Geomorphology - irrigation on riverine plains

1. Seminar
on
GEOMORPHOLOGY-- IRRIGATION ON RIVERINE
PLAINS

2. CONTENS
• Introduction
• Irrigation
• Irrigation on riverine plains
• Levee
• River flood prevention
• Northern riverine plain
• South eastern riverine plain
• Delta
• Conclusion

3. INTRODUCTION
• The application of geomorphic studies to irrigation project will be descried
with particular reference to the advantage to be gained from an understanding
of geomorphic history of an area
• The development of an area for irrigation may be considered in terms of five
sequential stages, the first of which is a pre-feasibility study based on aerial
photographic surveys and ground reconnaissance
• The next stage of development involves the location, design and the
construction of irrigation channels and selection of crops for various types of
soil.
• The selection of an area for irrigation , the disposal of drainage water, the
monitoring the groundwater levels, and the selection of the most appropriate
drainage method for reclannation works there for depended in the main , up
in geomorphic mapping and interpretation.

4. IRREGATION
• Irrigation is practiced by the orderly concentration of water
onto extensive tracts of flat or gently sloping ground
• Such areas are developed for the production of marketable
crop
• The largest geomorphic units such as riverine plains are
selected by interpreting areal and satellite photographs in
order to ensure the economic viability of the scheme.

5. IRREGATION ON RIVERINE PLANES
• In arid and semiarid regions , riverine plains are usually best suited for
intensive irrigation because of the large area available for this purpose, 1
million hectares are not uncommon, and the flat nature of the surface
which is suited to grading.
• Riverine plains may have been built up over millons of years as a
succession of land surfaces, each with a distinctive drainage pattern.
• The planis are the uppermost surface consisting of the material
transported by streams and deposited as either sheets or as cut and fill
sedimentary structures.
• Although the buried land surfaces may not have a surface expression past
drainage patterns , 50,000 years or so old , can often be recognized.
• These features are of great value in land reclamation studies.

7. Cont…
• The drainage system on the plain may have been altered by
one or a combination of factors including
a) Climatic change
b) Tectonic activity
c) Fluctuations in sea level
d) Magnitude and incidence of flooding

8. EXAMPLE
• Climatic changes in southern Australia during the
past 30,000 years have been described by Bowler in
his Lake Keliembele study.
• He showed that from 18,000 to 30,000 years B.P..
Conditions were wetter than at present.
• Temperatures were higher from 9,000 to 18,000 B.P.
and climatic cooler and wetter from 5,500 to 9,000
B.P

9. • Temperatures had risen considerably and were
stable until 4000 B.P , with drier conditions ending at
3100 B.P,
• Minor oscillations have occurred since then until the
present.
• As a result of these changes the surfaces of the
Victorian- New south Wales riverine plain is
characterized by remnants of former climatic
conditions.

12. LEVEE
• A levee, levée, dike (or dyke), embankment,
floodbank or stopbank is an elongated naturally
occurring ridge or artificially constructed fill or wall,
which regulates water levels. It is usually earthen and
often parallel to the course of a river in its floodplain
or along low-lying coastlines.

13. Natural levees
• Levees are commonly thought of as man-made, but they can also
be natural. The ability of a river to carry sediments varies very
strongly with its speed. When a river floods over its banks, the
water spreads out, slows down, and deposits its load of
sediment. Over time, the river's banks are built up above the
level of the rest of the floodplain. The resulting ridges are called
natural levees.
• When the river is not in flood state it may deposit material within
its channel, raising its level. The combination can raise not just
the surface, but even the bottom of the river above the
surrounding country. Natural levees are especially noted on the
Yellow River in China near the sea where oceangoing ships
appear to sail high above the plain on the elevated river. Natural
levees are a common feature of all meandering rivers in the
world

14. Artificial levees
• The main purposes of an artificial levee are to prevent flooding
of the adjoining countryside and to slow natural course
changes in a waterway to provide reliable shipping lanes for
maritime commerce over time; they also confine the flow of
the river, resulting in higher and faster water flow. Levees can
be mainly found along the sea, where dunes are not strong
enough, along rivers for protection against high-floods, along
lakes or along polders. Furthermore, levees have been built for
the purpose of empoldering, or as a boundary for an
inundation area. The latter can be a controlled inundation by
the military or a measure to prevent inundation of a larger
area surrounded by levees. Levees have also been built as field
boundaries and as military defences. More on this type of
levee can be found in the article on dry-stone walls.

