Dune Geomorphology in Maputaland, Mozambique

Abstract

The coastal region of Maputaland-Mozambique is characterised by an extensive lowlying coastal plain, which rises to a height of more than 100 metres in some places and attain a width of 2 kilometres. Maputaland in Mozambique extends from Ponta de Ouro, which borders South Africa to Cabo Santa Maria stretching for a distance over 100 kilometres, and encloses several swamps and coastal lakes such as Satine, Piti, Munde and Nela running in north south direction. The main objective of this study was to access the different categories of dune morphology in Maputaland- Mozambique by using aerial photographs, satellite images and field checking. Two major distinct dune systems on the Maputaland coastal morphology were mapped: (1) vegetated dunes form a coastal dune system, which face the sea, and characterised by undulating surfaces and continuous irregular crests running in north-south direction. Transfer dunes move along the foot of slope of the vegetated dunes towards north and northeast. The recent dunes can be either mobile or partial mobile and can attain a height of 5 meters. (2) Inland dunes system comprises a series of dunes including the reworked, parabolic and climbing dunes. These series of dunes often truncate on the first coastal dune system indicating different spatial and temporal events of dune formation. Weathering and reworking processes have affected these dunes, altering their typical shape and smoothing their surface giving them a hummocky aspect. The climbing dunes, running east west in most cases, separate the coastal lakes, and seem to be a result of fragmentation of previous existed large coastal lagoon by the several blowouts events as the lagoon water level fell down. These blowouts seem to follow the uppermost paleo-topographical areas of the lagoon, and the superimposed climbing dunes suggest high rates of sediment transport and deposition. The fragmentations of coastal lagoons by blowouts, which are superimposed by climbing dunes, are common modern processes along Mozambique Coastal Plain (e.g. Umbedje Lagoon in Bilene Holiday Resort located about 100 km north of Maputo).