1.1 ECOLOGICAL STUDY OF RIVERINE FLOODPLAIN
1.1.3 Ecological study of riverine floodplain all over the world
Assessment of ecological status and biodiversity of riverine floodplains have been a very hot topic since the last century. Important resolutions have been taken worldwide aimed at the protection and preservation of the ecosystems and biodiversities of river basins (Gómez-Pompa et al., 2004; Kearns et al., 2010; Ramsar Convention Secretariat, 2010). Environmental issues were given prominence at the United Nations Conference on Environment and Development (UNCED) held in Rio in 1992 and a number of targets relating specifically to biodiversity and ecosystem protection were incorporated into the Convention on Biological Diversity (CBD). A detailed discussion was
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documented in the freshwater Chapter 18 of Agenda 21, which devotes a Programme Area to the Protection of Water Resources, Water Quality and Aquatic Ecosystems. In 1998, the World Water Council had set up a commission to produce a ‘Vision’ for the world’s water, towards the end of a decade that had seen rapid growth in awareness of freshwater resources management as a global environmental issue. The primary contribution on environmental aspects was the World Vision for Water and Nature (IUCN, 2000), based on the understanding that the protection of ecosystems, that must remain central to sustainable development because “environmental security, social well-being and economic security” are intricately intertwined and fundamentally interdependent.
In this context, principles of transboundary co – operation within river basins were laid down in a convention under international law, the 1992 UNECE Convention on the Protection and Use of Transboundary Watercourses and International Lakes (Water Convention). The Convention aims to achieve a good status for waters and related ecosystems, taking into account the specificity of river basins. This assessment includes 140 transboundary rivers (most of them with a basin area over 1,000 km2) and 30 transboundary lakes in the European and Asian parts of the UNECE region, as well as 70 transboundary aquifers in South-Eastern Europe, the Caucasus and Central Asia (UNEC, Report). Some of the acclaimed ecological assessments of rivers worldwide is discussed below:
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1.1.3.1 Asian countries
In Asia, a holistic approach has been seen towards the ecological status of some of the major rivers. The Environment (Protection) Act enacted in 1986, last amended in 1991 with the objective of providing for the protection and improvement of the environment include 12 environmental problems of which one is the “loss of ecology.” In India, Brahmaputra Board Act, 1980 deals with planning implementation of measures for the control of flood and bank erosion in Brahmaputra Valley. While in other parts of India ecological assessment and restoration activities in lakes and rivers are widely surveyed.
In North Eastern India, ecological assessment in terms of faunal biodiversity has been procured in Kameng, Subansiri, Dikrong, Pachin, lranga, Siang, Dibang, Lohit, Noadhing, Buridhing and Tirap (Nath, 2000). There is a huge record on biological and physicochemical monitoring of Brahmaputra River and its adjoining tributaries (Girija, 2007; Das et al. 2012; Baruah, 2013; Kalita 2013). Ecological status of Yamuna River, Kali River and some stretches of Ganga River has been evaluated. Other rivers include Periyar River, Cauvery River and several small water bodies in Bhopal (Gupta et al., 2006). Restoration of Lake Anasagar was reported in Rajasthan, restoration measures included forests, soil, watersheds, green infrastructure and vegetation with sand dunes (Pandey, 2013). Bahukhandi et al (2013) reported development of a building-block methodology assisted knowledge-based system for e-flow assessment and management for Suswa River of Dehradun district. Backwaters of South west coast of India cover a total area of 46128.94 ha, most of the region is under agricultural and urbanization stress, current status and modification of biodiversity have been monitored by researchers (Nandan, 2008). Ecologists have evaluated the environmental impact
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assessment of the national large solar telescope project and its ecological impact on Pangong Lake in Merak area (CES, IISC, 2011). Zutshi et al (1980) broadly evaluated the limnological status of Surinsar Lake, Mansar Lake, Manasbal Lake, Nilnag Lake, Trigam Lake, Alipather Lake, Anchar Lake and Naranbagh Lake in Jammu and Kashmir.
