Wetland ecological condition

Freshwater (inland aquatic) realm

Nacelle B. Collins1 , Nancy Job2 , Adwoa Awuah2 , Ryan Kok3 , Phumla Mayekiso2 , Jock Currie2 , Dean Ollis4 , Donovan Kotze5

1. Free State Department of Economic, Small Business Development, Tourism and Environmental Affairs

2. South African National Biodiversity Institute

3. EcoPulse

4. Inland Waters

5. University of KwaZulu-Natal

Published

December 5, 2025

While numerous policies and strategies aim to improve or at least stabilise the ecological condition of wetlands in South Africa, overall wetland condition continues to deteriorate. Continued wetland loss and declining ecological condition has led to significant ecological and financial loss. This deterioration is often gradual and ‘out of sight’ and, therefore, generally not perceived as an immediate threat. It is, however, a serious concern which should be addressed through restoration (where feasible and strategic) and improved, frequent, monitoring and reporting.

Musa Mlambo from the Albany Museum surveying a wetland for aquatic invertebrates, Eastern Cape highlands. (© Nancy Job)
49%
of wetland extent
Natural or Near-natural
58%
of 171 303 inland wetlands
Natural or Near-natural
Figure 1. Ecological condition for inland wetland ecosystem types. The inset graph shows percentage of ecosystem extent within each condition category.
Table 1. Ecological condition of inland wetland ecosystem types. Note that extent figures have been rounded.
Natural Near-natural Moderately modified Heavily modified Severely modified Critically modified
Albany Thicket_Depression Extent (km2) 4 13 1 1 1 5
Percentage 17 52 4 5 2 20
Albany Thicket_Floodplain Extent (km2) 1 11 6 1 10 0
Percentage 2 39 22 2 35 0
Albany Thicket_Seep Extent (km2) 2 1 1 1 1 0
Percentage 33 21 21 12 14 0
Albany Thicket_Unchannelled valley-bottom Extent (km2) 1 1 0 0 2 0
Percentage 23 12 5 7 53 0
Bushmanland_Depression Extent (km2) 376 2 655 200 17 15 8
Percentage 11 81 6 1 0 0
Bushmanland_Floodplain Extent (km2) 93 1 0 0 0 0
Percentage 99 1 0 0 0 0
Bushmanland_Seep Extent (km2) 16 1 0 0 0 0
Percentage 96 4 0 0 0 0
Bushmanland_Unchannelled valley-bottom Extent (km2) 690 17 0 0 0 0
Percentage 98 2 0 0 0 0
Central Bushveld_Depression Extent (km2) 3 38 8 2 1 2
Percentage 5 71 14 4 2 3
Central Bushveld_Floodplain Extent (km2) 167 194 821 244 151 2
Percentage 11 12 52 15 10 0
Central Bushveld_Seep Extent (km2) 43 21 52 43 36 3
Percentage 22 11 26 22 18 2
Central Bushveld_Unchannelled valley-bottom Extent (km2) 52 212 86 48 46 1
Percentage 12 48 19 11 10 0
Drakensberg Grassland_Depression Extent (km2) 6 4 0 0 0 0
Percentage 56 39 1 2 0 1
Drakensberg Grassland_Floodplain Extent (km2) 24 22 86 93 14 0
Percentage 10 9 36 39 6 0
Drakensberg Grassland_Seep Extent (km2) 58 13 25 27 12 3
Percentage 42 9 18 20 9 2
Drakensberg Grassland_Unchannelled valley-bottom Extent (km2) 9 0 1 1 7 0
