WETLANDS & OUR SURVIVAL

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1 WETLANDS & OUR SURVIVAL at current supply and demand South Africa s water resources will be fully utilized by 2030 wetlands manage water over 50% of of South Africa s wetlands have been destroyed continued wetland destruction means: increased flooding less reliable water supplies less pure water This will result in: lower higher agricultural productivity industry tourism mining death rate of humans WHICH EQUALS A DEAD ECONOMY!

2 WHAT IS A WETLAND? To be a wetland, a piece of land must have: waterlogged soils waterloving plants high water table wetland is a family name given to many different wetland types, eg: seeps & springs (top of catchment) marshes floodplains Lakes & pans swamps estuaries coral reefs river banks (Bottom of catchment) (Linking all together)

3 WETLANDS CAN BE WET AT DIFFERENT TIMES OF THE YEAR temporary wet seasonally wet permanently wet (1-4 months) (5-11 months) (12 months)

4 A seep, found on hill slopes and mountains. Most rivers have their beginnings in seeps. A seep is formed where groundwater is forced to the surface by an impermeable layer of rock. Very sensitive wetlands, as they often have shallow soils and are prone to damage from overgrazing and incorrect burning. Found all over South Africa.

5 A typical Phragmites marsh clearly showing the temporary (grasses), seasonal (sedges) and permanent (Phragmites) waterlogged zones. Found all over South Africa. A typical Phragmites marsh clearly showing the temporary (grasses), seasonal (sedges) and permanent (Phragmites) waterlogged zones. Found all over South Africa.

6 A typical marsh with open water, bulrushes and water lilies found in the flat areas in the middle of the catchment, all over South Africa.

7 A papyrus marsh found up in Zululand, KwaZulu-Natal. These wetland types are mainly found along the coastal areas of South Africa.

8 A floodplain with a meandering river, which in times of high rainfall flows over the entire floodplain. The floodplain area (red line) is often far larger than most people think, as the very outer areas are only flooded on a temporary basis. As a result many farmers cultivate these areas. This wetland type is found all over South Africa.

9 An inland freshwater lake, such as Lake Sibaya in northern KwaZulu-Natal. South Africa does not have many natural lakes (not to be confused with dams which are man made). The only other lakes apart from those in the Isimangaliso Wetland Park in KwaZulu-Natal are found in the Southern Cape from Knysna to Wilderness, and Lake Fundudzi in Limpopo.

10 A mangrove swamp found in the coastal areas of KwaZulu-Natal and ex-transkei. Much of this wetland type has been destroyed in many coastal areas of KwaZulu-Natal, due to development such as the building of Richards Bay and Durban

11 An estuary is found at the bottom end of the catchment, where a river enters the sea. If the wetlands in the upper catchment are degraded, then the estuaries below are often also affected by excessive silt being deposited in them, or pollution.

12 Linking all these different types of wetlands together, from the top of the catchment to the bottom of the catchment are rivers and riverbanks.

13 WHY IS A WETLAND IMPORTANT? WETLANDS PROTECT SOUTH AFRICA'S SCARCEST RESOURCE: WATER They: purify water store water ensuring supply in droughts attenuate flood peaks recharge ground water control erosion They also are important for: biodiversity livestock grazing recreation

14 HOW CAN WETLANDS HELP ATTENUATE FLOOD PEAKS? wetlands can change storm runoff peaks to slower discharges over longer periods of time since flood peaks = flood damage, wetlands have potential to reduce damage generally, if 15% of catchment = wetlands, peaks reduced by 60-65% WETLANDS ABILITY DEPENDS ON: topography wetland size wetland shape roughness of wetland surface location in catchment water regime permeability of soil CUMULATIVE IMPACT VERY NB

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16 CHARLES RIVER FLOODS, 1955 (BOSTON CITY, USA) US Army Corps of Engineers (COE) found that for a 35 km reach of the Charles River: peak flow was reduced by 65% delayed by 3 days 75% of this storage occurred in 17 wetlands (3400ha) COE bought these wetlands for $17 million instead of building a $30 million flood control structure If wetlands destroyed = increase of flood damages by 17 million

17 HOW CAN WETLANDS PURIFY WATER? Through trapping pollutants: suspended sediments - silt & clay excess nutrients - nitrogen/phosphate toxicants - pesticides/heavy metals viruses & bacteria They do this by: reducing the velocity of water flow filtering out suspended solids long contact between water and sediments anaerobic & aerobic processes high plant productivity high soil organic matter microbial decomposition

18 WHAT ARE THE PROBLEMS? BAD LAND MANAGEMENT HAS DESTROYED 50% OF OUR WETLANDS drainage of wetlands for pastures & crops overgrazing = erosion incorrect burning = erosion timber production incorrect siting of dams pollution mining urban development lack of wetland workers All these impacts alter the water flow and water quality which kills the wetland

19 A drain, which is dug to dry out this wetland. The moment the wetland is dried out, it dies. Rather like taking the plug out of your bath, a drain draws the water out of the wetland and sucks it dry.

