The water balance

Question 1

What is it?

Answer 1

balance between inputs an d outputs of water to/from a drainage basin
/budget

Question 2

water balance equation?

Answer 2

precipitation= river discharge + evapotranspiration +/- storage

Question 3

describe the hydrological cycle & drainage basin in relation to open and closed?

Answer 3

h= closed cycle, recycled water
d= open system, inputs of sediment

Question 4

describe the water cycle in wet seasons

Answer 4

water surplus - precipitation>evapotranspiration

river levels rise, ground stores fill with water, more discharge and surface runoff/overland flow

Question 5

describe the water cycle in dry seasons

Answer 5

water deficit/ground store depletion E>P

lost from surface stores- some flows into river channel, not replaced by precipitation, reduces through flow

Question 6

Reasons for high runoff in summer and winter

Answer 6

winter= too much rain, saturated
summer= ground goes hard and becomes impermeable if too dry

Question 7

2 drawbacks of the water budget graph

Answer 7

uses potential evapotranspiration data rather than actual
focuses on changes in soil storage and only considers the balance between the input of precipitation and output of evapotranspiration

Question 8

What is a storm hydrograph?

Answer 8

shows how a river responds to a rainfall event/ a succession of events - short time scale, helps manage river

Question 9

what is river discharge? Measured in?

Answer 9

amount of water in a river flowing pasta particular point

cumecs m3/seconds-1

Question 10

Human factors affecting a storm hydrograph

Answer 10

urbanisation/land use, afforestation=flood prevention, deforestation= less interception more erosion & stream flow is increased, agriculture (ploughing breaks up topsoil, greater infiltration), soft engineering flood management schemes- slows water, water abstraction reduces base flow and more water must reach channel before reaching back full capacity

Question 11

Physical factors affecting a storm hydrograph

Answer 11

amount and intensity of rain, antecedent rainfall (how much rain before/saturated?), soil type, steep slope, season, geology (imporous=overland flow, porous= water flows along bedding planes), thick vegetation increases lag time, drainage density (streams/tributaries), intense storms/tides and storm surges, high drainage basin has a flashy hydrograph as all water arrives at same time

Question 12

What is base flow?

Answer 12

represents normal day to day discharge of the river

Question 13

describe the drainage basin water balance across the seasons

Answer 13

winter/early spring- water surplus
late spring/summer- soil moisture utilisation
late summer- soil moisture deficit- soil pores empty
early autumn- soil moisture recharge- soil pores replenished and recharged back to field capacity