Rivers: Sustainable decision making geography

[blank_start]Surface run off[blank_end] is water flowing across the surface of the earth Interception is water [blank_start]collecting[blank_end] on objects [blank_start]infiltration[blank_end] is water soaking into soil Thorughflow is when water seeps through [blank_start]soil[blank_end] towards a [blank_start]river/ the sea[blank_end] [blank_start]Percolation[blank_end] - downward movement of water below water table transpiration water [blank_start]evapourating[blank_end] from plant's [blank_start]leaves[blank_end]

A drainage basin is...

the boundary of a basin is called its...

Large rivers have [blank_start]vast[blank_end] drainage basins eg. the [blank_start]nile[blank_end]

precipitation outside the river's drainage basin will...

Physical causes of flooding [blank_start]Prolonged[blank_end] heavy rain - ground becomes [blank_start]saturated[blank_end] so can't absorb any more [blank_start]water[blank_end] [blank_start]Short burst[blank_end] of heavy rain - ground can't absorb water [blank_start]quick[blank_end] [blank_start]enough[blank_end] so runs into [blank_start]river[blank_end] which then burst = [blank_start]flash[blank_end] floods Rapid snow [blank_start]melt[blank_end] - increases water [blank_start]flowing[blank_end] into river, can be too much so river [blank_start]bursts[blank_end] its banks.

Human causes of flooding [blank_start]Urbanisation[blank_end] - [blank_start]tarmac[blank_end] + concrete so water doesn't [blank_start]infiltrate[blank_end] drains take it straight to rivers decreasing [blank_start]lag[blank_end] time [blank_start]Deforistation[blank_end] - less [blank_start]interception[blank_end] so more [blank_start]surface[blank_end] [blank_start]run[blank_end] [blank_start]off[blank_end]. Also more [blank_start]soil[blank_end] washed into rivers reducing river [blank_start]capacity[blank_end] River [blank_start]management[blank_end] - effect river [blank_start]elsewhere[blank_end]

Label the graph

label hydrograph

label the hydrograoh

Sustainable flood control includes: new [blank_start]technology[blank_end] - rivers are monitored so [blank_start]warnings[blank_end] can be given [blank_start]afforestation[blank_end] in upper catchment area - more [blank_start]interception[blank_end] [blank_start]Dams[blank_end] and reservoirs - control of discharge and used for [blank_start]hydroelectric[blank_end] power and lakes used for [blank_start]recreation[blank_end]

Today focus on sustainable river management called integrated management, which uses

[blank_start]Environment[blank_end] agency warn about floods, their advice is to: prepare [blank_start]emergency[blank_end] kits keep phone [blank_start]charged[blank_end] prepare [blank_start]sandbags[blank_end] move [blank_start]electrical[blank_end] / [blank_start]valuable[blank_end] goods to [blank_start]high[blank_end] places

Soft engineering includes: [blank_start]zoning[blank_end] - stop planning permission on flood [blank_start]planes[blank_end] plant water [blank_start]loving[blank_end] plants to soak up water and reduce water [blank_start]table[blank_end] [blank_start]afforestation[blank_end] - increase interception digging a flood [blank_start]relief[blank_end] channel - provide another path for water when [blank_start]discharge[blank_end] to high [blank_start]dredging[blank_end] to remove [blank_start]silt[blank_end] - increase capacity

[blank_start]hard[blank_end] engineering includes building [blank_start]embankments[blank_end] to increase [blank_start]capacity[blank_end] of the river channelisation - [blank_start]straightening[blank_end] and [blank_start]deepening[blank_end] river so it flows [blank_start]faster[blank_end] Building [blank_start]Dams[blank_end] and reservoirs - [blank_start]traps[blank_end] water slowly [blank_start]releasing[blank_end], stop [blank_start]river[blank_end] becoming overwhelmed

Which are true for channelisation

Hydraulic action is when rocks collide, eroding cliff/bank as they scrape of material with them

Attrition is when rocks collide with one another so breaking into smaller pices

Abrasion is the force of running water undercutting banks and eroding beds

Solution is...

What erosion occurs in the plunge pool?

undercutting is caused by [blank_start]abrasion[blank_end] from the [blank_start]load[blank_end] of the river and [blank_start]hydraulic[blank_end] action from the force of [blank_start]running[blank_end] water

when waterfalls move upstream what do they create

In water falls an overhang is caused by [blank_start]undercutting[blank_end]. This occurs because there is a [blank_start]band[blank_end] of [blank_start]hard[blank_end] rock above [blank_start]softer[blank_end] rock

large rocks being dragged and rolled along the bed is called

smaller sediment being bounced along the bed of the river

fine particles of silt/clay held in the water

As the river flows through lower lying land: Discharge is [blank_start]higher[blank_end] gradient is [blank_start]lower[blank_end] bedload is [blank_start]smaller[blank_end] [blank_start]lateral[blank_end] erosion more prominent than downwards erosion

Formation of meander and ox bow lake 1) water flows faster on [blank_start]outside[blank_end] so [blank_start]erodes[blank_end] more quickly, [blank_start]deposition[blank_end] occurs on inside 2) river [blank_start]floods[blank_end] so then takes [blank_start]easiest[blank_end] route 3) more water flows through [blank_start]easier[blank_end] straight route 4) [blank_start]meander[blank_end] cut off 5) ox bow [blank_start]lake[blank_end] forms and eventually [blank_start]dries[blank_end] up

A river drops its load when...

[blank_start]larger[blank_end] sediment is deposited first

pebbles, gravel, sand and silt is deposited in the

dissolved load is carried out to sea

Mouth of a river forms a wide funnel shape called an [blank_start]estuary[blank_end] Estuaries are [blank_start]tidal[blank_end] and a mix of [blank_start]fresh[blank_end] and salt water deposition of [blank_start]salt[blank_end] and [blank_start]clay[blank_end] here form mud [blank_start]flats[blank_end] and [blank_start]salt[blank_end] marshes

Deltas forms when silt accumulates at the mouth of the river because...