THE ever-increasing demand for river sand following the construction boom in Kerala in recent years has led to indiscriminate sand mining, resulting in the destruction of the riverine ecology system.

In fact, there is no sand left in the rivers of Manimala and Achankoil while it is available only in Pampa in a stretch between Ranni and Kozhenchery in Pathanamthitta district.

Therefore, the mining has been concentrated in this region. Revenue authorities conduct monthly auction and permit the highest bidder to quarry 14truckloads of sand daily.

But, instead 50-60 truckloads of sand is mined and transported from the permitted `kadvu' point in the river. Unauthorised mining is also going on unabated in the river, which is estimated at around 50 truckloads of sand daily.

The auction price per truckload ranges between Rs 400 and Rs 900. When it reaches the construction site, the cost goes up to Rs 3,500 to 4,000 depending on distance. As river sand is not available in other districts it is supplied to buyers in those areas also, an official said.

One of the points seeing hectic mining activity is Mokkannur in Ayroor Panchayat, while unauthorised quarrying is taking place at Edapavoor and Varavur in the region.

Ever since the responsibility of granting permission was vested with the Revenue Department, no `kadavu committee meeting' had been convened, Mr Jagmohan Das, a member of the committee, told Business Line. He said according to the rules, trucks are to be parked away from the quarry. Also `vallams' (country boats used for bringing the sand to the ghat) having no licence were not allowed in the ghat. But these restrictions were being flouted.

Sand mining from the rivers has resulted in lowering the riverbed. According to a recent report by the Centre for Earth Science Studies (CESS), Thiruvananthapuram, the riverbed in Anchankovil at Thumpamon had been lowered by 136 cm that in Manimala at Kalloopara by 120 cm and in Pampa at Malakara 123 cm.

Besides, small islands of thickets have come up in all the rivers and that, according to experts, shows the `ailing stage' of the river system.

According to CESS reports, the volume of sand mined from these rivers is 32 to 100-fold more than the sand that arrives in the riverbed every year after the monsoon rains.

Restrictions have been in force for over a decade now, but are not being enforced, Mr N.K. Sukumaran Nair, General Secretary, Pampa Parirakshana Samithi, an NGO, told Business Line.

The local people, worst hit by the indiscriminate sand mining due to the fall in underground water table and sliding of river embankments, are supposed to be vigilant and report such mining to the authorities but are maintaining silence.

According to CESS sources, the whole river sandbed used to act as a natural check dam because of the voids of 45 to 50 per cent in the soil where the water is retained. "This phenomenon maintains the ground water level in all the catchment areas and the river basin". When the riverbed level falls, the hydraulic gradient increases, leading to higher velocity. As a result, immediately after the monsoon, the water flows into the rivers are drained out quickly.

Unlike in the past, rivers are filled during the rains but after a few days of dry weather, the level goes down, the sources said, adding "In the absence of sand, no natural retention of water takes place." Environmental degradation is pointed out as the reason for such a dangerous situation.

According to a study of the Kozhikode-based Central Water Research establishment, the water availability by 2050 in the rivers Achankovil, Pampa and Manimala would drop by 459 million cubic metres, 3537 million cubic metres and 398 cubic metres, respectively.