Pattern of spatial variability in granulometric and mineralogical characteristics across an ecologically sensitive sub-tropical wetland (Bihar, India)

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Floodplain wetlands are dynamic systems undergoing frequent hydro-sedimentological changes. Tropical/subtropical wetlands have even more pronounced climatic and biological influences on the sediment dynamics. In the current study, a protected subtropical wetland in Bihar (India) has been assessed for its sedimentary and mineralogical status. Sediment characteristics and associated granulometric parameters are discussed to highlight the wetland's hydrogeomorphic character, energy dimension, and the depositional processes taking place. Statistical grain size parameters like graphic mean, graphic skewness, graphic kurtosis, and their interrelations studies have helped in understanding the sources of deposited materials. Multivariate statistics have identified, sand fractions, measures of central tendencies (mean, median, and mode), percent organic matter (%OM) and percent carbonates (%carbonates) as primary factors explaining the maximum variance in the data. The non-parametric Kruskal–Wallis test has identified %sand, %clay, electrical conductivity (EC), and %carbonates as the major factors responsible for significant spatial variability. The grain texture analysis shows that the majority of samples fall in the brackets of clayey silt; silty sand; and sand, silt, and clay. Common mineral components associated with these are quartz, feldspar, clay minerals, etc. The range for the mean grain size lies between 3Φ to 9Φ (Φ is diameter of the sediments) where most of the grain size distributions are symmetrically to fine symmetrically skewed, indicating intermediate energy to adjust to environmental conditions. The granulometric and physicochemical characteristics of the sediment samples also indicate the directional distribution pattern of sediment along the hydrological pathway. Future studies concentrating on the fluvial discharges of water and sediment will be highly insightful in reconstructing the past net sediment accumulation processes in the Baraila Wetland.