Continuous contour trenches are dug along slopes and above the fields to slow down runoff and recharge groundwater (Image: WOTR)
Every monsoon, Maharashtra celebrates the arrival of rain. Rivers swell, reservoirs begin to fill, waterfalls return to life and the Western Ghats turn lush green. Yet beneath this seasonal transformation lies a quieter crisis. Every spell of intense rainfall washes away fertile topsoil from farms, forests and hill slopes into rivers and reservoirs. Unlike floods, soil erosion is slow and often invisible, but its impacts are long-lasting. Once the nutrient-rich topsoil is lost, it can take centuries to regenerate naturally, while the sediment it carries reduces reservoir capacity, degrades rivers and raises the cost of irrigation and drinking water infrastructure.
Soil erosion is therefore much more than an agricultural problem. It directly affects water security, biodiversity, climate resilience and rural livelihoods. As rainfall patterns become more erratic due to climate change, the challenge is expected to intensify across the Western Ghats and the Deccan Plateau, making soil conservation an urgent policy priority rather than a routine watershed activity.
A recent study published in Results in Engineering provides important insights into how this challenge can be addressed. In Application of Analytic Hierarchy Process for the Assessment of Soil Erosion Risk in the Urmodi River Watershed of Maharashtra State, India, researchers Wasim Ayub Bagwan and Ravindra Sopan Gavali demonstrate how satellite imagery, Geographic Information Systems (GIS) and multi-criteria analysis can identify erosion hotspots before irreversible damage occurs.
The study examines the 412 sq km Urmodi River watershed in Satara district, part of the Krishna basin. The upper catchment includes the ecologically fragile Kaas Plateau, a UNESCO World Heritage Site known for its seasonal wildflowers and unique biodiversity. Steep slopes, shallow lateritic soils, expanding infrastructure and increasingly intense rainfall make this landscape particularly vulnerable to erosion.
The findings extend well beyond Satara. Similar geological and climatic conditions occur across much of the Western Ghats, from Kolhapur and Sangli to Nashik and Sindhudurg. As extreme rainfall events become more frequent, many of these watersheds are likely to experience accelerated soil loss unless conservation efforts become more targeted and science-driven.
Mapping invisible risk: How science is transforming watershed planning
Conventional watershed programmes generally rely on field surveys to identify degraded areas. While useful, these surveys are time-consuming, expensive and often fail to capture the complex interaction of factors that influence erosion.
The Urmodi study adopts a more comprehensive approach by integrating ten variables that govern soil erosion. These include rainfall erosivity, geology, geomorphology, slope, drainage density, drainage texture, lineament density, soil texture, land use and land cover, and vegetation health measured using the Normalised Difference Vegetation Index (NDVI).
The researchers combined these datasets using the Analytic Hierarchy Process (AHP), a widely used decision-support framework that assigns relative importance to each factor. Rather than treating all variables equally, AHP recognises that rainfall, terrain, geology and vegetation influence erosion differently. The weighted datasets were then integrated in a GIS environment to produce a watershed-wide soil erosion risk map.
The results reveal a distinct spatial pattern. Nearly half of the watershed falls within the very low-risk category, largely corresponding to the flatter lower catchment. However, around 15 per cent lies in high or very high erosion-risk zones concentrated in the upper catchment, where steep slopes, barren land and intense rainfall combine to accelerate soil loss. The erosion risk gradually declines from the elevated western hills towards the eastern plains, illustrating how topography and land cover shape watershed behaviour.
To test the reliability of their model, the researchers compared the AHP-generated map with the Revised Universal Soil Loss Equation (RUSLE), the internationally accepted model for estimating annual soil loss. Although the two approaches differ in methodology, both identified broadly similar erosion hotspots, and statistical validation showed good agreement between them. This confirms that the GIS-AHP framework can provide a reliable basis for planning conservation interventions.
The study's significance lies not merely in producing another erosion map, but in demonstrating how modern geospatial tools can support better public investment decisions. Instead of treating entire watersheds uniformly, planners can identify the most vulnerable locations and prioritise interventions where they will have the greatest impact.
The implications are substantial for Maharashtra, where multiple schemes—including MGNREGA, the National Mission for Sustainable Agriculture, CAMPA and watershed development programmes—already invest heavily in soil and water conservation. Integrating scientific erosion-risk maps into these programmes could make public spending far more effective by directing resources to the landscapes that need them most.
Beyond the map: What the findings mean for Maharashtra
The Urmodi watershed may cover just over 400 sq km, but the lessons emerging from the study are relevant across Maharashtra. The state encompasses diverse landscapes, from the steep escarpments of the Western Ghats to the drought-prone Deccan Plateau. Despite these differences, soil erosion remains one of Maharashtra's most widespread forms of land degradation, undermining agricultural productivity, reducing reservoir life and weakening climate resilience.
Fig. Soil Erosion Risk (SER) zones using AHP approach for the Urmodi River watershed. (Map: Wasim Ayub Bagwan et al)
Perhaps the study's most important contribution is its demonstration that not every hectare requires the same intervention. Watershed programmes have traditionally followed a uniform approach, constructing check dams, contour trenches and other structures across administrative boundaries rather than ecological ones. While such programmes have generated benefits, they often fail to distinguish between landscapes that are highly vulnerable and those that are relatively stable.
