The process of soil erosion starts when rainfall occurs on the soil or when water flow (runoff) displaces the soil particles.
Soil erodibility is the susceptibility of soil particles to become detached and reflects the combined effect of rainfall, infiltration, and runoff. It is one of the major factors used to estimate soil loss and reflects the effect of soil structure, texture, permeability, and organic matter content in countering soil erosion.
Take two tiny planters/pots. Fill both pots to the top with two different soils. Add some water and press the soil so that it is well settled into the pots. After a day, try to flood both pots and measure the soil that falls out of each pot as a result of this flooding. You can keep a wide circular tissue under the planters to collect the soil. Why does one pot have more soil eroded than the other? This is the erodability of each soil.
Till now, soil erodibility assessments have been conducted in specific regions or catchments, but a national-scale assessment of soil erodibility was required. Now, researchers at IIT Delhi have developed a national-scale mapping of soil erodibility, a first of its kind in the country.
This national-scale mapping of soil erodibility highlights specific areas where the soil is most vulnerable to erosion.
The researchers in their study have found that out of the 50 districts with the most erodible soil, 29 are in Uttar Pradesh, 13 in Bihar, 3 in Gujarat, 2 each in Haryana and Rajasthan, and 1 in Punjab.
“This reflects the combined effect of rainfall, runoff, land use, land cover, deforestation, and agricultural practices. This study fills a critical gap and brings us one step closer to estimating soil-loss at a national level and developing a soil erosion model”, said Prof. Manabendra Saharia, Department of Civil Engineering, IIT Delhi.
Prof. Saharia added, “Soil erosion is a significant trigger for land degradation and a major global geo-environmental issue. Being able to assess its causes and impacts at a high-resolution will help us develop a national soil conservation plan that can help our vital agricultural sector”.
The original paper can be accessed here: https://doi.org/10.1016/j.catena.2023.107271.
The dataset has been freely released as the Indian Soil Erodibility Dataset (ISED, https://zenodo.org/record/8011445) at a spatial resolution of 250 m.
The study estimated the national average soil erodibility factors for India as 0.028 and 0.034 t-ha-h/ha/MJ/mm using Nomograph and EPIC models, respectively.
In addition to this, the researchers conducted a comprehensive statistical analysis of the soil erodibility map to visualize its distribution over the national territory in terms of the different soil types, textures, and percentage ranges of erodibility values.