Notes from ADE Workshop at WRC
Notes from Aquifer Dependent Ecosystems Workshop at WRC 01/04/04
Present
Name / Address / E-mailGary Marneweck (GM) / P O Box 72295, Lynwood Ridge, Pretoria 0040 /
Coral Biess (CB) / Department of Agriculture, Conservation, Environment and Land Affairs, Johannesburg /
Kevin Pietersen (KP) / WRC, P Bag X031, Gezina 0031 /
Piet-Louis Grundlingh (PG) / Working for Water, National Botanical Institute, Pretoria 0001 /
Gillian Maree (G) / Environmentek CSIR, P O Box 395, Pretoria 0001 /
Johan Wentzel (JW) / Directorate of RDM, DWAF, P Bag X313, Pretoria 0001 /
Christine Colvin (CC) / POBox 320, Stellenbosch, 7599. /
David Le Maitre (DLM) / POBox 320, Stellenbosch, 7599. /
Apologies
Dr Terrance McCarthy, Wits University.
Dr Heather McKay, WRC.
Dr Steve Mitchell, WRC.
Marlese Nell, DWAF.
Main Points
The project team must be clear on the implications and consequences of a cut-off based on the traditional, human-use oriented geohydrological definition of an aquifer. We need to spell out the kinds of systems that would be in and out and be careful to adopt a conservative approach.
Do not underestimate the ecological importance of ADEs even though their yields may not be substantial. An example is the (at least partly) perched systems of the gently undulating grasslands of the highveld plateau in Gauteng, Mpumalanga (and the Free State?).
Management guidelines / prescriptions arising from this work need to be practical and implementable by people who do not necessarily have the technical / scientific insight or knowledge.
The identification of gaps in knowledge and understanding of ADEs is a key priority for this project.
Consider making springs separate and grouping seeps with wetlands.
Actions
DLM – contact GM to get copy of SASAqs paper and other relevant information (e.g. contacts for peat study data sets). Get Bruton Maputaland book and read chapter on Lake Sibaya. Ricky Taylor (via PG) re St Lucia refugia study. Arrange for meeting with Jeanne & CC on RC planning project and how we can collaborate and contribute.
CC - Contact CB to get more info on the logical framework analysis for the WHS and the issues relating to the dolomites; also other information on existing geohydro studies in the dolomites e.g. by Wits staff and Eddie van Wyk (re-watrering). Also contact Leslie Gibson (CGS) about Karoo dyke work. Get copy of final Karoo ring-dyke report. Follow-up with Pierre Nel on springs in Langebaan springs.
Notes from the workshop
JW – initially DWAF concentrated mainly on Reserve Determinations but they now realise that a more holistic approach is needed, thus a shift to the full RDM and an emphasis on classification. Sandveld study has shown the need to correctly ID water sources. The severely impacted longitudinal vleis are not perched systems but probably fed by springs from the TMG underlying the Quaternary deposits based on drilled sections.
GM – the newest approach in wetland type classification is to differentiate ito flow pattern of water and the kind of system. Particularly concerned about the almost completely neglected and understudied perched aquifer systems characteristic of the gently undulating plateau on the highveld. These aquifers can be very extensive and large, forming an extensive mosaic which can make up as much as 30% of the landscape in the upper Olifants River (see Palmer et al. WRC report). These are very important ecologically – they do not appear to contribute large volumes to the rivers but are important for biodiversity.
Comments during presentation
There was general concern in response to CCs introduction that the project was concerned mainly with Aquifer Dependent Ecosystems where ADEs would be recognised where the aquifer was capable of supplying sufficient water to a well or borehole. There was agreement that although this was probably a practical and necessary cut-off for the project, the implications, assumptions, etc needed to be explicitly discussed in any reports.
GM – experience on the Limpopo had shown that even subtle changes could be significant ecologically – reason for caution.
PG – the ecological importance of perched systems and seeps is always underestimated, mentioned work of /study by Anton Lindstrom.
GM – confirmed the need to highlight perched systems.
KP – groundwater was the main reason why Steve Mitchell’s KSA is now named water-linked ecosystems rather than aquatic systems.
CC – agreed & highlighted importance of recognising terrestrial systems where plants had groundwater within root zone but there was no evidence of surface water. These were not aquatic systems.
