geo rivers test

what is a drainage basin

areas of land where water from rain or snow melt drains downhill into a body of water like a river, lake or ocean.

what are the features of a drainage basin

watershed

source

tributary

confluence

floodplain

mouth

what is a watershed

the boundary between drainage basin, the peak of hills/mountains

what is a source

the beginning of a river, in upland areas

what is a tributary

a smaller river which joins up to a larger river

what is a confluence

the join of two rivers

what is a floodplain

the flat land either side of a river, larger in the lower course of a river

what is a mouth

the end of a river, usually flowing into a lake, the sea or an ocean

what is an open system

allows energy and matter to exchange

what is a closed system

only allow for energy transfer within the system

what is the only input in a drainage basin system?

precipitation

what is the above ground transfers/flows in a drainage basin

throughfall

stemflow

overland flow

channel flow

what are the below ground flows/transfers in a drainage basin system

infiltration

percolation

throughflow

groundwater

base flow

what are the above ground stores in a drainage basin system

interception

surface water

channel storage

what are the underground stores in a drainage basin system

soil water

groundwater

water tables

recharge

springs

what are the outputs in a drainage basin system

evaporation

evapotranspiration

river discharge

what is precipitation and is it an Input, Output or Store

any moisture from a cloud which falls in the drainage basin

(Input)

what is throughfall and is it an Input, Output or Store

any precipitation dripping off branches and leaves to the ground after interception

(Above ground Transfer/Flow)

what is stem flow and is it an Input, Output or Store

any precipitation running down plant stems, trunks after interception

(above ground transfer)

what is overland flow and is it an Input, Output or Store

any precipitation flowing over the ground surface towards a river or other body of water

(transfer above ground)

what is channel flow and is it an Input, Transfer, Output or Store

water flowing within the river channel

(Above ground tranfer)

what is infiltration and is it an Input, Transfer,Output or Store

the process by which water is absorbed by soil. in a downward movement from the surface

(below ground transfer)

what is perolocation and is it an Input, Transfer,Output or Store

the downward movement of water through the soil and bedrock after infiltration has taken place

what is throughflow and is it an Input, Transfer,Output or Store

water moving through the soil under gravity towards the stream

(Transfer below ground)

what is groundwater and is it an Input, Transfer,Output or Store

water moving through the rock under gravity towards the stream

(underground transfer)

what is base flow and is it an Input, Transfer,Output or Store

the lateral movement of water in the bedrock which discharges into a stream from ground water store

(underground transfer)

what is interception and is it an Input, Transfer,Output or Store

the trapping of water during rain on leaves of vegetation preventing it from initially reaching the ground

(stores)

what is surface water and is it an Input, Transfer,Output or Store

water stored on the ground surface in lakes, puddles or ice

(store)

what is channel storage and is it an Input, Transfer,Output or Store

water held within the river channel itself (store)

wha is soil water and is it an Input, Transfer,Output or Store

water from rain is stored in the soil pores after infiltration (store)

what is groundwater and is it an Input, Transfer,Output or Store

water is stored in the permeable rocks after perolocation beneath the water table

what is the water table

the upper surface of the saturated zone, where all soil and rock pores are full with water

what is recharge

the process when water is added to the groundwater store via rain infiltration, percolation

what is evaporation and is it an Input, Transfer,Output or Store

water changes phase from a liquid to a gas with the addition of heat (output)

what is evapotranspiration and is it an Input, Transfer,Output or Store

the combined total of evaporation and transpiration where water moves from soil and plants surfaces in the atmosphere (output)

what is transpiration

biological process where water is released as vapour through stomata in leaves

what are the two types of evapotranspiration

potential evapotranspiration (PET)

Actual evapotranspiration (AET)

what is PET (potential evapotranspiration)

the amount of Evapotranspiration that would occur if there was unlimited water supply

High in hot dry regions due to intense solar radiation

what is AET (Actual evapotranspiration)

the real amount of Evapotranspiration, often lower than PET because of limited soil moisture

what are storm hydrographs

a type of graph that shows how the discharge changes overtime in response to a rainfall event

what is river discharge

amount of water flowing in a river

what are the key components of a storm hydrograph

time on the x axis (usually in hours)

river discharge on the y - axis (measured in cumecs)

rainfall shown as a bar chart

baseflow

rising limb

peak discharge/flow

lag time

falling limb

what does the rising limb of a hydrograph represent?

the steep part of the graph where discharge increases rapidly after rainfall

what is the lag time

the time between peak rainfall and peak discharge

what is the baseflow

the normal day to day discharge of the river before and after rain

what is peak discharge/flow

occurs when the river reaches its highest level

what is the falling limb represent

when discharge decreases and river levels fall. it has a gentler gradient than the rising limb

is a hydrograph is flashy what are the characteristics and where is it located

• steep rising limb and short lag time

• likely in urban areas

if a hydrograph is gentler, what are the characteristics and where is it located

• gentle rising limb and longer lag time

• likely in rural areas where is there lots of vegetation

what are some factors which affect a storm hydrograph

climate, and drainage basin characteristics like size, shape, density, soil and rock type, slopes, and vegetation and land use

what are some ways the climate influences the storm hydrograph

torrential rain produces overland flow, a steep rising limp and high peak flow

low intensity rainfall produces infiltration, a gentle rising limb and low peak flow

high temps cause more evaporation so river discharge decreases

dense vegetation cover intercepts more rainfall and leads to less river discharge

saturated ground leads to a steep rising limb and high peak flow

what are some ways drainage basins influences the storm hydrograph

smaller drainage basins produce a steep rising limb and high peak flow

circular drainage basins respond quickly to rainfall than linear basins

impermeable rocks slow down infiltration and percolation

steeper slopes slow down infiltration and speed up surface runoff

whats an annual hydrograph show

how a rivers discharge changes over the course of a year, rather than just during one rainfall event. it reflects seasonal patterns in climate, vegetation, and human activity that influence river flow.

what is the other name of annual hydrographs

river regime

what are the key features of an annual hydrograph?

peak flow - month with the highest discharge

low flow - month with the lowest discharge

what are all the factors that influence annual hydrographs

climate and precipitation

temp

vegetation

soil and geology

human activity

snowmelt rivers

monsoonal rivers

how does climate and precipitation affect annual hydrography

rivers in temperate climates may peak in winter (more rain, Low ET) Monsoonal regions have one strong wet season peak. Glacial Rivers peak in summer due to snow/ice melt

how does temperature influence annual hydrographs

high summer temps - High ET

lower discharge in some rivers.

