DOI: 10.5281/zenodo.17704343
title: Lake Yojoa Bathymetry & Shoreline Dataset (Honduras) — Digitized Contours, Depth Raster, Boundary Polygons & Derived Layers

description: This dataset contains a digitized and georeferenced version of the public bathymetric map of Lake Yojoa originally published by the Escuela Nacional de Ciencias Forestales (ESNACIFOR). The dataset includes:





Digitized depth contours (0–26 m)




Digitized shoreline boundaries




Extracted bathymetry points / vertices




A 5-m resolution depth raster interpolated from digitized contours




A clean lake polygon boundary




All data provided in EPSG:26716 – NAD27 / UTM Zone 16N



Source and Acknowledgment

The depth information used here is derived from the bathymetric chart published in:

Escuela Nacional de Ciencias Forestales (ESNACIFOR), Departamento de Investigación Forestal Aplicada.Revista Técnico-Científica Tatascán, Vol. 19, No. 2, 2007.ISSN 2219-1143.

This Zenodo upload is a digitized, geospatially calibrated derivative of the original printed bathymetric figure.The original survey, measurements, and scientific work belong entirely to ESNACIFOR and the authors of the 2007 publication.

 
description: 1. Data Source Identification

The original bathymetric information was obtained from the printed bathymetric chart of Lake Yojoa published in:ESNACIFOR – Revista Técnico-Científica Tatascán, Vol. 19, No. 2 (2007).This publication provided the iso-depth contours (0–26 m), shoreline outline, and hydrographic reference figure used as the basis for digitization.



2. Georeferencing

The original bathymetric figure was georeferenced in QGIS using the following approach:





Digitized reference markers and identifiable shoreline features.




A minimum of 8–12 control points distributed across the image to minimize distortion.




Transformation method: Thin Plate Spline (TPS) / Polynomial 2, depending on local error.




RMS error was minimized until shoreline alignment matched modern satellite imagery (MapTiler + Google Imagery).




Reprojection target CRS: EPSG:26716 — NAD27 / UTM Zone 16N.





3. Digitization of Bathymetric Contours

Depth contour lines were manually traced using high-resolution zoom and snapping tools.For each contour:





Lines were drawn following the exact printed isobath.




Depth labels (0–26 m) were extracted and assigned as attributes.




Topology tools were used to ensure continuous lines without gaps or overlaps.



Contours were then classified by depth value.



4. Generation of Bathymetric Points (Vertices Extraction)

To obtain evenly distributed depth reference points:





Each contour line was converted into vertices.




Vertex geometries were exported as a point layer.




The depth attribute of the parent line was transferred to each point.This produced a high-density point cloud suitable for interpolation.





5. Shoreline Digitization

A clean shoreline polygon was created by:





Extracting only the 0 m contour.




Correcting for small breaks in the line using the “Fix Geometries” tool.




Converting the line to a polygon using "Lines to Polygons."




Smoothing and validating geometry to match the current lake extent.





6. Raster Interpolation (Depth Surface)

A continuous bathymetric raster was produced from the depth points:





Interpolation method: IDW (Inverse Distance Weighting) and/or TIN triangulation.




Cell resolution: 5 meters (chosen to balance detail and file size).




Raster clipped to the lake polygon to avoid artifacts.




Color ramps selected to match conventional bathymetry palettes (light to deep blue).





7. Quality Assurance & CRS Standardization

All layers were:





Reprojected to a unified CRS (EPSG:26716).




Checked using QGIS geometry validation tools.




Assigned clean attribute tables with meaningful field names.




Compared against modern shoreline references for spatial consistency.





Recommended Tools





QGIS 3.x (preferred)




GDAL 3+




ArcGIS Pro




Python (rasterio, geopandas)




R (terra, sf)
description: General Use

This dataset is suitable for environmental analysis, hydrological modeling, limnology, terrain visualization, GIS teaching, heritage reconstruction, and cartographic production.All layers are provided in open formats (SHP, GeoTIFF) and can be loaded directly into QGIS, ArcGIS, or any GIS software that supports standard geospatial formats.



Accuracy and Limitations





The bathymetric information was digitized from a printed 2007 map, not from original field depth measurements.




The interpolated depth raster represents a best-effort reconstruction and should not be used for navigation, bathymetric engineering, or legal purposes.




Some local deviations may occur due to scale, print distortion, and the quality of the original figure.





Coordinate System

All vector and raster data use:

EPSG:26716 — NAD27 / UTM Zone 16NUnits: metersProjection: UTMDatum: NAD27

Users should reproject layers as needed for their workflow.



Layer Dependencies

For correct visualization and analysis:





Raster layers (depth surface, hillshade) should be clipped to the lake polygon if remixed.




Depth contours maintain the depth attribute in the depth field.




Vertices include one point per line segment and can be used as interpolation seeds.




Styles (*.qml) can be applied to recreate the same look and feel in QGIS.





Reproducibility

The dataset includes:





Digitized vertices




Contour lines




Lake boundary polygon




Processing CRS




Documentationwhich allow users to fully reconstruct the bathymetric workflow.