University of Venda,
Email: [email protected]
Wetlands contain numerous goods and services that have an economic value not only to local populations but also to people living outside the periphery of the wetland. They are an important source of water and nutrients necessary for biological productivity and often sheer survival of people. Despite their significance, wetlands continue to be destroyed and poorly managed. The aim of this study is to investigate the pattern of wetland use, assess ecological and socio economic effects of wetland use and to come up with strategies that can ensure sustainable healthy condition of wetlands in Thohoyandou. Ground field survey method was used to collect data from the field. The aspects that were considered during field survey include vegetation, hydrology, soil and land use activities that were taking place in the area. It was found out that the wetlands in urban areas are mainly adversely affected by settlement and infrastructural development, sewage and solid waste disposal as well as cultivation; whereas wetlands in rural areas are mainly affected by cultivation, unsustainable harvesting of plant species and using wetlands as grazing land for domestic stock. Different strategies that can enhance, restore and sustain the quality of resources in wetlands are suggested.
Wetland is a collective term used to describe land where an excess of water (that is water logging) is the dominant factor determining the nature of the soil development and the types of plants and animals living at the soil surface. Wetlands are essentially designed by nature to catch, clean and preserve any unused surface water (Kotze 1996).
Much of Africa lies within arid and semiarid climates, where freshwater is scarce and many regions face serious water shortages. In these contexts, wetlands are an important source of water and nutrients necessary for biological productivity and often sheer survival of people (Kirsten 2005).
The wetlands provide habitats for a wide range of animal species such as aquatic invertebrates, water birds and reptiles (Cooper et al, 2006). Wetlands also reduce severity of droughts and floods by regulating stream flow, and provide superb recreational areas for people (Kotze 1996, Wyatt 1999). Despite their importance, wetlands are being modified or reclaimed, either their resources are overexploited and converted to other uses or upstream developments alter the magnitude, timing and quality of river water feeding the wetlands (Kirsten 2005).
Wetland destruction by human intervention commenced long ago and has accelerated in recent times. As a consequence, wetlands are among the most degraded of all ecosystems. The relatively recent acceptance of the socio-economic and ecological importance of wetlands in developed countries has not yet succeeded in reversing this trend (Amezaga et al 2002).
Hitherto, wetlands have been considered wasteland and, therefore, worthless. Their transformation through draining, dredging and infilling seemed a fitting fate for them (Davies and Day 1998). Direct anthropogenic activities such as irrational uses of wetlands for agriculture, pollution and conversion of wetlands into settlement areas are responsible for wetland degradation and loss (Turner 1991, Kassenga 1998).
The protection of wetlands, however, reflects the protection of numerous goods and services that have an economic value not only to the local population living next to wetlands but also to communities outside these wetland areas. This study intends to make a comparative analysis of the problems facing wetlands in urban versus rural areas of Thohoyandou. Once these problems are clearly understood, the study will proceed to devise strategies for conserving remnant wetlands habitats, and rehabilitating those that have been degraded.
2. MATERIAL AND METHODS
2.1 STUDY AREA
The study area is Thohoyandou in Limpopo Province of South Africa (see Fig. 1). Thohoyandou is located at the heartland of the former black homeland of Venda. It is under Thulamela municipality in Vhembe region. It lies between latitudes 22° 15′ and 25° 45′ south and longitudes 29° 50′ and 30° 31′ east. The Vhembe region extends northwards to the Limpopo River which marks the boundary between South Africa and Zimbabwe. To the east, Luvuvhu River forms a boundary with Kruger National Park in South Africa (Rix et al 1989).
Thohoyandou is located within a subtropical climatic region with high temperatures and humidity in summer and mild winters. It has hot summer months and cool winter months. The study area experiences seasonal rainfall. The area receives high rainfall of over 150mm during summer months. The rain season in the study area is from November to March. Little rainfall is experienced during winter months from April to October (Source: AgroMet No 0766/898 7).
Fig.1. Map of the study area
2.2 FIELD SURVEY
The study area has got a total of nine wetlands. Out of the nine wetlands, three wetlands are found in urban areas of Thohoyandou and six wetlands are found in rural areas of Thohoyandou (Fig 2). With reference to Fig.2, the numbered wetlands are as follows:
- Wetland found at Thohoyandou next to Golgotha Location (300 27′ 00”E-300 27′ 04”E and 220 58′ 10”S-220 58′ 14”S).
- Wetland found at Thohoyandou block F (30027′ 55”E-30028′ 04”E and 22058′ 04”S-22058′ 45”S)
- Wetland found at Thohoyandou west of Liivha Secondary School (300 27′ 50”E-300 27′ 60”E and 220 57′ 28”S-220 57′ 57”S)
Wetlands in rural areas are:
- Wetland found at Mbaleni Village (30031’00”E-300 31’59E and 22057’30”S-220 57’47”S)
- Wetland found at Duthuni Village (30024′ 30”E-30051’42”E and 22058′ 15”S-22059’10”S)
- Wetland found at Maniini Village (30027’53”E-30029’28”E and 22058’15”S-22059′ 34”S)
- Wetland found at Magidi Village next to Makwarela stadium (300 29′ 04”E-300 29′ 08”E and 220 56′ 55”S-220 58′ 13”S).
