and saturated with water either permanently or seasonally and therefore, these characteristics instigate to make as a distinct ecosystem in the earth surface (Turner et al., 2000, Schuyt and Brander, 2004). It is important to note that although wetlands constitute 6 percent of the earth surface but it has the ability to produce 24 percent of the primary production (Goldie, 2001). Wetlands are considered as the most productive ecosystems in the world which provide resources and different kinds of services to human society (Khan et al., 2009, Millennium Ecosystem, 2005).

In developing countries significant portion of rural people depend upon the use of wetland resources for sustaining their livelihoods. The ecosystem services play an important role in maintaining the relationship between wetlands and their surrounding communities. In Assam, wetlands are mostly confined to the floodplain areas which are hydrologically connected to the nearby rivers and streams. Within the state, the highest number of wetlands are found in Nagaon district with a total number of 379 (ARSAC Report, 1997) and most of them are located in the agricultural environment. Wetlands play a direct role towards the neighbouring communities by providing food, fuel and fiber to the local inhabitants.

The wetlands of Nagaon district are showing typical physical characteristics in respect of their distributional pattern, morphological characteristics, hydrological characteristics and biodiversity of wetland resources due to diverse physio-climatic setting of the district. The wetlands of the district are endowed with varied shape, size and origin and these are mainly influenced by their topographic regime, diverse fluvial process as well as variation in climatic condition within the district. The riverine landscape of the district is provided favorable condition to formation of numerous wetlands in the district. The wetlands in the district which are resemble with lake like water bodies locally known as beel and on the other hand swamp and marshy areas are termed as doba, hola, jalah, pitoni and doloni etc (Sharma, 1994). It is worth mentioning that the depth of swampy and marshy type of wetland normally shallower than the natural lake like beels. Most of the wetlands in the district are riverine origin and it has maintained a hydrological connectivity with nearby rivers and streams through a narrow channel which is locally known as jan. On the other hand many wetlands have completely lost their connectivity with rivers and turn into close wetland due to perform several developmental activities most commonly by agriculture. These connecting channels of wetland play important role towards maintaining the hydrological dynamism and ecological perspective of wetland resources. The water levels and its flowing pattern of wetlands are showing in dynamic nature (Kulser, et al., 1994) and which is considered as an integral part of wetland ecology.

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ISSN- 2394-5125 VOL 7, ISSUE 18, 2020 This paper is an attempt to study the present status of wetlands in the district in respect of their distributional pattern, shape, size and their origin in geo-physical setting.

II. OBJECTIVES

The main objectives of the study are

1. To study about the distributional pattern of the wetlands and their source of origin. 2. To analyze the morphological and hydrological characteristics of wetlands in the study region.

III. METHODOLOGY

Survey of topographical sheets are used to delineate the distributional pattern of the wetlands within the study area. The number of topographical sheets which are used in preparing base map include 83 B/6, 83 B/7, 83 B/8, 83 B/10, 83 B/11, 83 B/12, 83 B/14,83 B/15, 83 B/16, 83 C/9, 83 C/13,83 F/2, 83F/3, 83 F/4, 83 F/6, 83 G/1, 83 G/2 of the year 1971 on a scale of 1: 50,000. The present study is based on primary data and information which collected through extensive field survey and investigation during 2014 – 2018 to investigate hydrological characteristics of wetlands like wetland depth, fluctuating water levels and inlets- outlets system of wetlands which regulate the wetland flow. Arc GIS 10.2 has been used to carry out database creation and preparing the maps and identify the shape and size of the wetlands in the study region. A well structured questionnaire has been used to acquire the relevant data and information for the study. Interaction with the people of adjacent wetland communities was made to know the present status of the wetland resources.

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ISSN- 2394-5125 VOL 7, ISSUE 18, 2020

Fig: 1

IV. BACKGROUND OF THE STUDY AREA

Nagaon district is situated on the southern bank of the river Brahmaputra along with central most part in the state of Assam. The district is located between 25o41/45// North and 26o41/45// North latitude and 92o23/45// East and 93o20/ 00// East longitudes. It is bounded on the north by , on the east by and Karbi Anglong districts, on the south by Dima Hasao and Karbi Anglong districts and on the west by the . Nagaon district covers an area of 3973 sq. km. which accounts for 5.09% of the total geographical area of Assam (78438 sq. km.). Nagaon district has 10 revenue circles under three sub divisions, viz. Nagaon Sadar, and . The name of revenue circles are Kaliabor, Rupahi, Dhing, Nagaon, Samaguri, Nagaon, Raha, Kampur, Doboka, Hojai and . The district comprises 239 Gaon Panchayat, 18 CD Blocks and 1412 no. of villages.

