Minimum ecological flow is based on the principle that a certain amount of minimum flow must be present in a flowing freshwater ecosystem such as a river or an estuary so that the ecological quality of the flowing freshwater ecosystem is maintained. The term minimum ecological flow is also used sometimes, in association with the term environmental flow that denotes the amount of water running in a flowing freshwater body that can keep the water body at a desirable environmental condition.
The Concept of Environmental Flow
In order that the ecological and hydrological functions of flowing freshwater systems be conserved, a minimum ecological flow is required so that the physical regimes around flowing freshwater ecosystems are not significantly altered or that water flow in these bodies does not decrease significantly (EEA, 2016). The concept assumes importance in respect of water management, and brings up many issues in terms the physical, ecological and hydrological regimes of flowing freshwater ecosystems.
The terms ‘minimum ecological flow’ and ‘environmental flow’ have come into focus in modern times especially with the ever-increasing impacts of human activities on the flowing freshwater ecosystems. Significant degradation has occurred in the case of biodiversity of freshwater systems in contemporary times, due to human influence in altering the physical, hydrological and ecological regimes of flowing freshwater ecosystems. With greater understanding of human intervention in flowing freshwater ecosystems over time, approaches to assessing environmental flows have developed significantly as the concept has evolved.
The World Wildlife Fund, or WWF (O’Keeffe & Le Quesne, 2009), lists new learning that has contributed to an understanding of the concept of environmental flow over time. The aspect of physical processes for example and greater knowledge about how they impact environmental flow regimes in the wet or dry season can help in forming a better understanding of the desired environmental condition in a flowing freshwater body. These different physical processes constitute an obvious link with environment flows in flowing freshwater bodies and form a first point of reference in external factors influencing the desired environmental conditions in flowing freshwater bodies. As new insights on environmental flows developed, the second experience became one of the competing social claims over the desired environmental conditions.
Coming to conclusions on a desired environmental condition of flowing freshwater systems can be a contentious issue. In this aspect, one critical learning has been the fact that assessments of environmental flows place social choice at its core, in how other than being a scientific issue, these assessments can also carry the influence of social motivations depending on what different people might desire from a flowing freshwater body. As such, conclusions on the correct regime of environmental flow can, in many instances, be a contentious issue. In many cases, no single conclusion can be arrived at, which is compounded by the fact that different circumstances may acquiesce due to the different priorities and requirements of different physical features, hydrology and ecology of distinct flowing freshwater bodies.
Social choice can be a massive and influential factor when one takes into account the immense value of water to various human activities in relation to the need for environmental conservation. The approaches to determining the correct regime of environmental flow can differ widely depending upon the human need for a flowing freshwater body. For example, different needs can arise for a flowing freshwater body in the case of freshwater being utilized for irrigation as against freshwater that falls under a protected area. In the realm of human choice, another aspect thus has arisen in terms of the use of spare water from flowing freshwater bodies that can be extracted without severely impacting ecosystem services in these water bodies. This serves to add to the contentious issue of environmental flows and adds a new dimension to the evolving debate of social needs.
The debate over environmental flows faced further challenges when it was considered that establishing a minimum ecological flow for flowing freshwater bodies by itself might not be enough if maintaining the requirement of fulfilling desirable environmental conditions was to be considered. The factors influencing the characteristics of ecological communities in a flowing freshwater body can importantly be floods and droughts as well as the normal flow regimes. Even within the normal flow regimes, ecological communities can also be severely impacted by arbitrary ecological changes such as with the introduction of certain pest species, for instance. Also, sometimes the hydrological characteristic in the form of seasonally decreased flows can be undesirably affected by the artificial releases of water from dams or by inter-basin transfers. The case that there is a requirement to increase the current flows might not always be the case. More comprehensive solutions are required that can balance environmental flows with flowing freshwater ecology as also with the influence of socio-economic needs.
The Need for Sustainability in Managing Environmental Flows in India
However contentious issues over estimating how environmental flows are to be managed, it can become an important issue in undertaking the water resource development projects. Thus, an approach that looks to balance the socio-economic needs from water resources with environmental requirements would need the sustainable management of water resources. Considering that water use by humans is a necessity that in many cases involves extraction of water from flowing freshwater bodies, managing environmental flows becomes important to taking a sustainable approach.
Although methodologies of environmental flow assessment have been in development since 1940s globally, the aspect of water management with environmental goals in India is still given much less importance than that for socio-economic purposes. Due to the seasonal nature of the Monsoons in India, a great many facilities exist for the purposes of water storage and for the utility-based distribution of water. A great amount of regulations thus exist to manage water flow in flowing freshwater bodies in India such as for hydropower generation, irrigation, domestic and industrial use and for controlling floods. Development activities also are at the same time impacting amounts of water flowing in flowing freshwater bodies. For example, development activities are increasing the amount of sediment load carried by flowing freshwater bodies that can change the regime of environmental flow in these ecosystems. To cite another example, ecology is also impacted by discharges of waste in flowing freshwater bodies.
Although dam building in India remains a controversial issue especially in terms of managing the flow of freshwater, dams can assume great importance over the issue of managing environmental flows. While dams can abruptly alter the natural flow of flowing freshwater bodies, water flow that is sometimes released downstream from dams, for maintaining the environmental balance, is sometimes included as a measure in India for managing environmental flows (Jain & Kumar, 2014). In reality however, the building of the dams themselves greatly alters the flow of water, leaving many rivers dry and polluted downstream. The need for a sustainable approach is even greater when we see that socio-economic needs in India have greatly dominated over the needs of conserving ecosystems in flowing freshwater bodies, with many actions for conservation being mere concessions as compared to the widespread human intervention to fulfil socio-economic needs.
The effects of pollution can be more severe when lack of water in flowing freshwater bodies causes effluents to accumulate in places along the course of the water body. This can be severely harmful to ecology in these flowing freshwater ecosystems. A minimum ecological flow in this case would require either prevention of the dumping of effluents and/or appropriate water flow to prevent excess accumulation of effluents in these ecosystems. The problem can be worse when a dam upstream causes less release of water downstream, thus leading to the accumulation of effluents. Apart from finding a balance between conservation and socio-economic needs, as seen in this scenario, building sustainability in managing environmental flows needs to look also at the impacts of developmental processes on flowing freshwater ecology.
The basic step in building sustainability in managing environmental flows is to have a comprehensive regime of conducting flow assessments and bring out the full impacts of human needs and activities on the ecosystems. This also requires greater and more comprehensive research on ecosystems in flowing freshwater bodies that can help scientists in better understanding the nature and functioning of these ecosystems. For example, South Africa made environmental flow assessments in the late 1980s, and later in South Africa’s Water Act of 1998 structured ecosystem protection was included within the legal document (IUCN, 2003).
WWF began studies on environmental flows in India in 2007-08, preceding which no specifically tested methodology for comprehensive assessments of environmental flows existed among various stakeholders in India. As part of its Living Ganga Programme between 2008 and 2012, the WWF made an attempt to develop a methodology for environmental flows in the Upper Ganga basin with the help of several national and international partners (Kaushal & Babu, undated). Following WWF’s project, in terms of research on assessments of environmental flows in India, a number of individual studies have been undertaken of flowing freshwater bodies in India. The country in this aspect requires multidisciplinary research in many fields so that a greater strength is provided to policy makers in managing environmental flows in India.