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One of the biggest challenges facing climate change scientists today is the ability to downscale global circulation models to regional scales.
The "envelope of uncertainty" in model products is just too great to meaningfully inform decision makers for local scenario planning. The need for in situ data - particularly in underrepresented areas - used to develop, train and test models has been highlighted as a critical need to reduce these levels of uncertainty in downscaling1.
Understanding global change impacts on South Africa’s critical water resources is a unifying theme among SAEON nodes. The value of building on historic experimental catchment stream-flow and weather data for current global change challenges, such as those outlined above, has been highlighted in several SAEON eNews articles.
Following the successful refurbishment of a number of the Jonkershoek experimental catchments by SAEON’s Fynbos Node, the SAEON upper catchment stream-flow and weather monitoring programme was extended to Cathedral Peak (in the uKhahlamba Drakensberg Park World Heritage Site) by the SAEON Grasslands Forests Wetlands (GFW) Node.
Looking backwards to help us move forwards
By May 2012, landslides blocking the Mike’s Pass access route had been cleared, the four focus weirs had been cleaned and the process towards resurrecting the historic instrument array had been initiated.
SAEON GFW Node staff members and lecturers Dr Michele Warburton and Mark Horan from the University of KwaZulu-Natal (UKZN), decided it would be worthwhile to hold a “tacit knowledge transfer meeting”, bringing together those who had worked in the catchments over the last few decades with those more naive to the responsibilities that lay ahead in continuing the legacy. The idea was to tap into unwritten lessons, the history and the anecdotal stories that are the stuff of legends.
Drawing on the summed experience of those who attended, we also took the opportunity to consider how to make the most of the long-term monitoring programme that had been initiated all those years ago in the 1930s. The meeting provided a clear context and direction for the programme, but also acted as a strong catalyst for stakeholder interest. Subsequent support and value-adding research collaborations were the net positive result.
Deploying the instruments
Armed with a plan of action, August 2012 saw the historic Mike’s Pass weather station site resurrected with a new automatic weather station (AWS). This station collects detailed data on various meteorological parameters. It is one of very few stations at this “mid” altitude (1890m) in what constitutes the most important water catchment in the country.
An additional weather station has been placed at the base of Mike’s Pass (1364m). Funding for a third full AWS for a high-altitude site (approx. 3000m) has been secured, with deployment planned for September 2013. High-altitude precipitation dynamics in the Drakensberg catchments, like in Jonkershoek are poorly understood. Even less understood are the potential impacts of climate change on this high-altitude dynamic and the consequential hydrological responses that may ensue.
A milestone in May 2013 was the completion of the weir refurbishments and the installation of pressure level transducers controlled by data loggers that monitor stream flow in the four weirs selected for continued monitoring. The loggers have had their first check and are working well.
Next on the cards is the installation of 15 rain gauges that replicate the historic array of gauges that complement the stream-flow data, an additional three wind stations and a series of soil moisture and temperature probes across the catchments.
Students as beneficiaries
The weather data being generated from Mike’s Pass is already being used by UKZN hydrology honours students for "real time" hydrology monitoring training. This is the second year of honours students benefiting from the Cathedral Peak living laboratory. To bring the data alive, the 2013 class were recently taken into the catchments for hands-on training and were tasked to “GPS” the catchment boundaries and previous rain gauge sites.
The resurrection of the weather station and the stream-flow monitoring are also stimulating postgraduate interest and already enabling several projects. Luke Bodmann from UKZN, supervised by Dr Warburton, Prof. Trevor Hill and Dr Jemma Finch recently registered his Masters project with SAEON. The project is titled “Detection and Attribution of Change of Afromontane Archipelago: Cathedral Peak, South Africa”. Luke will be using historic and current stream flow, weather and fire data, combined with sedimentary records (fossil pollen-vegetation, microfossil charcoal-fire) to detect global change patterns. This is an interdisciplinary project bringing the palaeo, hydrological and meteorological sciences together by comparing long-term palaeoenvironmental data with short-term instrumental datasets.
As the subject of her Honours research last year, Ntombi Ngoloyi was able to reconstruct a recent fire history by analysing sediments accumulated within catchment sediment traps before they were cleaned. Tristan Duthie, working with Prof. Trevor Hill, has also registered her MSc project with SAEON. The project focuses on “modern pollen dispersal and deposition rates of vegetation communities of the Cathedral Peak area, KwaZulu-Natal Drakensberg”. Feroza Morrise, supervised by Dr Warburton, Dr Hartley Bulcock and Alistair Clulow, has also just started her MSc and is tackling the central question of regional rainfall patterns in the Drakensberg.
