School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
India has a large network of river systems of which three major rivers - Indus, Ganga and Brahmaputra - which originate in the Himalaya, drain nearly two-thirds of the land area and account for nearly the same proportion of the countrys total water resources. They form extensive floodplains and deltas. At least a part of their basins lies in neighbouring countries (China, Nepal, Pakistan and Bangladesh). The three river basins are also among the most densely populated regions of the world where human activities have influenced the landscape for several millennia. During the past five decades, rivers have become rapidly degraded. They are extensively regulated for water diversion, flood control and hydropower by a series of dams, barrages and embankments. Discharge of domestic and industrial effluents, besides numerous activities in the catchments, floodplains and within the river channels have rendered the water unfit for human use. The biodiversity in general and fisheries in particular have declined very sharply. The Water (Prevention and Control) Act adopted in 1974 to regulate discharge of industrial and other effluents in surface waters and the Ganga Action Plan started in 1985 to provide for treatment of domestic sewage in major cities along the River Ganga have aimed at improving water quality. The National River Conservation Directorate under the Ministry of Environment and Forests, has until now focussed mainly on the treatment of domestic sewage and industrial effluents, ignoring the importance of environmental flows and habitat diversity (including floodplain) to the conservation and management of river water quality as well as biodiversity, particularly fisheries on which millions of people depend for their livelihoods. The need for improving river flows and habitat restoration has now been recognised and plans are being formulated to initiate action in the Yamuna River basin starting from the uppermost parts of the watershed. While dams and barrages will continue to be in place and the embankments cannot be removed, it is proposed to focus on the restoration of floodplain areas between the two embankments and in unregulated stretches. This paper presents the conceptual framework for the proposed floodplain restoration program.
Rivers play a major role in the economy of a country by sustaining agriculture, industry, energy generation and providing biological resources. However, humans have grossly abused the rivers worldwide by extensive regulation of flows, habitat alteration and disposal of all kinds of wastes into them. The impacts of these activities are already appearing in declining fisheries, increasing incidence of floods, lowered groundwater tables and growing incidence of water-borne diseases. Conservation and restoration of rivers have become vital for the overall sustainable development of a region.
The Indian mainland is drained by 15 major (drainage basin >20 000 km2), 45 medium (2 000 to 20 000 km2) and over 120 minor (<2 000 km2) rivers, besides numerous ephemeral streams in the western arid region (Rao 1975). These river systems are grouped, according to their origin, into Himalayan and Peninsular rivers. Rivers Indus, Ganga and Brahmaputra are three major rivers, which together with their many tributaries, originate in the Himalaya. Their basins cover nearly two-thirds of the Indian subcontinent and are shared by different neighbouring countries (China, India, Nepal, Pakistan, Bangladesh). Rivers Ganga and Brahmaputra form extensive floodplains and a delta that ranks among the largest in the world. The three river basins are also among the most densely populated regions of the world where human activities have influenced the landscape for several millennia.
These rivers have played a major role in shaping the history of human civilzation in the subcontinent. The early agrarian civilizations of Harappa and Mohenjodaro, which flourished in the Indus river basin, were dependent upon intensive irrigation that required diversion of river water through an extensive system of canals. Human settlements on the banks of River Ganga and its tributaries have continued to exist for more than 5000 years. The rivers were extensively used for irrigation, drinking water, recreation, fishing and transport. Interestingly, the rivers were revered as mothers and worshipped as goddesses.
RIVER DEGRADATION IN INDIA
Until recently India remained a primarily agricultural economy with more than 85 percent of the human population living in villages and dependent upon agri-pastoral activities. The climate of the Indian subcontinent is governed primarily by the monsoons which are described as "one of the most dramatic of all weather events, tantalizingly complex, rich in variations from place to place and year to year, day to day and difficult to predict" (Fein and Stephens 1987). It is further influenced greatly by the unique geomorphological features of the region that includes the worlds highest mountain ranges, to produce extremely large spatial and temporal variability in the total annual precipitation. The high variability of unpredictable precipitation necessitated the construction of reservoirs (irrigation tanks) for storing surface runoff and diversion of river water through canals for irrigation since prehistoric times (see Gopal 2000). The water of R. Yamuna was diverted as early as the 13th century and major canals were constructed on Rivers Ganga and Yamuna between 1789 and 1868 to divert their flow soon after their descent onto the plain.
