The history of development is the story of the struggle to achieve human security at the expense of ecological security. The aridity, human thirst, and water control have always been intricately related. The rainfall pattern in India is spatially uneven and temporally skewed; and about eighty per cent of annual rainfall remains concentrated during the four monsoon months. Accordingly, the challenge of water management in India during post-independence was storing the monsoon water in dams and reservoirs and transferring it to the non-monsoon season. The taming of rivers was done for purposes of flood control, expansion of irrigation, and hydro-power generation.
Lack of understanding
To date, flood-control mechanisms in India have been almost completely guided by the colonial legacy of embanking rivers, as well as by the simplistic engineering approach of dam-building. The enduring myth that freedom from floods can ever actually be achieved demonstrates a dramatic lack of understanding of how river basins function. In contrast, farmers in Assam, Bihar and Bengal had an age-old culture of living with floods. Indeed, they welcomed low-intensity flooding, having inherited a uniquely evolved technique of replenishing their farmland with layers of fertilising silt carried by the water, a method called ‘overflow irrigation’.
Despite having functioned well for centuries, such traditions began to disappear during the British Raj. At that point, many rivers in Bengal were embanked in an attempt to combat the annual flooding – including the Damodar, often called the ‘sorrow of Bengal’ due to its frequent flooding. These bunds did ensure security against low-intensity flooding, but the long-term effects were detrimental, leading to the decay of river systems and the congestion of drainage. As recurrent breaches of the embankments and drainage congestion became commonplace, the sense of security provided by the bunds proved to be misplaced. The rivers are not necessarily channels of flowing water; the four components of rivers are flowing water, embedded energy, sediment load, and biodiversity.
Myths in management
The river management in the Independent India was guided by some myths and those are:
- Human society has exclusive rights over the water resources; and the ecosystem services of flowing water have been grossly denied.
- The maximum possible withdrawal of water from the river may serve the greater interest; and, the impact of water withdrawal on downstream stretches was overlooked.
- It was thought that we could intercept and transfer water far away; and, none paid heed to the transmission-distribution loss of water.
- Groundwater was thought to be unlimited, which could satisfy our growing demand.
- The idea of using dam-induced water for twin purposes of irrigation and power generation proved futile.
- The environmental cost of polluting surface and groundwater matters little to society.
- The rivers might be used as the outlets for wastewater.
Be damned
The post-independent India witnessed large-scale dam building, and the work was considered synonymous with development. It is reported that 5334 large dams have been built so far; a further 447 are under construction. The completed structures can at best store 249 BCM of water.The Government of India admitted that less than 40 per cent of the stored water could reach the tail-end of the irrigation command area; more than 60 per cent was transmission-distribution loss.
While the dam-canal network failed to satisfy the irrigation demand, farmers were compelled to rely on the exploitation of the groundwater. The depletion of the groundwater reduced the baseflow towards rivers, and many of them became fordable during lean months. The 784 dams, 66 barrages, and 92 weirs built across many rivers of the Ganga basin have trapped so much sediment load that the growth of the delta is impaired. The littoral islands of the Sundarban are being reduced in size at an alarming rate. So the Indian Sundarban is described as a sediment-starved retrograding delta.
The rivers have been flowing along the lines, which are unquestionably the best possible routes of flowing water. But there was a plan in 2002 to alter the courses of rivers, popularly known as ‘Interlinking of Rivers’. The idea was to modify the delicately balanced natural system and introduce a controlled hydraulic system to combat the twin problems of flood and drought. It was decided to divert 174 billion cubic meters of water from the so called excess areas to the deficit areas to irrigate 35 million hectares of land. The plan was to divert water from the Ganga-Brahmaputra Basin to relatively dry peninsular rivers to achieve a hydrological equity.
Flow versus irrigation need
While there is nothing called excess in the perfectly balanced hydrological system, the proponents of the mega project declared the monsoon freshet in the Ganga-Brahmaputra basin as excess and the water that drained to the sea as ‘wasted’. The community-based water-harvesting plan that would have been eco-friendly and cost-effective, was grossly denied. The Indian agriculture presently consumes more than 80 per cent of the usable water in the country. The introduction of water-intensive crops replacing the drought-resistantones has aggravated the water crisis. Unfortunately, while the official storehouses are engrossed with 770 million tonnes of food grains, about 195 million people in India are undernourished!
The flood-control embankments caused horizontal disconnectivity of rivers from their floodplains and impaired the sediment dispersal mechanism; the dams and barrages led to longitudinal disconnection of the flowing water and interrupted the ability to transfer sediment load. Further, it caused habitat fragmentation and loss of biodiversity. The water was diverted without considering the crucial ecological flow in rivers necessary for biodiversity and the well-being of millions. We need to explore a rational meeting point between the volume of water that can be withdrawn for irrigation and the flow required for the functioning of the ecosystem.
Kalyan Rudra is a geographer by academic training being specialized in river and water management; presently the Chairman of the West Bengal Pollution Control Board.