Staff Reporter

Study of dynamics between earth and river flow systems will provide a proper remedy

Faults traced near Upper Anicut and Grand AnicutRivers while crossing such zones will have sluggish flow unable to carry their own load and flood adjacent plainsNeed for study on dynamics of flow in upper catchments of the Araiyar and the Koraiyar rivers

TIRUCHI: Aided by high resolution satellite-based pictures taken in the wake of flood in Tiruchi region, the Centre for Remote Sensing and Geosciences, Bharathidasan University, has identified two faults (deep earth cracks) one near Upper Anicut and the other near Grand Anicut.

The observations point to two major faults, continuing from Pondicherry to Cumbum Valley along Tiruchi.

There is more to flooding of Tiruchi region than sand choking in riverbeds, sand mining and encroachments, said SM. Ramasamy, Director of the Centre.

He said though these factors need to be looked into, only detailed study of the dynamics between earth and river flow systems will provide a proper remedy.

Confined to the faults, the `mega-eyed drainage,' formed by the splitting of the river south of Upper Anicut and rejoining in Grand Anicut, with Srirangam in between, is unusual since the river, having neared the coastal zone, could branch off.

The occurrence of extensive braided channels in the Cauvery, quick sand, convergence of ground water flow from either side of the faults, and water logging in certain sectors, amply document an ongoing land subsidence (caving in) in the central Tiruchi region, entrapped along these faults, says Prof. Ramasamy.

Sluggish mother channel

As per the dynamics, rivers, while crossing such zones of land subsidence, will have sluggish flow, unable to carry their own load, and thus flood the adjacent flood plains to reduce the load.

However, the flooding of Tiruchi was due to water overflowing from the Ayyar, the Uppar, the Araiyar and the Koraiyar rivers, which could not discharge water into the upper plains on either sides of the Cauvery, the mother channel, where the flow was already sluggish.

The flood management in Tiruchi region warrants detailed study on dynamics of flow in the Cauvery as well as upper catchments of the Araiyar and the Koraiyar rivers.

The floodwater in these tributaries could be cascaded by linking them with chains of water bodies located upstream, he added.

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