Since independence, the country has witnessed rapid, unplanned urbanization and industrialization and intensification of agriculture. The "green revolution" was achieved with the help of high yielding varieties, intensive application of agrochemicals and irrigation. The natural environment has been the victim of this economic development. Deforestation has reduced the forest cover from more than 23 percent before independence to a present 13 percent; land degradation and soil erosion have increased and both air and water are severely polluted particularly near major urban and industrial centres. The all-round environmental degradation has obviously affected the rivers, which have been over-exploited and even abused for development.
During the past fifty years, river regulation has proceeded at a faster rate. Besides barrages for diverting water; thousands of multipurpose reservoirs have been created by building high dams for water supply, irrigation, hydropower and fisheries. Large stretches of rivers, particularly those passing through the urban areas, have been modified for flood control and urban development on reclaimed land through channelization, the construction of embankments and filling up the floodplain. Besides reservoirs, water harvesting throughout the catchment areas by constructing smaller check dams or tanks for collecting the runoff has also affected flows in the streams and rivers downstream.
Urban and industrial growth has made a major impact on the river water quality through the discharge of untreated domestic sewage and industrial effluents. The impacts have been aggravated by greatly reduced flows and channelization of the rivers. In several stretches, many rivers have virtually turned into sewers. Human settlements, deforestation, mining, quarrying, grazing and other activities right up to the headwaters have extensively degraded the catchments and increased sediment loads of all the rivers (CPCB 1996). The increasing use of fertilizers and pesticides in agriculture has further contributed to the degradation of water quality. Consequently, the river biota have also been seriously affected. Riverine fisheries have declined considerably and many species have nearly disappeared.
Conservation and management of rivers started receiving some attention only during the 1970s. Considerable emphasis has been laid on the improvement of water quality through interception, diversion and treatment of domestic sewage and industrial effluents. However, water quality continues to deteriorate further largely due to the reduction or total absence of flow and increasing degradation of the watershed. Gopal (2000) discussed earlier the issues, policies and actions required for the conservation and management of rivers.
In this paper, I focus on the state of degradation of River Ganga and its largest tributary River Yamuna and present a conceptual framework of efforts that have recently been initiated to rehabilitate the watershed in the upper reaches and to restore the floodplain. There is considerable published information on the Ganga river system (Anonymous 1980, 1982, 1983; Gopal and Sah 1993; Gopal 2000), a brief overview of which is given below as a background to the proposed restoration.
R. Ganga - the longest river (2 525 km) in India arises from the Gangotri glacier (3 129 masl) in the Himalaya within India, flows southwest before descending in the plains at Rishikesh (350 masl). It then flows south and turns eastward meandering its way through the plain up to Farakka where it turns south and divides into two main channels one of which, the Padma River, flows through Bangladesh and meets R. Brahmaputra. It finally joins R. Meghna in Bangladesh in its last stretch just before forming the extensive delta (Figure 1). River Yamuna, the largest tributary (1 376 km long) of Ganga, also arises in the Himalaya from the Yamunotri glacier (6 320 masl) and flows almost parallel to R. Ganga until its confluence with the latter at Allahabad. The Yamuna River itself is joined by another major tributary R. Chambal, which drains a large area lying on the south and west of R. Yamuna and brings more water than the R. Yamuna at their confluence. The total discharge of R. Yamuna at Allahabad also exceeds that of R. Ganga. Several tributaries of Ganga originate in Nepal (Sharma 1997) and contribute over 40 percent of the annual flow of R. Ganga at Farakka (Khan 1994). A few tributaries that arise in Nepal meet R. Ganga inside Bangladesh, whereas others arising from the hills east of Vindhyan ranges, join from the right in its lower reaches.
