The Ganga River Basin impacts the lives of some 500 million people across four countries with a substantial proportion of these people being both poor and directly reliant on the river system for livelihoods and subsistence. The river (and hence the vulnerable population) is subjected to approximately 6614 million litres per day of waste water with an organic pollution load of 426 tonnes per day (CPCB, 2016). In addition, India, which hosts the longest element of the river course, is the largest consumer of groundwater in the world using 230 cubic km of water per year, which is 25 per cent of the world total (Rodell, Velicogna and Famiglietti, 2009). Indeed, most rivers in India only effectively flow for some 90-100 days every year. The rest of the year they are either dry or carry waste water. Yet water demand in the Ganga stem is high and growing rapidly with agriculture (85 per cent of the demand), industrial demand (9 per cent) and domestic demand (about 6 per cent) (Verma and Phansalkar, 2007). The vast majority of the agricultural demand is for subsistence rain fed farming. To compound issues further, there is evidence of a drying of the Ganga as a result of loss of glacial melt relating to climate change (Goodbred, 2003).
A consortium of Indian Institutes of Technology (IIT) has recently submitted a comprehensive Ganga River Basin Management Plan (GRBMP) to the Indian government. This plan provides a basic framework for developing a river management strategy based on five fundamental premises: Ganga must continuously flow; Ganga must have longitudinal and lateral connectivity; Ganga must have adequate space for its various functions; Ganga must function as an ecological entity and Ganga must be kept free from any kind of waste.
This plan adopts an ecosystem-based approach for river management and is the first of its kind for such a large river system. The recommendations from the IIT Consortium are yet to be implemented fully and it might be useful to discuss the basic objectives of this plan, major recommendations and the road ahead.
The first task of the consortium was to identify the major anthropogenic factors that led to the degradation of this large system. These primarily included over-extraction of water to meet the increasing human demands; discharge of pollutants causing deterioration in the quality of land and natural waters; reduction in the rate of replenishment and water-holding capacities of natural reservoirs (of both surface and ground water bodies); mutilation of rivers by piecemeal engineering operations and possible threats to geological processes governing the basin. It was concluded that human activities in the Ganga basin including industrialisation, extensive agriculture, urbanisation and catchment deforestation have severely affected the natural river processes and have led to a severe loss of ‘ecosystem services’ provided by the river. An important realisation has been that the Ganga is a diverse and complex river system in terms of both morphology and ecology and therefore, needs different solutions for different stretches of the river. This diversity is generated in various ways—discharge regimes and vegetation cover (driven by climatic setting), channel slope and bankline (driven by catchment morphology), sediment flux and accommodation (driven by geological settings). It is therefore important that any effort towards river rehabilitation must address these issues to derive a long term benefit.
The GRBMP argues for an ecology based river management plan and introduces the concept of ‘river space’. A river must have ‘adequate space’ to perform its myriad functions such as river dynamics, sediment transport and floodplain development and ecological services.The river ‘valley’ and ‘active floodplain’ define the ‘river space’ for the river albeit with different functionality that needs to be recognised and documented properly for a sustainable river management. A first order mapping of the Ganga River channel belt and its active floodplain from Gangotri to Farakka using satellite images has brought out extreme diversity in channel form, active floodplain and valley margin characteristics and reach-scale fluvial processes (Fig. 1). Similarly, the documentation of major flora and fauna in the Ganga basin reveals a rich biodiversity which needs to be protected. The GRBMP reports have documented severe loss of ecological connectivity and productivity of fresh water fishes owing to interception of flow by large hydro-electric projects such as Tehri, loss of flow due to abstractions from a series of barrages, increase of pollution load from the urban areas, increase of sediment load due to deforestation and indiscriminate fishing. Another serious issue is the overpopulation of some invasive fishes such as Chinese carp and Tilapia that have replaced/reduced the indigenous species in several stretches of the river leading to loss of biodiversity.
Maintenance of environmental flows in all stretches of the river has been strongly advocated and the criteria for the same have been developed based on ecological and geomorphological considerations. Despite a robust protocol developed through careful analysis of time series of hydrological data and site specific channel morphology and ecology, the GRBMP recommendations on environmental flows are yet to be adopted formally by the Ministry of Water Resources. Water pollution in different stretches of the river remains a major concern. Despite the fact that both the problems and solutions related to this are well understood for decades, the implementation has been extremely poor, leading to a disastrous degradation of river health. Flood risk and sediment management are two other important issues which plague the Ganga and several of its tributaries. Our traditional flood ‘control’ strategies based on embankments have time and again proved to be inappropriate for ‘sediment-charged Himalayan rivers and they need a hard and serious relook. A series of floods in the different parts of the Ganga basin in recent years have reminded us to rethink about our flood management strategy while the indiscriminate occupation of river space has increased the flood risk tremendously. Both of these can be tackled through soft engineering approaches such as floodplain zoning that involves designation of areas susceptible to floods and strict landuse regulations. A community based approach such as ‘living with floods’ advocates mitigation of flood disaster through disaster aids or through insurance coverage, but this also involves the development of a robust database and flood prediction capabilities.
