1. The Imperative of an Integrated View of Water

Over the last several millennia, river basins have been the cradles of many human civilizations. That dependence continues today. However, with economic growth becoming the paramount objective of the present uses of water,  river basins have become an open playing field for a reductionist perception of engineering, which looks at rivers primarily as a stock of resource to be stored and diverted to satisfy various supply-side requirements of human societies and economies. Though this reductionist approach was successful for several decades, its continued effectiveness is facing serious questions. This approach is increasingly proving inadequate and unable to address the emerging challenges humanity is facing in terms of the quantity, quality and sustainability of water even just to meet human requirements let alone develop. The need to evolve further and develop a new perspective has been stressed by many and described well in the United Nations World Water Development Report[1].

It was during the 1960s, that global criticism of the reductionist approach, backed by the widespread degradation of water systems and social unrest against many large-scale water projects, first took shape. The thought that we need a more holistic perspective in addressing the challenges related to water is not new. Such views were already being expressed in 1977, at the UN Conference in Mar Del Plata. Similar views have been held by many water professionals over the years, and reiterated on other occasions, especially in the Dublin Statement on Water and Sustainable Development[2]. Many water professionals have already published their ideas on taking water governance beyond reductionist management[3] and have cautioned that  “Contemporary society is in the midst of an existential crisis. On the one hand, the Information Age presents profound egalitarian potential associated with the rapid pace of technological and social change. On the other, there is profound disquiet and increasing alarm as existing governance arrangements fail to come to terms with environmental, socio-political and cultural problems at local, regional, national and global scales.” This article is a response to such alerts.

The emergent holistic perspective became identified with the name ‘Integrated Water Resources Management’ or IWRM[4]. While developing a more clearly laid out mechanism for IWRM is a great necessity, that task is complex and a conceptual breakthrough is necessary. Clearly, a lot more work is needed to reach the goal of operationalizing a framework for IWRM. This article attempts to contribute to the ongoing process of conceptual integration. It deals with four primary bio-geophysical dimensions of flows in rivers, while also assuming that similar developments in social and economic dimensions of water systems are progressing. It is hoped that in future decades an umbrella approach that relates individual elements of the natural river described below into a system will emerge.

2. An Integrated Perception of Flows Exemplified by the WEBS

From an eco-hydrological perspective, it will not be an over-statement to describe flows in river basins all over the world, whether of the Danube in Europe or the Ganges in South Asia,  as the most important environmental influence there exists in those basins in the shaping of terrestrial landforms, biodiversity and, as a result, resident human societies. There is a need for a multifaceted perspective to understand what flows in river basins are, what they have been doing in the geological past, and what the appropriate mechanisms for their governance in future will be so that the synergy of water systems is conceptually shaped. Such a synergy includes the satisfaction of human requirements in a fashion that can co-exist with the stability of river basin-based ecosystem services[5] [6]. In spite of a growing global consciousness of the limitations of reductionist water engineering, a clear articulation of a synergy-based perception of flows is yet to emerge. This article identifies a composite profile of  flows that recognises that water, energy, sediments and biodiversity (WESB) as primary constituents. This perspective is abbreviated as WESB[7] in order to show the similarity of the diversity and complexity of the interaction among these elements with a web. Thus the order in which the elements are mentioned has been altered slightly from WESB to WEBS (water, energy, biodiversity and sediments).

2.1 Elements of a Synergy-Based Perspective on Flows in River Basins

Water

Rivers, together with streams, lakes, wetlands and aquifers, play a crucial role in transporting water after its precipitation from the atmosphere to its final discharge into oceans via its passage over terrestrial landmasses. Flows are described in terms of volume passing a point per unit of time. Flowing water carries many constituents that are not used in the description of flows. As precipitated water travels through the atmosphere, it absorbs suspended particles and gaseous materials. As the precipitated water finds its way across a terrestrial landmass, its content gets further modified by land and land cover and it, in turn, alters the physiography of that land itself. In this fashion, the water of each stream or river gets its characteristic chemical composition, a composition vital for the appropriate biodiversity to flourish. On the basis of the physical structure and chemical composition of the river bed as well as the temperature of the water, different biological life emerges and evolves in each water body. In the case of river basins with large temporal variations in flows, the inundation of the floodplain results in the regeneration of both surface and groundwater as well as biodiversity in the diverse water bodies, even if they are a distance away from the main course of the flows.