Figure 1. The Ganga River system
The R. Ganga and its major tributaries are perennial but exhibit very large seasonal variation in their discharge. The rivers arising in the Himalayas receive snowmelt during the dry summer period, which is followed by the southwest monsoon. The north-flowing tributaries that arise in central India, also receive some runoff during the winter. A manifold increase in the river discharge during the rainy season and an extremely low gradient along most of the river course (10 cm km-1 in the middle reaches and less than 5 cm km-1 in the lower reaches) results in an extensive floodplain that extends to tens of kilometres on either side of the main channel.
Meandering and braiding are common to all floodplain rivers but the Ganga river system is characterized by shifting of river channels over long distances due to the high sediment load and an abrupt break in the slope. For example, R. Son has shifted back and forth during the past few centuries whereas R. Kosi flowing through the plains of north Bihar has moved about 120 km westwards during the past 220 years (Wells and Dorr 1987). Flow regulation has only contributed to greater shifting of river channels.
Notwithstanding the reverence, River Ganga and its tributaries have been the greatest victims of human onslaught. It is one of the most regulated river systems with dams and barrages on practically every tributary and extensive embankments throughout the river basin (see Agrawal and Chak 1991). For example, the small gradient of 36 m on River Ganga between Hardwar and Aligarh (about 200 km) has been exploited for 13 small hydroelectric projects. Recently, a dam has been completed in the hills at Tehri on its major tributary, R. Bhagirathi, to exploit its hydroelectric potential despite the fact that the area lies in a seismic belt. River Yamuna has a series of barrages for hydropower in a 50 km stretch shortly before the water is nearly completely diverted for irrigation at Tajewala.
Excessive water extraction, dams and embankments have rendered the rivers nearly dry in several stretches. The floodplains have been eliminated or greatly reduced and the river channels water carrying capacity has decreased further due to accumulation of silt that is neither carried downstream nor spread on the floodplain. Further and by far the greatest problem for rivers is caused by the discharge of untreated, or at best partly treated, domestic and industrial effluents. The problem of pollution is further increased by the disposal of solid wastes, religious offerings, idols, dead bodies and caracasses and other in-stream activities. Many studies on water quality, biota, bioindicators of pollution, assessment of heavy metal pollution and microbiology undertaken on River Ganga during 1983-1989 (Krishnamurthy 1991) revealed increasing levels of pollution in the plains. Though the Himalayan stretch had relatively unpolluted water, the middle stretch at Kanpur is heavily polluted with heavy metals from industrial effluents. Biological studies show that the species composition and the total population of various organisms along the river course have changed considerably. Chakraborty and Chattopadhyay (1989) have reported a shift in the species composition and an increase in abundance of the planktonic community in the estuarine section of R. Ganga (known as the R. Hoogly) after the construction of Farakka barrage, due to greater availability of freshwater and lowering of salinity.
Long-term studies on the fishery resources of the river have shown a sharp decline in the fish catch and also a significant change in the species composition. Dams have long been considered to impact upon the fishes (Jhingran 1991). In the Himalayan stretch, habitat alterations including dams have drastically impacted upon the fish communities. The characteristic coldwater schizothoraciine fishes such as mahseer (Tor putitora, Tor tor) and snowtrout (Schizothorax richardsonii, S. plagiostomus) have declined because their migration routes have been blocked (Sehgal 1994). In the lower reaches, the Farakka Barrage (which was constructed to ensure flow to the Diamond Harbor seaport) has frequently been blamed for causing the decline in hilsa (Hilsa (=Tenualosa) ilisha) and other fisheries. Hilsa is a typical long-distance anadromous species that used to migrate beyond the middle reaches of R. Ganga. Its catch declined from 19.3 tonnes to 1.04 tonnes at Allahabad and from 32 tonnes to 0.6 tonnes at Buxar after the construction of the Farakka barrage (Chandra 1989). In the plains, carps (Cirrhinus mrigala, Catla catla, Labeo spp) and catfishes (Mystus sp., Wallago attu, Ompok sp., Pangasius pangasius) constitute the major fisheries. Freshwater prawns (Macrobrachium spp) are also abundant. Fish landings have declined during the past 4-5 decades, from 961 kg per km in 1956-60 to 630 kg per km in 1981-87 (Chandra 1989; De, Ghosh and Unnithan 1989). The loss of feeding and breeding habitats in the floodplain lakes due to embankments, the increased silt load and the growth of macrophytes, which have reduced the deep perennial pools in the river channel, have been identified as major causes for declining fish catches (Jhingran 1991). Other river valley projects on the tributaries such as R. Kosi and R. Gandak have also adversely affected the fisheries in north Bihar.
