| PALMIET RIVER: Hydrology and geohydrology |
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eWISA Home | PALMIET: MAIN INDEX | ALPHABETICAL LIST OF RIVERS | |||||||||||||||||||||||||||||
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Map of the PALMIET River |
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| HYDROLOGY | ||||||||||||||||||||||||||||||
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The gross mean annual run-off of the Palmiet River catchment is 310x 106 m3. River flow measurements taken at gauging station at Welgemoed give the mean annual flow for the Palmiet as 192,48x106m3, however, the White Paper gives a figure of 245 x 106m3/annum. Run off varies considerably on both an annual and monthly time scale. Between 1963 and 1979 individual annual flow values ranged from a minimum of 105,01 X 106m3 to a maximum of 422,04 x 106m3. Generally there is little flow in summer while the highest flow occurs during the period June to September. Peak flow is extremely variable: it can be as little as one-fourteenth of the average monthly run-off and as much as five times as great. (Ref 2) |
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A comparison between the river flow data from the gauging weirs just below the Kogelberg Dam and just above the head of the estuary indicates the relative annual and monthly contribution the upper and lower regions of the river make to the estuary.(Ref 2) | |||||||||||||||||||||||||||||
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Monthly measurements of total suspended solids along the entire length of the Palmiet River indicate that siltation rates are generally low. Even in winter, when river flow rates are high, total suspended solids rarely exceed 20 mg/1. Suspended solids entering the estuary are notably low, ranging from 1,1 mg/1 to 7,5 mg/1. This seems to be for a number of reasons. Firstly, the mountains are composed almost entirely of sandstone of the Table Mountain Group with some tillite derived from Bokkeveld shale in the valleys. The hardness of these rocks results in low levels of erosion and consequently a relatively low sediment load in the water. (Ref 2) | |||||||||||||||||||||||||||||
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Secondly, the Palmiet River passes through several large dams in the upper middle reaches and a weir in the lower reaches. These impoundments act as silt traps. (Ref 2) | |||||||||||||||||||||||||||||
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| GEOHYDROLOGY | ||||||||||||||||||||||||||||||
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| References | ||||||||||||||||||||||||||||||
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Ref 2: Estuaries of the Cape Report no 37: Palmiet (CSW 12) CSIR RESEARCH REPORT 436 | |||||||||||||||||||||||||||||
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