Abstract

A simple matrix developed by a small group of ecologists, geomorphologists and an hydraulic engineer at a workshop in February 1995 was proposed as a standardised classification tool for the recognition of hydraulic biotopes, instream flow environments recognised on the basis of surface flow type and substrate class. Research was carried out in the Buffalo River, South Africa, to test the validity of this classification with respect to measurable hydraulic attributes. Hydraulic biotopes were classified at a number of sites representing a range of stream morphologies, channel scale and discharge. The hydraulic attributes at each sampling point were measured. Using simple measures of flow depth, velocity and bed roughness, hydraulic indices were calculated to describe both the near bed conditions (shear velocity and ‘roughness’ Reynolds number) and the mean flow in the water column (Froude number and Reynolds number). Results indicate that hydraulic biotope classes can be considered as significantly different in terms of flow hydraulics. Hydraulic characteristics appear to be consistent within classes across different spatial scales. An assessment of the influence of discharge showed that differences are recognised in the classes of the lower energy environments (pool and run) but despite considerable within class variability, no significant differences were observed across discharges in the higher energy environments. The hydraulic biotope classification and associated hydraulic biotope matrix shows good potential as a standardised method for classifying instream environments over a range of channel scales and discharges.

The text of this article is only available as a PDF.

References

Allen, K.R.
1951
.
The Horokiwi Stream: a study of a trout population. New Zealand Marine Department of Fisheries, Bulletin 10
231
231
.
Brakensiek, D.L., Osborne, H.B. and Rawls, W.J.
1979
.
Field manual for research in agricultural hydrology, Agriculture Handbook 224, USDA
(Coordinators)
Bovée, K.D.
1982
.
A guide to stream habitat analysis using the instream flow incremental methodology. Instream Flow Information Paper no 12. USDI Fish and Wildlife Service, Office of Biological Services. FWS/OBS-82/86
Chutter, F.M.
1970
.
Hydrobiological studies in the catchment of Vaal Dam
.
South Africa. Internationale Revue der Gestamen Hydrobiologie
,
55
:
413
422
.
Davis, J.A. and Barmuta, L.A.
1989
.
An ecologically useful classification of mean and near — bed flows in streams and rivers
.
Freshwater Biology
,
21
:
271
282
.
de Moore, F.C.
1990
.
The influence of fish on the structure and behaviour of macroinvertebrates in a second order headwater stream
.
Vehr. Internat. Verein. Limnol
,
24
:
2050
2055
.
Department of Water Affairs and Forestry (DWAF)
.
1995
.
Water supply and Sanitation Policy White Paper
,
Pretoria
:
Government Printer, South Africa
.
DWAF
.
1986
.
Management of Water Resources of the Republic of South Africa
,
Pretoria
:
Government Printer, South Africa
.
Gordon, N.D., Mc Mahon, T.A. and Finlayson, B.L.
1992
.
Stream hydrology. An introduction for ecologists
,
Chichester
:
Wiley
.
Harrison, A.D. and Elsworth, J.F.
1959
.
Hydrobiological studies on the Great Berg River Western Cape Province
.
Transactions of the Royal Society of South Africa
,
35
:
125
226
.
Henderson, F.M.
1966
.
Open channel flow
,
New York
:
Macmillan
.
Jowett, I.G.
1993
.
A method for objectively identifying pool, run and riffle habitats from physical measurements
.
New Zealand Journal of Marine and Freshwater Research
,
27
:
241
248
.
Jowett, I.G., Richardson, J., Biggs, B.J.F., Hickey, C.W. and Quinn, J.M.
1991
.
Microhabitat preferences of benthic invertebrates and the development of generalised Deleatidium spp. habitat suitability curves, applied to four New Zealand rivers
.
New Zealand Journal of Marine and Freshwater Research
,
25
:
187
199
.
Milliken, G.A. and Johnson, D.E.
1984
.
Analysis of Messy Data, Volume 1: Designed Experiments
,
New York
:
Van Nostrand Reinhold
.
O'Keeffe, J.H.
1996
. “
Where and Why — an overview of the scale of research on South African rivers
”. In
The Hydraulics of Physical Biotopes — Terminology, Inventory and Calibration
,
WRC Report KV84/96
Edited by: Rowntree, K.M.
4
8
.
In
Orth, D.J. and Maughan, O.E.
1983
.
Microhabitat preferences of benthic fauna in a woodland stream
.
Hydrobiologia
,
106
:
157
168
.
Padmore, C.L., Newson, M.D. and Charlton, M.E.
1996
. “
Instream habitat: geomorphological guidance for habitat identification and characterisation
”. In
The Hydraulics of Physical Biotopes — Terminology, Inventory and Calibration
,
WRC Report KV84/96
Edited by: Rowntree, K.M.
27
42
.
In
Price, P.W.
1975
.
Insect Ecology
,
New York
:
Wiley, Inc.
.
Rowntree, K.M., ed.
1996
.
The Hydraulics of Physical Biotopes — Terminology, Inventory and Calibration
,
WRC Report KV84/96
Rowntree, K.M. and Wadeson, R.A.
Translating channel morphology into hydraulic habitat: application of the hydraulic biotope concept to an assessment of discharge related habitat changes
.
Proceedings 2nd IAHR International Symposium on Hydraulics and Habitats
. pp.
A281
A292
.
Schlichting, H.
1961
. “
Boundary layer theory
”. In
Handbook of fluid Dynamics
, Edited by: Streeter, V.L.
New York
:
McGraw Hill
.
In
Smith, I.R.
1975
.
Turbulence in lakes and rivers
,
Scientific publication no 29
UK
:
Freshwater Biological Association
.
Wadeson, R.A.
1994
.
A geomorphological approach to the identification and classification of instream flow environments
.
Southern African Journal of Aquatic Sciences
,
20
:
38
61
.
Wadeson, R.A.
1996a
.
The development of the hydraulic biotope concept within a hierarchical geomorphological model
,
Grahamstown, , South Africa
:
Rhodes University
.
Unpublished Ph.D Thesis
Wadeson, R.A.
1996b
. “
The biotope concept: a geomorphological perspective
”. In
The hydraulics of physical biotopes — terminology, inventory and calibration
,
WRC Report KV84/96
Edited by: Rowntree, K.M.
10
17
.
In
Ward, J.V.
1992
.
Aquatic stream ecology, 1. Biology and Habitat
,
New York
:
Wiley
.
Wetmore, S.H., Mackay, R.J. and Newbury, R.W.
1990
.
Characterisation of the hydraulic habitat of Brachycentrus occidentalis, a filter feeding caddisfly
.
Journal of the North American Benthological Society
,
9
:
157
169
.
Whittaker, R.H., Levin, S.A. and Root, R.B.
1973
.
Niche, Habitat and Ecotope
.
The American Naturalist
,
107
(
955
):
321
338
.