hydrologi och akvatisk ekologi läsperiod 1ex 1, for an area the annual precipitation is 1300...
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Hydrological system
Learning goals:
- hydrological cycle- climate and water availability- catchment area- water balance equation (continuityequation)- runoff coefficient- how to calculate pollutant transport out from the project area
Hydrological cyclecomponents and turnover
time1 week
1 week -10 years
5000 years
8000 years
3000 years
Global water distribution
Atmosphere 0,001%Lakes, rivers, creeks 0,009%
Groundwater, soil 0.615%Ice caps, glaciers 2,04%
Oceans, saltwater lakes 97,31
Atmospheric flow decideswhere water availability is
large or small
Sun energy
Precipitation
Precipitation
No precipitation
No precipitation
Precipitation
Gulf stream suppliesNorthern Europe with 50%
of available heat
Direct sun insolation remaining 50% of the heat
Water balances
P
E
Q
ΔM
WATER FLOWS
Interception losses (evaporation from leafs, etc
Transpiration (from plants)
Soil evaporation Runoff
Soil water Groundwater flow
Storage changes ΔM approx. constant seen over
1 year!
spring spring
ΔM
Q
Lake water, snow, groundwater, soil water
1 year
Example water balancecalculations
Ex 1, For an area the annual precipitation is 1300 mm/year and annual evaporation is 800 mm/year. What is the average runoff?
Ex 2, For the same area precipitation was 700 and evaporation was 500 mm during 6 months. What was runoff if the increase in water storage was 100 mm?
Catchment area is definedby topographical water
divide
Catchment = rainfall collectingarea upstream a certain point in the water course.
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Remember: always use the same unit in the water balance equation;
for example mm/year, mm/month, m3/s,
Ex. A 1 ha catchment has received 100 mm rainfall during a month. During the same month runoff was 0.1157 l/s and storagechanges equal to zero. What was the evaporation during the month?
Ex. 2.1, Two rainfall events, just after one another, fall over a catchment. After the first rainfall of 24 mm, a total runoff of 11 mm was observed. The second rainfall is measured to about 14 mm. How large runoff can be
expected after the second rainfall?
P
Q
Rain 1; P1 = 24 mm Q1 = 11 mm Rain 2; P2 = 14 mm Q2 = ?
Ex. 2.2, A 121 ha large lake has an inflow via a river corresponding to 0.425 m3/s. There is also an outflow from the lake via another river that corresponds to 0.368 m3/s. During one month the water level in the lake increases corresponding to 19.7 · 103 m3. During the same month it rained 33 mm. How large was the total evaporation from the lake during this month (1 ha = 10 000 m2)?
Lake Qout
Qin
Ex. 2.3, For a catchment with an area of 20 km2 an average of 732 mm/year of precipitation and total evaporation of 550 mm/year have been observed during a 10-year period. Within the catchment there is an old waste dump and in the outflow water high phosphorous (P) contents have been found 0.25 mg/l P. What is the annual mass transport of phosphorous in the water out from the catchment?
Solution: Put up a water balance for the catchment. That is
P - E - Q = ΔM
A = 20 km2 P = 732 mm/year E = 550 mm/year C = 0.25 mg/l P
P
Q, C
E