20 A drain (the "z-shaped" line in the centre of the picture) that has been dug by farmers in the Eastern Cape, to dry out the wetland so that they can plant crops. The vegetation on the right-hand side of the drain is darker and therefore wetter than the dried out portion of the wetland on the left hand side of the drain.

21 A network of drains in a wetland dried out for the growing of pastures for dairy cattle, in KwaZulu-Natal.

22 A typical headcut (arrow), which is a form of erosion that erodes towards the flow of water leaving behind a donga (or gully) that drains and dries out the wetland. The eroding headcut also produces large amounts of sediment. Headcut erosion is often caused by overgrazing and poor burning practices. This is one of the most common causes of wetland degradation in South Africa. Headcuts may erodes as fast as 50m in one month, or as slowly as 2m per year, depending on the erodability of the soil.

23 A larger headcut (arrow) at a more advanced stage than the previous one showing the dried out areas (the lighter coloured vegetation) of the wetland above it. Note the inverse "V" shape between the shape of the headcut, and the shape of the dried out portion of the wetland! wetland destroyed wetland destroyed wetland

24 Crops that have been planted in a wetland. Note how the maize does not grow in those areas where the water has ponded. This is because the maize plants are a dryland crop, that has not adapted to live in waterlogged soils.

25 Cattle grazing in a wetland, if not managed properly, can cause headcut erosion through excessive trampling and overgrazing. The carrying capacity of the wetland, the timing and the length of the grazing

26 Plantation forestry planted in a wetland, which can be seen by the stunted gum trees growing in front of the picture, compared to those in the background. This is illegal.

27 Plantation forestry - pine trees have been planted right through this seep (red arrow showing the green finger going up the mountain). The trees can be seen by the rows (red line) they have been planted in. This is a good example of a seep.

28 wetland Fire can be a problem, especially if the wetland is burnt every year (for grazing or as a firebreak in a forestry area) reducing biodiversity or if the wetland is burnt with the wrong type of fire at the wrong time of the year resulting in erosion. Fire is an important management tool for South African wetlands preventing them from becoming moribund, but only if done correctly.

29 Dams can be a problem if too many are constructed in a catchment and they are built on top of the wetland. For example, the lack of vegetation in a dam severely reduces its ability to purify water and maintain biodiversity.

30 Roads can be a problem when drains are dug next to the road to prevent the road from being flooded, which then dries out the wetland (as can be clearly seen from this wetland on either side of the road!). If too few culverts are put in where the road crosses the wetland, the flow of water is concentrated at these few culverts and erosion occurs on the upstream side of the road while the downstream side is dried out. destroyed wetland destroyed wetland

31 In the urban areas residential and industrial buildings are often constructed in wetlands, because they are flat places, which are often the last open spaces to be found.

32 If riparian vegetation is cut down and replaced with exotic vegetation, the soil on the riverbanks becomes susceptible to erosion. In this photo the riparian vegetation (trees) was cut down and replaced with alien kikuyu grass to make way for a golf course, which then eroded. The shallow roots of the alien Kikuyu grass cannot hold the riverbank soil together as well as the indigenous trees.

33 Urban pollution in a wetland from the surrounding industrial and residential areas.

34 Mining in a wetland destroys the wetland and produces lots of sediment in this case, which is washed down stream further destroying downstream wetlands and rivers. Here a farmer is mining sand and rock. Many wetlands, especially in Mpumalanga, are threatened by open cast coal mining activities as high quality coal is often found beneath them.

35 CONTINUED WETLAND DESTRUCTION.. less pure water less reliable water supplies increased flooding lower agricultural productivity more endangered species

36 WHAT IS THE ANSWER? OUR WETLANDS CAN BE USED BUT WE MUST MANAGE THEM WISELY To do this we must: Build the capacity of agriculture, DWAF, conservation, land owners, commerce, industry, & key decision makers. Identify where the key wetlands are. Assess their condition. Rehabilitate those wetlands where there are problems, & secure those in good condition.