Rivers

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Introduction

Transportation

traction- when material is rolled along the river bed

saltation- small pebbles and stones are bounced along the river bed

suspension- particles are "suspended" in the water

solution- material is dissolved into the water

Erosion

attrition- where material is moved along the bed of the river, collides with other material, breaks down

corrasion (abrasion)- material rubs against the river bank

corrosion (solution)- some rocks forming the banks of river are dissolved by acids in the water

hydraulic action- the force of water hitting the banks of the river

Vocabulary

drainage basin- an area of land drained by a river and its tributaries

source- where the river starts

mouth- where the river ends

tributary- a river joins a larger river

confluence- point where rivers meet

watershed- the boundary dividing one drainage basin from another

discharge- volume of water that passes through cross-section*speed

occupied channel width- distance across channel, measured at water surface, increases down stream

area of greatest depth- thalweg

hydrolic-radius- how much volume is in contact with banks, higher number=less contact (flowing faster), cross-section/sides

load quantity- amount of material in the river

rising limb- amount of discharge and at which speed it is increasing

lag time- time interval between peak rainfall and peak discharge

runoff- shows the relationship between overland flow and through flow

floodplain- area surrounding a river that is covered during a time of flood

levee- an enmabkment to prevent the overflow of a river

V-shaped valley/interlocking spur

As the river erodes the landscape in the upper course, it winds and bends to avoid areas of hard rock, creating interlocking spurs

v-shaped valley is a hill

Hydrological Cycle

Inputs: precipitation

Stores: ground water

depression in storage (lakes, rivers)

interception

Flows: infiltration

surface runoff

percolation

channel flow

stem flow

groundwater flow

Outputs: evaporation

transpiration

Vocabulary

inputs- where water enters system

outputs- where water is lost to system

evapotranspiration- the loss of water directly from rivers or lakes

transfers- the process by which water flows or moves through the system

infiltration- the downward movement of water through tiny pores in the soil

percolation- movement of water downwards

surface runoff- when water runs on the surface

channel flow- how much water flows through a channel

stem flow- the flow of intercepted water

ground water- water stored at depths of rocks

transpiration- the loss of water from vegetation into the atmosphere

Water Falls

The water flows down wards due to gravity. Over time it erodes through the hard rock and then through the soft rock. it then creates a Plunge Pool and undercuts the rock, creating an over hang. This over hang with then fall, and the process will start again

Rapids

The water erodes soft rocks, but not the hard rock, creating bumps along the surface

Cross-section

width of river TIMES depth

increases as you go down stream

Oxbow lakes

upper-cource features- v-shaped valleys, interlocking spurs, rapids, waterfalls, gorges

middle-cource features- wider, shallower valleys, meanders, oxbow lakes

lower-cource features- flat bottomed valleys, flood plaines, deltas

ADVANTAGES OF LIVING IN MEKONG DELTA

Fertile land for farming, especially crops like rice

Plenty of water for fishing or aquaculture. This can feed families or provide an economic income.

Abundant drinking water

Water for cooking, washing, etc.

Tourism opportunities e.g. Mekong Delta

Houses can be built on water and are then transportable and they do not flood

Good transport links, possible to trade

DISADVANTAGES OF LIVING IN MEKONG DELTA

Hard to make transport links by roads - cost of bridges

Areas are at constant risk of flood

Vulnerable to rising sea levels

Water is often dirty and polluted (industry, agriculture, sewers)

Mosquitoes are attracted to water (Malaria, Dengue)

Storm surges from tropical storms

Cost of building defences

Case study- Mekong Delta, Vietnam

Case study- Tewkesbury, England

Human causes- very developed, lots of concert, water cant be absorbed

pluvial flooding (drainage system cant keep up with rain)

Natural causes- two tributaries (Seven+Avon rivers)

flat land

rainfall (also had rain before, so no space in ground)

Consequences- destroyed homes

destroyed water plant, no clean water, 150,000 homes had no water

5,000,000 litres of water

25,000,000 pounds to fix the water plant

insurance companies won't insure houses, houses cost less

5.43 meters of rain

Good things- it helped farming (alluvium from river)

fixed drainage system

Prevention- move stuff upstairs

by own flood gates

computer with flood warning

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