Diversion and containment of rivers is a centuries-old tradition and had challenged the ecological integrity of river systems. The Kauvery Delta canals in India (2nd century A.D.); Ifugao rice terraces of the Philippines (the 4000 year-old); Barrai irrigation dam in Burma (10th century A.D); the Dujiangyan irrigation system (250 B.C.), the Linqu Canal (214 B.C.) and the Grand Canal (6th century A.D.) are some the examples of man-made structures contributing to ecological stress in some major rivers of Asian domain. The Yellow River and the Mekong River Basin have been extensively studied (Yang et al., 2007, Mekong River Commission, 2003). Kummu and researchers (2014) studied water balance analysis for the Tonle Sap Lake floodplain system as an essential component of ecological assessment in Cambodia. Dudgeon (1992) described the pollution status of some of the large rivers in Asia as Chenab, Indus, Luni, Narmada, Brahmaputra, Ganges, Mahanadi, Godavari, Krishna, Cauvery, Yangtze (Chang Jiang), Salween, Mekong, Irrawaddy, Chao Phraya, Mae Nam Yom, Red River, Pearl River, DongtingLake (Yangtze River), Poyang Lake (Yangtze River), MinJiang; Perok, Tulangbawang, Cimanuk, Mas or Surabaya, Fly and Sepik. The pollution intensities in the rivers were correlated to ecological entities inhabiting the river waters.
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1.1.3.2 European countries
Around 162 streams in Europe were sampled in the year 2003-2004 under European funded projects after the implementation of the Water Framework Directive. The ecological status of Mediterranean Rivers (Vicenete et al., 2004), Alcantara River (Gugliandolo et al, 2009), Meuse River (Looy, 2008) and Danube River (Fischer-Antze et al, 2004) has been monitored. Lake Myvatn and the outflowing River Laxá has been ecologically examined based on spatial and temporal variations (Einarsson et al., 2004).
Long term changes in the ecological structure of Lake Myvat, basically eutrophication status and abundance of littoral planktons and invertebrates have been studied by Gardarsson et al (1988). Gerbersdorf et al (2011) provided a detailed report on the ecotoxicological aspects of Danube River, where he highlighted the state-of-the-art methods within the disciplines of concern related to contaminated sediments, ranging from ecotoxicological test systems, microbiological/molecular approaches to unravel changes of microbial ecosystems, up to the modelling of sediment transport and sorption/desorption of associated pollutants known as the “triad plus x” approach.
Ecological importance and anthropogenic change of subaquatic springs in ancient Lake Ohrid has been assessed in Macedonia (Jordanoska et al., 2013). Kachvoryan et al (2008) studied the biodiversity of zoobenthos in riverine ecosystems of Lake Sevan Basin’s Rivers in Armenia. Biomonitoring of large European rivers for invertebrate biodiversity and related environmental impacts were also studied in details (van Dijk et al., 2003). In this perspective, it was observed that Wye river (U.K.), the Upper Loire, the Aube and the Ardeche rivers (all three in France) and the Upper part of the Duero basin (Spain) represented almost natural rivers, whereas the Vistula river and the Warta
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river (Poland), and the Elbe river (before 1992, Germany) represented heavily impacted rivers in terms of water quality parameters.
1.1.3.3 Australian countries
The Murray-Darling River system drains over 1000000 km2, approximately one seventh of the Australian continent (Douglas, 1995). In Murray-Darling Basin (Gehrke et al., 2003), studies on the floodplains of the Alligator Rivers and the continuous wetland system associated with the Mary River and Adelaide River floodplains have been reported (Department of Natural Resources, Environment, Australia, 2007).
Kingsford et al (2004) found that Lowbidgee floodplain is the Murrumbidgee River’s major wetland in south eastern Australia in relation to destruction of wetlands and waterbird populations by dams and irrigation. Reformation of management criteria based on environmental flows associated with the hydrology, geomorphology and ecology for smooth ecosystem function was observed in Lachlan River, New South Wales (Hillman et al., 2010). Biodiversity and ecological assessment was evaluated specially on abundance and pattern of distribution of fish species in Warrego River in the Murray Darling Basin by Balcombe et al., (2006). Fish biodiversity was also reported in Cooper Creek, an arid-zone floodplain river (Arthington, 2001). Paroo River also witnessed similar fish biodiversity assessment in the in the Murray-Darling River Basin (Gehrke, 1995).