Flows of rivers, especially when they vary extensively over time, have both advantages and disadvantages, especially for human wellbeing, because they generate high and lean flows.  For more than five millennia, the flows of rivers have been blocked and diverted to meet human needs, including for irrigation and the moderation of the impacts of high flows, also called floods. As a result of the diversion of flows from the rivers by interventions made with a reductionist perspective, downstream flows have declined, and, as a result, ecological statuses and service have changed. In many instances, such diversions have been large enough to stop outflows to the ocean and destroy estuarian fishery economies. In the WEBS perspective, flows of water in river basins integrate four important elements identified from the point of precipitation to confluence with the oceans. In it, the flow of water in river basins is perceived as a continuum and described through its and not simply through a volumetric number. Flows of water in the WEBS perspective are also quantified by their chemical and physical contents. This perception builds on growth in modern water science and engineering to encompass a larger degree of interdisciplinary understanding for governance.

Energy

As evapo-transpiration, water from the surface of the earth (oceans, rivers, lakes, wetlands, soil, vegetation, animals, etc.) is lifted by solar energy. It returns to the surface of the earth as precipitation in the form of liquid, water, snow or ice, which falls on  both land and oceans.  Depending on the altitude at which it falls on the terrestrial surface, the precipitated water embodies a given potential energy. After deducting the water that goes back to the atmosphere as evapo-transpiration and the percolates into groundwater aquifers, the remaining precipitated water flows as surface run-off. Under the pull of gravity, the water moves downstream, transforming its potential energy to kinetic and creating river flow. Energy is an essential constituent of river flows that make their downward journey, all the way from their headwaters to their mouths at coastal areas and beyond. The energy constituent is why upland and mountain areas have traditionally been highly suitable for generating mechanical and electrical energy. In the upland parts of a river, where the slope of the river bed is high, the kinetic energy in the flow causes erosion, generating bed loads and suspended sediments. In mountainous areas, flows can be powerful enough to carry even large boulders as bed load. Thus, the energy that endows river flows with the ability to erode banks and beds, generating boulders, gravels, sediments, and silt also transports the eroded materials further downstream. Wherever the flow slows down, the flows increasingly perform their role of deposition of sediments. The deposited materials contribute to the growth of sand bars, riverine islands, and finally a river’s delta.

Early forms of navigation and transportation, like the floating of timber, were efficient users of the energy that is integral parts of flow of rivers. For millennia, humans have used the energy in the flow of rivers to run water mills in upland areas, grind food grains, and run simple machines. In the last two centuries the scale of extraction of energy from flows in rivers in upland areas has rapidly increased, culminating in hydro-power generation in industrially advanced countries. Thus, in recent times, the large quantities of energy in the flows of rivers have become an important provisioning ecosystem service. In many mountainous areas, energy from flows in rivers has become the main energy source. At the same time, the extraction of energy from flows impacts the ability of rivers to maintain other ecosystem services, like the movement of fish species and the generation and transportation of sediments, thus disrupting the ecological linkages along the longitudinal course of rivers. This disruption affects aquatic habitats and the biodiversity based on them. It is therefore imperative to see the energy content in flows as an integral part of their identity. Without its energy content, the description of a flow is incomplete and the assessment of any hydro-power project based on that flow will be misleading.

Sediments

During the downward journey from the mountainous and upland parts of a basin to the floodplains and on to the deltas, coasts and submerged delta, the flows of rivers generate, transport and deposit solids of various sizes. In many instances, such as in the Eastern Himalaya, which receives highly intense summer monsoon precipitation, the energy content in flows may be enough to roll down boulders more than a meter in diameter. At the other extreme, such flows also carry clay with particles smaller than 0.002 mm in diameter. The solid content of river flows plays a crucial role in shaping the physiography of the basin, fluvial geomorphology, and the formation of riverine islands, all habitats for large biodiversity, in all parts of the river basins[8]. Newson and Large have recorded the growing need to recognize sediments and the role of fluvial geomorphology in the governance of and restoration activities for river basins[9].

On the basis of the primacy of the three processes of erosion, transportation and deposition, basins of rivers are divided into three segments: the uplands, the floodplains and the delta. Most of the erosion processes occur in the uplands. As a flow crosses the foothills and reach the floodplains, the slope of  its bed drops, causing a marked reduction in its ability to erode. At this stage, the flow starts dropping boulders and large particles. In the floodplains, flows mainly transport fine sediments and, if a river periodically extends over large areas of the floodplains, it deposits sediments that may range in size from sand to clay, depending on its energy content. Such processes either rejuvenate the landscape in the basin area by depositing fertile soil or damage it by depositing of sand. Such ecosystem services occur extensively in the basins of the Nile, Ganga-Brahmaputra-Meghna (GBM) and other rivers and play a central role in supporting the agricultural economy in the basins. However, catastrophic natural events like earthquakes and human interventions not informed by the ecology of the basins often create conditions in which sand  is  deposited on fertile topsoil, to the detriment of agriculture.

