Aquatic ecosystems The Orange River forms a green artery of life through the harsh and arid desert along the border of South Africa and Namibia. Courtesy Senqu2SeaCourtesy team Scientists brave SA’s mightiest river to kayak from source to sea When Irrigation Department Director, hile not as substantial to undertake rare extensive field Dr Alfred Dale Lewis, explored the lower as its cousin, the research. “The Orange is the iconic Zambezi, to the north, South African river – long, ancient reaches of the Orange River in December SouthW Africa’s largest river has and traversing varied and incredibly 1913 he walked most of the 400 km-long always captured the imagination of beautiful scenery, from grass moun- journey in one of the hottest years on those who gazed upon it. Local Khoi tain highlands to rocky desert. We named it the Gariep, meaning ‘big wanted to spend an extended period record. Now nearly a century later, three water’ or ‘great river’, while the San’s in nature, experiencing a long rather young researchers of the University of name for it meant ‘Dragon River’. It than a technically difficult adven- Cape Town (UCT) have completed a similar was European commander, Colonel ture,” explains the team. Robert Gordon, who gave the river adventure, traversing South Africa’s its ‘royal’ name, naming the river VALUABLE RESEARCH mightiest river in kayaks from its source after Dutch ruler, Prince William of in the Lesotho mountains to its mouth on Orange, 300 years ago. hile enjoying the scenery For Masters graduate Sam Jack, Wthe team also took time to the West Coast of South Africa. Lani van PhD student, James Puttick, and, undertake vital on-site research. Vuuren caught up with them following the statistical science lecturer, Ian With funding provided by the Plant completion of their 2 000-km journey. Durbach, the river offered the adven- Conservation Unit at UCT and ture of a lifetime as well as a chance the South African Environmental 18 The Water Wheel July/August 2013 Aquatic ecosystems Observation Network (SAEON) An example of dirty Arid Lands Node the team was able unfiltered water (left) and clean filtered to undertake a true river mega- drinking water (right). transect. These snapshots of entire river systems are becoming increas- ingly important due to the need for baseline monitoring in the face of unpredictable changes due to future “The Orange climate change. is the iconic Photographic data, which consists South Afri- of high resolution landscape panora- can river mas, were taken at 40 km intervals, – long, while photographs of the riparian vegetation were taken at 2 km inter- ancient and vals. This collection of photographic traversing data forms a priceless baseline for varied and monitoring vegetation and land- incredibly scape change along the Senqu (as beautiful the river is known in Lesotho) and scenery.” Orange River. The GPS position of photographs will allow future visitors to retake the images or allow com- parison with historical images and Courtesy Senqu2SeaCourtesy team assessment of the degree of landscape change in terms of, for example, an average of 40 km a day. An aver- were few days when we struggled to development on the river banks and age day would see the team on the find a good grassy site,” James tells extent/composition of vegetation. river around 08:00 and covering the Water Wheel. Diatom samples were also col- 20 km before breaking for lunch, Jack, Puttick and Durbach would lected as part of a SAEON-sponsored then another 20 km before the late then spend the remaining few hours project led by Dr Jonathan Taylor at Local Lesotho afternoon glare would force them to of daylight carrying out the scien- youngsters take North West University. Diatom data start looking for a suitable campsite. tific programme and taking care of a closer look at will hopefully shed some light on the “Usually any flattish patch large chores. “There was surprisingly little the team’s diatom status of present water quality along enough for three would do, there spare time,” says Durbach. sampling efforts. the length of the river. In addition, numerous diatom sampling locations were selected to coincide with points which had been previously sampled to enable comparisons to be made with regards to changes in water quality over time. The team also collected water samples for an oxygen isotope project led by Roger Diamond of the Geology Department at UCT. These data are interesting for explor- ing the different conditions that exist within different tributaries’ water- sheds during rainfall events. HIGHS AND LOWS he team set off from Qachas TNek, in Lesotho, on 14 Janu- ary and arrived at the Mouth at Alexander Bay just over two month later, on 16 March. They travelled Senqu2SeaCourtesy team The Water Wheel