The river Brahmaputra flows through the northern boundary of the district, therefore the district represents floodplain environment and occurrence flood is a common phenomena during rainy season in northern most part of the district. The south-eastern part of the district represents hilly terrain. Physiographical setting of Nagaon district is very diverse under the influence of geomorphic processes, varying climatic condition and tectonic activity. The diverse physiography of the district is composed of floodplain areas, hilly ranges, low-lying areas

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ISSN- 2394-5125 VOL 7, ISSUE 18, 2020 and foothill region and plain landscape. Nagaon district is endowed with wetland resources of different shapes and sizes under varied physiographic make-up.

As Nagaon district is located in agro climatic zone, therefore the region is under sub- tropical humid climatic belt and it essentially enjoys characteristics of monsoonal climate (Taher and Ahmed, 1998). The district is characterized by excessive humidity, heavy summer rainfall, and cool dry winter. The mean annual rainfall was 141.5 mm and the mean annual temperature was 24.8oC during the period of 2010- 2013. During this period the major portion of rainfall received from May to September and July is considered as the rainiest month of the year by receiving average rainfall as 377 mm. The highest maximum temperature also recorded in month of July which was 33.3 and considered as hottest month of the year.

The river Brahmaputra flows through northern part of the district from east to west direction for a distance of 90 km. The southern tributaries of the river Brahmaputra and its sub streams altogether total number of 75 are drained the district extensively. Kolong, Kapili, Nonoi, Haria, Barapani, are the major rivers of the district and besides these some other small streams also drained the district extensively and all these are responsible to form large number of wetlands in the district which provide wide verities of aquatic floral and faunal species to rich the biodiversity.

Fig: 2

DISTRIBUTIONAL PATTERN OF WETLANDS IN THE STUDY REGION

In Nagaon district, the location and distributional patterns of the wetlands are not uniform throughout the district. Wetlands in the district are mostly confined to the floodplain areas which have hydrological connectivity to nearby rivers and streams. The wetlands of Nagaon district are identified based on the Survey of India toposheet. There are 288 numbers of wetlands identified within the study area which mainly belongs to beels and swamp and marshy type of wetlands. Most of the wetlands are confined in northern and central part of the district. A few wetlands are scattered in the southern part of the district. Wetlands distribution is mainly confined in older and younger alluvium soils in the district. The wetland area in the district covers an area of 9849.40 hectares which accounts for 2.48% of the total geographical area of Nagaon district (397300 ha.).

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ISSN- 2394-5125 VOL 7, ISSUE 18, 2020 Distribution of wetlands give proper interpretation if it is analysed on the basis of existing watershed and other physical parameters like slope, drainage etc.(Sahariah, 2009). Distance of the rivers from the wetlands plays active role in the location and distribution of wetlands. For this purpose several buffer zones has been created from the rivers like , , Borapani river, Sonai river and Nonoi river respectively and these rivers are playing significant role towards the maintaining hydrological cycle of wetlands in the district. Hence, 1,2,3 and 4 km buffers has been created from these rivers and wetlands has been identified within the buffer zones through select by location. Highest number of wetlands is found within 1km buffer zone from the Kolong river (Table 1).

Table 1 : Distribution of wetlands within buffer zones

Number of Wetlands Total nos. Rivers name of 1 Km Buffer 2 Km Buffer 3 Km Buffer 4 Km Buffer wetlands Kolong River 26 22 23 17 88 Kopili River 10 25 10 11 56 Sonai River 11 10 4 2 27 Borapani River 9 10 6 5 30 Nonoi River 1 9 4 7 21

Source : Computed by the researcher

Fig: 3

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ISSN- 2394-5125 VOL 7, ISSUE 18, 2020 From the distribution pattern of wetlands in Nagaon district, it is observed that wetlands area is covered by various types. Wetlands area are mainly dominated by perennial water body(4367.60 hectares), swampy and marshy areas(4311.47 hectares), seasonal or ephemeral water body (693.13 hectares) and muddy areas(477.20 hectares) which constitutes 44.34%, 43.77%, 7.04% and 4.85% of total wetland area respectively.

ORIGIN OF THE WETLANDS

It is noteworthy that as many as 189 numbers of wetlands in the district are originated under fluvio-geomorphic process which account for 65.63% of total wetlands (Table 2). On the other hand, waterlogged and man-made wetlands are constitute 34.37% of total wetland in the district which have neither feeder channel nor inlet-outlet systems are there to maintain their hydrological process and its mainly controlled by surface flow, ground water and precipitation. The man-made wetlands are created mainly for enhance fish production and in this regard Jungal Balahu fish firm is one of the remarkable man-made ponds in the district. It is important to note that the origination of the floodplain wetlands has been governed by several factors, like lithological and geological structure, tectonic activities, channel migration of the river, seasonal variations in water discharge and flow characteristic of the river (Deka, 2011). Most of the wetlands in the study area are originated from river. Feeder channels play important role to connect these wetlands with river. These feeder channels help to regulate the wetland hydrology. Large numbers of wetlands originate from Kolong river, Kopili river, Borapani river, Sonai river, Haria noi, Nonoi river Mara Diphalu noi etc. As like other parts of Brahmaputra floodplain,in Nagaon district the fluvial process is also responsible to form different types of wetlands like ox-bow lake or cut off meanders, swamps and marshes, lake like beel by changing their courses of river channels. It is noteworthy that the wetlands play significant role by maintaining the perspective of geomorphological, biological and socio- economic value in the region.

