The contemporary geomorphology of the Sabie River in the Kruger National Park

The Sabie River in the Kruger National Park has been described as the most pristine in South Africa. It has remained largely free of direct alteration along its 110 km length within the reserve and as such displays a high geomorphic diversity. This physical vari- ability supports a great diversity of flora and fauna including a number of species endemic to the river. The diversity in fluvial form is the result of a high degree of bedrock influence coupled with a rapidly changing energy regime. Steeper bedrockinfluenced areas alternate with more gently sloping alluvial segments to create a series of channel types ranging from bedrock anastomosing through to alluvial single thread and braided sections. Each channel type is part of a continuum that relates to the degree of alluviation of the river on the bedrock template. Descriptions of the characteristic channel types associated with the Sabie River, together with associated morphologic units are given together with the areal extent of the changing morphology in the Kruger National Park. Each morphologic unit is characterised by size, shape, sedimentology and flow influence. Recent research into the degree and direction of morphologic change in the Sabie River is also summarised in the light of possible catchment management

The February 2000 floods on the Sabie River, South Africa: an examination of their magnitude and frequency

The floods that affected much of Southern Africa in February 2000 have been reported as the largest in living memory by many observers. However, the force of the floods damaged the majority of the gauging stations located on the affected rivers, many of which were not constructed to measure flows of such a magnitude. This paper presents an estimation of the peak flood discharge on 6 February 2000 for the bedrock influenced Sabie River in the Kruger National Park, by simulating the hydraulic and geometric characteristics of the peak flow and relating these to the roughness character of the channel. Peak water surface slope data in the form of strandline measurements at channel type breaks along the river were collected for six sites along the Sabie River within the Kruger National Park. Flood conditions within each channel type were considered to approximate to uniform flow. The cross-sections are located between major tributary inputs allowing for approximate sub-catchment flow contributions to be estimated. The results indicate that the flow peaked at around 3000 mVs at the Kruger Gate entrance to the Kruger National Park, increasing to approximately 5500mVs at Skukuza and 7000 mVs at Lower Sabie close to the Mozambique border following inputs from the Sand River sub-catchment. These estimates compare well with the simulated rainfall runoff total of 4300 mVs at Skukuza, however, precipitation inputs over the lowveld appear to indicate that the discharge only rises to 4950 mmVs at Lower Sabie. A flood flow of this magnitude has never been experienced based on the simulated flow data generated by the ACRU hydrological model calibrated against measured flows therefore suggesting a return period in excess of the 60 years of record

Research and Implementation of Modeling Grid DEM Based on Discrete Data

International audienceInterpolation method is used to construct regular grid DEM (Digital Elevation Model) based on discrete data. The key to DEM interpolation algorithm lies in the efficiency of data search around the points to be operated and the precision of DEM interpolation by selecting an appropriate interpolation function model. At present, the point by point interpolation is very common. Based on the comparison and analysis of characteristics and application scope of various DEM interpolation algorithms, this paper proposed a new interpolation model which combines distance-weighted average method and least squares fitting method. Results show that proposed method can improve search speed and interpolation accuracy remarkably and has good application value for large area