Bathymetry survey of river Brahmaputra in a reach of 20 km, from 10 km upstream to 10 Km downstream of Vulnerable hotspot location of bank erosion in Majuli district

Preparation of high-resolution Digital Elevation Model (DEM) with horizontal resolution of 0.30 m and vertical resolution of 0.50 m, including the following: Survey Coverage: Full width of braided river channel and adjoining floodplain, including a buffer zone of 150–200 meters from both riverbanks to ensure continuity and stitching of DEMs. Hydrographic Survey (Water Portion): Multibeam Echo Sounder (MBES) to be used where feasible based on depth and channel conditions. Single Beam Echo Sounder (SBES) as an alternative in shallow or inaccessible areas. Survey to be conducted using boats, with proper calibration and tidal correction as per standards. Topographic Survey (Land Portion): Use of Drone-based LiDAR and/or Differential GPS (DGPS) for areas that are dry or get submerged during monsoon. Ground control points (GCPs) to be established for georeferencing and accuracy. Data Processing: Post-processing of bathymetric and topographic data to prepare high-resolution DEM of the surveyed area. DEM to be delivered in suitable GIS-compatible formats (e.g., GeoTIFF, LAS, or others as required). supply of minimum 75 nos. Cross sectional data and drawing (5 sets hard & soft copies) as directed by Dept.

Carrying GTS benchmark by double fly levelling

Carrying Out Topographic survey and preparation of Index Plan of the Brahmaputra River reach from 25 KM, from 15 km upstream to 10 KM downstream of Vulnerable hotspot location of bank erosion in Majuli district along with locations of existing hydraulic structures such as bridges, weirs, barrages, intakes and other features such as roadways, railways, towns/villages etc.