15. River flood prevention
• Prominent levee systems have been built along
the Mississippi River and Sacramento River in the
United States, and the Po, Rhine, Meuse River,
Rhone, Loire, Vistula, the delta formed by the
Rhine, Maas/Meuse and Scheldt in the
Netherlands and the Danube in Europe.
• The Mississippi levee system represents one of
the largest such systems found anywhere in the
world. It comprises over 3,500 miles (5,600 km)
of levees extending some 1,000 kilometres
(620 mi) along the Mississippi, stretching from
Cape Girardeau, Missouri, to the
Mississippi Delta.

16. They were begun by French settlers in Louisiana in the 18th century to
protect the city of New Orleans.The first Louisiana levees were about 3
feet (0.91 m) high and covered a distance of about 50 miles (80 km)
along the riverside. The U.S. Army Corps of Engineers, in conjunction
with the Mississippi River Commission, extended the levee system
beginning in 1882 to cover the riverbanks from Cairo, Illinois to the
mouth of the Mississippi delta in Louisiana. By the mid-1980s, they had
reached their present extent and averaged 24 feet (7.3 m) in height;
some Mississippi levees are as high as 50 feet (15 m). The Mississippi
levees also include some of the longest continuous individual levees in
the world. One such levee extends southwards from Pine Bluff,
Arkansas, for a distance of some 380 miles (610 km).

17. Northern Riverine Plain
•
On the Riverine Plain of northern Victoria, many
parallel streams head northerly across a strikingly flat
plain to meet the current course of the River Murray.
Initially the pattern would have been difficult to
visualise, but with long, detailed mapping of soils,
geology and landforms a clearer picture emerged, to
be confirmed by later mapping using aerial
photographs and satellite imagery. Studies of
groundwater and salinity, and recent dating by
luminescence, have also helped provided a better
understanding oflandscape evolution.

18. • The Riverine Plain of New South Wales and
Victoria is a very extensive and complex alluvial
plain associated with the River Murray and its
tributaries which developed following the retreat
of the Neogene (Pliocene) sea from the Murray
Basin. Two of these tributaries, the Avoca and
Wimmera Rivers, now fail to reach the Murray
River and terminate in lakes. Although the plain is
predominantly alluvial in origin, episodes of wind
blown deposition did occur during arid times.

19. • The most continuous and extensive part occurs form the
plains east of the Loddon River, where it extends northwards
from the Eastern uplands to the River Murray. In the west of
the state, around Horsham and Donald, it extends north of
the Western uplands to where it meets the Northwest
Dunefields and Plains. The climate of the Northern Riverine
Plains is semi-arid in the northwest and subhumid in the east
and southeast. Most of the area originally carried eucalypt
woodlands with occurrences of casuarinas, but there were
substantial areas of treeless plain. Changing climate,
vegetation, runoff and evaporation during the Quaternary
have produced palaeochannels of different ages.
•

20. CONT
•
The Riverine Plain consists essentially of two geological formations. The
most extensive and older is the Shepparton Formation of late Neogene
(Pleistocene) , and the Recent Coonambidgal Formation . The older
terraces and fans adjoining the Eastern Uplands and Western Uplands are
also regarded as belonging to the Shepparton Formation. Low residual
hills occur within the Riverine Plain but these are mostly comprised of
Palaeozoic rocks. Apart from the alluvial fans and aprons , the Shepparton
formation may be subdivided into three units – plains with small,
meandering, leveed stream channels , which died out as distributaries
away from their uplands source, plains without channels which are often
treeless, and plains with lakes and lunettes. Many of the present lakes in
the Murray Basin are ephemeral or relict features, evidence of much more
efficient hydrological regimes during the Neogene (Middle and Late
Pleistocene). Most are now either permanently dry or episodically filled
by floodwaters.

