The general aim of the expedition is to traverse the length of the Orange River, from Qacha’s Nek high in the majestic Maluti Mountains of Lesotho, down to Alexander Bay on the barren sandy Atlantic Coast, over the course of two months.

This equates to an average paddling distance of 40km per day, but will vary greatly depending on several factors not worth elaborating on here.

En route, the team will be – out of guilt for abandoning their primary work commitments / a compulsive desire to do science whenever and where ever they find themselves – undertaking some research which is unique to this type of venture: namely a true river mega-transect.

The team will be compiling a baseline photographic record of the river and surrounds by taking regular shots on river, and from elevated positions on the river bank. Professor Timm Hoffman from the Plant Conservation Unit at UCT is collaborating on this research and kindly contributed the use of a Mazda Wildlife vehicle to transport us to and from the start and end points of the trip. The GPS position of photographs will allow future visitors (with a focus on the images taken from the bank) to retake the images (or allow comparison with available historical images) and assess the degree of landscape change in terms of (for example) development on the river banks and extent/composition of vegetation.

Diatom samples – a proxy for water quality and the health of the river system – will be collected as part of a project sponsored by the SAEON Arid Lands Node and led by Jonathan Taylor at NWU. The aim is to take frequent samples (it’s essentially the slimy layer covering submerged rocks and macrophytes), focussing both on areas where a history of sampling exists, but also filling in gaps in the record due to isolation / access problems. This data will be used to determine / monitor changes in river health in space and time, and also allow for a useful comparison between chemical composition data (collected by DWA) and biological data.

An oxygen isotope project led by Roger Diamond of the Geology Dept at UCT will receive water samples collected from the main tributaries feeding into the Orange, as well as from the Orange itself, just upstream of these inflows. These data will be interesting for exploring the different conditions that exist within different tributaries’ watersheds during rainfall events

Data recording is going to be a great distraction on those long flat stretches and it’s also a unique opportunity to broaden our own scientific horizons and perhaps improve our understanding of the state of the !Gariep system. So we’re excited about this aspect of the journey.

The Senqu2Sea Expedition is generously supported by The Arid Lands Node of the South African Environmental Observation Network and the Plant Conservation Unit at the University of Cape Town.



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