coaltech upper olifants river catchment wetland inventory ...

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8.3 Database accuracy The database accuracy was determined during the field verification exercise. A total of 632 wetlands of various sizes were verified, a number of which (107) were deleted, since the wetlands could not be observed during the site visit. It was therefore determined during the site visit that approximately 17% of the wetlands verified do not exist. Eighty-seven percent of these wetlands identified, were seepage wetlands. Therefore, it can be concluded that seepage wetlands are most difficult to delineate accurately based on aerial photographs. Seepage wetlands are very similar to the surrounding grassland areas in vegetation structure and the two can easily be confused when delineating from aerial photographs. In addition, a total of 133 wetlands (21% if the verified wetlands) observed in the field, but absent from the database, were delineated. The wetlands were small (1 350ha in total) in comparison to the total area (105 843ha) of the verified wetlands. The added wetlands therefore only comprised 1.3% of the verified wetlands, an almost negligible difference. This inaccuracy is probably due to the scale of the aerial photographs. All of the wetlands observed in the field, but not included in the database, were significantly less than 100m 2 . The total area of wetlands in the UORC has been lowered from 3 105km 2 to 2 147km 2 , a difference of 31%. The total area of non-floodplain riparian wetlands and perennial pans changed little, but the total area of artificial wetlands doubled in size, while the total seepage area halved. The floodplain riparian and non-perennial pans diminished in total area by 36% and 26%, respectively. Most of the changes in the total wetland area in each wetland type are not due to changes in the delineated wetland areas, it is a matter of reassigning the wetland type. During the field verification visits it was determined that 28% of the verified wetlands were listed under the incorrect wetland type. It is important to note that an even larger percentage of the delineated wetlands may be artificial wetlands, and that this has not been picked up during the field verification site visits. A large number of seepage wetlands were erroneously indicated due to tonal and structural similarities between temporary wetland plants and terrestrial plants during the winter months. These similarities were noted during the field verification site visits and the entire wetland database amended accordingly, including areas not field verified. This amendment was based on the aerial photographs. It is therefore expected that the accuracy of the wetland layer has been improved to 70% accuracy. Wetland Database for UORC - 94 -
The attributes in the attribute table was also verified where possible. The most inaccurate attribute was the status of the wetlands. Sixty percent of the verified wetlands had an inaccurate status indicated in the database. The status was mostly increased, but in some cases the status of the wetlands were also decreased. This attribute is very difficult to determine from an aerial photograph. The connectivity attribute of 39% of the wetlands were changed, either lower or higher, and the threat attribute has been added to for 35% of the wetlands. Various threats were observed in the field, which are not visible on the aerial photographs. The attributes in the database has an overall accuracy of 60% and the wetland layer an accuracy of 70%. 8.4 The way forward o This layer, although baseline, is not intended as a static, once-off project and the data should be refined and corrected on a regular basis. o The layer should be handed over to a host organisation capable of refining and updating the wetland layer, e.g. SANBI. 9. CONCLUSION Limited literature is available on the wetlands in the UORC, but the literature available illustrates the importance of the wetlands in terms of services and functions of the wetlands in general and specifically in the UORC. In addition, the wetlands are under threat from various activities within the catchment. Although it is not feasible to prevent all activities impacting on the wetlands from taking place, the activities can be managed to obtain the most beneficial combination of economic development and wetland conservation. A wetland database and a dam layer have been compiled for the catchment, based on the existing wetland databases and 1:50 000 aerial photographs. The wetland layer is linked to a wetland database including various attributes such as wetland type, possible functions and status. The wetland database and dam layer should, however, be viewed as a baseline study to guide decision making, and should not replace more detailed, site specific, wetland assessments. Wetland Database for UORC - 95 -
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COALTECH UPPER OLIFANTS RIVER CATCH
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The following aspects are included
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The most common wetland types in th
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The attributes allocated based on t
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6. DATABASE CONSTRAINTS............