Percentage 50 1 7 3 38 2
Dry Highveld Grassland_Depression Extent (km2) 426 457 181 61 28 39
Percentage 36 38 15 5 2 3
Dry Highveld Grassland_Floodplain Extent (km2) 92 544 681 128 39 1
Percentage 6 37 46 9 3 0
Dry Highveld Grassland_Seep Extent (km2) 29 42 128 17 26 2
Percentage 12 17 53 7 11 1
Dry Highveld Grassland_Unchannelled valley-bottom Extent (km2) 46 314 375 68 33 0
Percentage 5 38 45 8 4 0
East Coast Renosterveld_Depression Extent (km2) 16 1 1 1 0 0
Percentage 81 5 7 5 2 2
East Coast Renosterveld_Floodplain Extent (km2) 4 12 142 101 90 0
Percentage 1 3 40 29 26 0
East Coast Renosterveld_Seep Extent (km2) 6 15 22 21 16 2
Percentage 7 19 26 26 20 3
East Coast Renosterveld_Unchannelled valley-bottom Extent (km2) 0 7 0 4 0 0
Percentage 0 64 1 34 1 0
Eastern Fynbos-Renosterveld_Depression Extent (km2) 0 3 0 0 1 0
Percentage 2 64 9 4 13 7
Eastern Kalahari Bushveld_Depression Extent (km2) 125 809 69 17 11 10
Percentage 12 78 7 2 1 1
Eastern Kalahari Bushveld_Seep Extent (km2) 189 22 46 10 17 0
Percentage 67 8 16 3 6 0
Eastern Kalahari Bushveld_Unchannelled valley-bottom Extent (km2) 153 167 45 12 6 0
Percentage 40 44 12 3 2 0
Kalahari Duneveld_Depression Extent (km2) 80 162 37 22 38 3
Percentage 23 47 11 6 11 1
Kalahari Duneveld_Seep Extent (km2) 8 0 0 0 0 0
Percentage 100 0 0 0 0 0
Karoo Interior_Depression Extent (km2) 154 479 18 13 4 1
Percentage 23 72 3 2 1 0
Karoo Interior_Floodplain Extent (km2) 595 184 143 257 114 0
Percentage 46 14 11 20 9 0
Karoo Interior_Seep Extent (km2) 76 5 3 2 2 0
Percentage 87 6 4 2 2 0
Karoo Interior_Unchannelled valley-bottom Extent (km2) 107 98 7 1 1 0
Percentage 50 46 3 0 0 0
Knersvlakte_Depression Extent (km2) 0 1 0 0 0 0
Percentage 1 87 0 0 12 0
Kwa-Zulu Natal Coastal Belt_Floodplain Extent (km2) 0 3 16 17 13 16
Percentage 0 4 25 27 20 24
Kwa-Zulu Natal Coastal Belt_Seep Extent (km2) 0 1 3 2 14 27
Percentage 1 2 6 4 30 58
Kwa-Zulu Natal Coastal Belt_Unchannelled valley-bottom Extent (km2) 0 2 4 2 9 10
Percentage 0 7 14 9 33 37
Lowveld_Depression Extent (km2) 4 59 14 3 8 3
Percentage 4 65 15 4 9 3
Lowveld_Floodplain Extent (km2) 187 82 160 127 59 9
Percentage 30 13 26 20 9 1
Lowveld_Seep Extent (km2) 49 26 56 53 46 8
Percentage 21 11 23 22 19 3
Lowveld_Unchannelled valley-bottom Extent (km2) 17 8 8 19 12 3
Percentage 25 12 12 28 17 5
Maputaland Coastal Belt_Depression Extent (km2) 3 90 107 11 6 6
Percentage 1 40 48 5 2 3
Maputaland Coastal Belt_Floodplain Extent (km2) 13 319 43 22 136 28
Percentage 2 57 8 4 24 5
Maputaland Coastal Belt_Seep Extent (km2) 7 1 8 4 9 9
Percentage 19 2 21 11 24 23
Maputaland Coastal Belt_Unchannelled valley-bottom Extent (km2) 15 7 10 10 10 6
Percentage 25 12 17 17 18 11
Mesic Highveld Grassland_Depression Extent (km2) 184 171 73 28 9 9
Percentage 39 36 15 6 2 2
Mesic Highveld Grassland_Floodplain Extent (km2) 168 1 293 2 232 828 227 8
Percentage 4 27 47 17 5 0
