RHP South African
River Health Programme
State of the Rivers Report
Crocodile, Sabie-Sand & Olifants 
River Systems
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ecoregion 4.04 in Sabie-Sand CatchmentCrocodile River SystemSabie-Sand River SystemOlifants River Systemsummaryecoregion 5.06 in Sabie-Sand Catchment
The Sabie-Sand River System

Ecoregion 5.05

Ecoregion and River Characteristics

Most of this ecoregion is in the Lowveld proper with upstream parts showing characteristics of more mountainous areas. The altitude is between 800 and 1 000 m amsl with moderate relief. Rainfall is still variable (400-1 200 mm per year), due to the variation in relief, and mean annual temperatures are warm (16-22°C). 

Sandy, sandy loam and clayey soils overlying iron, jaspilite and granite, support sour lowveld bushveld. 

In the upper parts cascades and rapids abound, in the lower regions rivers are wide, have gentle gradients, riffles and sandy pools, and mature riparian forests extending some hundred metres from the river. The river flows over sandy runs, characterised by reed beds, rapids, and through deep pools, where hippo are not uncommon. 

Sabie River downstream of Sabie - Ernita van Wyk
Present Ecological State

Sabie River: Overall the ecological state is good . In-stream habitats and fish are good ; riparian habitats and riparian vegetation varies between good and poor . The invertebrate index also reflects a varied picture, with results in this section ranging between natural and poor .

Sabane River: Poor to unacceptable . The riparian zone and in-stream habitats are severely degraded. The Sabane River and Langspruit have been dammed and impacted in several places for irrigation of banana plantations. The clearing of ground cover for banana plantations has also increased erosion and sedimentation in-stream. 

Mac Mac River: The ecological state is good . The fish populations show natural health, and the invertebrate community varies between natural and good

Ecoregion 5.05
The Ngwaritsana River is in an overall good state, but riparian vegetation is fair to poor .

Maritsane River: Overall good state but riparian vegetation is fair to poor .

Marite River: In-stream habitats and fish are generally good to fair . Riparian habitats and vegetation are fair to poor . Invertebrates give a highly variable picture, with results ranging from good to unacceptable .

Phasa Phasa River: Generally fair , but the invertebrate health is unacceptable .

Motitsi: Invertebrates and fish reflect a natural and good state respectively. 
In-stream habitats are good to fair and riparian habitats and vegetation are poor .

Mutlumuvi: The overall state is fair , although the state according to invertebrates ranges from good to unacceptable .

Drivers of Ecological Change (Land-use activities)

General: There is extensive forestry in this region of the catchment. Roads and plantations close to streams impair in-stream and riparian health due to erosion, sedimentation and resulting smothering of habitats. The extent of invasion/encroachment by alien vegetation is a serious threat to ecosystem health. Madumbi (similar to sweet potato) farming takes place in wetland areas. Loss of natural vegetation and water uptake in these areas destabilises the soils and the filtering functions of the wetlands. Black bass, an alien fish species, occurs in this ecoregion. These threaten indigenous species by preying on them.

Sabie River: Sawdust from sawmill impacts riparian zone and washes into the river during rain events. Cresols and phenols leach out of sawdust, acidifying the soil and water. The dust itself also smothers vegetation and in-stream habitats, lowering vegetation health and invertebrate diversity and abundance. Finer dust particles clog the gills of fish. Erosion and sedimentation results from dirt roads and fruit orchards such as banana plantations close to the river. This impairs in-stream water quality and reduces habitat availability. Blue gill sunfish, an alien species, is found in the Langspruit. 

Sabane River: This is the third worst affected river by alien plants in this catchment. Sedimentation, associated with floods, occurs in places, primarily due to agricultural activities. Although development in the Sabie Catchment is restricted by law (due to the conservation importance of this river), and all development requires an Environmental Impact Assessment, several banana plantations have developed along the Sabane River, and are causing severe erosion and sedimentation.

The Klein Sabie River is impacted by industry and urban development in the area. The riparian zone is affected by alien vegetation and forestry activities.

Marite: Disturbance and erosion from the construction of the Injaka Dam have caused sedimentation downstream. This results in loss of in-stream habitat through smothering of interstitial spaces between rocks on the riverbed. Sedimentation may also lead to increased frequency or severity of flooding.

Mutlumuvi: the Zoeknog Dam failed during 1993, resulting in severe scouring, sedimentation and habitat changes downstream. However, most of the habitats have since, at least, partially recovered. Of the approximately 30 hectares of disturbed soil which elevated the rate of erosion, some 5 ha have already been rehabilitated by the Save the Sand initiative. 

Desired Ecological State and Response by Resource Managers

It is desirable that streams in this region be maintained in a good state. Exceptions are the Mutlumuvi and Sabane, where only fair and poor states respectively are deemed realistically achievable. 

Clearing of alien vegetation is a priority management action, together with planning and maintenance of forestry roads to minimise impact on streams, due to erosion and sedimentation. The forestry and agricultural operators should protect the riparian zone by maintaining a buffer strip (at least 30 m) between the outer boundary of riparian zone and formal plantations or areas of cultivation. Roads within 20 m of the riparian zone must have a management plan for controlling erosion and sedimentation. The forestry companies have instituted a joint biomonitoring programme of streams and rivers in areas under their control. Implementation of recommendations forthcoming from this programme will be an important step towards marrying activities of the forestry sector with the health and sustainability of aquatic ecosystems.

Alien vegetation clearing in this region has also been successful, with extensive rehabilitation of wetlands and removal of alien vegetation in the upper Sand and Mutlumuvi Rivers. 

Working for Water workers treat alien tree stump to prevent regrowth

Alien vegetation and the Working for Water Progamme
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