Global Rivers

Question 1

what percentage of freshwater is liquid surface water?

Answer 1

0.3%

Question 2

where is the majority of liquid surface water found

Answer 2

lakes

Question 3

explain why rivers are important

Answer 3

connected to water resources, soils, ecosystems, land use
water crisis among top 5 global risks in past 7 yrs
chemical exchanged between atmosphere and biosphere
large source of methane and CO2

Question 4

what is the most accurate and up to date database of global rivers and streams

Answer 4

GRWL database

Question 5

what size is the Amazon basin (in comparison to other region)

Answer 5

same size as the US (roughly)

Question 6

which two rivers have the largest amount of runoff

Answer 6

Amazon and Orinoco

Question 7

types of river flow x3

Answer 7

perennial, intermittent (only flows seasonally when water table at max level), ephemeral (flow after occasional storms)

Question 8

4 sources of streamflow

Answer 8

1. channel precipitation
2. overland flow
3. infiltration into the soil (throughflow)
4. groundwater leading to baseflow

Question 9

what is infiltration capacity

Answer 9

the max rate that water can enter

Question 10

when does infiltration capacity decline

Answer 10

during rainfall, surface can pool with water and runoff

Question 11

what factors increase infiltration rate

Answer 11

more vegetation, sandier soil, gentler slope

Question 12

what is saturation excess overland flow

Answer 12

when the soil is full with water and forces it to pool on the surface

Question 13

what two occasions can cause hillslope runoff

Answer 13

1. infiltration-excess overland flow- when the rate of infiltration is less than the precipitation
2. saturation-excess overland flow- soil completely saturated and water table at the surface

Question 14

through what process does most water reach rivers

Answer 14

throughflow- water travelling laterally away from a source

Question 15

what is matrix flow

Answer 15

very fine pores, lateral throughflow will occur where hydraulic conductivity declines with depth

Question 16

what is macropore flow

Answer 16

chemical and water transport in larger pores

important role in throughflow

Question 17

what is pipeflow

Answer 17

transport of water very quickly through larger cavities

Question 18

what is groundwater flow

Answer 18

all flow below the water table

Question 19

what are aquifers

Answer 19

layers of rock porous enough to store water and permeable enough to allow water through them

Question 20

what is salinisation in relation to groundwater supply

Answer 20

bringing up of salt in soil from deeper waters

Question 21

what is the coefficient of runoff

Answer 21

the percentage of rainfall converted into overland flow

Question 22

how does watershed shape influence streamflow

Answer 22

at round basins, streams meet at a central point, where the discharge increases
at elongated basins, streams join at different points, leading to a gradual increase in discharge

Question 23

what is drainage density

Answer 23

the total length of all stream channels in a sq metre of land

Question 24

what is a river regime

Answer 24

the seasonal variation in river flow

Question 25

in what way can anthropological influence increase drainage density

Answer 25

farmyard erosion, land clearing

Question 26

how can the removal of wetlands influence runoff

Answer 26

wetlands store runoff, removal causes runoff to move faster and in greater volumes

Question 27

what human impacts can increase flooding

Answer 27

straightening channels and removing vegetation, removal of wetlands

Question 28

why can flow velocity actually be greater at the mouth of the river than the head

Answer 28

basin size increases and riverbed gets less rough and friction-ed