Large dams not an answer to water shortage
It's that season again: when the prime minister, the Union and state ministers for agriculture and water resources, the Planning Commission, the World Bank and others busy themselves in finding a panacea for agriculture's ills. In fact, they do have a surefire solution: increase water storage capacities through large dams.
This advocacy has assumed fundamentalist proportions of late, spurred on by the World Bank's 2005 report: India's Water Economy: Bracing for a Turbulent Future. But many questions have not even been asked. What are the options for water storage? How does one choose the best among them? Who makes the choice? What has been the experience with large water storages created at enormous costs? Have they delivered on their promises? Can we do anything to get them to perform better?
The Central Water Commission monitors a mere 76 of the over 4,000 large water storages, regularly.The agency's bulletins throw some light on the performance of these reservoirs. The information available for the last 12 years (1994 to 2005) reveals:
On an average, every year, 36.25 billion cubic metres (bcm, equivalent to 7.7 Sardar Sarovar Projects) of live storage capacity isn't filled -- remember, we are talking of only monitored storage capacity: 133.021 bcm
This means that annually an average investment worth Rs 37, 793 crore has remained unutilised
This has happened when in seven of the 12 years, the rainfall was average or above average.
Should we not try to find out reasons for such horrific underperformance? What can we do to ensure better use of existing capacity? To understand what exactly is going on, we would need a disaggregated analysis. But, the available figures by themselves are alarming enough to warrant an analysis of the state-of-affairs. Let's examine the state of two of the country's reservoirs:
bhakra: Between 1989 and 2005, it has never been filled to its full reservoir level of 514 metres. It must be recalled that Bhakra now gets a very large proportion of its flows from Beas river, where as to begin with, it was designed to store water only from the Sutlej river.
vaigai: Water for irrigation was released from this reservoir, according to recent reports, after a gap of twenty years. The reservoir did not have sufficient storage for the last twenty years.
One possible reason for such shocking underperformance is that the storage capacity of the reservoirs is way beyond the hydrological viability of their catchment basins. Overexploitation of groundwater in the upper basin could also have reduced inflows downstream.
There are other related matters crying out for attention. According to the 1999 report of the National Commission for Integrated Water Resources Development, about 1.4 bcm of existing storage capacity gets silted up every year. At today's rates, this means a loss of Rs 4 crore every day. Treatment of catchment areas of these reservoirs can significantly stop the siltation rate. But catchment area treatment is almost never done on ground -- though money is spent on paper.
In the lopsided pursuit of water storage through large dams, the government has neglected the much larger potential of small storages. Recharging of groundwater aquifers has been similarly ignored, though the two are possibly the most benign options.
In fact, the government does not even have a figure on the capacity of small storages in the country. One would have expected that the three minor irrigation censuses by the Union ministry of water resources would have looked into this aspect, but that has not been the case.
Government officials will usually tell you that the combined capacity of small storage facilities in the country is 3 bcm. They have been harping on this figure for two decades, at least. That it's a preposterous estimate is evident from the fact that the storage capacity of minor projects in Maharashtra alone is 3.733 bcm, as per state government's website. The capacity across the country is likely to be over ten times this figure.
The country urgently requires a credible and transparent assessment of the state of its water storages. Such an assessment will also help arriving at better decisions for future projects. In the meantime, it may help to put at rest the motivated advocacy for large water storages, and instead devote attention and resources to arresting siltation of existing storages and getting better performance from them. Groundwater recharge and small projects will take care of additional storage needs.
Himanshu Thakkar is with the South Asia Network on Dams, Rivers and People, Delhi