21. •
Much of the Riverine Plain west of the Campaspe River
is made up of plains without leveed stream channels ,
whereas to the east the plains have meandering
leveed channels which would have flowed to the
north and north-west. Within the Wimmera CMA
region are alluvial fans and aprons and lakes and
basins with lunettes and plains without leveed
channels . Higher terraces, alluvial fans and aprons of
uncertain age occur along the edge of the uplands, for
example along the Mackenzie River and north and east
of the Grampians.

22. South eastern riverine plains
• The Gippsland Riverine Plains dominate the region north
of the La Trobe River and south of the Eastern Uplands
between Traralgon and Bairnsdale. Smaller areas are
recognised around Yarram, Yinnar and south-west
Gippland near Toora. Also included are the present flood
plains and morasses. The plains are of alluvial origin, with
the most of the alluvium being derived from the Eastern
Uplands, and, in south Gippsland, the Southern Uplands.
The alluvium which comprises the surface material is
mostly Quaternary, but over the period of its deposition,
all of the stream courses which deposited the alluvium are
not evident, apart from the most recent.

23. •
Throughout the Quaternary have been several
considerable rises and falls in sea level. It is generally
believed that this was because of changes in volume of
the ice caps due to climate changes. Alternatively sea
level changes may have been associated with uplift of
the land surface. A number of distinct areas of similar
elevation, or terraces were formed during the
Quaternary in Gippsland, but whether they were
formed as a result of sea level change associated with
ice ages or by uplift or a combination of both is
uncertain.

24. •
During the last Glacial Period about 17 000 to 20 000
years ago a sea level fall of about 150 m resulted and a
land bridge was formed between Australia and
Tasmania. As well as being cold, the climate was dry
and windy. The Latrobe, Macalister, Thompson, Avon
and Tarra Rivers cut deep valleys into their earlier
flood plains as a result of the sea level fall which
subsequently became partly in-filled as the sea level
rose to its present level. This has resulted in a well
defined break between the old flood plain (upper
terrace), and the present flood plain (lower terrace)

25. • Six terraces are recognisable within the
Gippsland Riverine Plains, but it is more
convenient here to aggregate them here into
three geomorphological units: present flood
plains and morasses; prior stream plains; and
older alluvial plains and terraces. The second
oldest terrace is the most extensive, extending
from just east of almost to Bairnsdale. This
terrace, which is partly mantled with dunes, as
well as the oldest terrace, is described under
Section 7.3 “High level terrace and fans” .

26. • The inland sand sheets and dunes on the plains east of
Stratford were earlier interpreted as being sand
barriers and foredunes of marine origin and the
boundaries of the terraces regarded as stranded
shorelines. Their presence at elevations up to 128 m
above sea level, far higher than if the level of the sea
would reach if all of the world’s ice were to melt, was
attributed to continuous uplift of the land and sea
level changes associated with past glacial periods. It is
now believed that most of the dunes are younger than
the terraces upon which they lie and are terrestrial in
origin.

27. DELTA
• Streams flowing in to standing water normally
create a delta.
• A delta is body of sediments that contains
numorous horizontal and vertical layers .
• Deltas are created when the sediment load
carried by a stream is deposited because of a
sudden reduction in stream velocity.
• The surface of most deltas is marked by small
shifting channels they carry water and sediments
away from the main river channel’

28. CONCLUSION
• The application of geomorphic studies to irrigation
project will be descried with particular reference to
the advantage to be gained from an understanding
of geomorphic history of an area
• Irrigation is practiced by the orderly concentration of
water onto extensive tracts of flat or gently sloping
ground
• Riverine plains may have been built up over
millons of years as a succession of land surfaces,
each with a distinctive drainage pattern.

29. REFERENCE
• APPLIED GEOMORPHOLOGY ….
• www google.com
• www wikipedia.com

30. Thank you