Introduction

Question 1

Runoff R:

Answer 1

Flow rate of water per time interval, draining a catchment, subcatchment or defined area on and below the surface (units: e.g. mm/d). (Is applied here generally to describe the total flow from a catchment, when origin or flow paths are less important.)

Question 2

Discharge or streamflow Q:

Answer 2

Flow rate of water per time interval, passing a cross section of a defined natural channel (units: e.g. m3/s)

Question 3

Specific discharge q:

Answer 3

Streamflow QA at a certain point in a channel divided by the drainage area AC of the catchment

Question 4

Measurement of discharge methods:

Answer 4

-Volumetric
the only direct method to measure Q (e.g. for springs)

-Current meter
measurement of cup rotations per time n

-Tracer gauging
based on dilution of tracer along a measurement reach of a river (e.g. for turbulent small streams)

-Measurement weirs
water level measurements h given known weir geometry and known hydraulic losses

-Ultra sonic
velocity is deduced after differencing the time of travel of ultrasonic pulses diagonally with and against flow direction

-Electromagnetic
electromagnetic field is generated in the water by installing a coil under the river