SPATIAL PATTERNS OF ISLANDS AND SALT CRUSTS IN THE OKAVANGO DELTA, BOTSWANA

ABSTRACT

Islands in the Okavango Delta in Northern Botswana have a large influence on water flow, evapotranspiration and salinity balance. In this study island orientation and the occurrence of salt crusts on islands was explored in relation to both the regional Delta azimuth and proximity to channels. Islands, particularly those of larger size, are oriented along the azimuth of the Delta surface, with a local variation pertaining to the orientation of nearby channels. Salt crusts on islands tend to be displaced in the downstream direction. It is concluded that island growth occurs preferentially in a radial pattern, driven primarily by local hydraulic gradients. These local gradients also cause displacement of the salt crusts. Most island growth and salt crust formation is taking place in the more distal parts of the Delta.