The first high-resolution bathymetric model of Lake Victoria, Africa
LVBM is licensed by Stuart E. Hamilton under a Creative Commons Attribution 4.0 International License.
Dataset Name: LVBM, Lake Victoria Bathymetric Model.
Period: 1900 - 2017.
Type: GIS Raster and point shapefile.
Format: GeoTiff and shapefile.
Format: These data are created under grant NSF: 1518532.
Stable URL: http://bit.ly/LV_Bathy. For all our data for Lake Victoria, please visit https://dataverse.harvard.edu/dataverse/LakeVicFish.
Data URL: http://dx.doi.org/10.7910/DVN/SOEKNR.
Citation: Hamilton S.E. 2016 Creation of a Bathymetric Map of Lake Victoria, Africa. http://dx.doi.org/10.7910/DVN/SOEKNR.
Abstract:
A 100 m resolution bathymetric model of Lake
Victoria, Africa. The model was created from 4,087,217 points
collected by a lead line survey in the 20th Century or recent hydrographic
surveys. At least 3,920,000 of these points are post-2010 surveys using GPS-enabled
hydrographic survey systems. The points were either GPS referenced or
manually digitized via a process of fitting admiralty maps to the lake
shoreline using their graticule. All input data are either non-copyright
data collected by our research team or expired UK crown copyright (50+ years
old). Points were converted to a raster model by the process of simple
kriging. The deepest portions of the lake may not be captured as the lead
line had a maximum reach of 200 ft. in some locations. The bathymetric model
will continue to be improved as we capture more data. If your research team
have additional Lake Victoria bathymetric data, then send the data to us for
validation and incorporation. The projection is ESRI: 102024 and the
vertical units are meters with a resolution of 1 m. Data include the 4 million bathymetric points, the cross-validation points, the bathymetric
raster pictured above, the kriging settings, a standard error map, and the
respective world files. Please note the three bays of Mwanza, (TZ) Kisumu
(KE), and Port Bell (UG) contain almost 120,000 points with the remaining points
distributed across the rest of the lake.
----------------------------------
Dataset Name: Lake Victoria Contours.
Period: 1900 - 2017.
Type: GIS vector.
Format: Shapefile, Contour.
Format: These data are created under grant NSF: 1518532.
Stable URL: http://bit.ly/LV_Bathy. For all our data for Lake Victoria, please visit https://dataverse.harvard.edu/dataverse/LakeVicFish.
Data URL: http://dx.doi.org/10.7910/DVN/ZSWZIA.
Citation: Hamilton S.E. 2016 Creation of a Bathymetric Map of Lake Victoria, Africa. http://dx.doi.org/10.7910/DVN/ZSWZIA.
Abstract:
A 2 m contour model of Lake Victoria, Africa. The
model was created from 4,087,212 points collected by a lead
line survey in the 20th Century or recent hydrographic surveys. At least
3,920,000 points are post-2010 surveys using GPS-enabled hydrographic survey
systems. The points were either GPS referenced or manually digitized via a
process of fitting admiralty maps to the lake shoreline using their
graticule. All input data are either non-copyright data collected by our
research team or expired UK crown copyright (50+ years old). Points were
converted to a raster model using simple kriging. The deepest portions of
the lake may not be captured as the lead line had a maximum reach of 200 ft.
in some locations. The contours will continue to be improved as we capture
more bathymetric data. The projection is ESRI: 102024 and the vertical units
are meters with a resolution of 2 m.
--------------------------------------
Citable Facts:
-
Using a 100 m2 grid, we find that the average depth of the lake to be almost exactly 40 meters. Using constrained Delaunay Triangulation ,we find it to be 41.88 meters.
-
At 1:25,000 scale we find the shoreline length, including islands, to be 7,142 km (4,438 mi). This is double earlier estimates, and this is likely due to our higher resolution digitizing and the inclusion of more islands. We find the islands now contribute 3243 km of shoreline to the total.
-
We find the islands have a total combined area of 2060 km2.
-
We cannot state with certainty the maximum depth as the lead line did not hit bottom in all locations and sounding may have missed some areas. We estimate it to be approximately 80.77 meters (feature 8701) and the UN reports 84 meters. It is highly unlikely the deepest point has been surveyed.
-
We find the area of the lake to be 59,947 km2. We used WKID: 102022 African Equal Area Conic projection for this estimation.
-
We find that the lake contains 985 islands. The earlier UN number was typically around 85 islands.
-
We find that the volume of the lake to be 2,424,037,334,264 m3 or 2,098,871,058,350,812,416 imperial teaspoons.
-
We find the Lake Victoria Basin encompasses 169,868 km2 of land area and 59,947 km2 of surface water, for a total of 229,815km2.
Thanks to Gary Lucas for help with these statistics.
FAQ:
Will the data be updated? As we get
more points in an ad-hoc manner.
Where did you obtain the point data? Three
primary sources: (i) Greater than 90% of the data is acoustic hydrographic
data collected by NaFIRRI, TaFIRI, and KMFRI since 2010, (ii) points
collected as part of the UK Admiralty map collection greater than 50-years
old, and (iii) other old maps.
What is the correct version of the data? Generally,
use the latest version.
Can you do "x" for me? Sometimes
I can. Usually, I am too busy. Feel free to ask.
Who funded the project? NSF:
1518532 and local fisheries centers.