Mitigation measures for doubling of the Tiniaghat-Castlerock-Caronzol, SWR Railway track, Karnataka

Abstract

The Indian Railway network, spread across 1,23,542 km (as of 2018-2019), is a vital component of transportation infrastructure since its inception in 1850. The railways have been pivotal in integrating markets, increasing trade, shaping finances besides serving as the backbone of linear transportation services. Even though railways are regarded to be an environmentally friendly option when compared to other forms of linear infrastructure, the development and expansion of rail networks pose challenges to the environment and biodiversity of the forest areas it passes through. Railways can pose both physical and behavioral barriers to wildlife and have negative impacts such as disturbance and mortality on populations living in proximity. The Railway Vikas Nigam Limited (RVNL) has proposed the doubling of the existing railway track between Hospet, Tinaighat, and Vasco Port that measures 345 km in length. The sanctioned project consists of 2 main phases: doubling of a line between Hospet and Tinaighat (Phase I) and between Tinaighat and Vasco (Phase II). At present, the existing single line limits the capacity of running trains in the critical ghat (hilly) section. Given the terrain of the region, landslides during the monsoons interfere with the functioning of the line. RVNL has justified the doubling of the railway track by stating that in addition to improving mobility and all-weather rail links in the region, the proposed doubling would also increase connectivity, trade, and commerce, enhance tourist flow, augment intermediate railway station facilities, and reduce bottlenecks of railway traffic in the ghat section. The Western Ghats that extend along the south-western parts of India, is known to harbour a wide diversity of flora and fauna and is one of the four biodiversity hotspots of the Indian subcontinent. In terms of faunal diversity, the area is home to about 30% of Asian elephant population, about 33% of India's wild tiger population and about 26% of India's leopard population (Jhala et aI., 2019; Jhala et aI., 2020). The landscape forms one of the largest and most contiguous protected area networks in the country. Within the Western Ghats, the Anshi-Dandeli-Sharavathi Valley complex consists of the protected areas of Mollem-Netravali, Anshi-Dandeli, Sharavathi Valley-Mookambika along with reserved forests of Goa which continue to the Sahyadri Tiger Reserve in Maharashtra. The major tiger source population in the complex is that of the Anshi National Park and Dandeli WLS (Qureshi et aI., 2014) that together form the Kali Tiger Reserve. Among the important tiger source populations in the landscape is the Anshi and Dandeli tiger population that provides a critical link to the northern Western Ghats, extending up to Goa and South Maharashtra (Sahyadris), which is threatened by anthropogenic activities such as land-use conversion and construction of linear infrastructure. The landscape is also home to 252 species of amphibians with 90% endemics, 108 species of reptiles with 56% endemics (Dahanukar & Molur, 2020; srinivasulu et al. 2015), and about 600 species of evergreen woody plants with more than 60% endemic. In the past decade, more than 100 species of amphibians and -50 species of reptiles have been discovered from Western Ghats (Aengles et aI. , 2018; Dahanukar & Molur, 2020; reptiledatabase.org). The area where the railway doubling is proposed falls in the Uttara Kannada region of the northern Western Ghats which is known to harbor approximately 50 species of amphibians that constitute almost one-fourth of the total Western Ghats amphibian diversity (Ramachandra et aI., 2012). The approved alignment of the proposed line is parallel to the existing railway line and mostly lies within the railway land. However, the new railway (i)line is deemed to pass through the Kali (formerly Anshi-Dandeli) Tiger Reserve in the Uttar Kannada district of Karnataka and would impact the ecosystem during the construction and operational phase. Considering the irreplaceable ecological importance of the landscape and the critical link it provides for the Western Ghats, the project was required to obtain environmental clearance that included an environmental impact assessment study and a mitigation plan to reduce, offset and mitigate the negative impacts of the proposed doubling. A biodiversity assessment for the proposed line was then conducted by the Indian Institute of Science (IISc) during the years 2017-2020. Environmental and Biodiversity Assessment by IISc Two environmental assessment reports were submitted by IISc (Sukumar and Sitharam, 2017 and Suresh et aI., 2020), detailing the floral and faunal studies of the project area in two stretches