GM – the perched systems and the underlying systems may not always be completely separate. On the highveld the clay from the shale-derived soils had elluviated to form a “plinthic” layer beneath the surface sands. The lower aquifer beneath the plinthic layer and the upper one intersect in places. This structure, and the complexity of the wetland systems, was revealed in the laying of the gas pipeline from Secunda to Komatipoort and into Mozambique.
PG – certain geological substrates react differently, deep sandstones will intersect with shallow systems, depends on the confining layer; we (project team) must be clear on what we have left out by using our definition.
JW – interested in the notion of the equivalent of an IFR for an aquifer or groundwater resource, perhaps closer to the approach explored for wetlands.
CC – this could also give an indication of the degree of impact
GM – there was a distinct difference between grassland and bushveld systems – wetlands in grasslands are more obvious even in the same geological settings and environments; reasons for this difference not understood.
PG – recommended contact UPE for information on observations in Algoa Bay (CC mentioned that we were aware of evidence for springs around Jaheel Is). Another site is Lake Sibaya on the Zululand coastal plain – see Mike Bruton’s book (I think Pat M has copy). There are important differences between granites, which weather to sands, and basalts, which weather to clays, which need to be considered. The various wetland types differ with a variety of drivers for the different habitat types. We were only considering two very different systems (Langebaan and KNP) and need to recognise the variety in between
(DLM - this is not a one-dimensional [linear] relationship but multi-dimensional and we should try to define some of the key axes in the multi-dimensional space. Addit note – where do Kalahari “eyes” and subterranean TMG in Sandveld fit in that table – the aquifer medium or the water source?).
GM – suggests a grouping rather of: springs which are discreet and generally tightly confined discharge points vs. wetlands/seeps which form more of a continuum and are typically diffuse discharge. These difference affect hydromorphy and also functional differences. A secondary characterisation by flow-regime would be useful e.g. perennial - seasonal – ephemeral.
CC/DLM – the reliability of temporal flow-regime is related also to aquifer storage, GROUNDWATER flow paths and fact that groundwater discharge often occurs as overflow.
PG – what about rainfall (variability) as input
JW – also structural controls over upwelling as in Sandveld TMG
PG – Recommended we contact we contact Ricky Taylor who is working on a U Norway project on refugia on St Lucia wetland system. Suggested we get hold of the logical framework analysis done for the Cradle of Mankind WHS and the issues concerning the Dolomites as raised by pressure groups. Mentioned Patrick Degan(?) – contact Carol.
JW – lot of concern about the impacts of the rewatering of the dolomites following mine closures – contact Eddie van Wyk
PG – also contact Lesley Gibson – CGS Bellville and working on dolerite rings in Karoo.
KP – Luc Chevalier – first report now published and new project begun.
GM – new definitions of wetlands focus on the hydrological regime (water source, hydrogen type), hydrological function and role of water they give (input - through flow – output).
CC - similar to Acreman paper – send to GM & PG. Our focus in on water they receive rather than what they yield to the catchment.
GM – to send us draft of SASAq paper by Katz et al.
PG – Working for Wetlands mandate has expanded, now includes a national inventory of wetlands.
JW – whatever the approach it must be able to be defined and designed to fit in a legal framework linked to the licensing conditions - through classification and RQOs to set envt allocation - and make it enforceable.
Further discussions
GM – re-emphasised importance of the perched systems in highveld grasslands (see earlier). We should look at the work on peat wetland mapping at Ecoregion level 2 done for the NDA – available as a GIS layer and report – for managing peat mining. All permanent wetlands with springs. Peatlands not key for plant biodiversity often mono-specific except for Dullstroom area where the biodiversity role was higher – also National Bird Area because of water birds (Flufftail) – check PMs book. Some deposits considerable e.g. >1 m at Lakenvlei near Dullstroom (post-glacial). Includes unexpected peat wetlands in the Soutpansberg. Also the study on the Steenkampsberg – confined seepages. Restoration of peatlands depended on mining technique. Set by NDA?? Remove and re-engineer setting was not always successful. Alternative approach was to maintain sections and rebuild – more successful?? European classification approach to peats based on role in filtering etc but not generally relevant here as they were too dense and water flow passed under and/or over peat body. Zululand peats more coarse and porous.
