CE 598 River Restoration
Lyle C. Begay
February 20, 2012
1.
Introduction
Fluvial Geomorphology (FGM) is the study of streams and their interaction with the geologic terrain it has formed therein. It is a multidisciplinary synthesis of engineering, biology, geology, earth science, hydrology and other science disciplines. It is a developing practice in the area of natural stream channel design stemming from movements to restore river systems. Fluvial
Geomorphology is a holistic science-based view of restoring stream channels by empirical studies such as sediment transport, river discharge, channel size, mapping and others.
2.
History of the Fluvial Geomorphology Field
Fluvial geomorphology has its roots in the fields of engineering and geoscience that have progressed over the past two centuries. The term fluvial is defined as of, relating to, or inhabiting a river or stream and geomorphology is the scientific study of landforms and the process that shapes them (en.wikipedia.org). In essence fluvial geomorphology is the study of landscapes formed from a flowing body of water. Geomorphology is a sub discipline of geoscience and holds a closer relationship to contemporary fluvial geomorphology. In its essence, geoscience adheres to the inductive scientific method of observation, hypothesis and experimentation.
Experimental geoscience is based on a Baconian methodology by conducting research and producing data for future studies.
In contrast, engineering applies mathematical Newtonian mechanics in order to design structures and systems to promote quality of human life. Since the 18 th
century engineering design was applied to river systems in order to alleviate flood risk, develop nautical transportation, energy generation and recreational use. The engineering practices provided the framework for early river management, developing laws and standards for water operations. Detention dams, locks and stream channelization were all measures of river control and stabilization but recently have shown costly effects. Such examples include maintenance cost, bed armoring, sediment loading, non-point source pollution and riparian degradation.
Over the past several decades the environmental disruptions of channel stability, water quality and habitats have gathered a growing movement in evolving river restoration and management.
A cooperative approach to stream restoration requires understanding the biophysical nature of

the river based on its geographic structure and the region’s fluvial process. This incorporated with hydrologic and hydraulic engineering data allows for a more rounded approach to river rehabilitation and non-degrading structures.
Society has become disenchanted with full exploitation of riverine systems and governments such as the US and UK has required environmental consideration in their developments. At the same time fluvial methods have expanded and literature has been appropriated especially during the past three decades. Understanding of river systems involves its historical evolution and definable future involving the implementation of river design. This understanding established the demand for geomorphologists to develop a body of knowledge into rather unknown topic areas such as gravel bed-rivers in extreme environments and continues so today. Specialists in fluvial geomorphology arose in the 1980s such as Schumm who describe morphologists as investigators that evaluate models of the landscape by deductive reasoning and measurements of erosion based on extrapolation of empirical relations. During this time Schumm described the components of the fluvial system in three parts and the sediment process which will be discussed further.
Leopold and Baker further described the fluvial process in geomorphic terms by publishing field and laboratory research which illustrate water impact on varying landforms, drainage basin patterns and methods for management.
In management discourse policy makers and legislation aligned engineers and geomorphologists during the turn of the century. The two schools of thought formed a relationship around water with differing views; the engineer with intervening institutionalized solutions and the geomorphologist with long-term independent observations. Together the field of FGM has evolved with the bond between the two camps over numerous case projects.
Engineering
Table 1: Comparison of skills in FGM Integration
Geomorphology
Design Experience
Hydraulics
Project Timescales
Field Experience
Sediment Supply/Transport
Longer Timescales
Specialist Function
Protection Techniques
Simple Channel Forms
Reach Scale
Accredited Standards
Hard Hat
Generalist Breadth
Erosion/Deposition Processes
Complex/Sinuous Channel Dynamics
Basin Scale
Personal Insights
Chest Waders