The Ganga river management programmes have so far been primarily targeted towards water allocation and water quality and there has not been a consolidated effort towards river restoration from an ecological perspective. The GRBMP has provided this opportunity with a clear concern for improving the overall ‘river health’, if the recommendations can be taken up by the government without much delay. The GRBMP advocates a fine balance between the ‘science’ of the river and the ‘engagement’ of the governmental agencies and local communities through a knowledge brokerage (Fig. 2).
Apart from reducing pollution load of the river, one of the major focus in river rehabilitation measures should therefore be to increase the morphological complexity of the Ganga which apparently increases the habitat availability and biodiversity. However, it is important again not to apply this concept indiscriminately. It is commonly observed that the aquatic life sometimes adapts to relatively simple morphology of the rivers and therefore it may not be necessary to increase the heterogeneity. Another issue is to recognise the enhanced heterogeneity due to human disturbance, which can be counter-productive in terms of biodiversity. It is important therefore to identify the ‘natural’ condition and habitat of the aquatic life and understand their interrelationships rather than forcing an unsuitable river restoration work. Human modifications on river systems have been so extensive that it is often impossible to reconstruct the ‘natural’ condition of a river. As such, the definition of a natural stream may itself have to be re-examined. This then brings us to the question of defining the ‘reference’ condition for the river. It has been argued that selection of single-site reference condition without any consideration of morphological characteristics runs the risk of inducing landscape homogeneity across the region.
Just as the rivers have a range of morphology and behaviour, their sensitivity to adjust to forcing functions is also different. While some of these have a ‘threshold’ to change and subsequently are very sensitive to change, the others may adjust gradually and are therefore, relatively insensitive to imposed changes/disturbances. In the same context, it is also important to be able to differentiate human disturbances from the natural variability of the system. In some cases, human disturbances may also modify the rate and pattern of river adjustments. Therefore, the evolutionary pathway of the river must be understood to be able to identify the causes of changes so that rehabilitation procedures can address them.
The issues highlighted by the GRBMP and from my own understanding, the following are the set of parameters that all government departments dealing with Ganga must have a complete handle on for designing a sustainable management plan:
- E flows or environmental flows—to recommend the desired level of water in the river in different seasons;
- The state of flora and fauna—to formulate a healthy score that provides an insight into the good health of the river;
- Land use and development index—to provide parameters on the systemic risk introduced;
- Value for money—to provide an indicative return on investment for each of the projects that are developed;
- Balance sheet—to prepare country’s water resources balance sheet which helps understand its status;
- Disaster warning—to make a score card for flood and drought risk; and,
- River health assessment—to integrate of most of the above parameters for complete assessment of river health.
The Ganga river basin is now a part of highly modified landscapes where human activities are dominant. Any efforts towards river habilitation cannot realistically aim to reconstruct pristine conditions as the catchment conditions under which the river now functions (e.g. water transfer, sediment dynamics and vegetation cover) have been fundamentally altered, in many cases irreversibly. Since the river system is now adjusting to a new set of boundary conditions, river management programmes must strive to adopt river rehabilitation strategies that work with the contemporary catchment conditions. As the Ganga demonstrates remarkably different characters, behaviours and evolutionary traits (both between and within catchments), individual catchment need to be managed in a flexible manner, recognising what forms and processes occur where and why and how often and how these processes have changed over time. A process-based understanding and determination of appropriate river structure and function of differing positions in catchments are critical components in sustainable rehabilitation of the riverine ecosystem of the Ganga. Since an inventory of all possible micro-habitats within the catchment is an unrealistic goal, a practical approach is to assess the structural attributes that influence micro-habitat character and diversity that is ecologically relevant and that allows habitat to be related to river processes. The most appropriate approach therefore is to use a biophysical template for a first order assessment of river health and for designing sustainable rehabilitation strategies for the Ganga.
The management of a large and complex river system such as the Ganga is a challenging task as it needs a multi-disciplinary and flexible approach. The River drains through different climatic, geomorphic and ecological regimes and also has a variety of cultural issues associated with different stretches of the river. Any sustainable strategy must maintain a fine balance among these different aspects of the river to derive the desired benefits and at the same time be acceptable to the community. While a first hand road map has been provided by the GRBMP, some clarity may be necessary on various aspects and of course a strong resolve from the government to make a difference.
Central Pollution Control Board (CPCB). 2016. CPCB Bulletin, 1: 8-13.
Goodbred, S. 2003. Response of the Ganges dispersal system to climate change: a source-to-sink view since the last interstade. Sedimentary Geology, 162 (1-2): 83–104.
Rodell, M., I. Velicogna and J. S. Famiglietti. 2009. Satellite-based estimates of groundwater depletion in India. Nature, 460 (7258):
Verma, S., S. J. Phansalkar. 2007. India’s Water Future 2050: Potential Deviations from ‘Business-as-Usual’. International Journal of Rural Management, 3 (1): 149-179.
The author is Professor, Department of Earth Sciences, IIT Kanpur. email@example.com