As a river flows further downstream and enters the delta region, its energy level declines, and so does its capacity to transport sediments. Here it starts to deposit even the finest of sediments transported from upstream areas. Even beyond the point of confluence of rivers with oceans, the transportation and deposition of sediments continues, with the formation of a submerged delta and the continuing outward growth of the delta. The submerged delta of the GBM basin, for example,  has an annual sediment load of 2,179 million metric tons,[10]  a length of about 3,000 km and a width of about 1,000 km.

The synergy of water, energy and sediments is basic.  They are the closely related identities of flows,  and changes in the status of one directly impacts the statuses of the other two. Their systemic links support the diverse habitats in a given basin and the related biodiversity. The generation of large amounts of sediments in the flows of rivers can be the result of purely natural processes, like tectonic activities or landslides. In the last several decades, however, the processes of sediment formation and transportation have been substantially impacted by human interventions like mining, afforestation, and the building of roads, railways, dams, barrages, and embankments. With large parts of the sediments getting trapped in the artificial storage systems that are built, there has been a great change in the processes and amounts of sediments being carried by the flows in the rivers of the world to the oceans. This change has affected the ecological status of many rivers, large and small. In the case of the Yellow River, for example, human intervention has reduced the outflow of sediments. It is thus important to recognize and assess sediment as an integral element of flows in river basins and one which needs to be considered with attention in the assessment of all engineering interventions for river basin governance.

Biodiversity

From their headwaters in the mountains and uplands to their confluences with the oceans, water, energy and sediments constitute the basic contents of flows and generate a great variety of  ecological niches and habitats, which, in turn, support a rich biodiversity, starting from micro-organisms and progressing to simple algae and large fish varieties[11].  Study of the three constituents can provide an important account of the biological life around flows in streams and rivers. Biodiversity in river basins is closely linked with the chemical composition, acidity level, and temperature of and temporal variations in the flows in rivers and the nature of the vegetation and animals on the banks or in the rivers. Fish from the rivers have been a key food for both humans and animals since the beginning of civilisation. The aquatic biodiversity of flows in river at specific parts has undergone rapid changes due to both natural processes, and more recently, human interventions that have changed river flows and their courses. As part of their annual migration, several varieties of fish move from the oceans upstream to their breeding grounds in freshwater. Salmon in Europe and hilsha in South Asia are examples of expensive varieties of fish that make such migratory moves.

The ponds, lakes, wetlands, and creeks found in great number in the floodplains of rivers provide cheap sources of protein in the form of small fish varieties that grow in open-access aquatic bodies, including wetlands. Since the state of biodiversity in the flow of a river is an indicator of the environmental status of that flow, it needs to be recognised as a basic description of that flow. The restoration of the ecological status of the flows in rivers is an essential part of the integrated governance of rivers. In such governance, biodiversity is a primary indicator and tool in the restoration process, one which has deep implications for global water security[12]. In this way, biodiversity becomes a signature of the flows in rivers and a crucial element for riverine governance. In the coming decades, the large and rapidly urbanising population in many parts of the world will generate greater and more diverse demands for water, energy and food, raising important challenges to riverine governance related to the allocation of water across time, space and sectors[13]. These challenges, in particular, are related to the issue of sustaining ecosystems so they can maintain their natural functioning and ensure the continuity of their ecosystem services. In achieving such sustainability, a crucial and new starting point will be the generation of a perception of river flows as not being described simply as a quantity of water but as consisting of an inter-related combination of water (with dissolved contents), energy, biodiversity and sediments, or WEBS. This preliminary perspective needs to be further expanded and refined in the future to include other relevant parameters.

A river is a collective flux of water, energy, biodiversity and sediment (WEBS)

3. Closing Remarks

The global water crisis indicates that there is a serious crisis in the natural environment as a whole. The widely discussed need for holistic governance of water systems is a global priority. To move towards the much needed interdisciplinary governance of water in the future, it is urgent to reorganise our perceptions of water as a system. The predominant framework of water engineering, a reductionist framework, needs to be replaced by a composite and synergy-based framework. There is much literature on the path traversed by the thoughts of experts which suggests that the river basin should be the spatial unit for integration[14]and that ecosystem services should be incorporated using the IWRM framework[15].

