RHP South African
River Health Programme 		State of the Rivers Report
Crocodile, Sabie-Sand & Olifants
River Systems
go back to RHP homepage Table of Contents introduction/background overview of study area indicators and indices list of infoboxes with links
Crocodile Catchment: ecoregion 4 Crocodile River System Sabie-Sand River System Olifants River System summary ecoregion 5.06 in Crocodile catchment

The Crocodile River System

Ecoregion 5.05

Ecoregion and River Characteristics

This ecoregion is typical of lower escarpment reaches and the start of the lowveld. Altitude range falls to 800-1 000 m, with moderate relief. The rainfall is variable within the ecoregion with some areas receiving as little as 400 mm per year, although most areas receive within 600 to 1 000 mm. Temperatures are higher (16-22°C), and soils are sandy, sandy loams, and clays overlaying iron, jaspilite, syenite, hornblende granite, foskorite, and gneiss, which is conducive to a shift in vegetation from grassland to bushveld.

The river in this long section is mostly characterised by large rocky pools with occasional rapids. Upstream from Kaapmuiden the river flows through a gorge where rocky habitats and big boulders abound.

Present Ecological State

The overall state of this section can be described as fair . Upstream from Nelspruit the in-stream biota reflect a good to fair ecological state. Around Nelspruit the in-stream and riparian conditions deteriorate as indicated by riparian habitats and vegetation ( poor ), fish ( fair to poor ) and invertebrates ( poor to unacceptable ). Downstream from Nelspruit the river gradually recovers to a fair state.

Ecoregion 5.05

Drivers of Ecological Change (Land-use activities)

This section is under pressure from intensive agricultural, industrial and urban land uses. Large areas are used for irrigated agriculture, ranging from fruit (predominantly citrus) orchards to vegetable and tobacco cultivation.

Sugar cane becomes more dominant in the lower parts of this section. Water is abstracted from the Crocodile River for irrigation and to purify for domestic use. In addition to formal agricultural activities, alien plants and aquatic weeds such as water hyacinth have an impact on the riparian and in-stream health respectively. A sampling site near Schagen, which has been used since the 1970s, is now so densely infested with alien vegetation that it is barely accessible. Domestic runoff and urban and industrial waste from Nelspruit have a significant impact on the health of the Crocodile River.

Desired Ecological State and Response by Resource Managers

It is desirable to manage this section of the Crocodile Catchment to achieve a good ecological state. This is regarded as an achievable and realistic goal. The biggest challenge is in the vicinity of Nelspruit, where multiple disturbances need to be managed. These disturbances include disposal of solid wastes that often ends up in and close to the river, and the quality of effluents that are being discharged.
An improvement in water quality, through improved pollution control, is required to achieve a good ecological state for in-stream biota at and downstream from Nelspruit. Improved management of the riparian zone is also required.

Back to RHP homepage back to table of contents back to top of page ecoregion 4 in Crocodile Catchment ecoregion 5.06 Crocodile catchment