Among other fauna that have been seriously affected by changes in the river habitat and water quality, the Ganges River dolphin (Platanista gangetica) is the most important. This dolphin was once abundant and widely distributed in the Ganga-Brahmaputra river system, with its distribution limited upstream by the lack of water and rocky shores and downstream by the salinity. Pollution, water withdrawal and dams are considered responsible for its population decline to only 152 from about 2000 in 1988-89 (Smith et al. 1994; Sinha 1997).
The River Yamuna is the most important river after the Ganga and has attracted much attention because Delhi, the capital of India, Agra, the city known for Taj Mahal and Mathura, the birthplace of Lord Krishna, are all located within a stretch of 200 km on its banks. This stretch is the most polluted and degraded in the entire country. Gopal and Sah (1993) have described the characteristics of Yamuna river basin and reviewed the state of knowledge of the river. A barrage 200 km upstream of Delhi, the diversion through the Agra canal of the wastewater from Delhi and extensive channelization has resulted in the nearly complete withdrawal of water from the river. This together with heavy discharge of untreated domestic and industrial effluents has turned the river into a sewer at least between Delhi and Agra. Upstream of Delhi, it remains nearly dry for most of the year except for a few weeks during the short rainy season. It partly regains its riverine characteristics after its confluence with the R. Chambal, which has a larger flow than that of the Yamuna. The water quality and the biota have changed greatly over the past four decades (Gopal and Sah 1993). Turtles and crocodiles, once abundant in the river, have almost disappeared. Even in the River Chambal, the crocodiles have declined, necessitating the establishment of a National Chambal sanctuary for the Gharial.
Various anthropogenic impacts occur in the floodplain and extend to the entire upper watershed. In floodplains excessive grazing and cultivation have completely eliminated the natural riparian vegetation. Tree species such as Tamarix dioica, Anthocephalus kadamba and Mitragyna parviflora and reeds (Phragmites and Arundo) which once dominated the banks of River Yamuna have disappeared or occur only rarely. The riparian forests, dominated by species of Barringtonia, Syzygium and Calamus, which were common (Champion and Seth 1969), are now extremely rare.
The upper watershed of R. Yamuna (particularly that of its major tributary R. Tons) lying between 1 000 and 4 000 m altitude, is under intense human pressure as most of the local communities are wholly or largely dependent on the natural resources in the region. The area is increasingly threatened by deforestation, forest fires, herb gathering, over-grazing, poaching and construction (personal observations). Tourism is also slowly but steadily picking up. The area is highly prone to landslides and landslips, which are increasing largely due to road construction and various anthropogenic activities. Large areas (~30-40 percent) have become deforested and de-vegetated, resulting in severe erosion and landslides. Over-grazing in the alpine meadows is resulting in heavy erosion and rill and gully formation. The river is heavily loaded with silt that affects water quality and biodiversity as well as the use of water (such as in power generation). Available data suggest that the peak discharges during the monsoon season have increased whereas the lean period discharges have decreased.