- Wetland found at Lufule Village (300 29′ 30”E-300 30′ 60”E and 22055′ 08”S-220 56′ 13”S)
- Wetland found at Dzingahe Village (30030’08”E-30030’35”E and 22055’05”S-22055’15”S)
- Wetland found at Maungani Village (30025’45”E-30026’30”E and 22058’45”S-22059’05”S)
The locations of all these wetlands are indicated by the map below.
Fig.2. Location of the wetlands in the study area (Source: Topographical Map 2230CD Thohoyandou, 1987)
Field surveys were undertaken in all the wetlands to collect data on the types and conditions of hydrology, land use, soil and vegetation of the area. A Global Positioning System (GPS) was used to record the coordinates of each wetland. This was done in order to locate different wetlands on the map. During field survey some samples of water were collected for laboratory analysis. Social survey was also used to collect data in the study area. Under social survey, personal interviews were conducted with the relevant individuals affected by or who had knowledge about the problem in question. Local communities who were using the wetlands for different purposes were interviewed.
There are a number of activities that took place and that are still taking place in the wetlands in urban versus rural areas of Thohoyandou. Land-use activities such as settlement and infrastructural development, sewage and solid waste disposal, cultivation, harvesting of wetland plant species and grazing land for domestic stock have been and continue to be undertaken in the wetlands in urban versus rural areas of Thohoyandou as indicated by the diagram below.
Table.1. Different land use activities in urban versus rural areas of Thohoyandou.
|Sewage and solid waste disposal||Grazing land for domestic stock|
|Settlement and infrastructural development||Harvesting of plant species|
The larger portion of the wetlands in the urban area is used for settlement and infrastructural development whereas in rural areas the larger portion of the wetland is used for agricultural purposes. Cultivation is practiced in both wetlands in urban and rural areas of Thohoyandou. The settlement and infrastructural development and solid and sewage disposal in wetland in urban area is end up leading to the total destruction of wetlands in urban area of Thohoyandou.
4.1 IMPACTS OF WETLAND USES
The use of wetland for cultivation, settlement and infrastructural development, solid and sewage disposal and the use of wetlands as grazing land for domestic stock have got ecological and socio-economic consequences on the functioning of the wetlands, mainly the following.
4.1.1 Infilling in Wetlands
The use of wetlands for cultivation has led to the problem of infilling into the wetlands which has also led to the reduction of water in wetlands. This is mostly taking place in the wetlands in rural areas as compared to urban areas of Thohoyandou. The people originally were cultivating the crops far away from the wetlands. They were increasing their area of cultivation each and every year in the direction of the wetlands. Intensive ploughing and harrowing next to the wetlands have accelerated soil erosion. This has led to the problem of infilling in the wetlands due to deposition of inorganic materials carried in by surface runoff/overland flow.
With the plantation of crops (maize) in the wetlands, the soil has been greatly disturbed because maize does not bind or cover the soil like the natural wetland vegetation. Wetlands are now the most unstable ecosystem in the area because of the decline of species diversity.
Most of the indirect benefits of the wetlands have been lost as a result of cultivation in the wetlands, for example:
- The wetlands are now less effective at regulating stream flow and purifying water because the drainage channels speed up the movement of water through the wetlands.
- The hydrological conditions have changed. The hydrological changes resulting from cultivation have negative effects on the soil. For example, it reduces soil organic matter and moisture level. This is mostly taking place in the wetlands in rural area as compared to the wetlands in urban area of Thohoyandou.
4.1.2 Alien Invasion in Wetlands
The use of wetlands for cultivation has also disturbed the species composition in the area. The disturbance of the area has attracted rooted plants particularly the alien plant species such as Lantana camara (Lantana), Caesalpinia decapetala (Mauritius thorn), Psidium guajava (Guava), Ricinus communis (Castor-oil bush) and Melia azedarach (Syringa). These alien plant species have now invaded the wetlands and are now out-competing the wetlands plants species and as results the ecology of the area have changed. The presence of alien species is also leading to the reduction of water in the wetlands.
The presence of rooted plants (alien species) in the wetlands has strong negative effects on the habitat value of wetland. Under increased shading beneath the trees, the vigour of indigenous plants such as sedges, bulrushes and reeds which were not adapted to these condition (that is the absence of water and infilling in the wetlands) has been reduced and they have been out-competed by alien invasive plants. The invasion of alien plant species is taking place both in the wetlands in urban and rural areas of Thohoyandou.
4.1.3 Loss of Biodiversity
The use of wetlands for settlement and infrastructural development has led to the destruction of most of wetlands plant species such as reeds, sedges and grasses. In the absence of these plant species, the wetlands are failing to play their important functions such as trapping of sediments, removal of waste materials and purification of water. The habitat required by wetland-dependent species is frequently lost. This is also leading to the total destruction of the wetlands and this has impacts on the ecology of the area because it is making the area to change from wetlands to a settlement area. This is only taking place in the wetlands in urban areas of Thohoyandou.
