The drainage basin system

fluvial hydrology and geomorphology

what soil conditions lead to a shorter lag time (flash)

high antecedent soil moisture conditions 
impermiable soil

what soil charecteristics lead to a subdued hydrograph 

dry soil 
permiable soil 

what is the water table

the upper surface of the zone of saturation where soil are permenantly saturated with water

what drainage basin lead to a subdued hydrograph 

low drainage density 
shallow slopes 
permiable rocks 
high vegitation cover 
deep soil 
lakes 
rural land 
good agricultral practices 

what precipitation types lead to a subdued hydrograph

low intesity rainfall 
small amounts of rainfall 
slow snow melt 
high rates of evapotransperation 

what climatic conditions lead to a shorter lag time (flash)

high intensity rainfall 
large amounts of rainfall 
fast snow melt 
low rates of evapotransperation 

what are the two types of storm hydrographs 

flash and subdued

what are the two types of rock

sedmentry and ignious 

what are the drainage charecteristics that lead to flash hydrographs 

high drainage density 
steep slopes 
impermiable rocks
little vegiation cover
thin soil 
urban development 
poor agricultral prectices 

waterfall

a place where a river decends vertically usually where hard rock overlies soft rock

v-shaped valley 

a river valley with evenly sloped sides in the shape of a v cuased by erosion and weathering

urbanisation

the proportion of people living in towns and cities increases and so therefore does the size of towns and cities

transportation

the removal of weathered matitial and eroded matirial in rivers 

river regime

expected seasonal pattern of discharge over the year at one particular point

ox bow lake

Cut off crecent shaped lake left after a meander neck has been cut through

Meander

A loop or bend in a river with a slip off slope on the inside bend and a river cliff on the outside

input/output

when something is either added or taken away from a system

Hydrograph

Graph showing variations in river discharge over a piriod of time

hydrocolic cycle 

the circulatory system by which water is transfered between oceans atmosphere and land

human use 

the way in which people make use of rivers to futher economic development and water supply

how does urbanised areas effect overland flow

increaced overland flow due to unpermiable surface preventing infiltraition

how does steep slopes effect overland flow

increase speed of overland flow reducing rate and time taken for interception to be able to take place

how does overgrazing effect overland flow

reduces vegitation and thus interception increacing overland flow

how does frozen of saturated soils effect overland flow

increaces over land flow as there is no unsaturated soil preventing infiltraition

how does deforestaiontion effect overland flow

reduces rate of interception increacing overland flow 

how does bare rocky surfaces effect overland flow

increaces overland flow due to unpermiable surface preventing infiltaition

flood plain 

flat low lying are of the valey floor which floods from time to time

flood 

when a river channel recives more water than it can hold 

Field capacity

The amount of water a drainage basin can hold 

erosion

the wearing away of the beds and banks

drainage density

total length of all streams in the drainage baisen divided by total area of drainage basin

drainage basin

an area of land drained by a river and all of its tributrys 

discharge

the volume of water in a river passing a mesuring point in a given time cubic meters per second

Delta

Landform produced by the deposition of sedement at the mouth of a river as it enters lake or sea

what is the hydrological cycle flows and stores

what is recharge

When precipitation exceeds evaporation causing soil moisture to increace 

what are the 6 factors that increace overland flow

• deforestation

• steep gradient 

• Frozen + saturated soil 

• overgrazing 

• bare surfaces 

• urbanisation

What are the three types of river flow

Helicoidial

laminar

Turbulent

what are the three types of river channels

Straight

meandering

braided

what charicteristics can be atributed to braided channels

Braided channels

• Trubulent flow

• steep and complex system

• eyots form

what are the charecteristics of a straight channel

straight channel

• Laminar flow

• middle and lower cource

• symetrical

• Rare in real life

what are the charecteristics of a meandering river

Meandering river

• corkscrew motion

• asemetrical

• helicoidial flow

what are the four transportation process

• Traction - large stones roll

• suspension - small particals

• soloution - disolved minerals

• saltation - small stones skip

what factors effect transportation in a river

• Competence - the diameter of the largest partials it can carry at a given velocity

• Capacity - the total volume of load a river can carry

what are the four types of erosion

• Hydraulic action - pressure of water

• abrasion - scraping and rubbing of matirial

• attrition - reduction in size of fragments in river

• soloution - carbonates dissolved

what factors effect rate of erosion

• Speed/velocity

• Discharge

• Climate

• Geology

• PH

• Load

what is sineocity

curvyness of a river over time

what are the all the causes for a subdued hydrograph

• Low intensity

• High evapotransperation

• Dry soil

• permiable soil

• low drainage density

• gentle slopes

• permiable rock

• forest and vegitation

• lakes

• rural land

• good agricultral practive

what are the all the causes for a flashy hydrograph

• high intensity

• fast snow melt

• low evapotransperation

• high antesedent conditions

• impermiable soil

• high drainage density

• steep slopes

• little vegitation

• thin soil

• no lakes

• urban development

• poor agricultral practices