RIVER CONSERVATION EFFORTS
The government, the scientific community and also the people have been conscious of the problem of growing water pollution in rivers, declining fish yields, increasing frequency of floods and droughts and the growing scarcity of water resources (e.g. Agrawal and Chak 1991). As early as 1974, the Water Prevention and Control Act was adopted by the Parliament to regulate discharge of effluents into the rivers and other water bodies. An irrigation policy was formulated in 1972 that promoted maximum crop production per unit area of arable land and highest possible use of river water to bring maximum possible area of agriculture under a single irrigation scheme. The National Water Policy (MOWR 1987) emphasises the development, utilisation, management and conservation of water resources, according to water use priorities with supply of drinking water at the top followed by irrigation, hydropower, navigation, industrial and other uses. It has recognized the need for modification of the prevailing pattern of agriculture and introduction of accountability and transparency on use of water and its source. The Ganga Action Plan, launched in 1985, provided for interception, diversion and treatment of sewage in all major towns along the River Ganga. This programme had been extended later to River Yamuna and all other rivers in the country and a National River Conservation Directorate (NRCD) had been set up within the Ministry of Environment and Forests (MOEF) to implement it with the help of the State governments.
However, these policies and programmes follow a sectoral, short-term approach instead of a holistic long-term planning and many policies are contradictory to each other. There is no coordination between different ministries and agencies concerned with water resources, agriculture, industry, environment, urban planning, energy, transport and watershed development. Several ministries deal with water as a commodity and treat it differently according to individual sectors including: drinking water supply, irrigation, hydropower, etc. Rivers are the responsibility of the states under the government federal structure as far as sharing of water resources is concerned. Similarly land is a state responsibility whereas the central government can deal with issues like water pollution and biodiversity.
Thus, while there are many stakeholders in the river systems and their watersheds, no one seems responsible for their conservation. The conservation of rivers has been limited to efforts towards improving water quality by treatment of wastewaters. Unfortunately, there has been no appreciation of the nature of rivers as ecosystems whose ecological integrity depends upon their physical, chemical, biological characteristics and interactions with their landscape (watershed).
PROPOSAL FOR YAMUNA RIVER FLOODPLAIN RESTORATION
During the past few years, serious concern has been voiced at the continued degradation of River Yamuna at Delhi and the inability of the Government to take remedial action. Public Interest Litigation was moved in the Supreme Court, which has directed the Government to ensure improvement in the river to bathing quality of water within a specified time. Among other factors mentioned earlier, the degradation of River Yamuna at Delhi is attributed primarily to the lack of flow and discharge of large volumes of partly treated sewage. Only about half of the sewage generated in the metropolis of Delhi is treated. Often, the treatment plants function inefficiently and the effluent does not meet the prescribed standard. A large population of slum dwellers residing on the riverbank also contributes to the pollution load. Currently projects are underway to provide for additional STPs for treating most of the sewage and to relocate the slums from the riverbank. However, lack of the freshwater required for dilution of treated effluents discharged into the river remains a serious problem. The river discharge at Tajewala (about 200 km upstream of Delhi) is completely diverted and shared by four states. Delhi receives only a small amount through a canal for drinking water supply to the city. The neighbouring states are unwilling to reduce their share so as to make some water available for the river at Delhi. The problem is further compounded by extensive use of the upstream floodplain and also the riverbed for agriculture by exploiting groundwater and with the application of agrochemicals. Whatever little land is unfit for agriculture is intensively grazed. Natural riparian vegetation is almost non-existent except for annual ruderals.
The problem of in-stream flow is not unique to the R. Yamuna or Indian rivers in general. The instream flow requirements are being debated worldwide in terms of "minimum", "adequate" or "environmental" flow and methods are being developed to estimate these requirements under diverse conditions (Tharme 1996; Richter et al. 1997; Richte et al. 2002; Richter and Richter 2000). At the same time, several approaches have been suggested and/or employed for restoring flows in different countries (The Nature Conservancy 2002). These approaches include removal of dams, regulated release of water from the reservoirs, reduction in water use and various nonstructural methods of floodplain management including restoration of the original conditions (FISRWG 1998; Rutherford, Jerie and Marsh 2000; Phillips, Bennett and Moulton 2001).
