Land use/land cover (LULC) information is essential for proper management, planning and monitoring of natural resources of any region. The present study delineated the catchment of a part-length of Burhi Gandak river falling under Samastipur district of Bihar, estimated its area and LULC change over a period of ten years (2008-2018) using Remote Sensing (RS) and Geographic Information System (GIS) techniques. LULC mappings were done by supervised classification technique using GIS. Overall accuracy of image classification processes was 79.07 % and 75 %, whereas Kappa coefficients were found to be 0.71 and 0.68 for the year 2008 and 2018, respectively. Over the 10-year period, the area under agricultural land increased by 3,329 ha (6.51 %), settlement increased by 4,554 ha (58.20 %), and wasteland (barren and sand) increased by 685 ha (34.05 %); while natural vegetation cover reduced by 6,523 ha (33.58 %) and water bodies reduced by 2,045 ha (54.23 %). Hence, a significant portion of land under natural vegetation and water bodies in the catchment had been converted into either agricultural land or settlement (e.g. buildings) during the period. This change might affect the ecosystem of the area