Quantitative morphometric analysis of dzumah watershed of upper dhansiri, Nagaland, India

In the present study, an attempt was made to quantify the morphometric characteristics of Dzumah watershed located in Nagaland, India. The Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) of 30 m spatial resolution was used in ArcGIS environment for evaluating the morphometric parameters and generation of maps. The Dzumah watershed is a fifth order drainage basin with an area of 65.55 km² with 228 stream segments (total stream number) with a total stream length of 130.71 km. A low drainage density of 1.99 km/km² indicates coarse drainage texture revealing that the watershed has good infiltration/permeability and vegetation cover. The analysis of various aerial aspects such as form factor, circularity ratio and elongation ratio revealed that the watershed is elongated in shape. The analysis of relief aspects revealed that the lowest and highest elevation in the watershed was 328 m and 2345 m above mean sea level, respectively. The observed values for relief ratio and ruggedness number are 0.14 and 4.02, respectively, indicating that the watershed has rough, steep and uneven topography. The high permeability as inferred by low values of drainage density could be negated by high rainfall and steep uneven terrain characteristics of the watershed which would not only decrease the absorption time but also increase the velocity of accumulated surface run off. The overall results from the study showed that the watershed is characterized by rugged uneven terrain with steep slopes which would favour a considerable increase in flow velocity, thus increasing the risk of soil erosion.