Table 2: Origin of wetlands

No. of Origin of wetlands wetlands Origin of wetlands No. of wetlands Diphalu Noi 8 Kadam Noi 1 Lateri Noi 2 Khalanga Noi 3 Lutumari Noi 1 Kolong River 19 Nonoi Noi 14 Kopili River 27 Balichara Noi 1 Lali jan 2 Bandarkhal Noi 5 Mailu Noi 1 Batamari Noi 4 Mara Diphalu Noi 18 Borapani River 25 Mara Lateri Noi 6 Bramaputra River 7 Sonai River 14 Diju Noi 1 Tulsi Noi 7 Dimoru Nadi 1 Watelogged/Depressional 99 Haria Noi 19 Man-made 1 Jamuna River 2 Total 288 Source : Computed by the researcher

MORPHOLOGICAL CHARACTERISTICS OF THE WETLANDS

Morphological characteristics of the wetlands include mainly size and shape of the wetlands and these are showing in the study region with diverse and peculiar pattern. Hence, morphological pattern and processes are governed by several factors like fluvio-geomorphic process, lithology, soil texture, feeder channel characteristics as well as human interference to surrounding land use pattern. It is important to note that physical as well as human both the factors are responsible to change the morphological characteristics of wetlands in the district. It is noticed that the wetland area is getting shrinkage in size from the last few decades due to increasing population growth in peripheral wetland areas and their unplanned developmental activities which distorted the morphological characteristics of many wetlands in the district. Hence, this process leads to degeneration and degradation of the wetland and caused a detrimental situation to the sustainability of the wetland environment.

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ISSN- 2394-5125 VOL 7, ISSUE 18, 2020 SIZE The wetlands of Nagaon district are characterized by varied size in morphological characteristics and it is categorized as small size beel (<100 hectare in area), medium size (100-200 hectare in area) and large size beel having area above 200 hectare. Altogether 288 wetlands are found within the study area. The total area covered by the wetlands of the district is about 9849.40 hectares. The size of the wetlands has been ranges from 0.59 hectare as minimum to 334.88 hectares as maximum. Among 288 wetlands, the size of 269 wetlands has less than 100 hectares (93.4%). Of these the size of 12 wetlands are fall within the range of 100-200 hectares (4.16%) and six wetlands have the range of within 200- 300 hectares (2.08%). Only one wetland falls more than 300 hectares (0.5%) (Table 3). Table 3 : Frequency of wetland distribution in terms of area

Area in ha No. of wetlands <50 231 50-100 38 100-150 10 150- 200 2 200-250 4 250-300 2 >300 1

Source : Computed by the researcher

SHAPE

Shape is another important morphological characteristic of wetland studies. The wetlands of Nagaon district are showing different types of shapes like Irregular, discrete, compact, linear and ox-bow type. As many as 89 numbers out of 288 wetlands are compact shaped followed by 73 linear, 50 discrete, 52 irregular and 24 ox-bow shaped wetlands in the district. Ox-bow shaped wetlands are formed due to intense meandering of river channels by cut-off their some parts. The important wetlands of this category are Samaguri beel, Morikolong beel, Era Kopili beel, Morakololong beel, Patoli beel etc which are mainly form by Kolong and Kopili river process. The prominent linear shapes of the beels in the district are Raumari beel, Dighali beel, patari beel, Puthimari beel, Katimari beel, Kuji beel, Dighali beel and Phakali beel etc. The compact shapes of the beels include Amtala beel, Balichara beel, Jayasagar beel, Bogidoba beel, Hahila beel, and Garalmari beel, etc. The prominent irregular shape of the beels include mainly Banbara beel, Kachupit beel, Nalani doba,Barphakali beel etc. The Haribhanga beel, Lathimari beel, Juria beel, Achila beel and Tindighali beel are fall in discrete pattern of shape in the study region. HYDROLOGICAL CHARACTERISTICS OF THE WETLANDS

