WEDNESDAY, APRIL 24, 2024
Antonio Mascarenhas
The wetlands of Goa of which khazan domains form an integral part, seem to be gaining prominence at present, but simultaneously these fertile agro-ecosystems are constantly in the news for many wrong reasons. The precarious condition of some of these ancient productive lands due to human impact have been highlighted by scientists in various fora as well as the routine press reports. Khazans have been intensely described over the years but mostly from a historical perspective. Few recent reports on ‘Khazan ecosystems of Goa’ by Sonak, and earlier the ‘Khazan land management in Goa’ by Kamat, have attempted certain crucial issues based on available data. Surprisingly however, scientific research activity dealing with a multifaceted study of khazans was never undertaken. Thus, several issues remain as mere speculation for want of scientific evidence.
The Government of India had issued a notification entitled “Wetlands conservation and management rules in 2017. This document had mandated the constitution of a ‘Goa Wetland Authority’, in place since 2017. Some of the key objectives are: (a) an integrated management plan” which describes strategies and actions for achieving wise use of wetlands, management actions required, detecting changes in ecological character for measuring the effectiveness of management; (b) prepare a list of wetlands to be notified; (c) recommend identified wetlands for regulation under these rules; (d) prepare a comprehensive digital inventory of all wetlands (e) develop a comprehensive list of activities to be regulated; (f) define strategies for conservation; (g) ensure ecosystem functions (such as water storage, groundwater recharge, flood buffering) and values (such as recreation and cultural) are maintained or enhanced. Here again, the document does not offer any scope for research that is needed, and data to be collected to understand the evolution, role and functions of khazans from a scientific viewpoint.
Several topics that call for a scientific approach need attention:
(1) The geological evolution of Goa wetlands was never attempted. Such research is essential so as to understand the formation, accretion and temporal growth of wetlands during the recent past. A closely spaced, vertical, subsurface sediment sampling is needed to identify the chronology of events. (2) The distribution, diversity and richness of flora and fauna is not studied, and hence would need extensive contributions from botanists and ecologists. Plant species need scientific documentation. A data inventory of plant communities is imperative. (3) Invasive floral species in khazans have been noted at several sites. The type of these plants is unknown. Alien vegetation is known to expand over native plants, a process that often occurs in wet regions. Weeds commonly lead to oxygen deficient conditions. Unless undesirable vegetation is identified and removed, our wetlands are bound to get converted into anoxic wastelands. (4) Invasion by mangroves into the khazans due to natural or man-made breaches in bundhs has resulted in the loss of cultivable lands and paddy fields. Large areas are colonised by mangroves. A remote sensing study with latest pictures, aided by ground truth, will reveal to what extent mangroves have expanded into erstwhile paddy fields, and how much fertile land is lost due to invasion by mangroves.
(5) Embankments for rail and roadways across wetlands have, for example, bisected the Carambolim – Mandur – Neura – Agassaim khazan. Field checks show clear differences in vegetation patterns on either side of these structures. The new bypass being built through the khazans of Salcete will create similar problems as only few cross culverts are seen. Water stagnation on the landward side is the major cause for the emergence of strange plant species due to a disruption in the free flow of water. (6) Tidal regimes within creeks, lagoons and backwaters are not documented. The net tidal influx at distal narrow ends of creeks is generally higher than within rivers. Since some khazans are located at or below sea level, a slight breach in the encircling bundhs can induce extensive flooding of lowlands, as already observed at places. (7) Anthropogenic impacts of reclamation of wetlands need urgent restoration measures as low-lying fields are being taken over at a rapid pace. A study of multi-dated satellite imageries, supplemented by ground data, will accurately identify khazan areas sacrificed under the banner of ‘development’. (8) The role of man in reclaiming land from the sea is a contentious topic. Most historical records insist that khazans were created artificially. Where was the position and level of the sea at that time? What were the ancient engineering methods employed to accomplish this feat? Where did the huge volume of sediment come from? How were the surface levels achieved along the entire length of Goa?
The urgent need for a comprehensive policy for the conservation and management of wetlands has been discussed by several authors. The ‘comunidades’ of Goa, the original custodians of khazan lands, are storehouses of knowledge related to the functioning of khazans; these bodies are ignored and rarely taken into confidence. The local stakeholder is the ultimate beneficiary of khazan management. But pending a scientific conservation policy, the destiny of khazans is rather dreadful.
The above discussion forms only a gist of certain issues that merit attention from a scientific viewpoint. Wetlands are geological units of recent age. Understanding their evolution in space and time is a prerequisite for management. In particular, the long-held belief that khazans were reclaimed from the sea by our ancestors needs a solid geo-technical backing with geological data for a time series geo-chronological analysis. Such research has rarely been attempted except, to our knowledge, a paper on ‘ancient mangroves of Goa’ by this author about two decades ago.
(Dr Antonio Mascarenhas is a former Scientist, NIO, Goa)