July/August 2013 19 Aquatic ecosystems While finding a place to spend The team’s travel blog reveals “All this data amounts the night was easy, finding clean many tales of adventure, from bro- to a thoroughly and water was not. Obtaining sediment ken paddles and lost gear, to hot carefully captured free drinking water was a challenge, days, monkey thieves, and thunder- particularly in Lesotho, where the storm nights. The team learnt by snapshot of the Orange water in the main channel was heav- bitter experience how to keep their River system; it is ily silt-laden. This required laborious equipment safe and dry – sometimes something we are daily filtering sessions. learning the hard way. quite proud of.” The longest stretch paddled in In general, the Orange River a single day was about 62 km, pad- proved kind to the kayakers. “Some weirs with a bad reputation, tricky dling hard to reach the luxury of the sections, for example, dams, took rapids, the location of waterfalls Felix Unite camp near Noordoewer. longer than expected, but we were and the preferred passage through The team resupplied their foodstocks generally able to make up time on sections where the river is highly whenever passing through or close other sections,” Puttick explains. The braided,” notes Puttick. “Naviga- to small towns, generally every three team portaged around the Gariep tion through braided sections of to five days. The longest stretch and Vanderkloof dam walls; a hand- the river was sometimes slow and between resupply points was about ful of weirs deemed too dangerous to tricky. It forced us to be patient and ten days from the start of the journey run; and a couple of waterfalls. made us appreciate the wide open in Lesotho, to Aliwal North. “One can paddle 99% of the channel when it finally arrived at Orange River system, but it helps the other end.” to have some prior knowledge of The most physically demand- obstacles along the way, such as ing stretches were the Gariep and Vanderkloof dams, due to the lack of flow and occasional headwinds accompanied by choppy water. The stretch from Augrabies to Noord- oewer was also tough due to consist- ently high temperatures (upper 40s) 20 The Water Wheel July/August 2013 Aquatic ecosystems and hot winds, which often persisted activity, starting from the town of tributaries, the Makheleng River, throughout the night. Aliwal North. In addition, Puttick while it was in flood. “It had the Any hardship was soon rewarded studiously recorded bird species colour and consistency of chocolate by breathtaking scenery, from enor- observed on a daily basis, amount- milkshake,” Jack says. “Sediment mous sheer cliffs, stately quiver ing to a continuous record of species inflow such as this is projected to tree forests, to unusual wild animal presence along the entire length of decrease the storage capacity of sightings and the sight of huge storm the river. These data will form the Gariep Dam by 80% by 2050.” systems brewing. basis for several popular articles and The team also clearly observed specific data to be sent to experts in the effect weirs and dams have had VALUABLE DATA the relevant fields. A significant observation was the he team returned home with a extremely heavy silt load carried by Tmountain of data, which will the river during the rainy season, take some weeks to work through. A especially in the upper portion. The total of 61 diatom and water samples team happened to pass one of the were collected; 53 isotope samples taken in tributaries of, and within, the Orange River, well over 1 400 GPS locations of interest, including around 500 water abstraction points and around 700 fish eagle, goliath heron and giant kingfisher sightings. The team also recorded and photographed the location of all significant bird nesting colonies along the length of the river, as well as mining activity. Hundreds of points record the location of fishing The Water Wheel July/August 2013 21 Aquatic ecosystems on the natural ecology of the Orange plants were found to dominate it is something we are quite proud River system, mainly by evening portions of the riparian vegetation of,” says Puttick. “We hope it will be out the natural variability of flow in places. Despite these impacts the of much use as a baseline dataset and in the river. Apart from influenc- water quality below the Gariep Dam as a resource to current and future ing the natural aquatic ecosystem, appeared reasonably good. researchers of the Orange River sys- this has impacted the river’s ability “All this data amounts to a tem.” SAEON and the Plant Conser- to flush itself out every few years thoroughly and carefully captured vation Unit at UCT will be primary during flood events. Alien invasive snapshot of the Orange River system; repositories for the data.