The Mandovi and the Zuari estuaries of Goa hold unique treasures in the form of variable stretches of sandy beaches, a feature that only a few world estuaries may boast of. Coco, Campal, Miramar and Caranzalem in the Mandovi, and Vainguini, Odxel, Siridao and Kariwado in the Zuari estuaries comprise coasts with notable sandy deposits. Of these, Miramar and Kariwado have borne maximum brunt from human activities as sensitive ecosystems are treated with impunity, and thus need urgent attention from a coastal management viewpoint.
Miramar is the most dynamic beach of all the sandy shores of Goa. The coast shows unique geomorphological patterns as the prominent sand bar erodes and accretes seasonally, and beach width oscillates by about 150 metres periodically. Miramar beach is located along the southern bank of Mandovi estuary, about 3 km west of the capital city of Panjim. Prominent 5 m high well-formed dunes carpeted with luxuriant bushy vegetation are identified here, but grade into lower dunes towards Caranzalem. This stretch constitutes the only sand dune belt within the estuaries of Goa.
Sadly, Miramar presently represents a brutally wounded beach as over-use and overcrowding has taken a heavy toll on this dune field. A significant portion (140m x 145m) of about 21,000 sq mts adjacent to the traffic circle has been opened up and is now bare, flat and completely devoid of dune vegetation. Removal of vegetation that acts as sand binders is attributed to trampling by excessive footfalls, being one of the three most frequented beaches of Goa. Cultural events and sports activities also end up damaging dune plants and flattening dune sands. Shockingly, the tourism watch tower is wrongly located on a dune field; movement of jeeps has damaged vegetation and exposed sand across the dunes. To add insult to injury, the recent grounding of a vessel in the surf zone caused dune retreat of about 5 metres with a vertical scarp of about 1.2 metres, along 50-70 metres of the shoreline.
The most severe impact is the wind-blown sand that ultimately accumulates at the roundabout. During windy days, large quantities of sand are blown inland. As a result, the Miramar roundabout in particular, and the road opposite the local school are covered by sand for most part of the year, creating nuisance to road users, hazards to motorists and dangerous conditions for traffic. Sand is thus rendered loose. Such a continuous loss of beach sand since decades may prove detrimental to the very existence and stability of Miramar beach.
The coast of Kariwado, oriented NNE-SSW, constitutes a 1.1 km long fishing enclave of Vasco city. In general, the eastern part consists of a sandy beach but the western part is devoid of sand. This part of sea front is severely degraded as a variety of waste material is scattered along the water line.
The recent evolution of Kariwado beach can be compared using multi-dated Google Earth (GE) satellite images of the period 2002–2016. The following features and shoreline changes can be identified: 12/2002: a very narrow sandy beach; habitations are sparse; 12/2003: the beach gets narrower; 01/2005: a wide beach all along the coastal strip; 01/2006: a wide beach almost up to the fishing jetty in the west; 02/2010: the entire coast shows a significantly wide beach; 04/2010: the beach has accreted evidenced by a long and wide beach; 02/2013: only the eastern part shows a narrow beach; 03/2014: the entire beach seems to have disappeared; 11/2014: a shorter beach is noted; western part completely devoid of sand; 04/2015: the beach gets narrower and shorter; note heavy wave activity; 12/2015: a longer sandy beach can be identified;03/2016: a sandy beach about 400 metres in length; dense habitations are observed.
Based on the above comparisons, the following is observed: (a) Over the years, a sandy area is found only at the eastern half of the coastal strip almost at all times of the year; (b) In comparison, the western part is under the grip of chronic erosion; (c) A multi-dated analyses reveals that the sandy portion accretes and erodes showing that this process may be annual and/or cyclic; (d) The habitations in the western part have increased dramatically over the last decade; (e) Some of these structures have invaded the beach; (f) It is well known that human interference on sandy areas leads to damage of dunes/backshore leading to sand starvation; (g) It is also possible that ever since the berth 11 was constructed in the early 1990’s (and the area deepened to 13 mts), the impact was that the beach sand got drained into the channel; (h) Elders from Vasco city clearly recollect that a normal sandy beach existed all along the 1 km long coast; this beach vanished over time.
As a consequence of excessive gatherings, Miramar beach is flattened considerably and is losing sand due to eolian transport, a process occurring over the last 35 years at least. The excessive mobility of sand needs to be curtailed on priority. Concerted efforts of dune (re)building and restoration, as successfully attempted in 2007, are called for. In comparison, Kariwado beach is under the grip of chronic sand loss due to marine erosion.
The navigation channel within the bay is routinely deepened, and considering sediment starvation (manifested by erosion) at this site, the beach morphology needs to be studied to ascertain whether (a) the dredging of the channel or (b) human interference is the cause of prolonged erosion.
(Dr Antonio Mascarenhas is a former Scientist, NIO, Goa)
