Water induced surface erosion risk assessment in Jumar agricultural watershed, Jharkhand, India using multivariate statistics and GIS

Abstract

Abstract The state of Jharkhand suffers immensely from water-induced surface erosion causing loss of socio-economic Jumar watershed of Ranchi district, Jharkhand was selected for a study period of 2020 and 2021 to analyse climate change, seasonal change in quality of water and soil resources, hydro-geomorphometry and land cover land use (LULC) using GIS and multivariate statistics. The water quality analysis revealed the presence of higher content of presence of metals such as Ca, Mg, K, and Na, higher alkalinity, TDS, and turbidity in monsoon and post-monsoon months of 2021. The soil quality analysis showed that the region has excessive carbonate salts with dominant presence of metal such as calcium, magnesium and sodium, disturbing the soil structure and lowering its infiltration capacity, promoting nutrient deficiencies, and leading to possible metal contamination in few years. Lack of vegetation covers adds to surface erosion under high intensity rainfall (1685-2083mm). The correlation analysis was done seasonally for both soil and water quality revealing the strong influence of metal ions with pH, alkalinity, salinity, and TDS, showing a prominent silicate weathering and ion exchange process indicating prominent surface erosion in watershed. The PCA on water and soil quality data showed that salinity, TDS, Alkalinity, Hardness and EC are the principal components. The morphometric study showed that the Jumar watershed has rolling and slightly undulating terrain, with mild slope and dendritic stream pattern of 4th order stream. Low basin relief and drainage density, compactness constant (0.00192), Ruggedness number (0.0609), and basin relief ratio (0.00552) indicated the dominance of low stream orders (1st ) in the area pointing to low potential energy in surface flow. The hydrological indices indicated that the watershed is low risk of gully formation in lowlands. Through the application of other GIS based rainfall, LULC and spectral indices (NDMI, MSI, SAVI and BSI) it was found that there has been a huge increase in urbanization, barren land, sparse vegetation cover, and immense water stress especially in summer and winter season of 2020 and 2021 in the watershed. The Lack of water conservation and traditional agriculture using agrochemicals is very prominent in the watershed, hence an immediate need for water and soil quality management is required.