Mesic Highveld Grassland_Seep Extent (km2) 277 275 553 296 205 19
Percentage 17 17 34 18 13 1
Mesic Highveld Grassland_Unchannelled valley-bottom Extent (km2) 26 41 219 87 44 3
Percentage 6 10 52 21 11 1
Mopane_Depression Extent (km2) 0 11 1 0 0 0
Percentage 0 87 10 1 1 0
Mopane_Floodplain Extent (km2) 238 7 37 20 2 1
Percentage 78 2 12 6 1 0
Mopane_Seep Extent (km2) 1 0 0 0 0 0
Percentage 86 0 14 0 0 0
Mopane_Unchannelled valley-bottom Extent (km2) 42 1 0 0 0 0
Percentage 97 3 0 0 0 0
Namaqualand_Depression Extent (km2) 2 77 21 4 2 17
Percentage 2 63 17 3 1 14
Northwest Fynbos_Depression Extent (km2) 1 10 0 1 0 0
Percentage 9 79 1 7 3 0
Northwest Fynbos_Floodplain Extent (km2) 10 6 94 26 8 4
Percentage 7 4 64 18 5 3
Northwest Fynbos_Seep Extent (km2) 10 2 10 6 7 0
Percentage 27 7 29 18 20 0
Northwest Fynbos_Unchannelled valley-bottom Extent (km2) 1 0 3 1 2 0
Percentage 11 3 43 17 26 0
Pondoland Coastal Belt_Floodplain Extent (km2) 1 1 1 1 0 0
Percentage 22 25 20 26 7 0
Pondoland Coastal Belt_Seep Extent (km2) 4 4 4 1 2 0
Percentage 25 26 24 8 14 3
Pondoland Coastal Belt_Unchannelled valley-bottom Extent (km2) 1 1 3 0 0 0
Percentage 23 17 58 1 2 0
Southern Fynbos_Depression Extent (km2) 1 14 0 0 0 0
Percentage 6 93 0 1 0 0
Southern Fynbos_Floodplain Extent (km2) 40 12 34 93 55 1
Percentage 17 5 14 39 23 0
Southern Fynbos_Seep Extent (km2) 40 8 24 13 19 6
Percentage 36 8 22 12 17 5
Southern Fynbos_Unchannelled valley-bottom Extent (km2) 6 2 6 5 5 1
Percentage 24 8 24 20 20 3
Southwest Fynbos_Depression Extent (km2) 3 4 0 0 0 0
Percentage 37 56 4 2 0 0
Southwest Fynbos_Floodplain Extent (km2) 33 36 146 94 32 14
Percentage 9 10 41 26 9 4
Southwest Fynbos_Seep Extent (km2) 95 13 35 22 32 3
Percentage 47 7 17 11 16 2
Southwest Fynbos_Unchannelled valley-bottom Extent (km2) 3 1 8 0 1 0
Percentage 22 10 56 3 9 1
Sub-Escarpment Grassland_Depression Extent (km2) 5 8 29 2 1 1
Percentage 11 17 62 5 3 2
Sub-escarpment Grassland_Floodplain Extent (km2) 39 54 383 565 177 8
Percentage 3 4 31 46 14 1
Sub-escarpment Grassland_Seep Extent (km2) 170 130 316 370 326 45
Percentage 13 10 23 27 24 3
Sub-escarpment Grassland_Unchannelled valley-bottom Extent (km2) 25 28 76 96 44 4
Percentage 9 10 28 35 16 1
Sub-escarpment Savanna_Depression Extent (km2) 0 2 1 0 0 1
Percentage 4 47 18 10 6 15
Sub-escarpment Savanna_Floodplain Extent (km2) 1 5 38 52 63 14
Percentage 1 3 22 30 36 8
Sub-escarpment Savanna_Seep Extent (km2) 13 16 25 29 73 36
Percentage 7 8 13 15 38 19
Sub-escarpment Savanna_Unchannelled valley-bottom Extent (km2) 1 0 4 5 7 2
Percentage 3 2 22 28 37 9
West Coast_Depression Extent (km2) 2 4 8 3 1 0
Percentage 12 24 42 14 6 1
West Coast_Floodplain Extent (km2) 0 15 68 91 24 0
Percentage 0 8 34 46 12 0
West Coast_Seep Extent (km2) 1 1 17 6 7 1
Percentage 4 3 50 20 21 3
West Coast_Unchannelled valley-bottom Extent (km2) 1 1 2 1 1 0
Percentage 10 9 29 25 23 4