GM - The upper Olifants report wetland classification – based on Brinson - was too complex with 17 types now reduced to 7 in Kotze et al. paper. The highveld grassland perched systems of Gauteng & Mpumalanga (DLM – also Free State?) were critically important for biodiversity and specialist species. Where there were footslopes, groundwater discharges sustaining wetlands in addition to the typical river/stream flows the biodiversity increased from 30-40 spp up to 160-170 spp. More than 50% now lost due to ploughing for maizefields (most fertile soils, easily accessible) and be surface mining. In many cases incision of the river system had reduced seasonal flooding and increased importance of groundwater discharge. The impacts of open-cast mining are important but the wall and pillar (?) approach maybe equally destructive by causing slumping and increasing drainage or otherwise degrading integrity of perched systems.
G – River conservation planning project team did not understand enough about the potential role of groundwater in rivers and river associated systems (e.g. floodplain wetlands). Their main emphasis was on identifying types/classes of rivers, describing their state and recognising/prioritising threatened types (e.g. unique, highly transformed), assessing their resilience and state of ecosystem processes. They too are operating at the national scale and there are many synergies. Like the grassland wetlands there are probably rivers where the groundwater contribution is small but the ecological importance is high. RC project has focussed on pattern, now trying to link pattern & process. River types are based on an ecosystem pattern or signature and now they want to link these to wetlands and estuaries (DLM – important to get whole picture of river-groundwater-ocean linkages).
CC – hydrologists & aquatic ecologists link much to baseflow assessment (index) but there are insufficient groundwater data for this.
G – An important problem for the RC project had been the generation of regional (sub-national) data sets as national data were not necessarily appropriate. They had to generate many of these themselves.
CB – we need to make contact with Nico ?? who is involved with the WHS and the dolomites and with Dr (Dean) Peinke. Also Wits Geosciences where ?? Jameson and Elna ?? had been doing work on the impacts of water abstraction.
CC – problem with dolomites is that they have been too severely impacted but Sayomi Tsasaki was looking at the in-aquifer ecosystems
JW – a BIG problem in the dolomites is re-watering with the high acidity and the potential for structural impacts.
CB – she also knew of a spring on Jutten Is in the Langebaan lagoon and of springs (fw pools) in the saltmarshes. Pierre Nel (WCNP) also knew of these springs.
KP – the project team must identify areas where there is a lack of understanding (knowledge gaps) and prioritise these. Need to know who our target managers are and ensure we understand their needs and priorities.
JW – DWAF is moving towards full RDM approach (IPP??) and the incorporation of the river conservation planning inputs. But there needed to be more linking up via the RDM. Classifiaction was the primary step in ensuring adequate protection. It is critical that RQOs should be appropriate for operational management to implement and need to be enforceable. [CC – RHP approach might be appropriate with simple, unambiguous indicators of ecological health]. Need to address EFR in practical terms, perhaps in the way proposed for wetlands. [CC – our approach is to address this through type settings and types of ADEs so that we can give discharge/water levels that reflects natural variability and that things are dynamic e.g. springs to change naturally.
KP – very important to maintain inter-disciplinary cross-fertilisation and not to ignore water quality (Zebra do not drink murky water).
JW – identify more areas for potential case studies – perhaps in the Sandveld [prolem of impacts again]. Squeeze the most out of the RDM e.g. Sandveld site needed more work on surface survey work. Need top bring groundwater back into Olifants-Doring assessment as its importance was being underestimated (e.g. Cate – temperature of permanent pools for indigenous fish). Need to integrate with other players (in RDM?) as important stakeholders. NWA aimed at human use and this needed to be tempered.
KP – there were issue in the RDM approach and there was a one-size-fits-all mentality, need to design approach more around issues and make them more specific. [CC – contact Linda Godfrey on Resource Quality Policy].
JW – Once we have a methodology we can adopt the EIA approach. [DLM – I think an SEA approach the NWA at CMA level is needed. Principle already recognised for Commercial Forestry, now needs to adapted for CMA/WMA level and water resources]
KP – this should be raised as an issue for research.
GM – E Cape RHP reports – contact Dirk Roux and Wilna Strydom. E Cape regional study for RC would be an ideal opportunity to introduce groundwater into the picture.