Chapter 08: Streams & Flooding

Question 1

Hydrologic cycle (7)

Answer 1

1. Evaporation & transpiration
2. Condensation
3. Precipitation
4. Infiltration & groundwater flow
5. Runoff

Question 2

Rivers of Long Island (5)

Answer 2

1. Peconic
2. Connetquot
3. Stony Brook
4. Patchogue
5. Carmens

Question 3

Discharge

Answer 3

volume per time

Q = WDV

Q = width * depth * velocity

*units cubed

Question 4

Alluvial fan

Answer 4

River that empties out onto land and deposits sediment in a fan-shape because of the drop in velocity

Question 5

Delta

Answer 5

River that spills out into a body of water via distributaries

Deposits sediments which create the distributaries

Deposit of sediment is sudden because of the drop in velocity

Question 6

Gaining stream

Answer 6

Water table is saturated and feeding the stream water

Question 7

Losing stream

Answer 7

Water table is low and the stream is losing water to the water table

Question 8

Lag time

Answer 8

Time between precipitation event and rise in stream discharge

Lag time decreases as urbanization increases

Question 9

Effects of urbanization on streams (5)

Answer 9

1. Runoff increases
2. Infiltration decreases
3. Lag time (of flooding) decreases
4. Peak discharge increases
5. Flooding is worse

Question 10

Recurrence interval

Answer 10

Helps predict frequency of flooding events

RI = (N+1)/M

RI = (number of years of data + 1) / magnitude or rank of event

Question 11

Stage

Answer 11

Describes a stream’s discharge status

Stage can be expressed in elevation/height of stream

or

as “flood stage” or “x ft above flood stage”

Question 12

Natural factors of flooding (3)

Answer 12

1. Type of precipitation event
2. Ground conditions
3. Vegetation cover

Question 13

Human factors of flooding (4)

Answer 13

1. Removal of vegetation
2. Destruction of wetlands
3. Construction activity
4. Urbanization

Question 14

Flooding reduction methods (4)

Answer 14

1. Dams
2. Levees
3. Channelization
4. Retention basins (recharge basins)