Natural And Human-Induced Land Degradation And Its Impact Using Geospatial Approach In The Kallar Watershed Of Tamil Nadu, India

Abstract

Land degradation is human-induced and natural process that adversely affects the land, to function effectively within a complex ecosystem. In recent years, the Kallar watershed has encountered various kinds of multifarious problems on both land and water in the urban and its environs. The upper part of the study area is facing water scarcity problems in the past few years, but which included no such rare occurrences in the past. The mid-portion in the vicinity of foothills are highly affected by soil erosion, whereas the lower portion of the area has faced problems like land degradation, such as an unusual increase of wastelands and conversion of good agriculture lands into construction plots. Apart from these, the study area is frequently affected by nature induced disasters like a landslide, forest fire, flooding, and drought. In this complex situation, the qualitative assessment of human-induced land degradation and its impact is essential. For this, Geospatialbased Multi-Criteria Evaluation (MCE) as a multidisciplinary approach has been adopted. To assess land degradation, six major criterions are preferred such as terrain (slope, elevation), environment (landuse/land cover, NDVI), soil erosion, and demography (population density). Considerable weights and ranks were assigned through an empirical MCE method. Based on the criteria, the land degradation was carefully delineated into five significant categories such as low (38.3%), moderately (23.6%), marginally (15.4%), highly (4.8%), and severely degraded (17.8%). The depletion of vegetation cover on hilly terrain and subsequent cultivation without proper protection measures constitute the possible reason for severe soil erosion and land degradation.

Efficacy of Synthetic Sediment Graph Developed using Various Modified Time-Area Methods

“…The spatio-temporal analysis of sediment yield is needed for watershed management, especially for soil and water conservation and watershed health assessment (Sadeghi et al 2019;Hazbavi et al 2020;Mirchooli et al 2021). The amount of SS produced in a watershed depends on the distribution and duration of precipitation, sediment availability, flow velocity, geomorphology, land cover and human activities (Seeger et al 2004;Messina and Biggs 2016;Rahaman and Solavagounder 2020;Sokolov et al 2020;Waiyasusri and Wetchayont 2020;de Paula et al 2021). Most watershed management studies provide general estimates of soil erosion using empirical or non-distributed models such as Universal Soil Loss Equation (USLE), Revised Universal Soil Loss Equation (RUSLE), and Water Erosion Prediction Project (WEPP) (Wischmeier and Smith 1978;Sadeghi and Mizuyama 2007;Srivastava et al 2020;Zheng et al 2020).…”