The GIS-AHP framework offers a more strategic alternative. By identifying erosion hotspots with considerable precision, it enables planners to target investments where they are likely to yield the greatest environmental returns. In a state where watershed development is funded through multiple schemes—including MGNREGA, CAMPA, the National Mission for Sustainable Agriculture and state watershed programmes—such prioritisation could significantly improve both ecological outcomes and the efficiency of public expenditure.
Fig. Potential soil erosion risk zone using RUSLE for the Urmodi River watershed. (Map recreated using Raj et al by Wasim Ayub Bagwan et al)
The study also reinforces an often-overlooked reality: soil conservation is fundamentally a water security intervention. Soil erosion does not simply remove fertile earth from farms; it transports sediment into rivers, reservoirs and irrigation canals. As reservoirs accumulate silt, their storage capacity declines, reducing their ability to supply drinking water, irrigation and flood protection. Investments in dams and water infrastructure therefore become progressively less effective if upstream catchments continue to degrade.
Climate change makes this challenge even more pressing. Scientific evidence increasingly indicates that western India is experiencing shorter but more intense rainfall events. Such cloudbursts generate high runoff that rapidly strips exposed slopes of topsoil. Protecting catchments, therefore, is no longer just about conserving land—it is about improving the landscape's ability to absorb rainfall, recharge groundwater and reduce flood peaks.
Fig. 15. Overlaying view of SER prepared by AHP and RUSLE methods. (Map: Wasim Ayub Bagwan et al)
The paper also highlights the growing influence of human activity on erosion. Expanding roads, tourism infrastructure, hill cutting and changing land use patterns are altering the hydrology of fragile mountain landscapes.
The researchers acknowledge that the Analytic Hierarchy Process relies partly on expert judgement and therefore contains an element of subjectivity. They recommend integrating machine learning techniques, drone imagery and higher-resolution satellite data to improve prediction accuracy. Such advances could eventually enable dynamic erosion-risk monitoring, allowing governments to update vulnerability maps regularly rather than relying on one-time assessments.
Fig. Soil conservation measures needed to adapt to control the soil erosion in the Urmodi River watershed. (Map: Wasim Ayub Bagwan et al)
From prediction to prevention: A new agenda for soil conservation
The value of the Urmodi study lies not simply in identifying erosion-prone areas but in showing how science can guide more effective watershed management. Its findings point towards a new agenda for Maharashtra—one that shifts from treating erosion after it occurs to preventing it through informed planning.
The first priority should be to make erosion-risk mapping a standard component of watershed planning. Every major conservation programme should begin with spatial assessments that identify vulnerable slopes, drainage corridors and degraded landscapes. Public investments in contour trenches, check dams, afforestation and vegetative barriers should then be guided by scientifically identified priorities rather than administrative boundaries.
Second, conservation measures must be tailored to different landscapes. Steep hill slopes require interventions such as contour trenching, assisted natural regeneration and slope stabilisation. Agricultural fields benefit from contour farming, mulching, conservation agriculture and strip cropping, while degraded forests require enrichment planting and better grazing management. Applying identical measures across every landscape reduces both ecological effectiveness and returns on investment.
Vegetation restoration deserves particular attention. Healthy vegetation intercepts rainfall, stabilises soil, enhances infiltration and reduces runoff. The study highlights the effectiveness of vegetative filter strips and grasses such as vetiver in trapping sediment and slowing overland flow. Expanding native vegetation should therefore become a central element of watershed programmes rather than relying primarily on engineering structures.
Institutional reforms are equally important. Watershed management in Maharashtra remains fragmented across departments responsible for forests, agriculture, irrigation, rural development and environment. Developing a shared geospatial platform for erosion-risk mapping would enable these agencies to coordinate investments, avoid duplication and monitor outcomes more effectively. Such convergence is especially important as India pursues ambitious land restoration and climate adaptation targets.
Community participation must also remain central. Farmers and local institutions are the long-term custodians of watersheds, and conservation measures are far more likely to succeed when communities understand their economic and environmental benefits. Technical support, incentives and community-based monitoring can ensure that restoration efforts continue well beyond the life of individual projects.
Ultimately, the study makes a compelling case for recognising soil as strategic natural capital. Discussions on water security often focus on dams, canals and groundwater recharge, but these investments cannot compensate for the continued loss of fertile topsoil from upstream catchments. Healthy soils regulate runoff, recharge aquifers, support biodiversity, sustain agricultural productivity and store significant amounts of carbon. Protecting them delivers multiple environmental benefits simultaneously.
The science is now available. The technologies are accessible. The remaining challenge is institutional: ensuring that watershed planning moves beyond conventional engineering towards data-driven, landscape-based management. If Maharashtra succeeds in making that transition, it will not only conserve its soils but also strengthen the resilience of its rivers, farms and communities in an increasingly uncertain climate.