http://commons.wikimedia.org/wiki/File:US_humvee_crossing_a_small_river_in_Afghanistan.jpg
On the right side of this photo, the difference in depths can be seen in the river. The thalweg is the darker, deeper part of the river. The sandy/rocky area on the right is the pointbar.
Thalwegs are formed when the fast flowing water of a stream or river cuts at the riverbed. Thalwegs are the deep parts of the river where the sediment has been stripped away. As the sediment is stripped away, it is carried down river and dropped in slow areas of the river. This is what creates a point-bar in a river. The sediment is dropped in the low velocity areas of the stream, as it collects it creates point-bars.
http://www.flickr.com/photos/11398985@N05/2157126685/
As you can see, when it is possible, this river meanders from side to side due to the high velocity water cutting at the edges of the river.
As the point-bars push out, the direction of the high velocity portion of the stream pushes out as well. This cuts away at the outside edge of the stream/river. Continuation of this causes the river to meander from side to side, creating meander scars.
http://indexresearch.blogspot.com/2008/05/water-world-crisis.html
Northern Afghanistan is pushed right up against the Tibetan plateau. This range is known as the Hindu-kush mountains. This range contains a glacier.
Areas with constant amounts of snow and cold weather allow for the formation of glaciers. As the snow builds and builds, it gradually becomes more dense eventually creating glaciers. As the years go by, the glacier density changes from alpine firn, to polar firn, and finally to blue glacial ice.
http://connect-afghanistan.org/?page_id=18
South-West Afghanistan is a very dry, arid climate. This is defined by a general lack of moisture. The demand is much greater then the supply of moisture. There is also a lack of plant growth, typically under 25%.
http://fast.ucdenver.edu/case/1202/Landscapes/Arid/AridLandscapes.htm
As this map shows, taken from Professor Allen's lecture, the lower portion of Afghanistan is located in a climate categorized as "Arid."
Much of Afghanistan can be classified as an arid climate. Located at the base of the Tibetan plateau, Afghanistan’s arid climate is cause by many things. Because it is landlocked, it is far from large sources of moisture. It is also located on the leeward side of the Himalayas.
For soldiers working in the Southern portion of Afghanistan, the dry, arid climate creates difficult conditions. For the locals that live near these rivers, life can either be frustrating or good (depending on which side of the river they live on). If a person owns the cut bank side of the river, they will gradually loose land, but if they own the point-bar side of the river, they will gradually gain land. Having looked closely at the different areas of Afghanistan in these blogs, and having lived there, I can safely say that Afghanistan is a difficult place to live in. The unforgiving mountains and desert areas of Afghanistan present a lot of difficulties to the people that live and work there.
