Runoff Factors and Impact Quiz

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Runoff is that portion of ______ that flows over land surfaces toward larger bodies of water.  Before runoff can occur, rainfall must satisfy the immediate demands of infiltration, evaporation, interception, surface storage, surface detention and/or channel detention.  Some are very minor losses, e.g., interception by a corn crop is only about 0.02 inches. However, in a forested area, interception may not be minor, accounting for up to 25 percent of the rainfall.

precipitation

A graph of runoff rate vs. time is called a runoff hydrograph. The shape of a hydrograph depends on the ______ and upon watershed flow characteristics. However, most hydrographs bear some resemblance to the 'typical shape' shown below:

time distribution of rainfall

E.g., interception by a corn crop is only about 0.02 inches. However, in a forested area, interception may not be minor, accounting for up to 25 percent of the rainfall.

losses

Indirect Methods )Equations( Direct Methods )______( Current meter Direct Methods Crest stage gauge Staff gauge Talbot’s CN (SCS) Rational Indirect Methods Manning’s Formula Unit Hydrograph Equation Creager’s SCS-CN

measurements Signup and view all the answers

The SCS-CN method is one of the most popular methods for computing the volume of direct surface runoff for a given rainfall event. On one hand, SCS model is an ______ and it just needs a single parameter-Curve Number which lumps together the hydrological impacts of land use SCS Curve Number Method (Indirect Method)

empirical model Signup and view all the answers

Match the runoff loss with its description:

Infiltration = Immediate demand of rainfall before runoff can occur Interception = Portion of precipitation intercepted by vegetation Surface storage = Water held on the land surface Channel detention = Retention of water in natural or artificial channels Signup and view all the answers

Match the runoff estimation method with its type:

SCS-CN method = Indirect Method Manning’s Formula = Indirect Method Unit Hydrograph Equation = Indirect Method Current meter = Direct Method Signup and view all the answers

Match the hydrograph component with its description:

Runoff rate vs. time graph = Runoff hydrograph Time distribution of rainfall and watershed flow characteristics = Factors affecting hydrograph shape Typical shape = Characteristic of most hydrographs Flood and runoff estimation methods = Methods for analyzing hydrographs Signup and view all the answers

Match the runoff measurement tool with its description:

Crest stage gauge = Measures water level in natural channels Staff gauge = Simple device for measuring water depth Direct Methods = Measurements used for estimating runoff directly Rational method = Equation for estimating peak discharge in drainage basins Signup and view all the answers

Match the runoff control method with its description:

Surface detention = Temporary storage of water on land surface SCS Curve Number Method = Method for computing direct surface runoff volume Direct Methods = Methods using measurements to estimate runoff directly Indirect Methods = Equations used to estimate runoff indirectly Signup and view all the answers