Value of collaborations
The SAEON GFW Node has secured significant resources through the National Research Foundation’s Strategic Research Infrastructure Grant (SRIG) to replicate the historic instrument array with modern sensors as well as add additional, much needed, sophisticated observation instruments to address critical data needs for global change science.
The strength of a programme like this depends, in many respects, on the level to which stakeholders and scientists engage with the programme to make the best use of the data platform provided by SAEON, as well as to what level they co-support and add value to the platform.
UKZN has signed a participation agreement with SAEON to facilitate collaborations within the Cathedral Peak catchments. In particular, the GFW Node has developed close ties with the Centre for Water Resources Research (CWRR), School of Agricultural, Earth and Environmental Sciences who have historic links to the catchments.
Following from this, a joint proposal between UKZN, SAEON and Ezemvelo KZN Wildlife (EKZNW), spearheaded by the UKZN team, was submitted to the Water Research Commission. The successful application - entitled “Establishment of a more robust observation network to improve understanding of global change in the sensitive and critical water supply area of the Drakensberg” - is enabling a valuable scientific injection into the programme, additional research-related equipment as well as much needed support for students. It symbolises a strong unison between SAEON and UKZN in striving to attain the full monitoring and research potential that these catchments have to offer.
Collective efforts mean these catchments will provide significant monitoring and research data to enable sophisticated research analysis and modelling pertinent to addressing global change questions. None of this would be possible without the continued support from land custodians EKZNW. They provide support both from a strategic level as well as operational ground-based support. On that note we are pleased to announce that SAEON has just renewed its hosting agreement with EKZNW.
A platform for integrated, multidisciplinary, global change science
An important output from the Tacit Knowledge Transfer workshop was the realisation of the wealth of data from catchment 6 collected by Colin and Terry Everson on water and energy balance (see WRC report no 493/1/98).
Some source of uncertainty in climate models is the lack of detailed water-carbon-energy balance data from different systems. Subcomponents of these include precipitation, evapotranspiration, subsurface flow, stream flow, ground water and radiation balance and primary production.
As we walked down the hill contemplating if there had been an expansion of C3 Festuca grass in the area, Prof. Colin Everson turned to me and said, "You know what would be ideal? A full eddy covariance system in catchment 6!” Of course yes. Thanks again to the SRIG NRF grant which has procured an extended eddy covariance system, which is an instrument that measures a number of these key variables, including gross primary production. It is currently being deployed under Colin’s close supervision.
SAEON is fortunate to have Prof. Everson as a current collaborator. Tantalised by the revitalisation of the catchments and the promise they hold, he has returned to his old stomping ground of 18 years, to build on the work he initiated in the 1970s when running catchment monitoring programmes. The only difference now is that the “toys” he likes to measure things with are a little more sophisticated, with a bigger range of what can be measured, and come at slightly more extravagant price tags.
While SAEON is providing the long-term monitoring array including the eddy covariance system, Colin and his team from Commercial Waste Reduction and Recycling and the University of Pretoria are expanding on this with some exciting new research-related equipment fairly novel to South Africa, but more about that in the next update on Cathedral Peak.
Interdisciplinary integration of data and model inputs and outputs looking at land management, vegetation response and soil, water and energy dynamics has also emerged as a possible means to improve downscaling. A major challenge is that not all disciplines are often studied to the appropriate scale at the same site to enable this. The work SAEON is planning and implementing in the Cathedral Peak research catchments is designed to address exactly this challenge.
In addition to the projects already mentioned, we are also initiating soil and carbon work through various linked collaborations, as well as the resampling of historic vegetation plots with Dr Terry Everson to assess long-term vegetation response. The node’s ultimate aim is to provide the means, through data provision, for experts to integrate data across disciplines, reduce the envelope of uncertainty in regional predictions and enable more confident, informed decisions for society toward climate adaptation and mitigation.
Interested potential collaborators are welcome to contact Sue van Rensburg for further information.
1 Proceedings of SANCIAHS 2012, and DST-NRF Global Change Conference 2012
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