Landscape (drainage and drainage pattern)

By: vandana s. talikoti

2nd sem M.Arch

bmsce

WHAT IS A DRAINAGE PATTERN? Streams seek the lowest path as they move downhill, and they tend to erode their beds in places where the ground is weak. Therefore, both topography and geologic structure influence the path streams follow through an area, which we call the drainage pattern. By looking at a map view of a stream, you can often infer the underlying bedrock structures.

THE DRAINAGE SYSTEM

• Natural drainage patterns are created where stream courses follow the lead of a landscape’s geological history and features.

• Characteristics of the under lying rock, steepness of slope, faults and joints in the Earth’s surface, the specific shape of particular geological formations, and the soil’s susceptibility to erosion are among the factors that affect the pattern established for the flow of water in a particular place.

• Drainage patterns, generally rectangular to circular, might be elongated like a feather, braided at certain points like a net, or broken up by natural impoundments like lakes. They might, like the spokes of a wagon wheel, radiate from a centre such as a peak, or converge toward a point, as in a closed basin.

• The pattern might fan out over a delta or collect myriad, many-pronged branches into a central stem.

• Because the shape of the pattern is determined by the land itself, it’s a useful image in analysing and understanding the rocks and geologic structures of a particular drainage.

CHARACTERISTICS OF THE DRAINAGE SYSTEM

• Dendritic drainage pattern: it is also common where the rock layers are horizontal. • Rectangular drainage pattern: A region that has prominent parallel and perpendicular

faults, repeated folds, or a strong rectangular jointing pattern will display a rectangular drainage pattern.

• Radial drainage pattern: occurs in an eroded dome A radial drainage pattern resembles the spokes of a wheel.

• Annular drainage pattern: Annular drainage is a pattern of concentric circles that are connected by short radial stream segments.

TYPES OF DRAINAGE PATTERNS

DENDRITIC DRAINAGE PATTERN: The most common stream pattern is a dendritic drainage. Dendritic streams flow downhill in the same general direction and they join to make larger streams. As a result, they have a branching appearance. This pattern is common where the bedrock is uniform, without faults, folds, or other major structures or zones of weakness to capture the streams.

Rippling along rough surfaces and the beautiful meadows, the numerous rivers that dot Indian mainland are central to our history as well as to Indian mythology. The main rivers of the Himalayas group are the Indus, the Ganga and the Brahmaputra. These rivers are both snow-fed and rain-fed and therefore they are flow through so many year. Himalayan rivers discharge about 70% of their inflow into the sea. This includes about 5% from central Indian rivers. They join the Ganga and drain into the Bay of Bengal.

HIMALAYAN RIVERS

INDUS RIVERS

It has believed by the early Tibetans that this forceful and full river that guarded the frontiers of united India rises from the lake Mansarovar in Tibet. A few expeditions later, it was discovered that the Indus actually originates a few kilometres north of lake Mansarovar and together with it arise the Brahmaputra and the river Sutlej, through Mansarovar.

GANGA RIVERS

Northern Uttaranchal is the source of Bhagirathi, which joins with Alaknanda to form Ganga at the craggy canyon-carved town of Devprayag. Interestingly, the sources of Indus and the Brahmaputra are also geographically fairly close then takes a sharp turn near the north-eastern tip of India, gathers momentum through Assam before joining the major stream of the Ganga near Dacca in Bangladesh to become the mighty Padma, river of joy and sorrow for much of Bangladesh.

BIBLIOGRAPHY

new york natural wonders . INDIAN drainage systems Wikipedia, the free encyclopedia topographic map, drainage basin