Cold winters - snow storage

with a sudden melt peak in spring

how does vegetation affect annual hydrographs

dense vegetation intercepts rainfall and increases ET, reducing discharge during growing seasons.

how does soil and geology affect annual hydrographs

permeable soils even out flow; impermeable geology causes flashy seasonal variations

how does human activity affect annual hydrograph

dams, irrigation and water use flatten or alter natural seasonal patterns

how does snowmelt rivers affect annual hydrograph

low flows in winter when precipitation in locked as snow, sharp rise in spring melt.

how do monsoonal rivers affect annual hydrograph

distinct high flow in monsoon season prolonged low flows in dry season

what are some examples of factors affecting annual hydrographs in NZ

Waikato river:

more even flow year-round because of lakes and reservoirs flattening seasonal variation.

list some short facts about the waikato river case study

Longest River in NZ - 425km

Source:: Ruapehu (2797m)

Dams: Waipapa, Arapuni

what is the Abbreviation for Erosion

A . A. S. H

Abrasion

Attrition

Solution

Hydraulic Action and Cavitation

what is abrasion

the rivers load is thrown against the bed and banks scraping them away like sand paper

major process of channel widening and deepening

common in steep river areas

what is attrition

particles carried by the river collide with each other breaking down into smaller, rounder smoother pieces

• doesn’t erode the river channel itself but reduces sediment size

what is solution

soluble minerals (e.g limestone) are dissolved by acidic water and carried away in solution.

• most effective in rivers flowing through chalk

• chemical process rather than physical

what is HA and cavitation

the force of fast flowing water hitting the riverbank and bed. compresses air in cracks, causing rock to weaken and break apart

what are some factors affecting erosion

deforestation

bed load

ph level

agriculture

river engineering

climate change

channel shape

discharge

vegetation

climate and weather

does the upper course experience more lateral or vertical erosion

vertical

does the lower course experience more lateral or vertical erosion

lateral

what is the global sediment yield

the amount of sediment (soil, sand, rock and shingle) transported from land to oceans by rivers per year, usually measured in tonnes per kilometre per year

what types of regions usually have high sediment yields

mountainous, tectonically active regions (Himalayans, Andes mountains)

Deforestes tropical basins (Amazon)

what types of regions usually have low sediment yields

flat, heavily vegetated basins (Amazon Floodplains)

cold stable landscapes with permafrost (Siberia)

what are factors influencing sediment yields

Relief

Climate

Rock type

Vegetation Cover

Drainage Basin Size

Human Activity

Glaciation

how does relief affect sediment yields

steeper mountain rivers, (Himalayans, Andes) have high energy flows, eroding quickly and producing huge sediment yields

how does climate affect sediment yields

heavy rainfall - high runoff and erosion

arid climates have flashy flows causing bursts of erosion

how does rock type affect sediment yields

soft rocks and soils produce higher yields than resistant rocks

what is the waikato’s global sediment yield

50-100 t/km squared per year as although there is volcanic soil, lots of dams trap the sediment in the upper course and prevent it from being transported downstream.

what is the Acronym for Transportation

TSSS

traction

saltation

suspension

solution

what is Traction

heaviest material is rolled along the river bed this requires the most energy.

what is saltation

sand sized particles are bounced along the riverbed in a leap-frog motion

what is suspension

small particles are carried within the water by turbulent flow

what are factors affecting the amount of material that a river can transport

discharge - increase discharge = more transportation

velocity - increased speed = more transportation

what is capacity

the largest amount of load that a stream/river can carry

• the greater the discharge, the higher the capacity

• the greater the velocity the higher the capacity

what is competence

the diameter of the largest particle that can be carried

the greater the velocity the higher the competence

what is deposition

when a river loses energy and drops the load its carrying, ususlaly largest and coursest material first, then smaller finer material

what is the smallest material and what is the largest

smallest: clay

largest: boulders

what are the main causes of deposition?

decrease in velocity

decrease in discharge

channel widening or gradient decrease

obstructions

meeting still water

how does a decrease in velocity cause deposition

slower flow reduces the rivers ability to transport material

e.g) inside bends of meanders

how does decrease in discharge cause deposition?

less water means less energy to carry load

how does channel widening and gradient decrease cause deposition

rivers spread out and lose energy

how does obstructions cause deposition

natural/ man-made features slow water like dams

what does the hjulstrom curve show

the relationship between a rivers velocity and its ability to erode, transport or deposit sediment of different sizes.

what are the three key terms relating to channel flow

Velocity

Discharge

Thalweg

what is velocity?

the speed at which water moves through a river channel measured in metres per second (m/s)

what are some key points about velocity?

slower near banks and beds due to friction

influenced by channel gradient, roughness, width depth etc..

velocity is not uniform: fastest flow is slightly below the surface and follows the thalweg

finish the sentence about velocity: the higher the gradient…..

the faster the river flow