The state of knowledge of the Groen is poor. The area, being remote, has received little attention in the past and the bulk of information in this report originates from the Estuarine and Coastal Research Unit (ECRU) survey. Although the Groen flows infrequently, probably once in about five years, surface water always present in the estuary, even during dry periods and often when river mouths on the coastline between the Groen and Orange are dry. The water body in the estuary appears to be partially maintained during dry periods, by springs situated in the upper reaches of the estuary on the flood plain.
Reference:
CSIR, Estuarine and Coastal Research Unit. 1981. Report 3 of the Estuaries of the Cape, Part 2: Synopses of available information on individual systems series, edited by Heydorn, AEF and Grindley, JR. Stellenbosch: CSIR. (CSIR Research Report 402)
Estuarine and Coastal Research Unit, E. (1981). Groen (CW7) (CSIR Research Report number). CSIR, National Research Institute for Oceanology. Retrieved from http://hdl.handle.net/10204/3469
Estuarine and Coastal Research Unit, ECRU Groen (CW7). CSIR Research Report number. CSIR, National Research Institute for Oceanology, 1981. http://hdl.handle.net/10204/3469
Estuarine and Coastal Research Unit E. Groen (CW7). 1981 [cited yyyy month dd]. Available from: http://hdl.handle.net/10204/3469