CSM Data Collection & Analysis 3

Question 1

A Parshall flume is used in stormwater monitoring primarily to:

Accepted Answer

Measure open-channel flow rate based on water depth

Answer

A Parshall flume is a calibrated flow measurement device that converts a depth reading (via stage-discharge relationship) into volumetric flow rate.

Question 2

When using a rain gauge network to estimate watershed-average rainfall, the Thiessen polygon method accounts for:

Accepted Answer

The spatial area of influence attributed to each gauge

Answer

Thiessen polygons assign each gauge a weight proportional to the watershed area closer to that gauge than any other, giving a spatially weighted average rainfall.

Question 3

In stormwater quality monitoring, the 'first flush' phenomenon refers to:

Accepted Answer

The disproportionately high pollutant concentrations occurring early in a runoff event

Answer

First flush describes the tendency for pollutant concentrations to peak early in a storm as accumulated surface pollutants are mobilized before dilution by continued rainfall.

Question 4

Which QA/QC sample type is used to assess potential contamination introduced during field sampling and transport?

Accepted Answer

Equipment blank

Answer

An equipment blank (or field blank) is collected using reagent-grade water passed through all sampling equipment and containers to detect contamination introduced during collection, transport, or processing.

Question 5

A stormwater manager wants to determine whether total phosphorus concentrations differ significantly between an agricultural sub-watershed and an urban sub-watershed. The appropriate statistical test for two independent groups with non-normal data is:

Accepted Answer

Mann-Whitney U test

Answer

The Mann-Whitney U test is the non-parametric alternative to the t-test, appropriate when data are not normally distributed and two independent groups are being compared.

(CSM) Certified Stormwater Manager Practice Test

(CSM) Certified Stormwater Manager Practice Test

CSM Data Collection & Analysis 3