1.2 Ecological study of Brahmaputra River floodplain
1.2.2 Kamrup: Amingaon and Umananda River Island
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taken a better form in the recent decades. Paddy cultivation is main agricultural practice in Majuli. Wetlands provide a good platform fulfilling the water and nutrient requirement for paddy cultivation. Other crops cultivated in Majuli are mustard potato, lentil, cowpea, vegetable crops and a few cereals. The inclusion of crop management activities has left an influential effect on the microbial communities in the soil.
However the application of weedicides and pesticides has been reported as minimal when surveyed among the local inhabitants. In addition to it literature review on use of weedicides and pesticides showed passive results (ICAR Proceedings, 2011).
The areas cultivated for crops are mostly active floodplains, old floodplains and channel fills (NBSS and LUP, 2006 and Bhaskar et al., 2013). These flood inundated land forms are characterized by deposition of sediments differentiated into silt and fine sand with mineral composition like tourmaline, rutile, zircon, epidote, kyanite, silimanite, staurolite, micas (biotite and chlorite), hornblende, zoisite and opaque minerals and clay content containing mineral as illite, kaolinite and chlorite (Singh, 2011). Deposition of flood driven sediments and its role in cropping activities can be directly correlated to the microbial abundance in the soil (Unger et al., 2009).
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guards the southern part of Kamrup district. Darrang and Kamrup (Metro) shares the eastern border and Goalpara and Nalbari shares the western boundary of Kamrup district. Brahmaputra River floodplain in Kamrup is characterized by hilly terrain inundated with alluvial soils known as inselbergs comprising of mostly precambric gneissic rocks. Scattered hillocks with discontinuous plains are observed in the outskirt region extending upto Shillong Plateau on the southern boundary.
Topography of the region is a combination of hilly undulating landscape as well plain landmass. Meghalaya on the southern part is a continuation of the patchy hilly terrain dispersed by a few plain landscapes that gradually converge into a flat terrain towards Brahmaputra River in Kamrup. The hilly terrain bears small hills to residual hillocks. The steepness deceases towards the plains with a land slop less than 10 mkm-1 areas and land slop is from 300-600 mkm-1 in the hilly areas.
Some important rivers in Kamrup district are Brahmaputra and its smaller tributaries like Puthimari, Bornoi, Nona, Kulshi, Pagladia and Kalajal. Flooding is popular in low lying areas during May to August every year whereas late floods occasionally occur in later part of the year in September and October. Inflow of flood waters is contributed by Brahmaputra River and its adjoining tributaries in Kamrup.
Soil varies in places depending upon topography, bedrock composition and sediment transport activities by the rivers. Main soil type of the district contrasts from sandy loam, loam, sandy clay and clay loam. The overall organic carbon and nitrogen contents are reportedly high due to the downstream river driven alluvium. The plains contain comparatively higher pH values than hills. (State Level Nodal Agency, IWMP, Guwahati, 2014).
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Average annual rainfall in the area is about 1738 mm since the last ten years.
Metrological data indicates approximately 90% of rainfall occur between April and September with maximum occurrence in June, July and August. The driest month of the year is January with an average rainfall of 5.46 mm since last ten years. The highest temperature is recorded at 33°C in the month of July and August and lowest temperature at 10.82°C in the month of January. Climate is hot humid in summer with maximum relative humidity of 90%. High humidity is experienced in the month of January. Kamrup district is under High Risk Zone-V of earthquakes incidents, where a maximum intensity of IX can be expected. Occurrence of flood events leads to bankline erosion by the Brahmaputra river (Guwahati City Disaster Management & Response Plan 2014).
Amingaon is located on the mainland near the bank of Brahmaputra River in the north of Guwahati and Umananda River Island or Peacock Island is located on the north east of Guwahati separated by the Brahmaputra River. Amingaon and Umananda River Island are two economically important sites in Kamrup experiencing a tropical wet monsoon climate, at an altitude of 31-55 m above mean sea level, predominantly depending on the terrain. Amingaon is an industrial area lying between 26°11′0.5″N latitude and 91°40′1.2″E longitude. A few of the industries located in Amingaon are vanaspati plant, a mini steel plant, tea dry port, tea godown, ware house, pharma manufacturing units, cosmetic manufacturing and bottling plant, bamboo processing and manufacturing unit, pvc plastic manufacturing unit etc. Umananda is a highly visited tourism and pilgrimage site located between 26°11′47.76″N latitude and 91°44′43.44″E longitude. Umananda River Island is home to the endemic species,
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Golden langur (Trachypithecus geei). Geomorphological features are characterized by flood driven fertile alluvium. Major floods are inconspicuous, however flash floods are frequently witnessed during the monsoon downpour.