1.1.3.4 African countries
In African countries, the Nature Conservation Research Division is associated with the conservation of South African Rivers. Rivers were seen primarily as ecosystem
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components that upholds a set of larger values. Ecological assessment of rivers as Orange River, Zambezi River, Palala River, Buffalo River, etc. was one of the initiatives taken towards conservation riverine ecosystems. In Calabar River, ecological impact assessment and limnological characterization in the intertidal region was emphasized (Andem, 2013). Everard et al (2002a, 2002b) studied the biodiversity of and flowed ecological management activities towards sustainable development of Lake Naivasha, Ramsar site in Nigeria. Odadaa et al (2002) studied the environmental assessment of the East African Rift Valley Lakes. Species richness of fishes in different habitat and hydrologic variables were studied in Nile (flowing into the Mediterranean waters) Senegal, Gambia, Tomine, Konkour, Kolente, Jong, Sewa, Moa, Manu, Loffa, St. Paul, Nipoue, Cavally, Dodo, Nero, San Pedro, Sassandra, Boubo, Bandama, Agnebe, Me, Comoe, Bia, Volta, Mono, Oueme, Ogun, Niger, Cross, Mungo, Wouri, Sanaga, Nyong, Lobe, Ntem, Ogowe, Niari and Zaire (Hugueny, 1989)
1.1.3.5 American countries
The most thoroughly studied rivers in American territories are the Mississippi and the Amazon Rivers. Sedimentation is the most critical ecological problems of the Upper Mississippi River System (UMRS). Lateral flooding in Orinoco River and its geological features have been reported in Venezuela. Scientists have evaluated the physical status of the river to identify its impact on the floodplain ecosystems (Hamilton et al., 1990). The Great Lakes in America namely, Lake Ontario, Lake Superior, Lake Huron, Lake Michigan and Lake Erie forms one of the largest groups of fresh water ecosystem in the world. Biodiversity and ecosystem of the Great Lakes have extensively reported. Kline et al (1985) focussed on the impact of pollution on
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fresh water organisms in relation to toxicity of wide range of pollutants on the vertebrates and invertebrates. Ecosystem restoration studies have been observed in the floodplain ecosystem under potential impacts of damming of Rio Grande River in Mexico (Molles, 1998). Benke (1990) considered Yellowstone River as an exception for hydropower generation in terms of water quality. Graf (2006) discussed the downstream hydrologic and geomorphic effects of large dams on American rivers at a continental scale, outlining the general physical changes that play an important role in the riparian ecosystems and ultimately disturb the wildlife populations. According to Dawdy (1991), researchers have been studying the impacts of dam functioning on hydrological regime and ecological aspects of Colorado River. Similar studies were concentrated on Connecticut River watershed (Magilligan et al., 2001). Ecological implications were broadly studied in some of the dam affected river as Hudson River in New York; Platte River in Nebraska; Lower Missouri River in Missouri, Kansas, Nebraska, and Iowa; Upper Missouri River in Nebraska, South Dakota, North Dakota, and Montana; Gila River in New Mexico and Arizona; Yakima River in Washington and Willamette River in Oregon (Benke, 1990).
1.1.3.6 The Arctic and the Antarctic circles
The Arctic and Antarctic Circle remains frozen for most part of the year, however, some lakes as Char Lake, Toolik Lake, Anguissaq Lake, Burton Lake, etc. were studied (Vincent et al., 2008). Management of terrestrial ecosystems in Arctic Tundra has been considered as a necessity to conserve vegetation as a thermal barrier to permafrost melt and prevent loss of wildlife habitats (Bliss, 1973). Yenisey, Lena, Ob’, Mackenzie and
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Yukon are a few Atlantic rivers evaluated for nutrient status more specifically the organic carbon pool in the river ecosystems (Raymond, 2007).
Borja et al (2007) worked on the benthic ecological status assessment in the North Atlantic ecoregion. Williams (1996) provided a detailed report on the Antarctic microbial diversity, the basis of polar ecosystem processes and role of microorganisms in degradation of organic substrates in ice covered regions. Fish biodiversity as an ecological indicator was studied in Northeast Cape Fear River, Lumber River and Neuse Rivers in the Atlantic region (Kwak, 2006).