From the point of view of both interdisciplinary water science and holistic water engineering, in the present context of large-scale human interventions in the flows of rivers, the synergy among water, energy, biodiversity and sediments (WEBS) is of great importance. For example, any intervention to store and transfer flows will impact sediment dynamics, water quality and biodiversity. However, most hydro-power projects look at flows only as a source of energy and are unconcerned about the impacts of river diversions on water quality, sediment dynamics and state of biodiversity. River restoration initiatives invariably try to revive the lost synergy or repair the distorted links among water, energy, sediments and biodiversity. The gaps in the present engineering approach are exemplified by many structures, including the large-scale hydro-power development projects in the ecologically fragile mountains of the Himalaya. In a more developed stage, the WEBS perspective will be useful in generating a more comprehensive, realistic and interdisciplinary vision for the use of flows in rivers, especially for reforming reductionist assessment processes and facilitating the integrated  governance of flows in river basins. Making this adjustment would also help avoid conflicts and crisis situations involving all stakeholders, including nature itself. It is hoped that the future generation of water professionals will move towards greater integration in their consideration of river dynamics.

References

[1] WWAP (United Nations World Water Assessment Programme)/UN-Water. (2018). The United Nations World Water Development Report 2018: Nature-Based Solutions for Water. Paris, UNESCO.

[2] WMO (1992) The Dublin Statement on Water and Sustainable Development World Meteorological Organization (Geneva).

[3] Brierley, Gary J (2000) Finding the Voice of the River: Beyond Restoration and Management Springer Nature (Switzerland).

[4] GWP (2000). ‘Integrated Water Resources Management’ TAC Background Paper No. 4, Global Water Partnership Technical Advisory Committee, Stockholm.

[5] Paola, C., E. Foufoula-Georgiou, W. E. Dietrich, M. Hondzo, D. Mohrig, G. Parker, M. E. Power, I. Rodriguez-Iturbe, V. Voller, and P. Wilcock (2006) ‘Toward a unified science of the Earth’s surface: Opportunities for synthesis between hydrology, geomorphology and ecology, Water Resources Research doi:10.1029/2005WR004336.

[6] Middleton, Nick (2012). Rivers: a very short introduction OUP Oxford.

[7] Bandyopadhyay, Jayanta (2017) ‘Restoration of Ecological Status of Himalayan Rivers in China and India: the Case of the Two Mother Rivers – the Yellow and the Ganges’ in Shikui Dong, Jayanta Bandyopadhyay and Sanjay Chaturvedi (Eds) Environmental Sustainability from the Himalayas to the Oceans: Struggles and Innovations in China and India Springer (Switzerland):69-98.  and Bandyopadhyay, Jayanta (2018) ‘Why we need a new perspective on rivers’ The Third Pole July 25 available at https://www.thethirdpole.net/en/2018/07/25/why-we-need-a-new-perspective-onrivers/

[8] Van Rijn, Leo C. Principles of sediment transport in rivers, estuaries and coastal seas. Vol. 1006. Amsterdam: Aqua publications, 1993.

[9] Newson, Malcolm D. and RG Andrew RG Large (2006) ‘Natural’ Rivers,‘Hydromorphological Quality’ and River Restoration: A Challenging New Agenda for Applied Fluvial Geomorphology,” Earth Surface Processes and Landforms 31(13): 1606–1624.

[10] Curray, Joseph R., and David G. Moore. “Growth of the Bengal deep-sea fan and denudation in the Himalayas.” Geological Society of America Bulletin 82, no. 3 (1971): 563-572.

[11] Giller, Paul S., Paul Giller, and Bjorn Malmqvist. The biology of streams and rivers. Oxford University Press, 1998.

[12] Vörösmarty, Charles J et al (2010) ‘Global threats to human water security and riverbiodiversity’ Nature 467, 30 September:555

[13] Varis, Olli, Marko Keskinen and Matti Kummu 2017 ‘Four dimensions of watersecurity with a case of the indirect role of water in global food security’ Water Security 1: 36-45.

[14] Molle, Franço (2008) is ‘River-basin planning and management: The social life of a concept’ Geoforum 40(3): 484-494.

[15] Malin Falkenmark and Carl Folke (2000): “How to Bring Ecological Services into Integrated Water Resources Management,” AMBIO: A Journal of the Human Environment 29, no. 6 351–353.