1.2.2.1. Status of work done in Kamrup
Research in Kamrup is focussed on biodiversity, water and soil health. A huge survey on ethnobotanical properties plant species have been carried out in different regions of Kamrup (Sharma et al., 2012; Barua et al., 1989; Gogoi et al,. 2013; Rao et al., 1979;
Choudhury et al., 2011; Sharma et al,. 2010; Das et al., 2013). Among the faunal population, a total of 62 ornamental fish species belonging to 41 genera, 18 families and 7 orders have been estimated (Kalita et al., 2013). In Silsakho wetland, Baruah and others (2013) reported 24 species of ornamental fish species. Among these, 18 have been classified as ornamental fish and others 6 were non-classified as ornamental fishes. Turtles as Pangshura sylhetensis, Chitra indica and Nilssonia nigricans, considered as some of the endangered species of turtles in the world, were reported in the islands (chars) of Brahmaputra River. Awareness camps were successfully organized to spread the message of saving turtles through education programmes, highlighting necessary conservation aspects. In – situ turtle egg conservation strategies and methods were also discussed by most of the scientists (Baruah et al., 2010).
Deka et al (2011) studied the landuse pattern in Muktapur village in Kamrup and found that agricultural practices are the major landuse undertakings. The team described a representative agro-ecological framework of Brahmaputra valley. Winter rice, autumn rice, ahu rice and bau rice were cultivated in the lowlands that meet the water requirements. Kharif crops and rabi crops are two seasonal cropping patterns that
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include rice as the main cereal and vegetables as key crops. Cropping pattern in Kamrup gave an overview of the agricultural activities flourishing in the alluvial floodplain of Brahmaputra River in its lower stretch.
1.2.2.2 Influence of urbanization and landuse activities
Kamrup has a forest area of approximately 1,16,694 ha. Amchang Wildlife Sanctuary and Deepor Beel Wildlife Sanctuary are examples of forest covered ecologically sensitive zones in Kamrup. Rapid urbanization and extensive land use activities have rendered the animals homeless, an excellent example of man animal conflict is the notorious activities of elephants and monkeys in Deepor beel wetland areas in the northern part of Kamrup. Human settlements have destroyed natural habitats of most of the wild animals living in that region. Numerous species of indigenous fishes, amphibians, birds and aquatic animals have undergone threat to extinct as an outcome of massive environmental pollution events. Devi et al (2008) highlighted one such event in Jalukbari, Kamrup where the incidences of homeless monkeys counteracting human activities have been troublesome since a long period of time.
Ecological assessment in Kamrup has been previously studied as evaluation of physicochemical and geochemical parameters of water and soil samples at several places along the floodplains of Brahmaputra River. Soil properties and the consequences of Jhum cultivation in Amingaon watershed, has been broadly discussed by researchers (Shougrakpam et al., 2012). They demonstrated that soil macroporosity have a wide range of applications in the region, some of them are water quality monitoring and groundwater pollution assessment due to preferential leaching of solutes and pesticides. In their research findings, they found low soil macroporosity in
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areas of previously practised Jhum cultivation, such areas showed disconnected subsoil macropores, not desirable for proper water infiltration in soils, possibly indicate occurrence of flash floods in the long run. In contrast, undisturbed forest areas showed high soil macroporosity. Chakrabarty and others (2011) discussed about fluoride geochemistry of groundwater in Kamrup. Metals like Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn were reported in the urban soils of Guwahati City (Mahanta et al., 2011). It was observed that metals concentrated in the urban pockets of Kamrup district where commercial activities and population density were high. Metal accumulation can be linked maximum human intervention in the market areas of Guwahati city in Kamrup.
Deka et al (2011) studied the impact of oil spillage on soil metal accumualtion in the popular Noonmati refinery. Zn, Pb, Fe and Mn were highly concentrated in the soils of industrial, commercial and residential areas. Cd, Zn, and Pb primarily enriched in areas of a 3 year old abandoned dumpsite of municipal solid waste MSW in Guwahati (Choudhury et al. 2013).
Socioeconomic studies have also been popularized in Kamrup. Das et al (2003) briefly recounted the educational pattern explaining the trend of privatization of tutorial classes, especially mathematics. There are several ground level studies on wild life conservation in Amchang Wild Life Sanctuary and Deepor Beel Wildlife Sanctuary that has been conducted by students for attainment of institute degrees and have not been communicated. The proper bridging of knowledge through scientific techniques would generate the information in a better way for implementation in decision making processes and baseline development.