Matrix flushing approach-based sediment mineralogical composition of Bhagirathi river basin in Indian Himalayas

The comprehensive information on sediment mineral composition is helpful in the design and development of hydropower projects. The present study reports the matrix flushing approach for quantitative sediment mineralogical analysis by X-ray diffraction (XRD) in the Bhagirathi river basin. Fifteen locations were selected, and sediment samples were collected from the bank deposits of the Bhagirathi river and its several tributaries. The minerals were identified using the XRD technique and were quantified by incorporating the matrix flushing method. XRD patterns reveal the presence of quartz, feldspar, diopside, biotite, muscovite, garnet, silicates, clay, carbonates, oxides, and zeolite minerals, with quartz being dominant. The highest content of quartz (85.58%), feldspar (6.99%), diopside (6.63%), biotite (8.39%), muscovite (8.47%), garnet (4.87%), silicates (17.71%), clay (2.71%), carbonates (3.89%), oxides (2.73%), and zeolites (5.78%) was observed in the sediments of Bhagirathi river basin. The maximum number of minerals was identified in the main Bhagirathi stem, the Kakoragad, and the Pilangad tributary. Principal component analysis shows that the first five eigen values account for 78.15% of the overall variance of the mineral distribution. This also reveals the interrelation of occurrence and source of multiple minerals identified in an individual principal component (PC), like PC1, which reveals interrelations between feldspar, muscovite, and clay, and PC2 indicates quartz, biotite, and oxides. As per the International Electrotechnical Commission standard 62364 (Hydraulic machines—Guidelines for dealing with hydro-abrasive erosion in kaplan, francis, and pelton turbines. In 62364 © Iec:2019 (2nd ed.)), sediment involves 84–99% of hard minerals, which determined hardness factors between 0.84 and 0.99, depicting high hydro-abrasive erosion potential in the Bhagirathi river basin. The outcomes of this study shall be helpful for developers in developing strategies to tackle the sediment related problems in HPPs. This study will enable hydraulic turbine developers to select suitable hydraulic turbine material and erosion-resistant coatings.