Human‐induced soil erosion is a widespread phenomenon in South Africa, and soil erosion rates reported are among the highest in the world. In addition to human disturbance, unfavourable environmental conditions are mentioned to explain the situation. But data on ‘natural’ erosion from undisturbed sites are rare. This paper presents the first assessment of sediment yield as an integrate measure of erosion, deposition and sediment transport from five catchments located entirely within Kruger National Park (KNP). KNP has been spared from agricultural development for a century and represents a near to natural geo‐ecosystem in the semi‐arid savanna biome. Sediment yield estimates are based on a survey of post‐dam deposits in five reservoirs located in the south‐eastern part of KNP. Reservoir lifetime ranges from 40 to 60 years and the size of the catchments from 8 to 100 km2. The results show distinct relations of long‐term average sediment yield (SY) and area‐specific sediment yield (SSY) with catchment size. Despite the unfavourable semi‐arid environmental conditions, SY is comparatively low. SY varies from 130 ± 45 t y−1 for the 8 km2 catchment to 1130 ± 230 t y−1 for the 100 km2 catchment. SSY is 55 ± 15 t km−2 y−1 for catchments of 12 ± 3 km2 and 11 ± 2·4 t km−2 y−1 for the 100 km2 catchment. The latter finding suggests that decrease of SSY with increasing catchment size is not attributable to human disturbance only. However, further research is necessary to improve and enlarge the database and to verify first results and hypothetical conclusions. Copyright © 2012 John Wiley & Sons, Ltd.

The southern Cape coast, South Africa, is sensitive to climate fluctuations as it is influenced by different atmospheric and oceanic circulation systems. Palaeoecological evidence of Holocene climate variations in this region is presently limited. Here, we present a lake sediment record spanning approximately the last 670 years from Eilandvlei, a brackish coastal lake situated mid‐way between Cape Town and Port Elizabeth. The results from geochemical and sedimentological analyses point to an increase in minerogenic sediment input from the catchment starting around ad 1400. Changes in the seasonal distribution of rainfall during the Little Ice Age may have altered river discharge and increased erosion rates and fluvial sediment transport in pre‐colonial times. A rising mean lake level, possibly associated with an altered water balance or relative sea‐level rise, may offer an explanation for the deposition of finer sediments. After ad 1450, reduced burial flux of elements associated with autochthonous sediment formation may have resulted from ecological changes in Eilandvlei. Enhanced sedimentation rates, increasing carbon, nitrogen, phosphorous and biogenic silica concentrations, as well as high concentrations of proxies for allochthonous sediment input (e.g. aluminium, titanium, zirconium) point to increasing sediment and nutrient flux into Eilandvlei from the late nineteenth century onwards. The most likely factor involved in these recent changes is land‐use change and other forms of human impact.

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The climate of Sulawesi is driven by the monsoon system as well as the El Niño-Southern Oscillation (ENSO). Until now, mechanisms and long-term variations of these complex interacting climate processes have been poorly understood. This paper uses a sediment record from Lake Kalimpaa to investigate long-term rainfall trends of the past ~1500 years. Granulometric and geochemical data provide indications for an increasingly wetter climate (higher rainfall intensities and/or mean rainfall) on centennial to millennial time scales from approximately ad 560 to the 20th century. Highest rainfall intensities probably occurred at the end of the 'Little Ice Age' (LIA). The trend towards wetter conditions during this time could also be detected in other palaeoclimatic studies from the region. A plausible explanation for these observations is the southward displacement of the Intertropical Convergence Zone (ITCZ) associated with changes in monsoon dynamics. However, comparison of the results with other proxy and model data indicates that the long-term rainfall variability in Central Sulawesi is also determined by variations in ENSO. During the 20th century, the climate signal in the Kalimpaa record is superimposed by human impact. Moreover, the data suggest that two periods of disturbance occurred within the lake catchment between about ad 1090-1190 and ad 1450-1620. Comparison with fire frequency derived from macro-charcoal analysis indicates that these events were caused by forest fires which likely took place during periods of drought. Broadly simultaneous drought periods have been detected in records from East Java suggesting a regional drought occurrence affecting at least East Java and Sulawesi.

No abstract available