Morphological characterization of an agricultural watershed using geospatial tools for effective planning of engineering structures

Morphometric analysis of watersheds is vital for understanding the hydrological behavior and planning conservation measures. Geospatial tools like remote sensing and GIS are efficient in morphometric analysis. The morphometric characteristics, like linear, aerial, and relief aspects, were derived for the Sillahalla watershed in Nilgiris, Tamil Nadu, using DEM and GIS. The study watershed was designated as a 5th order watershed. The linear aspects, like stream order, stream length, and stream length ratio, suggest that the watershed may experience flooding during the monsoon. Due to the high water flow in higher order streams, RR masonry and rubber check dams are recommended for 4th and 5th order streams, respectively, to avoid flooding agricultural lands. The mean bifurcation ratio of the watershed is 3.55, suggesting that the conservation structures can be rationalized to minimize their cost. The aerial aspects, like drainage density and form factor, suggested the scope of microscale water harvesting structures like farm ponds, lined farm ponds, and percolation ponds in the watershed. The relief factors showed the potential risk of soil erosion in the watershed. As the study watershed is dominated by agricultural land use, and the maximum area (52%) falls in the 16-33% slope category, the in situ soil conservation measures, like bench terraces, stone walls, and trenches, need to be intensified suitably based on the land use and slope. Researchers, policymakers, and field-level engineers can use the results of the morphometric analysis for effective watershed planning.