CEN 325: Water Resources Exam 1

Approximately what percentage of the world’s freshwater?

• 2.5% of the world’s water is fresh

What is the largest lake in the world by volume?

• Lake Baikal

At a minimum about how many liters per day does a person need for basic survival?

• 15 Liters

True or False: The Hadley Circulation is a theoretical model that assume that the earth is rotating.

• False; Hadley Circulation assumed that earth is not rotating

Small particles made of dust or salt that condensation occurs around are called:

• aerosols

The figures below represent:

What is the name of the graph that represents rainfall intensity as a function of time?

• rainfall hyetogrpah

True or False: A storm intensity with a return period of 10 years will definitely occur once every 10 years.

• False

What is the process of water penetrating soils called?

• Infiltration

What is the process of water changing from liquid to vapor stages?

• Evaporation

True or False: Saturated flow occurs when just some of the voids are filled with water

• False, saturated flow occurs when all voids are filled with water

Which of the methods used to calculate evaporation usually gives the most accurate answers assuming a small area?

• combined method

The runoff graph represents a less rough runoff

The runoff graph that could represent a steeper runoff

A hyetograph can be used to represent rainfall excess while a hydrograph can be used to represent runoff.

What is the term for ground water that enters a channel that is usually always present?

• baseflow

What are some assumptions about the unit hydrograph approach?

• Excess rain is uniformly distributed throughout the watershed

• the watershed is not changing

True or False: Infiltration rate generally increases with time.

• false

Terms and Definitions of the following:

• Lag Time:Time between the center of mass of the rainfall and the peak of the hydrograph

• Time of Concentration:Time for a particle of water to travel from the hydrologically most distant point in the water shed to a point of interest

True or False: A typical CN number for a grassy surface will be less than the CN number for an impervious surface

• true

Indicate each physical process that can be considered an abstraction

• Surface Storage

• Interception

• Evaporation

• Evapotranspiration

• Infliltration

Math the terms in the NRCS Model

• P: Total Precipitation

• VR: Rainfall Excess

• Ia: Initial Abstraction

• S: Potential Maximum Retention

• Fa: Continuing Abstraction

• CN: Curve Number

• True or False: For dry antecedent conditions, the CN number will be higher that it would be for wetter conditions

  • false

Which factors influence the relationship between rainfall and runoff?

• soil properties

• land cover

• ground slope

• watershed geometry

Definitions of the Terms:

• Vadose Zone: pores have mix of air and films of water

• Water Table: the upper boundary of the saturated zone

• Aquifer: pores filled with water through which water can flow

• Confined Aquifer : Between impermeable layers

True or False: Darcy’s velocity is usually greater than pore velocity

• false

True or False: The hydraulic conductivity of sand is greater than the hydraulic conductivity of clay

• true

Which equation would you use to calculate the flow in an unconfined aquifer?

True or False:The Theis equation (shown below) is used to calcualte drawdown for non-steady state conditions.

• true

True or False: Pump tests can determine hydraulic properties of aquifer by pumping well at an increasing rate and observing the drawdown.

• false

When a well starts being pumped the water level is lowered around the well and form a cone of what?

• depression