Searching for the Source of the Essequibo River

Between 1837 and 1838, Hermann Robert Schomburgk, a member of the Royal Geographic Society in London, explored Guyana, South America in search of the headwaters of the Essequibo River. In his expedition, he mapped and charted over 1,000 km of the river all the way into the untouched rainforest in the Acarai Mountains.

Essequibo river from the air

The Essequibo River, viewed from the air.

In 2013, a multifaceted team decided to utilize the amazing technological advancements in GIS and Mapping to locate, journey to, and film the never-before-recorded source of the Essequibo and its source valley.

Comprised of faculty from the School of Spatial Information at Germany’s Dresden University of Applied Sciences, camera men and the producer from “Blue Paw Artists,” and an expedition team from “Rupununi Trails”, they documented their journey for the French-German Public TV broadcast ARTE in HD and 3D.

But where should they begin?  Before even setting out, the team must first plan a course to follow. To do this, the Dresden University team collected geospatial data from NASA, the German Aerospace Center and DigitalGlobe.

Unfortunately, due to a limited timeframe and almost permanent cloud coverage over the rain forest and its river system, WorldView, Terra-SAR and TanDEM-X data were unavailable.  This meant that the only satellite data available was Landsat and ASTER-DEM data.

A lot of the Landsat image data was partially cloud-covered and of a radiometrically poor quality. Undaunted, the Dresden team utilized ERDAS IMAGINE’s powerful image processing technology to layer stack the available data, pan sharpen it, and then combine numerous LANDSAT 7 scenes into a cloudless mosaic.

Added to these challenges is the fact that upper Essequibo—called the Sipu River—is only about 5 meters wide. This means that the river itself was not visible in the data and, given the geometric resolution of the Landsat data, made it virtually impossible to accurately pinpoint.

To combat this, the team used more of the powerful tools in ERDAS IMAGINE to  create better views into the data. First, they combined the Landsat image data with an ASTER digital surface model to create a 2.5D surface model. Then they used the terrain operators to generate other alternate visualizations like hill shades.

Fully equipped with the best plan technology could provide and with the support of members of the Amerindian Wai Wai tribe, the team set out on a eight -week journey to compare its data to the data collected by Hermann Robert Schomburgk.

Once in the field, the work they had done in preparing the surface model proved priceless. Several times, they were confronted with highly dense, inaccessible and impassable bamboo forest. Using the surface model in combination with the satellite image data, the team could find alternative routes through the forest to reach the source valley.

Through the use of both field exploration and geospatial technology, the team was able to achieve a higher level of accuracy than ever before, even given the monumental and historical challenges. The end result of this effort was a powerful television documentary called “Expedition Essequibo,” which was showcased at the residence of the European Union Ambassador and broadcast in spring 2014 throughout Germany and France.

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