Stream flows: Discharge Estimation

Question 1

what is stream discharge?

Answer 1

volume of water that flows past a given point in the stream in a unit of time

Question 2

what is the equation for discharge?

Answer 2

discharge = width * depth * velocity

Question 3

what are the three options for estimating the volume of water that flows past a given point in the stream in a unit of time?

Answer 3

• average stream discharge estimation
• instantaneous stream discharge estimation
• continuous stream discharge estimation

Question 4

what is Manning’s equation?

Answer 4

V=(k/n) * R(h) ^(2/3) * S^(1/2)
where R(h) is the hydraulic radius, S is the channel slope and k is the unit conversion factor

Question 5

how can we estimate instantaneous stream discharge?

Answer 5

• use of a floating object + measurement of travel time
• dilution gauging to get velocity
• single-time use of a velocimeter of current profiler

Question 6

how does a velocimeter work?

Answer 6

you measure the velocity then multiply it by area, recommended to measure at 60% water depth to get a representative velocity

Question 7

what are two ways to estimate continuous discharge?

Answer 7

• continuous water depth and velocity measurements
• continuous water depth measurements + rating curve

Question 8

how can you make continuous water depth measurements?

Answer 8

through pressure transducers and velocimeters

Question 9

what are artificial controls for stream gauging?

Answer 9

weirs and flume that force flow through critical depth at which Q is known

Question 10

what is a rating curve for continuous velocity measurements?

Answer 10

measures water velocity when the river is at different water levels and uses the discharge equation to compute discharge -> curve with water level values and discharge values