MISSION 21 of 2010
Name of Mission: Working for Wetlands 05 of 2010 – Malutis in the Free State
Date of Mission: 23rd June 2010
Pilot: Dries Lategan
Beneficiary: Doug McCulloch
Beneficiary’s story of the mission : By DOUG McCULLOCH
Working for Wetlands is part of the South African government’s Expanded Public Works Programme, and is administered by the South African National Biodiversity Institute (SANBI). The objective of the flight was to try and identify problems within the identifiedwetlands that may require intervention in order to return or recapture wetland functioning. The problems may be in the form of:
- berms and other impoundments;
- eroding headcuts; and
- eroded channels.
Once identified from the air, and the co-ordinates marked, the problem sites will be visited during the field trip, and assessed from the ground.
The survey team comprised the following people:
- Dries Lategan, volunteer pilot with The Bateleurs
- Doug McCulloch, a wetland specialist with Wetland Consulting Services
- Tilivali Nyambeni from the South African National Biodiversity Institute (SANBI)
The intended flight path would take us from the airfield in Harrismith directly west over the sprawling farmlands to the north of Kestell, and the beginning of the survey. From there we would fly north-east to the northern edge of quaternary catchment C81J, and then west, following the two main river systems draining the catchment. The flight would then zig-zag south again, before ending in a loop over the less mountainous region of catchment C81G.
The survey area is characterised by extensive areas of cultivated farmlands interspersed with blocks of primary short grassland of varying sizes. The intensive nature of the landuse has had a considerable effect on the wetland systems through the alteration of their catchment characteristics. The soils in the catchment are sandy and free-draining and the natural vegetation cover would promote water infiltration following rainfall. Under natural conditions rainfall would percolate through the soil profile before encountering an impermeable layer, such as parent material, and being expressed at the surface as a wetland. The extensive removal of the covering vegetation, and its subsequent replacement by row crops, coupled with the contouring of the lands adjacent to the wetlands has had the following impacts:
- Surface runoff has been promoted at the expense of infiltration;
- This runoff has been concentrated on the sides of the lands by contour banks, leading to the point-source discharge of runoff into the wetland systems.
- The highly erodible nature of the soils, allied with the above effects, have facilitated channel incision and gully formation.
The net-result is a landscape generally characterised by degraded wetland systems, with what seems to be ample opportunity to undertake wetland rehabilitation initiatives.
The flight was carried out by Dries Lategan, an extremely pleasant and accommodating engineer and pilot based in Harrismith, who has an intimate knowledge of the entire district. There was a slight delay due to fog, and once underway, although the sky was cloudless, it soon became apparent that conditions would offer their fair share of challenges. Chief among these was poor visibility, highlighted by the realisation that, at a distance of 5km from Harrismith and a height of 500m, we were unable to see Platberg. Doubtless this is something we’ll have to get used to if Eskom carry on building coal-fired power stations. Compounding the poor visibility was the flat nature of the landscape, which often made it difficult to discern the direction and position of the primary drainage lines within the catchments. However, thanks to the endless patience of the pilot, we managed to criss-cross the landscape and gain a good overview of the drainage characteristics of the catchments.
- Aerial surveys are an exceptionally useful tool in directing work such as this because they:
- Identify physical problems on the ground;
- Enable the wetland ecologist to gain a good understanding of the kinds of wetland systems located within the catchments, as well as their hydrological characteristics;
- and Identify areas where work is not feasible, thus streamlining the fieldwork.
Approximately 39 problem sites were identified from the air. More importantly, however, the flight enabled the following conclusions to be drawn:
- The problems are generally small and widely dispersed, which will present logistical problems in terms of the implementation of the rehabilitation measures;
- The areas of wetland habitat where wetland rehabilitation is feasible within this kind of production landscape are few and far between; and
- The damage to the wetland systems is either too severe to be within the scope of Working for Wetlands, or too minor to warrant the time and expense involved with rehabilitation.
Altogether approximately five wetlands were identified for field survey. The Bateleurs, through Dries Lategan, have played a major part in streamlining the fieldwork component by helping to identify problems quickly and efficiently over an extensive area.