In India, while the rivers will continue to be threatened by ever-increasing withdrawal of water, there is also no possibility in the near future of dismantling dams and removal of embankments. The mitigation of the problem requires strategies for minimizing the wasteful use of water in agriculture, efficient wastewater treatment systems and recycling of water. These options have often been discussed at several forums but there has hardly been an attempt made to reduce water consumption. The policies of state governments to provide free electricity for irrigation have only increased water consumption. Floodplain restoration, therefore, remains the only viable alternative though it also requires great political will to support the change in land use back to that in the past.
It is encouraging that the importance of floodplains as an integral part of the river ecosystem has now been realized. The NRCD has recognized the hydrological role of floodplains in storing huge amounts of water derived from peak flow and storm runoff during the rainy season and later releasing it gradually, as well as in recharging the groundwater and improving its quality. Storage of the monsoon season runoff for augmenting flows in critical reaches had been suggested earlier also (e.g. Anonymous 1982; Bhargava 1985). Therefore, it is proposed to restore considerably large areas of floodplain, a 60-70 km stretch upstream of Delhi, with the primary goal of improving flow downstream.
The Survey of Indias topo sheets (1:25 000) based on the last survey made in 1969-70, show that during the past thirty years, the river-floodplain system between the embankments has undergone many changes. Only few additional embankments have been built on the left of the river, mostly near Delhi. The main river channel has shifted its course, generally towards the east and the meandering has decreased considerably. Sediments brought by the river have raised the floodplain level and filled up all side channels and water bodies. However, this area is still submerged for a short period (several days) during the peak flood period in the rainy season.
It is proposed to restore wetlands and lost channels that existed during late 1960s. Additional water bodies will be created for storing peak floodwater. Some river meanders will be restored and recreated. Habitat diversity of the main river channel will be enhanced by various structural and non-structural measures. Another major component of the restoration project will be the extensive plantation of native trees, shrubs, reeds and grasses along the natural levee for checking erosion and bank cutting. Appropriate vegetal cover will be promoted on the floodplain in between the water bodies and the area will be suitably landscaped. Fisheries and freshwater prawn culture will be introduced in the water bodies created on the floodplain.
These measures will help retain most of the peak floodwater in the river-floodplain system. Given the loamy to clayey loam texture of the sediments, the ground water recharge will certainly occur. The large volume of water proposed to be stored on the floodplain is also expected to help maintain some flow downstream for a few months after the rainy season. With a gradual rise in water table, more water is likely to be available for flow in the river.
An increase in habitat diversity and the vegetation is expected to revive the natural fisheries as well as other riverine biodiversity (birds, amphibia, reptiles, molluscs and macro-invertebrates) that once occurred in the area. The loss of agricultural production will be more than compensated by the potential for fisheries and the production of forage and fuel. Additional benefits will accrue in terms of improvement in water quality due to a reduction in the application of agrochemicals and through nutrient transformation in the restored floodplain wetlands.
Only incorporating the socio-economic aspects and community participation can ensure the implementation and success of any such project. A programme of rehabilitation by providing alternate opportunities for livelihoods to people who own or cultivate the land in the floodplain has yet to be developed. Efforts will be made to involve these people in the restoration and follow-up management activities and motivate them to take up fisheries and prawn culture that are economically more profitable.
REHABILITATION OF THE UPPER WATERSHED
Simultaneously with the floodplain restoration, the NRCD has initiated the preparation of another project for the rehabilitation of the upper watershed of the River Yamuna in the Himalayan ranges (>1 000 m altitude). The proposed rehabilitation measures include construction of a number of check dams on all drains and rivulets in a series to reduce the runoff and its velocity and re-vegetation of barren and open areas. In order to ensure that the environment is not degraded again due to continued impacts from local communities, the availability of natural resources has to be enhanced and their socio-economic condition and health has to be improved. Besides involving the local people in the rehabilitation work, an education and awareness programme is also planned.
It is hoped that these projects will be implemented soon with funding support from international agencies and the cooperation of the concerned departments and agencies of the state governments and the NRCD.
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