3.
Applications
The following are examples of case studies implemented with environmentally conscious river design as taken from the text Applied Fluvial Geomorphology for River Engineering and
Management (Thorne et al, 1997). In simplifying the amount of input from other disciplines
(biology, chemistry, law, etc), four classes of geomorphological consultations are represented in the studies.
Direct Intervention in Channel Management
Channel Designs for Flood Protection at Environmentally Sensitive Sites
The first case study was an evaluation of flood relief systems in England and Wales conducted for the UK Ministry of Agriculture. The objectives of the project were to 1) evaluate performances of implemented systems in terms of discharge capacity, channel stability, construction & maintenance costs and conservation value and 2) develop guidelines for the design of stable flood alleviation/land drainage schemes on mobile-bed channels on the basis of objective 1.
Table 2 Classification of Flood Alleviation Schemes
Urban
Upland Brecon
Duffield
Matlock
Kendal
Exeter
Tiverton
WDB
WSCRB
DBR
WDBR
WDRM
WD
Rural
Byton
Conistone
WDS
DBR
Lowland Banbury
Sidmouth
Bath
Trowbridge
Bury St. Edmunds
Saffron Walden
Colyton
W Widening
D Deepening
S Straightening
T Trapezoidal Section
DBR
DB
WDCB
WDT
RMF
Redhill
Abridge
Colyford
Newton Flotman
Saffron Walden
R Weirs
F Flood Banks
M Diversion Channel
P Partial Dredging
C Concrete-Lined Channel
B Bank Revetment
A 2 Stage Channel
RF
FP
DCTW
A
RMF
AM
WDT

The sites were chosen based on their representation of traditional engineering techniques and evaluated on their riverine environment impacts. The study sites were divided into upper and lower river environments to better compare different systems. The sediment transport equation displayed the best forecasting of erosion/deposition in the reaches coupled with the Hey resistance function to evaluate discharge conditions produced comparable measures of environmental impact of each structure. The only stable scheme were those incorporating distant flood banks due to the lack of sediment transport regime alteration (erosion/deposition). Twostage channels are viable due to minimal siltation if applicable, otherwise bank-adjacent levees would be the preferred over diversion channels and resectioning.
Indirect/Contingent Intervention: Protecting and Maintaining Channel Capacity
Erosion Protection: Banks
Headward and bank erosion at meander bends along a reach of the River Roding in Loughton,
Essex, UK was intensified by channel straightening. Geomorphologists were commissioned to evaluate the use of submerged vanes to alleviate the rate of erosion. The number, size and location of the vanes were calculated to oppose torque forces in the stream and subsequent trials and theory provided for higher degrees of erosion dissipation. Each vane was 3 m long and 1 m high and installed so as to be submerged even during low flow conditions. The developed vane was installed in January 1989 with a fixed position with a main and minor anchoring pile. A survey was carried out after installation and indicated erosion rates were significantly reduced along with bank undercut, over-steepened and mass failures.
Geomorphology of Channels and Water Resource Management
Regulating Reservoirs and Channel Stability
Severn-Trent and Welsh Water Authorities acquired consultation on the maximum levels of release that could be made to the Wye and Severn rivers which would allow their natural stability to be maintained. The basic necessity was to establish release thresholds in regard for bed material entrainment downstream from the outfalls, making the choice of sampling location important. Sites were determined from sinuosity changes implying net erosion and natural instability.
Channel Restoration and Habitat Creation
<Expand in greater detail with reference to geomorphic terms>

4.
Fluvial Process
In order to understand the geomorphic classifications in stream restoration the fluvial processes must be introduced. The hydrologic cycle pictured below takes place within high elevation ranges which form the boundaries of a watershed, the crown shaped area of land draining water to the lowest elevations where streams form. The running water infiltrates the soil along its travels, evaporates in to the atmosphere and/or collects into streams and forms a flowing concentrated body of water. The type of streams that evaporate without continual flow are called ephemeral streams carrying water only during rainfall. The streams that have steadier flows during rainy seasons are called intermittent streams fed by a developed groundwater table and disappear when the table lowers.
Figure 1 The fluvial process
Sustained dense year round flows are found at lower elevations and are called perennial streams.
The movement of water carries with it sediments from previous upstream elevations and are deposited along its path. The size of a watershed and its land type, human use, soil type, weather conditions and geography contribute to the characteristics of the perennial stream such as velocity, size, shape and direction. The observation of these contributions is the central focus of fluvial geomorphology and is categorized within the profession.

