Hydrological issues associated with the determination of environmental water requirements of ephemeral rivers
Article first published online: 1 JUN 2005
Copyright © 2005 John Wiley & Sons, Ltd.
River Research and Applications
Volume 21, Issue 8, pages 899–908, October 2005
How to Cite
Hughes, D. A. (2005), Hydrological issues associated with the determination of environmental water requirements of ephemeral rivers. River Res. Applic., 21: 899–908. doi: 10.1002/rra.857
- Issue published online: 28 SEP 2005
- Article first published online: 1 JUN 2005
- Manuscript Accepted: 24 NOV 2004
- Manuscript Revised: 20 OCT 2004
- Manuscript Received: 19 AUG 2004
- ephemeral rivers;
- environmental flow requirements;
- flow regulation
The paper reviews the generic characteristics of ephemeral rivers compared with seasonal and perennial systems in the context of southern Africa. The difficulties of estimating the natural characteristics of ephemeral systems are discussed as well as the difficulties of estimating the impacts of water resource management strategies. Many of the problems are associated with the potentially discontinuous occurrence of flow in both time and space and the fact that static pools, as well as flowing water, may be of ecological importance. The most obvious impact of water resource developments on ephemeral rivers may be a reduction in the number and size of flow events. However, delays in the onset of flow in seasonal rivers and changes in the duration, quantity and quality of in-channel pool storage may be of equal importance. In a number of South African ephemeral channels the major impacts have been caused by the importation of water from elsewhere and a consequent reduction in streamflow variability. The paper suggests that there are a number of gaps in the understanding of the hydrology of ephemeral rivers, but perhaps more importantly, in the methods that are available to supply the type of information required by ecological specialists to be able to determine ecological water requirements under managed flow situations. Copyright © 2005 John Wiley & Sons, Ltd.