Soil Salinity Mapping using Landsat 8OLI Data for Kundapura Taluk, Udupi District, Karnataka, India

Abstract

Soil salinization occurs when salts accumulate on the soil surface and in the root zone. It affects the growth of many crops and alters the physical and chemical properties of soil, especially in arid and semi-arid regions. This study was conducted in Kundapura taluk of Udupi district in Karnataka, the northernmost taluk with a geographical area of 1569 km2. The location is in the coastal region, where high soil salinity was observed due to saltwater intrusion. The high and very saline water comes near the coast of Kundapura taluk. Saline soils in such areas harm urban structures, primarily by causing land subsidence corrosion and adversely affecting groundwater quality. The soil in this region is lateritic, characterized by high iron and aluminum content, and is suitable for crops such as paddy, sugarcane, areca nut, coconut, cardamom, and plantains. Sandy soils are restricted to a narrow strip of shore with dimensions ranging from 100 m to a km in length. This study aimed to establish an analytical model of soil salinity reflectance suitable for open areas with dispersed salt flats using the spectrum near-infrared and short-wave infrared sections. The study findings revealed that models based on the SI-5 (R2 = 0.9392) and NDSI (R2 = 0.9252) indices produced nearly identical effects. However, many variables can impact the accuracy of mapping saline soils using remote sensing data. In saline soils, plant growth is adversely affected, primarily by excess salts that affect the osmotic pressure of soil solution, resulting in reduced water availability. To improve saline soils, removing soluble salts in the root zone through leaching and drainage is essential. Application of amendments may generally not be required. Saline soils tend to dominate in arid and semi-arid regions.