Western Ghats land erosion highest in TN, Gujarat in last 30 years: IIT-B study

Mumbai, Nov 26 (IANS) The picturesque UNESCO World Heritage Site, the 1,600 km-long Western Ghats Region (WGR) -- one of the 35 Biodiversity Hotspots on the planet -- is plagued by heavy and rapid soil erosion owing to multiple factors, warns a new study by IIT-Bombay.

The study by the Centre for Technology for Rural Areas (CTARA), led by Prof Pennan Chinnasamy along with Vaishavi Honap of the College of Engineering, Pune, has shown a net average increase of 94 percent in soil degradation in the WGR between 1990-2020, detrimental to the region’s globally important biodiversity.

“Using the available data from the 1990s and later, we have quantified the soil loss from 1990 to 2020. It shows the average soil loss for WGR was 32.3 tonnes per hectare per annum (1990), shooting to 46.2 tphpa (2000), climbing to 50.2 tphpa (2010), and again jumping to 62.7 tphpa (2020).

Given the scale of the WGR spread over 140,000 sq.km. across Gujarat, Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu, the researchers had to process large datasets with advanced technology and break down the task into multiple parallel jobs, he added.

The analyses revealed that Tamil Nadu recorded the highest soil loss rate of 121 per cent in the three decades, followed by Gujarat with 119 per cent.

Below them are Maharashtra with a soil erosion surge of 97 per cent, Kerala at 90 per cent, Goa with 80 percent and Karnataka the lowest at 56 per cent during the same period.

“These drastic and unsustainable rates of soil erosion pose a significant threat to the ecosystem, biological diversity, and the communities that depend on the WGR for survival,” said Chinnasamy.

The first-of-its-kind study covering the entire WGR deployed remote sensing data from satellites to quantify the long-term soil degradation across the huge area spanning half-a-dozen states, and not only confirmed the progressive increase in soil erosion rates, but also an alarming state-wise spike owing to various factors.

“The WGR is a biodiversity hotspot that harnesses multiple lifeforms, and is a very unique spot in the world. However, the management of this ecosystem needs more focus. Water and soil form the core for life here, and since soil erosion is not monitored, we have quantified the soil losses,” said Chinnasamy.

This was achieved using the Universal Soil Loss Equation (USLE) method which provides a convenient framework for assessing erosion and its factors like rainfall, topography, soil credibility, land cover and prevailing conservation practices.

“In the present study, the use of USLE for the WGR was novel and perhaps the first time such an assessment has been carried out at this scale (temporal and spatial),” said Chinnasamy.

Among the multiple factors leading to the large-scale soil erosion, the study points out that the escalating impact of climate change, coupled with land management, are the main culprits, besides the pressures of unsustainable and unplanned activities, heavy tourism, and other local challenges in all states.

The impact of this has been seen in the form of heavy floods witnessed in the past few years in Gujarat, Maharashtra, Kerala and Tamil Nadu, and to a lesser extent even in Goa and Karnataka.

The floods have drastically hit agricultural productivity, reduced water quality, affected fresh water sources, posed major ecological and socio-economic challenges and affected the unique biodiversity of the WGR, raising some tough questions for the policy-makers to address.

Chinnasamy feels that state agencies could work on the region of influence or administration and conserve soil by taking measures to prevent its erosion, through local or regional zones and IIT-B experts can assist them in the endeavour, and strategic focus on reducing human disturbance in the WGR.

There is also a need for physical monitoring of soil loss and erosion at multiple locations across WGR to scientifically validate the remote sensing data used in the study, increase soil conservation efforts and reduce anthropogenic disturbances.

These, in turn, can not only help mitigate climate change impacts but also avert the imminent erosion-induced damage to the fragile ecosystem of the WGR here, he urged.