Wetland hydrology is often used to describe in terms of its hydro period, the pattern of fluctuating water levels, ground water conditions, and regulation of water flow (Mitsch and Gosselink, 1986). Precipitation, surface and ground water are regarded as a prominent source for hydrological flow into the wetlands. Generally wetlands are connected by rivers through some narrow channels which are called as feeder channels. These connecting channels are important for the ecological health of wetlands as because they help wetlands to perform their normal ecological functions efficiently by maintaining their natural water flow. Theses connecting channels are very much significant as they facilitate a number of activities, such as exchange of water flow and sediment fluxes, seasonal replacement of fish stock, flushing out the pollutants from water and rescue them from high turbidity and the process of eutrophication. They act as a medium for smooth running of the incoming and outgoing flood waters which ultimately regulate flood control in the concerned areas. It is however important to note that there have been seen a seasonal variation of water level in some of the selected wetlands in the district viz. Samaguri beel, Haribhanga beel, Hahila beel, Kachupit beel and Banbara beel. It is because of the fact that due to heavy rainfall in monsoon season, the wetland areas get inundated and the adjoining areas are filled - up with water. On the contrary, during post- monsoon season the water level goes down and the wetland areas gradually dried up and ultimately they converted to grazing lands. Therefore, there is a variation in the depth of water level in summer and winter respectively. It has been observed that during summer season the level of water goes up relatively high in Samaguri beel (30.5 feet) , followed by Haribhanga beel (15.5 feet) and Hahila beel of 14.5 feet. The very low level of water has been seen in Kachupit beel (1.5feet) during winter season. Human activities, particularly irrigated agriculture and the construction of man- made ponds instigate water diversions from wetland on one hand and siltation on the wetland on the other hand are important factor responsible for decrease the depth of the wetland. The shape of the wetland also considered as an influencing factor for having depth in the wetland areas. Generally we found that compact shaped beels are

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ISSN- 2394-5125 VOL 7, ISSUE 18, 2020 shallower than the oxbow-shaped beels (Sharma, 1993). Besides, the inlet-outlet systems of wetland play an important role to maintain the water flow in wetland hydrology.

V. CONCLUSION

The foregoing discussion reveals the scenario of distributional pattern, evolution of wetlands in general manner and also highlights their geo-physical characteristics in floodplain region of Assam. The wetlands of the district are endowed with varied shape, size and origin and these are mainly influenced by their topographic regime, diverse fluvial process as well as variation in climatic condition within the district. It is worth mentioning that the wetlands in the district mainly confined in northern floodplain areas which have hydrological connectivity with nearby rivers though their inlet-outlet system. These inlet-outlet systems play important role to maintain their water level and wetland depth. The wetlands in the district are getting shrinkage in their size from the last few decades due to increasing population growth in peripheral wetland areas and their unplanned developmental activities like construction of road, culvert, conversion to man-made pond, industrial as well as agricultural activities which distorted the morphological characteristics of many wetlands in the district and also impact upon their hydrological characteristics.

VI. REFERENCES

[1] ARSAC (1997): A Report on Wetlands of Assam : Assam Remote Sensing Application Centre, , Assam, India. [2] Deka, D.R. (2011): Geo-ecological Status and Economic Potentials of Wetlands in Dimoria Region of Assam, India, unpublished Ph.D Thesis, Gauhati University, Guwahai. [3] Goldie, A. (2001): The Nature of the Environment, Blackwell Publisher, Oxford. [4] Khan, S., Hafeez, M., Abbas, A., and Ahmed, A (2009): Spatial Assessment of Water Use in an Environmentally Sensitive Wetland, Ambio, Vol. 38(3), Pp. 157-165. [5] Kulser, J.A., Mitsch, W.J. and Larson, J.S. (1994): Wetlands, Sci Amer, Pp 64-70. [6] Mitsch,W.J and Gosselink, J.G. (1993): Wetlands, Second Edition, John Wiley, New York. [7] Mitsch,W.J. and Gosselink,G.J.(1986): Wetlands, Van Nostrand Reinhold Company, Pp 56 [8] Sahariah, D. (2009): Wetlands of the Brahmaputra Floodplain in , Assam : A Fluvio - Geomorphic Study, Unpublished Ph.d thesis Gauhati University, Guwahati. [9] Schuyt, K. and Brander, L. (2004): The Economic Values of the World’s Wetlands, Swiss Agency for the Environment, Forest and Landscape (SAEFL), Amsterdam. [10] Sharma, P. (1994) : Ph.D Thesis, “Geo Ecological study of Beels and swamps in Nagaon and Marigaon District, Assam, unpublished Ph.D Thesis, Gauhati University, Guwahai. [11] Taher, M. and Ahmed, P. (1998): Geography of North-East India, Mani Manik prakash, Guwahati. [12] Turner, R.K., Van den Bergh, J.C.J.M., Söderqvist, T., Barendregt, A., Van der Straaten, J, Maltby, E. and Van Ierland, E.C. (2000): Ecological-Economic Analysis of Wetlands: Scientific Integration for Management and Policy, Ecoloical Economics, vol 35, Pp7–23.

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