Sunday, December 4, 2016

Fluvial Morphology

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Fluvial Morphology: Definition, concept, scope and importance

Introduction:
The history of mankind is always connected with history of river as well as fluvial geomorphology. Fluvial geomorphology is strictly the geomorphology of rivers. As rivers have always held a prominent role in the study of landforms, it is not surprising that debates about fluvialism, as to whether rivers could produce their valleys, continued to rage early in the nineteenth century until uniformitarianism prevailed, whence temperate areas were seen as the result of rain and rivers.

Geomorphology:
Geomorphology is the scientific study of landforms and the processes that shape them. Geomorphologists  seek to understand why landscapes look the way they do, to understand landform history and dynamics, and to predict future changes through a combination of field observations, physical experiments, and numerical modeling.  

Fluvial:
Fluvial refers to the processes associated with rivers and streams. Fluvial and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used.

Fluvial geomorphology
Fluvial geomorphology is the study of the form and function of streams and the interaction between streams and the landscape around them.
In addition, Fluvial Morphology is the study of landforms and the fluvial processes that shape them. Fluvial processes which are associated with flowing including sediment erosion, transport, and deposition.
“Fluvial geomorphology has as its object of study not only individual channels but also the entire drainage system.”
Kruska and Lamarra (1973) cited by Schumm (1977)

 “A primary objective of fluvial geomorphology must be to contribute to an explanation of relationships among the physical properties of flow in mobile-bed channels, the mechanics of sediment transport driven by the flow, and the alluvial channel forms created by spatially differentiated sediment transport.”
   Richards (1987)

“Geomorphology is the study of Earth surface forms and processes; fluvial phenomena those related to running water.”
                                                                                        Graf (1988)

“The science that seeks to investigate the complexity of behavior of river channels at a range of scales from cross sections to catchments;it also seeks to investigate the range of processes and responses over a very long time scale but usually within the most recent climatic cycle.”
                                                                                                            Newson and Sear (1998),                            


Concept:
Fluvial Geomorphology considered is a most significant discipline in modern period for its’ The term “fluvial geomorphology” is combined with two words Fluvial and Geomorphology where Fluvial produced by a river; from Latin fluvius and from Greek, Geo - earth, morphs - form and -ology – science. So Geomorphology is the science dealing with the nature and origin of the earth's topographic features.
Fluvial geomorphology is a science devoted to understanding rivers, both in their natural setting as well as how they respond to human-induced changes in a watershed. One goal is to predict what changes will occur to a stream channel in response to alterations in watershed conditions; and, in turn, how these changes will impact human infrastructure and fish habitat.
The Bradshaw Model is a geographical model which describes how river's characteristics vary between the upper course and lower course of a river. It shows that discharge, occupied channel width, channel depth and average load quantity increases downstream. Load particle size, channel bed roughness, and gradient are all characteristics which decrease downstream.
 
Figure 1: Stream Morphology Monitoring Stations in the Credit River Watershed and their Status (2012).

The Scope of Fluvial Morphology:
Scope of a science may be defined as - extent or range of view, outlook, application, operation, effectiveness, etc.
Interestingly different scholars have described the scope of fluvial morphology differently. This is because they all define fluvial morphology in a different light. These definitions set the parameters for the nature of river landform studies by Geomorphologists .
In Present time, there are many portions of fluvial geomorphology for more transparency and analysis is used in the world. There are some fluvial geomorphologic objectives are given below-

1. Qualitative fluvial geomorphology: Here this subject discusses abut traditional Fluvial Geomorphology. Such as-
    • River system
    • Catchments area
    • Water flow flood management
    • River features
    • Flood control etc.
2. Quantitative Fluvial Geomorphology:
    • Water Technology
    • Water Quality treatment
    • Stream discharge
    • Changing nature of river
    • Quantitative analysis of river depth, width, length etc.
Some particular scopes and objectives of Fluvial Geomorphology which are found in modern period are given bellow-
      • River channels and drainage basin
      • River Management System
      • The engineer sees the river
      • The Geomorphologist sees the river
      • Channel types
      • Flood plains and terraces
      • Bankfull flow
      • Types of river
River channels and drainage basin
A channel has two basic functions within a drainage basin. It must convey all of the— WATER, and  SEDIMENT  that the drainage basin delivers by the various runoff and hill slope processes. In order to accomplish these tasks, any channel must take on a particular form, by which we mean its width, depth, sinuosity, and distribution of such small-scale features as pools and bars.
River Management System:
Activities and processes, linked through economics and human actions—irrigation, navigation, etc are shown through the following figure.
Fig: River management.



