Hydrology

Use this for “A lake holds 2.4 × 10⁹ m³ and its outlet carries 30 m³/s. How long does water stay in it?”

Use this for “A basin’s rain and potential ET are given for each month. When does the soil dry out, and by how much?”

Use this for “A basin with curve number 80 gets 75 mm of rain in a storm. How much runs off?”, or the curve number from a storm’s rain and runoff.

Use this for “A channel 10 m wide flows 2 m deep on a slope of 0.001 with n = 0.035. What are its speed and discharge?”, or the depth that carries 50 m³/s.

Use this for “Rain is heaviest at hour 2 and the stream peaks at hour 5. What is the lag time, and why is there one?”

Use this for “A piezometer’s screen is 120 m above sea level, and the water pressure there is 98.1 kPa. Find the pressure head and the total head.”

Use this for “A well pumps a confined aquifer 15 m thick with K = 20 m/day. Observation wells 10 m and 100 m away read heads of 40 m and 41.2 m. Find the pumping rate.”

Use this for “A well is drilled into fractured basalt, then into a clay layer. Which is the aquifer and which the aquitard?”

Use this for “A gauge has 49 years of yearly peak flows. What are the return period and yearly chance of the largest one?”

Use this for “Yearly peak flows average 500 m³/s with a standard deviation of 150 m³/s. Estimate the 100-year flood by Gumbel’s method.”