ES 105 Exam #2 Hydrographs and water budgets

What is Discharge?

Volume of water passing an area per unit time.

What is the formula for discharge?

Q= V(velocity)A(rea)

Weir method

Constant measurment of discharge using a v and looking at the discharge in gal/minute for varying notch angles

Velocity-area-method- manual site-based measurement

Velocity measure at 60% depth in the center of the area.

Where is water velocity greatest?

Greatest near center of the channel

Where is velocity lowest?

Lowest as sides and bottom

Rating curve method

An empirical relationship between river stage and discharge, but requires background data collection a priori. Works really well on large bodies of water.

Slug injection method

Using conservative tracers and advection/dispersion: pour in salt solution and measure electrical conductivity downstream

Factors that control Q in streams

Precipitation

Drainage basin area’

geology

soils

impervious cover and disturbance

Hydrograph

Continuous record of Q over time