Blames mining and other human interventions
The Pampa is no longer a continuum, especially in summer when the river turns into a chain of pools and grassy islands, says a recent study.
The river-bed is dotted with pools as deep as four to eight metres, it says, attributing the problem to indiscriminate mining of sand.
N.K. Sukumaran Nair, general secretary of the Pampa Parirakshana Samithi (protection committee), which organised the study, told The Hindu here on Monday that a team, including him, had conducted the study between the Kizhavara Kadavu, near Aranmula, and the Ranni bridge to assess the degradation of the entire riverine system during the past decade and a half.
A CESS study report by its senior scientist D. Padmalal, who was involved in the present study, on the sand budget of the Pampa was taken as the benchmark for the assessment.
The team included T.N. Ramakrishna Kurup, president of the committee, K.R. Vinayachandran Nair, vice-president, and M.V.S. Namboodiri, executive committee member.
The study has found that the pools formed are connected by streams along certain stretches, especially downstream. Most sand deposits and sandy plains, recorded by CESS previously, have shrunk or disappeared. Some sand deposits have turned into grass isles where cattle graze.
The unscientific removal of construction-grade sand, using an illegal ‘pole-and-net mechanism,' from the river-bed has wreaked havoc on this once-perennial freshwater source in central Travancore, it says.
Dr. Padmalal said the pools had led to a manifold increase in the level of total suspended sediments in the river-water column in sheltered environments during floods.
Such an increase, along with ‘channel incision' (lowering of the river-bed), is responsible for the prolific growth of vegetation on the sand deposits. Although pure sand seldom supports vegetation, the silt admixture in it does so. The sewage outflow and disposal of solid waste from various development centres on the river banks may further fertilize the deposits and provide a favourable sub-stratum for dense growth of plants.
A 1995 CESS report says such deposits, locally known as ‘Manalputtu,' were confined to the Sathrakkadavu area, near the Aranmula temple ghats. And now, except the deposits at Varavur and Cherukolpuzha, the river reach under study has been considerably degraded, turning into stabilised islands with vegetation.
The once-abundant sand deposits at Maramon has totally degraded, leaving the river-bed a slushy grassland. The discharge of sewage from the Kozhencherry township and silt from the sand-mining centres upstream during high-flow seasons are responsible for the accelerated growth of grass and other vegetation here.
The study says that a 417-metre-long unscientific granite protection wall built along the Maramon convention venue on the river-bed has been counterproductive.
Another important observation made by the expert team is the sad state of various drinking water supply schemes tapping the river water. The Pampa is a major source of drinking water to several lakhs of people. The fall in the water level consequent on the lowering of the river-bed and river degradation has affected the water-storage capacity of the river, especially during summer. The decline in base flow and the prolific growth of weeds in the river channel lower the availability of water at the intake points of the schemes.
River degradation has affected the lift irrigation schemes. The team has stressed the need to make earnest and concerted efforts to contain the ill-effects of the indiscriminate sand-mining and other human interventions to restore the Pampa to its old glory.
The study calls for stringent measures to regulate mining, strictly on the basis of sand-auditing as envisaged in the Kerala River Bank Protection and Sand Mining Regulation Act, 2001.