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Addendums Addendum A - Plant specie
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Figure 1. Extent of the UORC (refer
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The aim of the wetland layer is to
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3.3 Wetland biodiversity Wetlands p
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Table 1: Species of concern Species
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Species name Common name Hottentot
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Species name Common name Cordylus g
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3.3.2 Birds Various bird species ut
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3.3.6 Fish The UORC has a low diver
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Figure 2. Schematic illustration of
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3.4.1.2 Floodplain riparian Floodpl
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3.4.4 Other non-riparian wetlands O
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3.5.1.2 Groundwater recharge Variou
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More important in the removal of me
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The flow velocity in the channel of
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The most important fishing activity
Page 43 and 44: 3.5.6.3 Livestock Diseases Various
Page 45 and 46: 3.6.2 Mining and Quarrying There is
Page 47 and 48: • Dwars-in-die-wegspruit at the l
Page 49 and 50: 3.6.4 Burning Wetlands are burnt on
Page 51 and 52: 3.6.9 Alien Fauna and Flora 3.6.9.1
Page 53 and 54: Category 3 plant invaders are plant
Page 55 and 56: o The Fish Assemblage Integrity Ind
Page 57 and 58: Figure 4. The ecoregions of the Oli
Page 59 and 60: Sixteen fish species (four of which
Page 61 and 62: Figure 5. Extent of the UORC accord
Page 63 and 64: 3.9 Common wetland types in UORC Ac
Page 65 and 66: In a wetland assessment conducted a
Page 67 and 68: In a wetland study at Douglas Colli
Page 69 and 70: Figure 8. Status of assessed wetlan
Page 71 and 72: Figure 9. Portion of the wetland la
Page 73 and 74: Figure 11. Portion of the water bod
Page 75 and 76: Figure 13. Portion of the separated
Page 77 and 78: Figure 15. Portion of the wetland l
Page 79 and 80: Since the field verification site v
Page 81 and 82: Figure 18. Portion of the final wet
Page 83 and 84: Upon a request from DWAF the status
Page 85 and 86: 5.8 Functions The functions likely
Page 87 and 88: 5.11 Wetland types The entire catch
Page 89 and 90: 6. DATABASE CONSTRAINTS The greates
Page 91 and 92: Figure 21. The wetland in the UORC
Page 93: 8.2 Mapping o Small wetlands (of le
Page 97 and 98: 10. REFERENCES Abbott Grobicki (Pty
Page 99 and 100: Goudie, A.S. & Thomas, D.S.G. 1985.
Page 101 and 102: Merot, P., Squividant, H., Aurousse
Page 103 and 104: Wilson, R.T. 2003. Animal health an
Page 105 and 106: Addendum A - Plan species list Wetl
Page 107 and 108: var. lachnantha Lamiaceae Ajuga oph
Page 109 and 110: Asteraceae Berkheya onopordifolia B
Page 111 and 112: Poaceae Chloris pycnothrix Chloroph
Page 113 and 114: Poaceae Boraginaceae incompletus Cy
Page 115 and 116: Poaceae Echinochloa cruspavonis * *
Page 117 and 118: Asteraceae Gamochaeta subfalcata Y
Page 119 and 120: Sterculiaceae Sterculiaceae Poaceae
Page 121 and 122: Cyperaceae Kyllinga erecta Kyllinga
Page 123 and 124: Asteraceae Nidorella anamola Nympho
Page 125 and 126: Polygonaceae Apiaceae Poaceae Apiac
Page 127 and 128: Brassicaceae Rorippa nudiuscula * *
Page 129 and 130: Poaceae Setaria verticillata * Malv
Page 131 and 132: Asteraceae Ursinia nana * * * Lenti
Page 133 and 134: Addendum B - Mammal species list We
Page 135 and 136: Cynictis Yellow Carnivora penicilla
Page 137 and 138: Addendum C - Bird species list Wetl
Page 139 and 140: Actitis hypoleucos Actophilornis Co
Page 141 and 142: Ceryle rudis Nectarinia Pied Kingfi
Page 143 and 144: Eremopterix verticalis Estrilda ast
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Netta erythrophthalma Numida meleag
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Spizocorys conirostris Pinkbilled L
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Addendum D - Reptile species list W
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Elapidae Naja haje Egyptian cobra X
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Group Species name Common name Pipi
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Addendum F - Fish species list Wetl
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Austroglansis sclateri X X Barbus a
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Phylum Group Species name Common na
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Arachnida Tanycypris obtusa Hydroze
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gibba Daphnia pulex Simocephalus ca
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Ischnura senegalensis Pseuddgrion s
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Micronecta sp. Micronecta piccanin
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Hydraenidae Hydrophilida e Berosus
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MOLLUSCA Simulium adersi Simulium ?
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