Consider this: “Salcete gets ready to boycott CZMP”; “No let up to opposition to CZMP”, are some of the disturbing headlines in the media. The turmoil being witnessed along the littoral villages of Goa since the last two months yet again shows that all is not well with the development and management of coasts. The CRZ 2011 guidelines mandate that coastal zone management plans (CZMP) ought to have been prepared then; but the draft plans have been opened for suggestions in 2019. Unfortunately however, these proposals do lack vital components, reasons for the outcry in every coastal or riverine village. Here, only a few topics of major importance are presented from a scientific viewpoint.
(1) Demarcation of High Tide Line (HTL): Based on CRZ 2011 rules, the HTL is defined as “the line on the land up to which the highest waterline reaches during the spring tide” and shall be demarcated in all parts of the country.HTL (and LTL) shall also be demarcated in the CZM maps along banks of tidal influenced inland water bodies with the help of the geo morphological signatures or features. The 500-metre and 200-metre lines with respect to the HTL need to be shown. The above definition of HTL takes into consideration inundation due to maximum tide (spring tide) and also the wave uprush during monsoon choppy seas. The criteria used for HTL mapping include: (a) Vegetation line is the seaward most boundary up to which ‘ipomoea’ creepers advance, mostly in a linear fashion, also marks the base of dunes, and can also be called the dune line. Although the most stable, frontal vegetation may be obscured at places due to footfalls/trampling. (b) Beach berm is a sandy crest from where the beach slopes abruptly sea ward, often considered as HTL. (c) Sea walls or embankments wherever present are the direct indication where marine water can reach, hence the HTL limit. (d) The base of cliffs, promontories or rocky shores marks the maximum reach of sea waves. (e) Wherever dunes are eroded, the foot of the vertical scarp is the HTL. (f) In the case of mangroves, wetlands or marshes the issue of HTL may be slightly complicated due to large horizontal marine transgression and needs field verification.
A look at the CZMP, the demarcation of HTL appears disputable. In Candolim, the berm, a feature found about 20-25 metres ahead of the dune, is marked as HTL. Similar seems to be the case from Calangute towards Baga where a berm has found favour. In Sernabatim, the vegetation line is taken, as is the case for most parts of Salcete coast. In Miramar, the dense vegetation line is distinct on any satellite image but it is not clear from the maps supplied whether vegetation boundary is considered. In Morjim, the vegetation line of the turtle nesting site is indeed the HTL, as is the case in parts of Mandrem and Arambol. In Querim however, the HTL mark is easy due to the sea wall, but this structure is not shown. The HTL issue needs a revisit. A sandy berm is unstable and flattens easily; in comparison, dune vegetation is a stable point up to which dune vegetation advances and stabilises. The vegetation line must be marked uniformly (and extrapolated wherever obscured) along the entire sandy coast of Goa. Therefore, HTL mapping certainly needs a relook.
(2) Mapping of sand dunes: Delineating coastal sand dunes of Goa became necessary following a court order in 2015. Assigned to National Centre for Sustainable Coastal Management (NCSCM), Chennai, (an undated) report was submitted in 2018. It reveals the following: Arambol, Morjim, Mandrem only some tiny dune patches; Calangute, Candolim hardly any dunes present; Miramar devoid of dunes; Cansaulim, Arossim, Utorda without dunes; Majorda, Consua, Colva few patches shown; Betalbatim, Sernabatim has only half the coast with dunes; Benaulim, Varca, Cavelossim shows discontinuous small patches; Agonda and Galgibaga do not feature at all. The document dealing with occurrence and distribution of coastal sand dunes is rather shocking and leaves much to be desired.
Sand dunes of Goa have been researched by NIO scientists since the 1980’s. Wagle (1989) had mapped the coastal dunes of Goa using aerial photographs; maps reveal that all sandy coasts of Goa are invariably backed by linear active pioneer dunes, stabilised dune fields, and a series of parallel beach ridges. At places, dune complexes of Salcete are more than 350 metres wide. Agonda, Palolem and Galgibaga were marked by linear sand dunes, albeit a narrow strip. Subsequently, Mascarenhas (1998, 2009) reported field based morphological features and methods to restore degraded dunes. The entire coast of Salcete, from Cansaulim to Mobor, is backed by majestic linear dune belts, with dune peaks of 7-8 metres height. Miramar consists of low dunes capped by luxuriant vegetation. Candolim-Sinquerim still has massive sand dunes. Morjim-Arambol dunes are prominent, except at places. Yet, the NCSCM has ignored all such work and publications done earlier by NIO; bibliography of the report is pathetic.
(3) Mangrove proliferation: Mangrove forests being conspicuous on satellite images are easily mapped. It is known that mangrove cover has increased five-fold during the last 25 years or so. It is well known that mangroves function as opportunistic colonisers of soft soils. These trees are presently thriving where they should not grow (paddy fields), but are vanishing from their rightful places where they belong (river banks). Such an invasion of mangroves has resulted in loss of cultivable fields and decline in livelihood and agro activities. Therefore, their evolution needs to be curtailed at certain places (paddy fields and khazans), but promoted at appropriate places as fringing mangroves (river banks). The CZMP ought to have presented management solutions, but have not, also indicating that consultations with farmers never happened.
(Dr Antonio Mascarenhas is a former Scientist, NIO, Goa)
