The tidal records of existing South African and Namibian tide gauges are examined and corrected. Regional sea level trends vary, with the West Coast rising by +1.87 mm y -1 , the southern coast by +1.48 mm y -1 and the East Coast by +2.74 mm y -1 . The effects of barometric pressure and vertical crustal movement changes on these trends are examined. The derived relationship between sea levels and barometric pressure changes varied between 5.71 and 7.67 mm hPa -1 , significantly less than the theoretical inverse barometric correction. Barometric pressure has been dropping along the west coast at 1.63 hPa per decade (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006), has remained fairly static along the southern coast and is rising at 0.30 hPa per decade (1970-2007) along the east coast of southern Africa. The West Coast barometrically corrected sea level trends show that most of the change can be attributed to falling barometric pressure, whereas along the East Coast, the barometric pressure increase is suppressing sea level by 0.2 mm y -1 . Vertical crust movements vary, with the largest recorded movements of +1.11 ± 0.25 mm y -1 found along the East Coast. Movement rate reduces southwards. Eustatic sea level trends vary from +3.55 mm y -1 along the East Coast and +1.57 mm y -1 along the southern coast to +0.42 mm y -1 along the West Coast.
/ One of the most pressing problems facing wilderness managers in the ecologically fragile Drakensberg Mountains, South Africa, is that of path erosion, since it detracts from the wilderness experience and is very costly to remediate. As increasing demand for wilderness and outdoor recreation places greater pressure on paths and trails, it will be necessary to increase path network size and capacity, and it is important that new paths are routed such that maintenance requirements are minimal.This study describes the development of a technique based on the site and environmental variables of rainfall, topographic slope, and lithology, which enables assessment of path erosion risk before paths are planned and constructed. The technique was tested on a path at the Drakensberg resort of Loteni, and showed good correlation with actual path degradation. When used as a tool in path network planning, it can aid in the selection of low-maintenance routes and also help in planning maintenance budgets.
Although dunes fronted by sandy beaches constitute approximately 80 per cent of South Africa's coastline, few studies have addressed the formation and life cycle of coastal foredunes, the small, ephemeral shore-parallel dune ridges typically less than 5 m high and 20 m wide, which form seaward of the storm line. This study used regular, detailed topographic surveys of embryo and foredunes at Tugela mouth, an aggrading stretch of shoreline on the subtropical east coast of South Africa, over a 32-month period, to gain insight into the formation and motion of these highly mobile landforms over the short term.Average wind drift potential at Tugela mouth during the study period, at 2·35 m s −1 , was an order of magnitude lower than that typical of most parts of the eastern South African coast. The dominant sand-moving wind for the region was from the southwest to west-southwest at 10·7 to 13·8 m s −1 , with a secondary vector from north to north-northeast at 10·8 to 13·8 m s −1 . Significant shoreline retreat, a result of the low sediment yield of the Tugela River during the study period, was one of the main results. This provided the context for redistribution of sand from the inland to the seaward side of the study area, a consequence of the dominant wind direction, and for frequent creation and destruction of short-lived embryo dunes. Those foredunes which survived the whole study period tended to increase in height, but there was no consistent directional trend in foredune crest movement throughout the 32 months.The study results generally supported Psuty's model of foredune development, but could not confirm his contention of landward retreat of dune forms under conditions of shoreline erosion. This may be due to the relatively short duration of the study, or possibly to low wind drift potential at the site.
The objectives of this paper are (1) to show the hydrological effects of changing the spatial resolution of radar-derived rainfall and (2) to show the effect of discretization of radar data on hydrological modeling for flood forecasting. Simulated hydrographs are compared for 2, 5, and 10 km basin grid sizes for the Grand River watershed in Ontario. An eight-level discretization of rainfall is compared with a 256-level scale of rainfall intensities. Spatial averaging tends to reduce the effect of erroneous radar readings and give comparable results with those obtained using finer resolutions. The appropriate level of discretization depends on the area being modeled and appropriate levels are recommended. The level of discretization of radar precipitation data does not significantly affect the generation of hydrographs. Hydrographs based on the radar-derived rainfall generally reproduced measured hydrographs better than those derived from the rain gauge data.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.