of the proposed railway track (Kulem to Castlerock, and Castle rock to Tinaighat). The authors carried out detailed assessments on the vegetation of the area during both study periods, and the structu ral and functional aspects of vegetation, and forecasts of a loss of vegetation in alternative rail alignment scenarios were reported. For mammals, sign surveys, camera trapping, and opportunistic sightings were recorded to assess the presence of mammals near the railway track and to identify areas of high animal activity and movement. As a result, stretches of railway tracks specified by chainages and critical animal crossing zones were reported. General recommendations for mitigation were proposed for such areas. For the herpetofaunal component, the studies documented the diversity and rail kills of amphibians and reptiles in and around the study area. However, no specific mitigation measures were provided aimed at reducing the impacts on amphibians and reptiles. The Wildlife Institute of India (WII) was subsequently requested to undertake the task of proposing mitigation measures for the proposed railway track doubling project by the DIG (Wildlife), Ministry of Environment, Forest and Climate Change, Government of India vide Letter F. No. 6-55/2020WL(part) dated 28th August, 2020 recommending that "detailed study for prescribing mitigation measures in this difficult terrain may be conducted by Wildlife Institute of India, Dehradun. The study may cover the entire 25 km stretch of the project area from Castlerock in the Kamataka side to Kulem in Goa. The objective of the study by WII was to assess the length of existing and proposed railway track to suggest site-specific mitigation measures that will reduce the barrier effect, (ii) allow permeability for wildlife movement across the railway, and minimize rail-induced mortality. We carried out a rapid survey from 19th November to 5th December 2020. The main aims of the exercise were: 1. To assess potential animal crossing zones along the existing and proposed railway track. 2. To carry out inventory of herpetofauna along the railway track, identify potential microhabitats along the track. 3. Coalesce information obtained from field survey with baseline data in IISc assessment reports (2017, 2020), and 4. Suggest site-specific mitigation measures based on the intensive track survey, information obtained from field study and IISc reports. To identify potential animal crossing zones, we carried out camera trapping and sign surveys along the railway tracks. We also used rail mortality data from the Karnataka forest department and any opportunistic sighting or sign encountered during the survey to identify such areas. Visual encounter surveys, opportunistic surveys, stratified plot sampling, and collection of opportunistic rail kill data to assess the herpetofaunal diversity and identify critical zones for mitigation. We also surveyed the entire length of the existing alignment accompanied by a railway engineer to assess the proposed rail alignment, and review the crossing and drainage structures proposed by the railways in terms of suitability for animal crossing. The scope of constructing additional mitigation structures based on topography, probability of animal movement and engineering constraints was discussed on field. Summary of results Camera trapping spanning 660 trap nights yielded 156 captures of 17 mammals species along the railway track. We recorded 203 animal signs through sign surveys of 175 habitat plots near the railway track. A total of 47 species of herpetofauna was recorded during the survey. This number is expected to be higher since the study was conducted within a short period during the non-breeding season. The study revealed that perennial and seasonal streams, and ephemeral water bodies were crucial habitats for herpetofauna. Camera trap data indicated that tunnels along the railway track are being used as natural passages by animals for their movement across the landscape. Hotspots of animal activity were visualized by overlapping all animal signs, sightings, photo-captures and mortality data using kernel density analysis on GIS-platform. These were then combined with the hotspots identified in the IISc reports, and potential multi-taxa animal crossing zones were thus delineated. Mitigation measures for the rai/way track Mitigation measures for the proposed railway track evolved through a multi-step simultaneous process. We first evaluated the existing and proposed drainage and crossing structures on field, assessed the possibility of making the structures more suitable for wildlife movement and constructing additional non-drainage crossing structures, and finally overlapped potential multi-taxa crossing zones to finalise the location and dimensions of the crossing structures.