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Integrated Capstone Practical: River Basin Delineation and Analysis

This capstone laboratory integrates the spatial workflows, geoprocessing techniques, and remote sensing calculations developed throughout the 5-day curriculum.

1. Project Scenario and Objectives

The Water and Energy Commission Secretariat (WECS) requires an integrated environmental study of the West Rapti River Basin in Nepal. Your team is tasked with delineating the catchment area, calculating morphometric parameters, classifying changes in surface water extent, and generating a professional map booklet for policy submission.

2. Target Deliverables

You must submit a single compressed ZIP file named WECS_Capstone_Group_[Number].zip containing:

  1. Catchment Database (rapit_basin.gpkg):

    A GeoPackage containing your delineated watershed boundary, stream network line vectors categorized by Strahler order, and water extent polygons.

  2. Water Index Calculations:

    A GeoTIFF raster representing NDWI and dry-season surface water.

  3. PDF Layout Document (rapti_basin_report.pdf):

    A professional, publication-ready \(A3\) map layout showing the basin elevation, drainage lines, and surface water boundaries with appropriate grids, legend, and inset index map.

3. Step-by-Step Task Checklist

  • Task 1: Project Workspace and CRS Setup

    • Create a directory structure: /project/data/, /project/models/, /project/outputs/.

    • Initialize a new QGIS project. Set the Project Coordinate Reference System (CRS) to WGS 84 / UTM Zone 44N (EPSG: 32644).

  • Task 2: Catchment Delineation from DEM

    • Load the raw DEM dem_raw_rapti.tif.

    • Run SAGA Fill Sinks (Wang & Liu) to remove internal depression artifacts.

    • Compute Flow Direction and Flow Accumulation rasters.

    • Run Channel Network and extract a stream network vector layer using a flow threshold of \(> 5,000\) pixels.

    • Generate the catchment basin boundary polygon using your coordinate points for the downstream outlet location.

  • Task 3: Remote Sensing Water Index Analysis

    • Load pre-processed Sentinel-2 Band 3 (Green) and Band 8 (NIR) rasters.

    • Use the Raster Calculator to compute NDWI.

    • Reclassify the NDWI raster to isolate surface water bodies (where NDWI \(> 0.0\)).

    • Convert the water raster to a vector polygon layer and clip the output to your delineated catchment boundary.

  • Task 4: Symbology and Spatial Database Compilation

    • Save all vector outputs (watershed boundary, streams, water polygons) into a single database container rapti_basin.gpkg.

    • Apply a graduated line width to the stream vector based on the Strahler stream order attribute.

    • Style the DEM with a singleband pseudocolor ramp using elevation colors.

  • Task 5: Print Layout Design

    • Create a new print layout. Set page size to \(A3\) Landscape.

    • Add the main map canvas, a legend with edited descriptive labels, a dynamic scale bar, and a north arrow.

    • Add a coordinate grid overlay (UTM grid ticks labeled with unit meters on all borders).

    • Add an inset index map showing the location of the West Rapti Basin inside Nepal.

    • Export the finalized layout as a PDF file.