| Abstract: | Total evaporation (ET) is one of the major components of the water budget of a wetland. Very little research has been conducted on the loss of water to the atmosphere from different wetland vegetation types occurring in southern Africa. This study on the ET of taro (locally known as madumbe) and sedge within the Mbongolwane wetland was conducted to assess the potential impact of madumbe cultivation on the hydrology of the wetland. Sugarcane planted on the contributing catchment outside the wetland was the other crop examined. Two field campaigns were conducted in November 2009 and January 2010 during the growing season of the madumbe crop to quantify ET rates in the Mbongolwane wetland and from sugar cane in the surrounding catchment. ET was measured over two vegetation types in the wetland, namely: madumbe (Colocasia esculenta); sedge (Cyperus latifolius) with some reeds (Phragmites australis); and sugarcane in adjacent terrestrial areas. ET from the madumbes ranged from 1.0 to 6.0 mm day?1. The daily average ET rates in November 2009 were 3.5 and 4.9 mm for the madumbe and sedge sites, respectively, and 4.0 mm for sugarcane grown in the catchment. The daily average ET rates in January 2010 were 3.3 and 3.7 mm for the madumbes and sedge sites, respectively, and 2.4 mm for the sugarcane site. The daily ET was therefore lower at the madumbe site in November 2009 and in January 2010 compared to the sedge site. An average crop factor of 0.6 was obtained from this study during the growth stage of the madumbes. Copyright © 2012 John Wiley & Sons, Ltd. |
