ORIGINAL PAPER Estimation of soil loss by an integrated approach of USLE and geospatial techniques—a case study of Kumulur watershed Nagarajan Madasamy 1 & Mercy Backiyam Joshua 1 & Lalitha Rajangam 1 Received: 13 May 2020 /Accepted: 2 September 2020 # Saudi Society for Geosciences 2020 Abstract A study was conducted to estimate soil loss by an integrated approach of USLE and geospatial techniques from Kumulur watershed, Trichy district, Tamil Nadu, India, located at 10° 56′ 41.50″–10° 55′ 57.85″ N latitude and 78° 50′ 4.34″–78° 50′ 4.58″ E longitude with an areal extent of 848,694 m 2 . The factors in USLE were prepared as different thematic layers using GIS. The R factor was calculated using 28 years of rainfall data (1991–2018), and the average R factor was found to be 1862.892 MJ mm ha -1 h -1 yr -1 . The K factor was generated through textural classes of soil by collection of soil samples. The high-accuracy digital elevation model (DEM) (4-m resolution) was created using hand-held GPS instrument and Google Earth. The contour, aspect, and slope maps were derived from DEM. The slope classes revealed to be moderately steep sloping having 32.248 and 17.873°, and the LS factor was found to be 0 to 219.33. The C and P factors were obtained from different land uses, viz., barren rocky, built-up area, fallow land, open forest, and water bodies prepared from Google Earth image (2-m resolution—2018 image). The average annual soil loss was estimated as 4.927 t/ha/year which ranged between 0 and 1.469 t/ha/year for each grid cell. To arbitrate the soil loss, the surface runoff of the watershed was also estimated by the SCS-CN method. The runoff depth (2018 rainfall) for CN I, II, and III was found to be 52.19, 120.09, and 664.46 mm, respectively, which shows moderately high runoff potential and moderately low infiltration rate. Keywords DEM . SCS-CN . Runoff . GIS . USLE . Soil loss Introduction Currently, due to the rapid increase of mankind and migration to urban areas which enhance urbanization, climate change, irregular precipitation have to lead inappropriate management and conservation of natural resources which thereby affect the sustainability of the livelihood. The process for the sustain- ability of the water resources within a watershed to achieve a harmless environment is known as “watershed management.” With the ever-rising population, urbanization, and increase in demand, the natural resources are greatly exposed to exploi- tation. It is a known fact that soil and water are valuable resources on this planet. It is indeed a responsibility to pre- serve and conserve the assets (soil and water) to mitigate the natural resources for economic growth. In recent times, the conservation of soil and water becomes burdensome due to climate change, irregular rainfall distribution, and rapid in- crease in population and their demands. Therefore, it becomes necessary to evaluate the natural resources as they play a vital role in watershed management. Hydrology plays crucial job insecurity and executives of water along with other conditional assets related to the occur- rence of water above and underneath of the land surface. The possibility of occurrence and the quantity of the latter are highly dependent on the characteristics of the former, i.e., their intensity, duration, and distribution (Bhuktar and Regulwar 2015; Patel et al. 2017; Matomela et al. 2019). These compo- nents are the prerequisite in the design of hydrological struc- tures and the morphology of the drainage system. The estima- tion of runoff using empirical equations will be facilitated the prediction of the probable amount of water drained by the Responsible Editor: Broder J. Merkel * Nagarajan Madasamy nagarajan.m@tnau.ac.in 1 Department of SWCE, Agricultural Engineering College & Research Institute, Tamil Nadu Agricultural University, Kumulur, Trichy, Tamil Nadu, India https://doi.org/10.1007/s12517-020-05929-z / Published online: 30 September 2020 Arabian Journal of Geosciences (2020) 13: 1045