5.
Stream Classification
Bankfull Discharge
Bankfull as the term suggests is the crest elevation of water just before flooding begins. Likewise the bankfull stage is the flow that fills the stream to the top of its channel as water begins to spill onto the floodplain.This stream characteristic describes a morpholoigic standard that relates the stream to its current condition by means of formation and dimension.
Channel Pattern
This is a plan bird’s eye view of the stream and displays a sinuous formation across the land. The sinuosity of a stream is defined as the channel length of its deepest point divided by the valley length.
Figure 2 Channel Pattern
Channel Profile
This characterization of the stream is followed along the longitudinal slope from left to right, higher to lower elevation.
<Reference to Channel Characterization>

Channel Stability
The factors affecting aggradation and degradation were developed as a relationship entitled
Lane’s Balance. This evaluation displays the proportional relationship of sediment load x bed sediment size (D50) to stream discharge x stream slope (S).
Figure 4 Lane’s Balance Equation
6.
The FGM Discipline
The practice of fluvial geomorphology takes into account a gradient of physical variables associated with the stream from the entire watershed and its climate to the soil sediment type and groundwater influence. As the case studies before have demonstrated, evaluation of the river management project begins with a visit to the field site to begin observation and data collection.
Figure 5 Spatial Representations of FGM Considerations
Characterization of geomorphological conditions usually begins at the micro-level with a
Wolman Pebble Count as a method of calibrating the geological features of the river. The longitudinal profile is calculated into percentages of riffle and pool, and based on their respective ratios that value is the number of pebbles taken from their respective areas. For example, the

profile suggests 70% riffle and 30% pool; seventy pebbles are retrieved from the riffle and 30 from the pool.
The pebble samples are then measured along their axes as shown in Figure 3. The movement of sample retrieval is perpendicular to the stream flow and proceeds from the left bank to the right. The data is collected until all 100 pebbles are accounted for with their size and type and recorded in a spreadsheet, a tabulated cross-sectional representation of the stream’s geologic make-up.
<Continued fgm practice>
Rosgen Classification System
Montgomery Buffington Classification System
Biological Consideration a) Vegetation b) Aquatic
Design Approaches a) Passive Measures b) Active Measures c) Hydraulic Structures d) Operation & Monitoring
Progressions in FGM a) Practices b) Technology
7) Conclusion

References
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Bennett, S. J., & Simon, A. (2004). Riparian vegetation and fluvial geomorphology Washington, DC :
American Geophysical Union.
Gregory, K.J. Benito, G., Downs, P.W. (2008) Applying fluvial geomorphology to river channel management: background for progress towards a palaeohydrology protocol. Geomorphology, Vol 98 ( 1-
2):153-172.
Gilvear, David J. (1999). Fluvial geomorphology and river engineering: future roles utilizing a fluvial hydrosystems framework. Geomorphology, Vol 31 (1-4): 229-245.
Gregory, K.J. (2006) The human role in changing river channels. Geomorphology, Vol 79 ( 3-4): 172-
191.
Gregory, K.J., Thorndycraft, V.R., Benito, G. (2008) Fluvial geomorphology: A perspective on current status and methods. Geomorphology. Vol 98(1-2): 2-12.
Schumm, S., Mosley, M., & Weaver, W. E. (1987). Experimental fluvial geomorphology / Stanley A.
Schumm, M. Paul Mosley, William E. Weaver. New York : Wiley, c1987.
Jennings, J. N., & Bremer, H. (1985). Fluvial geomorphology : in memoriam J.N. Jennings / edited by
Hanna Bremer. Berlin : Gebr. Borntraeger.
Kondolf, G., & Piégay, H. (2003). Tools in fluvial geomorphology / editors, G. Mathias Kondolf and
Hervé Piégay. Hoboken, NJ, USA : J. Wiley.
Thorne, C. R., Hey, R. D., & Newson, M. (1997). Applied fluvial geomorphology for river engineering and management / edited by Colin R. Thorne, Richard D. Hey, Malcolm D. Newson. Chichester, England
; New York : John Wiley.