The Pongola Floodplain, South Africa – Part 1: Two-dimensional hydrodynamic modelling in support of an environmental flows assessment

Abstract

AND BACKGROUND /T_he Pongola Floodplain is an area of low topographic relief in the Makhathini Flats, northern KwaZulu-Natal, bordered by the Usuthu River and Mozambique to the north, the Lebombo Mountains and Swaziland to the west, and the Indian Ocean to the east (Figs 1 and 2). From Jozini Dam (Fig. 3) the Pongola River /f_lows in a north-easterly direction to its con/f_luence with the Usuthu River. /T_he river’s average longitudinal gradient is 0.039% over a total length of approximately (~) 139/uni00A0km and, being characteristic of a low-gradient channel, displays a meandering planform across the /f_lats, as illustrated in Fig. 4. /T_he /f_loodplain is interspersed with large depressions or ‘pans’ of varying size and permanence, and, whereas some pans are also fed by tributaries, most are dependent on the Pongola River for the bulk of their water supply.

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