4.1.4 Depletion of Pasture Resources
The use of wetlands as grazing land for domestic stock in rural area has got ecological impacts on the wetlands. The use of wetlands as grazing land for domestic stock has led to the problems of overgrazing in wetlands. The diversity of habitats required by specialised wetland-dependent species is decreased. In addition heavy grazing has caused valuable grazing species to be replaced by less productive and/or palatable species. Similarly, harvesting of wetland vegetation for crafts and construction has also led to the reduction of pasture resources and this is leading to the problem of soil erosion. This is mostly taking place in the wetlands in rural area as compared to the wetlands in the urban area of Thohoyandou.
4.1.5 Pollution in Wetlands
Solid and sewage disposal into the wetlands is taking place in the wetlands in urban area. Sewage disposal includes used water from baths, lavatories, dish washers and laundries whereas solid waste include suspended matter especially soil, fine sand and silts, floating matter such as sawdust, tins, plastics and old motor vehicles. As a result of this, the water’s natural purification process in the wetland has ceased as more and more solid and sewage is disposed into the wetlands. The waste has discoloured the water, thus reducing the penetration of sunlight that is essential to biological process in water. This in turn greatly lowers the quality of water. As a result, this foul smelling water is no longer home of fish and other organism; it becomes unsafe for human consumption. It has also made the area to be unsightly sites for human being.
5. CONCLUSION AND RECOMMENDATIONS
The land use activities that took place and that are still taking place in the wetlands in urban and rural area of Thohoyandou have got negative effects on the functioning of the wetlands. There is misuse, overuse and abuse of wetlands because they are used in an unsustainable manner. Unless action is taken to positively influence the activities of people affecting wetlands, the results could be very serious.
5.2.1 Establishment of “Set-Back” Lines and Buffer Strips
Development should be done far from wetlands banks to make provision for vegetated buffer strips. This will help to maintain the aesthetic quality of wetlands environment, and prevent disruption of natural processes.
Main communication routes such as roads and footpaths should be avoided in wetland areas as they have negative effects on the functioning of wetlands. They should be located perpendicular to wetlands rather than across the wetlands. Wetlands should be exempted from development, they have to be zoned as special buffer areas in which all developments or degradation is discouraged. If development is absolutely essential, the Transitional Local Council (TLC) has to employ impartial experts to carry out a need and desirability study and an Environmental Impact Assessment (EIA) before approving such development. This should be applied mostly to the wetlands in urban area as compared to wetlands in rural area.
5.2.2 Management guidelines for the cutting of natural wetlands vegetation for crafts and construction that should be followed
The following guidelines should be applied mostly to the wetlands in rural area as compared to the wetlands in urban areas of Thohoyandou.
- Harvesting should preferably take place outside or towards the end of the breeding season of bird species, thereby minimizing direct disturbance of the birds. Late summer/autumn breeding species may nevertheless be negatively affected.
- Rather than cutting a single extensive large area, it is better to break up the cut area into several small areas, which provides more suitable habitat for wetlands dependent species.
- When cutting by hand, communities should avoid unsustainable harvesting practices involving the cutting of all culms (including short young ones) and discarding material to form a mat of litter that retards new culm growth. Instead, people should select and cut only suitable culms (Kotze and Breen 2000).
5.2.3 Traditional Cultivation
The impacts of cultivation can be minimized in wetlands if traditional cultivation is followed.
- Tillage and harvesting by hands.
- People should avoid the use of heavy machinery in wetlands such as tractors as these disturb the structure of the soil and destroy the majority of plant species.
- Pesticides and fertilizers must be avoided because these have got negative effects on water quality and also they lead to death of many animal species such as fish.
- Add mulch to reduce soil organic matter depletion and associated problems.
- Not planting extensive areas but leaving indigenous vegetation between cultivated patches.
- Grow crops such as Madumbes (Colocasia esculenta) which are tolerant of waterlogging, in preference to crops with low tolerance as this minimizes the need to reduce the wetness of the soil. This strategy has been implemented in Kwazulu-Natal in a wetland called Mbongolwane and it has been very successful (Kotze 1997).
5.2.4 Physical Control/ Mechanical Control of alien plants
Physical/mechanical control is the best method that can control the invasion of alien plant species in the area. Most of alien plant species are growing in moist areas. Most of the alien plant species in the study area are in moist sites. Hand-pulling could be effective in removing small and shallow rooted seedlings of aliens in the study area. Tall trees can be cut down (Cronk and Fuller 1995, Wyatt 1999).
5.2.5 Control of pollution
Wetlands have a diverse range of colours and textiles and some very attractive. Wetlands add to the diversity and beauty of the landscape. Wetlands are good places to see birds (Kotze 1996, Dini 2002)). Wetlands that are found in urban areas should be conserved as this can make the town to look beautiful. The municipalities should not allow any activity like dumping of waste or sewage disposal into the wetlands. Municipalities should also organize campaigns to ensure wetland conservation. Monitoring should always be done to ensure that wetlands are not disturbed.
I want to thank the School of Environmental Sciences of University of Venda for the support they have given me when preparing this paper. A sincere thanks is also expressed to Dr C. Munyati for giving a valuable comment of an earlier draft of this paper.
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