DOI: 10.5281/zenodo.17674907
title: Concepción Reservoir Bathymetry & Shoreline Dataset (Honduras) — Digitized Pre-Dam Contours, Depth Raster, Boundary Polygons & Derived Layers

description: This dataset provides a digitally reconstructed bathymetry of the Concepción Reservoir (Honduras) derived from pre-dam topographic contours extracted from the 1956 AMS 1:50,000 sheet Ojojona (2757-IV). Because no official bathymetric survey of the reservoir is publicly available, this reconstruction uses historical elevation data to estimate water depth relative to the reservoir’s maximum operating level.

The workflow includes map warping, digitization of elevation contours, valley-floor shoreline extraction, TIN-based interpolation, depth inversion, and hillshade generation. All GIS layers—contours, shoreline, boundary polygons, depth raster, hillshade, vertices, and QGIS styling files—are included to ensure full reproducibility.

This dataset supports research in hydrology, water resource management, environmental modeling, geomorphology, cartography, and educational visualization of pre-inundation landscapes. It allows users to explore the morphology of the original river valley and analyze the reservoir basin in detail using open-source GIS tools.

All source materials from the AMS map are in the public domain, and all reconstructed outputs are released under CC-BY 4.0.
description: Methodology: Bathymetry Reconstruction of the Concepción Reservoir (Honduras)

 

1. Overview

This methodology describes how the bathymetry of the Concepción Reservoir (Honduras) was reconstructed using pre-dam topographic data, digitization, geospatial processing, and raster interpolation in QGIS. Because no official bathymetric survey is publicly available, the reconstruction is derived from historical topography that predates reservoir construction. All steps are fully reproducible using open-source GIS tools.

2. Source Data

 

-      Historic Topographic Map (1956)

-       The reconstruction is based on the 1956 AMS topographic sheet:

Topographic Map 1:50,000 — Sheet 2757 IV (Ojojona)

AMS Series E752, Edition 1-AMS

Retrieved from the Perry-Castañeda Library Map Collection: https://maps.lib.utexas.edu/maps/honduras.html

 

This map predates the reservoir and shows the original valley contours, which serve as the foundation for reconstructing depth.

Stored in dataset: Data/06_original_topography/

3. Map Reprojection (Warp)

The scanned AMS topographic map was already available as a georeferenced raster in its original coordinate reference system. No manual ground control point (GCP) georeferencing was required. The raster was reprojected to EPSG:32616 — WGS84 / UTM Zone 16N using QGIS Warp (GDAL), bilinear resampling, and clipped to the Concepción valley region.

4. Digitization of Bathymetry Inputs

4.1 Contour Lines (Elevation)

Contour lines were manually digitized as polylines, assigned elevation values, cleaned for geometry errors, and normalized. Stored in: Data/02_Contours/

4.2 Shoreline (0-depth Boundary)

The reservoir boundary was reconstructed from the lowest natural contour following the river channel. Steps included digitization, multipart-to-singlepart conversion, manual vertex editing, and conversion to polygon. Stored in: Data/04_ShoreLines/

4.3 Vertices Layer

All vertex points used for interpolation were exported for reproducibility.

Stored in: Data/01_Vertices/

5. Bathymetry Raster Interpolation

5.1 Converting Elevation to Relative Depth

Depths were computed relative to a reference elevation using:

depth = reference_level - elevation

5.2 Raster Interpolation (TIN)

A Digital Depth Model (DDM) was generated using TIN interpolation with 2–5 m resolution, clipped to the shoreline polygon. Output: Data/05_Rasters/Concepcion_Bathymetry.tif

6. Hillshade

A hillshade was created using azimuth 315°, altitude 45°, and Z-factor 1.0. Stored in: Data/05_Rasters/Concepcion_Hillshade.tif

7. Styling & Visualization

Custom QGIS styling (QML) includes blue bathymetric gradients, contour halos, smooth hillshade blending, and curved labels. Stored in: QgisStyling/

8. Layer Styling Summary

-        Bathymetry raster: bathymetry.qml — gradient symbology

-        Hillshade: hillshade.qml — grayscale multiply

-        Contours: contours.qml — thin lines with labels

-        Boundary: boundary.qml — thin outline

-        Shoreline: shoreline.qml — glow effect

-        Vertices: vertices.qml — small points

9. QGIS Project File

Concepcion_Bathymetry.qgz loads all layers with symbology.

10. How to Use This Project in QGIS

Quick Start: Open project file in QGIS.

Manual loading: Set CRS to EPSG:32616, load rasters and vectors, apply QML styles.

11. Quality Control

Verified contour topology, raster smoothness, shoreline accuracy, and canyon consistency.

12. Limitations

Based solely on pre-dam topography; no official bathymetric survey; vertical accuracy limited by 20 m contour spacing.

13. Reproducibility

All files needed to rebuild the model are included and reproducible entirely in QGIS.