Download the data by wetland type here.

Approximately 1 476 561 ha (49%) of total inland wetland extent is in a natural (class A) or near -natural (class B) condition, 808 325 ha (27%) is in a moderately modified (class C) condition, and 705 797 ha (27%) is in a heavily to critically modified (class D, E or F) condition.

Ecological condition was calculated for 171 303 wetlands. Of these, approximately 100 029 wetlands (58%) are in a natural (class A) or near-natural (class B) condition, 24 752 (14%) are in a moderately modified (class C) condition and 46 522 (24%) are in a heavily to critically modified (class D, E or F) condition.

Of the different hydrogeomorphological types, depression wetlands are in the best ecological condition, with 76% in a natural or near-natural condition, with 11% moderately modified and 14% in a heavily to critically modified condition. Floodplain, unchannelled valley-bottom, and seep wetlands have 34%, 35%, 42% of their extent in natural or near-natural ecological condition.

Figure 2. Inland wetland ecological condition according to hydrogeomorphological (HGM) category, showing the percentage of wetland extent (km2). ‘Valley-bottom’ represents the ‘Unchannelled valley-bottom’ HGM category.
Table 2. Ecological condition of inland wetland ecosystem types summarised by HGM category. Note that extent figures have been rounded.
Natural Near-natural Moderately modified Heavily modified Severely modified Critically modified
Depression Extent (km2) 1 396 5 070 768 187 127 106
Percentage 18 66 10 2 2 1
Seep Extent (km2) 1 094 597 1 327 923 850 164
Percentage 22 12 27 19 17 3
Unchannelled valley-bottom Extent (km2) 1 193 909 856 361 232 30
Percentage 33 25 24 10 6 1
Floodplain Extent (km2) 1 706 2 801 5 132 2 759 1 215 105
Percentage 12 20 37 20 9 1

Download the data here.

Approach

Wetlands are complex systems that are influenced by multiple biotic and abiotic factors. Determining wetland health therefore requires a multidisciplinary approach that will allow for determining a single condition score from all the influencing factors. While previous approaches to determine wetland condition were sound, they lacked the holistic and systematic characteristics of the WET-Health Level 1A approach1.

Wetland ecological condition was determined using an automated approach (ArcGIS python scripts) of the Level 1A method described by MacFarlane et al. (2020), which is a low confidence, non-detailed approach that is suitable for assessing multiple wetlands such as those of a national wetland inventory. In addition to being typed according to Ollis et al. (2013)2, the method also requires each wetland to have a 200 m buffer, as well as have its area of influence mapped. While the 200 m buffer is created by the automated process, the area of influence was created using a separate, but also automated, process. This allows the area of influence to be the actual wetland catchment.

Overall wetland condition was calculated from the combined state of wetland hydrology, water quality, geomorphology, and vegetation, which were all calculated from the inferred pressures of different land cover classes.

While allowing for a systematic assessment of wetland condition, the Level 1A approach also allows for the inclusion of in-field validated expert data, a process that has already been initiated through numerous expert engagements during which spatial extent, typing, and wetland condition data were captured for individual wetlands and wetland complexes. Such expert data, along with the Level 1A assessment, contributes towards an improved approach for national wetland condition assessment by building a reference dataset that will directly and indirectly inform future PES assessments.

In addition to allowing for the rapid assessment of multiple wetlands, the automation of a standardised wetland condition assessment method also provides opportunity for future temporal analysis by using land cover grids from different periods as input data. The results will not only reveal the change in wetland condition over time, but also the pressures responsible for such changes.

Future steps

The automated wetland ecological condition is a major step forward in reproducibility and an opportunity for ongoing improvement. It mirrors the categories and framework adopted by practitioners undertaking assessments in the field and sets in place great potential for teasing out drivers of degradation from the perspective of wetland hydrology, water quality, geomorphology or vegetation change, and the development of specific management responses. Going forward, work remains for wide expert engagement to continue inform future wetland ecological condition assessments.

Technical documentation

Coming soon

Related publications and supporting information

Coming soon

References

1. Macfarlane, D. et al. 2020. WET-Health (Version 2): A refined suite of tools for assessing the Present Ecological State of wetland ecosystems.
2. Ollis, D. et al. 2013. Classification system for wetlands and other aquatic ecosystems in south africa user manual: Inland system. https://doi.org/10.13140/2.1.3857.0248