The recent spate of projects announced by the central government appears to have created a flutter across Goa. One such issue is the “nationalisation” of rivers. A whatsapp group called ‘Our Rivers Our Rights’ is extremely active with incessant posts across the world. Discussions within the group indicate that certain issues are not at all understood by the society in general and stakeholders in particular, but there is no doubt that there seems to be no respite for our water ways. Of all rivers, the Mandovi is the most impacted, and as such, has undergone large scale landform changes and borne the maximum brunt of human actions.
The seven major rivers of Goa are influenced by tides by which water level rises and falls twice daily. The Coastal Regulation Zone (CRZ 2011) laws that govern human activities along Indian coasts guarantee protection of tidally influenced water bodies of India. Unfortunately, CRZ rules neither propose strategies for conservation of saline waterways nor does it guarantee the restoration of impacted river systems. In general, river banks of Goa are categorized as CRZ III, mangrove marshes qualify as CRZ I, and the saline water bodies as CRZ IV. The 100 metre strip or width of river is the No Development Zone. As such, the issue of “nationalization” cannot overrule the CRZ 2011, an act of parliament.
The issue of river dredging seems to have caught the attention of the public at large, the fisher community in particular. Should our rivers be navigable? What type of marine craft should be entertained? To what distance in the hinterland should vessels ply? A meaningful conservation and management policy for Goan rivers appears necessary. The evolution of our waterways during the last 50 years at least merit a scientific debate. The impact of natural processes and human actions along estuarine and river banks need to be identified. Therefore, following issues merit a thought:
(1) Sand spits at river mouths: Tiracol, Chapora, Sal, Talpona and Galgibaga rivers have accumulated elongated spits as a consequence of sand transport by littoral drift. Being highly dynamic, spits change in space and time, thus creating navigational hazards. Management initiatives are needed to: (a) Restrict the growth of the spit, by removing excess sand; (b) To fix the ‘managed’ sand spit once the deposit attains a desired dimension, or can be stabilized by appropriate plantations; (c) To manually transport excess sand and dump at places where sand dunes are damaged.
(2) Sand shoals within estuaries: Large areas where sand bodies get exposed at low tide are noted at Chapora, Sal and Galgibaga. Fishing trawlers often run aground. These sites can be dredged up to a minimum depth as required by trawlers to navigate out of the river.
(3) Formation of islands within rivers: Composed of fine sediment, several islands have increased in dimension over decades. A cursory look at Google Earth images reveal 5 in Tiracol, 6 in Chapora, 4 in Mandovi (in addition to Chorao), 1 in Zuari, 3 in Sal and 1 in Talpona.
(4) Concretisation of river banks: Scientific research has confirmed that hard structures exacerbate erosive processes, river banks get narrower, sediment vanishes over time, and the area gets deeper; retaining walls thus lead to a complete modification of coastal landforms and associated vegetation; mangroves simply disappear. Unjustified landscape alterations adversely impact micro habitat of many faunal assemblages; wild otters get trapped inland and take a heavy toll on riparian biodiversity. Concrete embankments should be banned.
(5) Mangrove proliferation at wrong sites: Dense mangrove forests now occupy erstwhile paddy fields, salt pans and ‘khazans’ as in Candolim, Patto–Ribandar, Rachol to Macazana, and from Carambolim to Agassaim, the largest ‘khazans’ of Goa. Also, the Patto–Ribandar causeway engulfed by mangroves needs a special strategy, so that the heritage structure maintains its identity.
(6) Fringing mangroves are endangered: The Chapora estuary is one example where fringing mangroves have disappeared in totality; whereas Panjim river bank has no mangroves left, only a few patches are visible on Betim side.
(7) Mangrove islands/ marshes as bio-reserves: The mangrove lagoons at Paliem, Patto– Ribandar–Merces mangrove complex, Cortalim-Quelossim backwater system, Agassaim–Durbat mangrove ecosystem, Rachol-Macazana ‘khazan’, all contain dense, luxuriant natural mangroves.
(8) Jetties and platforms: Jetties invariably induce accretion/erosion either upstream or downstream, as seen at Old Goa. Here EIA’s are imperative to confirm where jetties are best suited.
(9) Barge building yards: A large number of discarded barges have sunk and may have to be dismantled. No policy was ever in place as to how dockyards can fit in our river systems.
This report is by no means exhaustive. Intensive cross-sectoral deliberations by scientists, bureaucrats, politicians and coastal managers are needed. Importantly, public views have to be considered. Spits at river mouths and shoals within estuaries need solutions from coastal management viewpoint. Concrete embankments through swampy river banks have to be banned forthwith. Only floating jetties should be promoted. Proliferation of mangroves at wrong places (paddy fields and khazans) needs to be curtailed, but vigorously promoted as fringing mangroves (river banks). Shallow dredging can be attempted at specific sites only. River “nationalization” cannot overrule CRZ laws. A science-based river conservation and management policy for Goa is therefore an obligation.
(Dr Antonio Mascarenhas is a former Scientist, NIO, Goa)
