The MAR from the BRC (MAR = 45.8 106m3) constitutes 9% of the MAR from the Primary Gamtoos River catchment (MAR = 495.2 106m3) (Midgley et al., 1994). The rainfall intensity of the area is II to III in the Baviaanskloof area. The average annual rainfall on the north facing slopes of the Kouga Mountains, which drain into the valley, is 448 mm, while that of the south facing slopes of the Baviaanskloof Mountains that drain into the valley is 461mm. The 72-yr. long rainfall record from Zandvlakte station, the furthest west, shows that Feb/March and November are the wettest months, June/July the driest and that during the remaining seven months between 20 and 30mm can be expected. At the Studtis station, halfway up the valley less rain was recorded in late summer than at Zandvlakte. The easternmost station is Voorkloof, with a twenty years record and the profile is similar to that of Studtis.   Thunderstorms, flash floods and large floods are regular occurrences in the valley (10-20 Thunderstorms/ year - Kerley & Els 1989). Until recently snow occurred frequently during winter (Tyson 1971 & Bond 1981). (Ref 2)

The MAP is typically 20% of the MAE lending to arid conditions throughout most of the catchment. The short but intense duration of the rain coupled with the overall steep topography, high evaporation and infiltration rates lead to a predominance of ephemeral streams. As a result of these climatic and geological conditions, wetlands are relegated to the lower catchment areas, in particular the floodplains adjacent to the Rivers. This is evidenced by the large percentage of floodplains recorded.  (Ref 2)