Thursday, April 23, 2009

End Of My Trip

Omg Thats it!!! I have share with you people what i have seen in my trip!!! Hope you learn more things about rivers and its feature!! Now you know, a river is not only a river! It can be a WaterFall, a meander or a fast moving rapid!! Ok So long! Until my next journey...... (To be continued...)

PotHoles!


Potholes. It is a formation in rivers caused by a whirlpool eroding a hole into rock. The abrasion is mainly caused by the circular motion of small sediments such as small stones in the river. The interiors of potholes tend to be smooth and regular, unlike a plunge pool.

WOW! Thats one big pothole!!!

Gorge!!!


What is a Gorge???

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Well, A gorge, is a deep valley between cliffs often carved from the landscape by a river. Most canyons were formed by a process of long-time erosion from a plateaus level. The cliffs form because harder rock strata that are resistant to erosion and weathering remain exposed on the valley walls.


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Examples of some very large Gorges;


The Grand Canyon in Arizona, USA


The Yarlung Zangbo Grand Canyou in Tibet,China


The Yarlung Tsangpo River in Tibet, China

RELAX!!

This is the Powerscourt Waterfall, near Ireland
This is the
Niagara Falls in the province of Ontario, Canada and state of New York, USA

This is the HavasuFalls, near Arizona, an example of a plunge waterfall


Here's some interesting facts!!!
The world's tallest waterfall is Angel Falls at 979 metres (3212 feet) in Venezuela!!!
Tugela Falls is the world's second tallest at 947 m (3110 ft) in KwaZulu-Natal province, Republic of South Africa.
Jurong Falls in our own Singapore is the tallest artificial waterfall in the world!!!

The Upper Course Of The River

WaterFalls....beautiful, magnificient and very interesting when you learn how its Formed!!
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Waterfalls are formed when a river flows over a large step in the rocks that may have been formed by a fault line. As it increases its velocity at the edge of the waterfall, it plucks material from the riverbed. This causes the waterfall to carve deeper into the bed and to recede upstream. Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it.

A waterfall has many different types;

Block: Water descends from a relatively wide stream or river.
Cascade: Water descends a series of rock steps.
Cataract: A large, powerful waterfall.
Fan: Water spreads horizontally as it descends while remaining in contact with bedrock.
Horsetail: Descending water maintains some contact with bedrock.
Plunge: Water descends vertically, losing contact with the bedrock surface.
Punchbowl: Water descends in a constricted form and then spreads out in a wider pool.
Segmented: Distinctly separate flows of water form as it descends.
Tiered: Water drops in a series of distinct steps or falls.
Multi-step: A series of waterfalls one after another of roughly the same size each with its own sunken plunge pool.

Rapids!!!


When you hear the word Rapids, you would think of very fast and strong water.... and.... you're absolutely right!!!!
>>>You don't want to be in there!!!
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Rapids is a section of a river where the river bed has a relatively steep gradient causing an increase in water velocity and turbulence. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white colour, forming what is called "whitewater".

Continuing Features Of The Lower River Course


Next we have the Meanders and the Ox-Bow Lakes!! As you can see the picture on the right shows two ox-bow lakes cut off from the river.
Here's a question, if the two ox-bow lake continues to erode and meet what would it be called then? Maybe a M-bow lake? Here's some information about meanders n ox-bow lakes!
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A meander is a bend or curve in the course of a river. The river constantly alters the shape of a meander by eroding the outer bank of the bend and depositing sediment on the slipoff slope, the inner bank of the bend.

Cut Off OR an ox-bow lake, is a term that refers to a meander in a river course which is literally cut off from the present river. When a meander has almost formed a complete loop, the narrow neck of land may be eroded in flood conditions, allowing the river to by-pass the bend. Silt begins to build up at the entrances to the cut off section, eventually creating a lake known as either a cut off or an ox-bow lake.



For more Understanding of Levees here's a picture of how its formed! (Sorry for the colourless pic... can't findany with colours)

The Lower Course Of The River

Firstly, i'm going to talk about Floodplains which i came across to first.






Floodplains generally are a flat or near flat area of land adjacent river which experiences occasional or periodic flooding. The soil consists of alluvium which is deposited every time the river floods and overflows it's banks. The land tends to be slightly higher along the edges of the river where a levee forms. The floodplain also includes floodway, consisting of the river channels and adjacent areas that carry flood flows. The flood fringe, also included in the floodplain which are areas covered by the flood, but which do not experience a strong current.




Levees, are raised banks of alluvium along the edges of an old river. When a river floods its banks, the water spreads out and rapidly loses its load carrying ability. Deposition occurs close to the banks, increases their height. When not flooding, sediment is deposited on the river bed. After a period of time the river and its levees stand above the general level of the surrounding flood plain. Levees also have other names like levée, dike, dyke, embankment, floodbank or stopbank. They can be a natural or a artificial wall to regulate water levels.








Introduction

Hi! I've just came back from a two-month canoe and boat trip from the Ganges River and i really enjoyed mysielf! So, i decided to set up this blog to share my experience with everyone! My blog will be in a form of 'Educational' blog as i'm going to show you guys the various features and landforms that i saw and how they are formed. Getting excited? Hope you'll enjoy the following posts!!!