Rivers

Floods: lessons to be learnt from the massive flooding in Surat city

A report by IIM criticises the way in which dams are managed in the country and calls for the need to apply Management Science / Operations Research techniques and information technology to improve dam management and prevention of floods

Flood fury: are we ready to face such an event?

This report by the IES presents the findings of a study that explores the likely impacts of the recent proposals in India to build a dam at Pancheshwar in the Himalayas on the river ecosystems and the surrounding areas and people involved. This dam will be the world's second tallest structure intended to harness hydroelectric power and water by controlling the flow of the Kali river and its tributaries.

The document argues that although there are many benefits of the dam in terms of energy and water, the wider ramifications of the dam and its consequences for the people staying around the area have not been thought about in the planning process. The planning process has not engaged local people in the decision-making process, there is paucity of published information and the environmental and social consequences have been considered belatedly in the planning process.

This article is written in response to an earlier published article “Chasing a Mirage: Water Harvesting and Artificial Recharge in Naturally Water-Scarce Regions” in the Economic and Political Weekly and argues that the paper makes a number of assertions about small water harvesting systems, that are based on faulty assumptions and inadequate information.

This report deals with the social conflicts emerging out of the encroachments owing to the change in course of the Ganga upstream and downstream of the Farakka barrage. The barrage was built with the intention of diverting water into the Hugli river with a view to flush the sediment load into the deeper part of the estuary and revive the navigational status of Kolkata port. During the last three decades of its operation, the silt-management in the barrage was given scant or no attention. The sediment movement in the tidal estuary of Hugli is a function of a complex fluvial system that can hardly be governed by inducing 40000 cusec of water.

Integrated Hydrological Data Books are a compendium of important hydrological information of twelve non-classified basins (i.e., other than Ganga and Brahmaputra) consolidated at the national level by the Central Water Commission (CWC).

It covers basic hydrological data on gauge, discharge, silt, sedimentation and water quality collected on a regular basis by the CWC regional field offices, who document it in the form of a Water Year Book, Sediment Year Book and Water Quality Year Book. These along with the relevant land use statistics collected by the Ministry of Agriculture are integrated into this Data Book.

The information is of use to planners, researchers, policy makers and the public at large.

The study deals with the development of an operation policy for the Tawa dam. It adopts rule-curve based policy for conservation regulation of the dam developed for three levels viz. upper rule level, middle rule level (critical for irrigation) and lower rule level (critical for water supply and upstream use). The generated simulation model developed by the Water Resources System Group at the National Institute of Hydrology is used to simulate the system operation and to refine the rule curves.

The study deals with flood plain mapping in a part of Yamuna basin between Gangoh and New Delhi. A flood is a markedly high stage of flow in a river and may inundate adjoining lands, which is called the floodplain of a river. So, floodplain is land inundated by a flood of given frequency. Alternately it is also defined as flat land between valley walls.

In this study, HEC 2 programme has been implemented on river Digaru to compute flow regime or the water surface profile for various discharge conditions. In this reach, two bridges have been considered to compute water surface elevations, critical water surface elevations, energy grade elevations & slope, velocity in the channel, flow area, top width and Froude Number.

This is the first in a new series of articles that IWP will host on various aspects of Environmental Flows. We welcome your comments and original articles for this series, please mail us at portal@arghyam.org

The other side of the story: Free-flowing rivers around the world

With around 5100 large dams, India ranks third in the world with regards to the number of large dams. The ongoing debate over the economic, social and environmental costs of large dams has indicated many times that these costs are not commensurate with their benefits. Although we have dammed all our major rivers, (except Brahmaputra and plans to dam its major tributaries are on way, some like Ranganadi have already been dammed), profoundly changing their hydrological, ecological, social and cultural systems, we are yet to form a policy which states that environmental flows in rivers are a necessity. It is more than clear now that environmental flows relate to well being of not only ‘birds and fishes’, but also of the entire human society . Take an example of fisheries, lack of flows in rivers and contractor-owned reservoir fishing has affected the livelihood of hundreds of thousands of small fishermen . Environmental flows also dilute pollution load, so let us not hide behind the fact that pollution is wiping out our riverine fish, not the absence of flows. It is also clear that environmental flows do NOT mean a decommissioning of all the present dams, nor do they mean any random figure like 60% or 10% of MAR . Eflows require reaching a wise compromise through science and local negotiations, for each river.

While many countries have put in place policies and laws for maintaining environmental flows in their rivers, there is also a rarer category: Rivers which have not been dammed yet, rivers which retain their connection from the source to the sea, nurturing myriad ecosystems and communities in their wake! These are known by many names like Free flowing rivers, Wild Rivers, Pristine/ Virgin rivers, Heritage Rivers, etc., each indicating their rare character and value. In ecological and cultural terms, the value of these rivers is immense and as more and more rivers are being dammed the world over, this value is increasing steeply. Unfortunately, in today’s economic terms, these rivers are still waiting to get their due recognition, but as human systems evolve, they will surely be seen as ‘invaluable’ service providers with phenomenal use and non use values.

Organizer: Wageningen UR Centre for Development Innovation

Topics:

• Concepts in wetland and river basin management
• Facilitation of multi-stakeholder processes
• Fieldwork wetland management
• Adult education and social learning
• Curriculum development