The indiscriminate human intervention mainly by unscrupulous removal of sand from the beds of the major rivers in Kerala such as Pampa, Periyar, Bharathapuzha, Manimala etc., has transformed them into vast stretches of grazing lands following prolific growth of vegetation.
Urging all the authorities concerned to initiate concerted efforts to regulate the sand mining activities based on sand auditing as envisaged in the ‘Kerala River Bank Protection and Sand Mining Regulation Act, 2001' a team of experts warned that failure to do so might ring the death-knell of several rivers in the God's Own Country as the very characteristics of the rivers have been changed.
“Although pure sand seldom supports vegetative growth, the silt admixture in sand could support vegetation. The sewage outfalls and disposal of solid wastes from developmental centres located on the banks of the rivers may fertilise the deposit further, and hence provide a favourable substratum for dense growth of plants,” experts said.
As a result, vast stretches of such grasslands in the rivers can been seen from the bridge across Periyar on the Perumbavoor – Kalady road and in the holy river Pampa down stream the Kozhencherry bridge.
Water scarcity
“While it would lead to the gradual death of the rivers, it is threatening the very existence of natural water resources in the State as removal of sand lowered river bed and that in turn reduced the water holding capacity of rivers. Acute water scarcity is experiencing in the river basin even though Kerala have received moderately fair summer rains, pointed out experts.
The expert team of scientists and engineers under the auspices of the Pampa Parirakshana Samithi (PPS), an environmental organisation, conducted a field survey last week to study the present status of River Pampa found further environmental degradation of the river following continuous human intervention.
Sand budget of Pampa
The study report on the sand budget of Pampa river prepared by Dr D. Padmalal of Centre for Earth Science Studies (CESS), Thiruvananthapuram, was taken as a bench mark for assessment of the extend of degradation caused by the river over the past 15 years, Mr N.K. Sukumaran Nair, the PPS General Secretary told Business Line.
The expert study team observed that that the river has lost it's continuum in summer months as it is turned to a series of pools and grassy islands. The individual pools of 4-8 m water depth, resulted from indiscriminate scooping of sand, are often connected by a stream-let of water in certain stretches, especially in the downstream side. Most of the sand deposits and sandy plains, recorded by CESS previously, are either partially or completely disappeared.
Some sand deposits are turned into grass isles/ grasslands. Local people use the grass blanketed areas for grazing their livestock. The unscientific removal of construction grade sand using pole and net mechanism widespread in the river is the Villain to these changes.
The process could enhance many folds the Total Suspended Sediment (TSS) level in the river water column which in will be deposited in sheltered environments during flooding. This along with the channel incision (river bed lowering) is responsible for the prolific growth of vegetation over the sand deposits. The degradation has reached such a level that several stretches have become stabilized vegetated islands.
In fact, the sand deposit at Maramon is now totally changed to a grass land. The discharge of nutrient rich sewage from the Kozhenchery township and silt reaching from the sand mining centres upstream during high flow seasons are responsible for the accelerated growth of grass and other vegetations.
The unscientific granite structure for about 417m length, indented mainly for protecting the sandy plain at Maramon is counter productive as it contribute a low energy zone behind the granite construction.
On the other hand, the narrow active channel between the granite structure and the right bank acts as a flow amplifier and hence accelerating erosion of sediments in an area naturally meant for deposition. All these, in one way or the other, contribute a favuorable environment for the prolific growth of weed plants over the sand deposit.
Poor drinking water schemes
Another important observation made by the team is on the sad State of drinking water supply schemes. The river is the major source of drinking water to several lakhs of people in the Pampa river basin. The lowered water level consequent to channel incision and river degradation adversely affected the water storage capacity of the river, especially in summer months.
In order to make water supply steady, the Kerala Water Authority has to construct newer and newer intake structures every year. Last year, Mr Nair said, the authorities have to abandon the old intake structures and construct a new deep well in the middle of the river close to the active channel for water abstraction.
He said the authorities are now coming with a new proposal to remove the grass blanket over the sand deposit. The team of experts strongly feels that the proposal has to be implemented only after proper scientific studies by a competent agency. Mere removal of vegetative growth will not give fruitful and sustainable results as the root cause for degradation still persists. Treatment is needed for the root causes of environmental degradation and not for the surface.
The team also had three learned Senior Citizens residing on the bank of the River Pampa, apart from Mr N K Sukumaran Nair, Professor M.V.S. Namboothiri (Executive committee member), K.R. Vinayachandran Nair (Vice-President) and Professor T.N. Ramakrishna Kurup (President) of the PPS.