River engineering:
Adjacent sets of isolated, independent processes and problems—bank erosion, flooding, etc…
Fig: River engineering.
River Channel system:
River Channel system is most important object of fluvial geomorphology. Such as-

(1) Landscape is a system that produces and transports runoff and sediment.
(2) Channel network is like the veins of the landscape.
(3) Channels collect sediment produced on hill slopes and transport it to basin outlets.
(4) Channels influenced by sediment production, transport, routing, and storage processes.



 



Fig: River Channel system
Flood plains System:
To a Geomorphologist, a floodplain is the surface that has been built by a river channel under the current hydrologic and sediment logical regime. It is composed of alluvium, the sediment carried by the river. An alluvial channel is bounded by a floodplain; conversely, a channel formed within a true floodplain is by definition alluvial.
Fig: Floodplain system

Importance of Fluvial Morphology
Fluvial geomorphology is developing rapidly with the expansion of modern technology in present time. If this development process continue, this discipline will mere advance within few years. The importance of fluvial geomorphology is increasing day by day. There are about 72.5% areas of world is water body and 65 - 70% elements of human body are water. For this importance all living things are directly depended on water as well as Fluvial geomorphology. So we can say that the future of fluvial geomorphology will be so much developed and highly speeded each areas of the world. There are great possibilities to develop in future following things of fluvial geomorphology.
Fluvial morphology is particularly important to the hydraulic engineer as many of his greatest problems arise because of the form of streams brought about by the transportation and deposition of sediment by them. For the proper solution of these problems, a knowledge of t he principles of fluvial morphology is often necessary. Among the problems in which fluvial morphology is a very important factor are many of those dealing with water resources development and include some of the most important river problems in the world. Examples of these are flood control on the Lower Mississippi and on the lower Colorado Rivers, the development of the hydraulic resources of the Missouri and Arkansas Rivers, the Yellow and Huai River flood problems in China, the Iiosi River floods in India. A s stream s become more highly developed, and changes in sediment movement due to stream developments slowly become evident, the importance of the morphological aspect of river control problems will be increasingly appreciated.
One of the best contributions made by the geomorphologists to the science of fluvial morphology is the nomenclature which they have introduced.
As previously mentioned, the Geomorphologist is interested in fluvial morphology principally as a tool in explaining the origin of the present form of the surface of the earth. The science appears to be of comparatively recent origin. Although many able men contributed to its early development, the outstanding work is that of W. M. Davis. According to the Davis conception, the primary action in the formation of the earth by moving water is the geographical or geomorphic cycle which is a cycle of erosion passing through several stages.


Conclusion:
Geographic research on a broadened range of resource use and specific inquiry into the spatial and ecological linkages of various technologies appears to be required. The more important natural water is related with every steps of our life. For this fluvial geomorphology considered a significant discipline in modern period. A framework for assessing social desirability still needs devising but it could be hastened by careful assessment of that actually follows water resource development. Geographers freed from the traditional distraction between human and physical geography and with their sensibility towards water, earth and man, have in these both opportunity and challenge.               

References:
  •   Doyle, M.W., C.F. Rich, J.M. Harbor, and A. Spacie. 2000. Physical Geography 21: 155-181
  •   Charlton, Ro (2008). Fundamentals of fluvial geomorphology. London: Rutledge. p. 234
  •  Leopold, L.B., Wolman, M.G., Miller, J.P., 1964, Fluvial Processes in Geomorphology, San Francis
  •   Thornberry, D.W., 1958, Principles of Geomorphology, London: John wiley & sons Publications.
  •   Lobeck, A. L.; 1939; Geomorphology; McGraw-Hill Book Company
  •  Trimble, S.W. 1997. Science, 1442-1444.
  •  FluvialGeomorphology http://www.facstaff.bucknell.edu/brh010/research/fluvial_geomorphology.html


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I am sadik, simply sad :).Studied in Chittagong University,Bangladesh;Department of Geography and Environmental studies.

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