Chapter 2

Question 1

Surface water hydrology

Answer 1

is the study of moving water found in rivers, open channels, and runoff flowing across the open land surface

Question 2

a stream is

Answer 2

a “flow of running water, large or small,” whereas a river is a “large stream of water.”

Question 3

a stream is a “flow of running water, large or small,” whereas a river is a “large stream of water.” Most people use these terms interchangeably to denote

Answer 3

a body of running water of any size

Question 4

Most people use these terms interchangeably to denote a body of running water of any size. However, a stream is generally considered to be smaller than a

Answer 4

a river, a creek smaller than a stream, and a brook even smaller

Question 5

Rills form during

Answer 5

precipitation events

Question 6

Rills form during precipitation events and gather

Answer 6

downhill to form a brook

Question 7

Rills form during precipitation events and gather downhill to form a brook which, if it grows, creates a

Answer 7

creek

Question 8

river and stream will be used to denote a flow of running water

Answer 8

large or small.

Question 9

watershed

Answer 9

The total land area that drains surface water to a common point (or common body of water)

Question 10

water shed is also called

Answer 10

a river basin, drainage basin, and catchment

Question 11

Watersheds can be as small as a

Answer 11

parcel of ground that drains into a pond

Question 12

Watersheds can be as small as a parcel of ground that drains into a pond or as large as

Answer 12

the 1.26 million square miles in the United States and Canada that drain into the Mississippi River and its tributaries.

Question 13

A watershed is delineated by a

Answer 13

ridge or drainage divide that marks the boundary of the drainage basin and can be easily identified on topographic maps

Question 14

All surface water runoff below a ridge line will flow

Answer 14

downhill within the watershed

Question 15

The incline of terrain is generally downhill toward

Answer 15

the main channel of a river

Question 16

The boundaries of a watershed can be delineated by

Answer 16

first locating the lowest point, or watershed outlet, on a topographic map.

Question 17

The boundaries of a watershed can be delineated by first locating the lowest point, or watershed outlet, on a topographic map. Then, higher elevations can be followed until a

Answer 17

a ridge, or high point, is identified

Question 18

Three simple rules can be followed when trying to determine watershed boundaries on a map:

Answer 18

1. Surface water generally flows at right angles across contour lines on a map.
2. Ridges are indicated by the highest elevation contour line in an area.
3. Drainages are indicated by contour lines pointing upstream.

Question 19

Once the boundaries of a watershed have been determined, several watershed parameters can be computed such as

Answer 19

size, maximum and minimum elevations, shape, slope, and drainage patterns.

Question 20

Surface water flows can also be predicted based on

Answer 20

various potential precipitation events

Question 21

Hydrologists-

Answer 21

people who study and measure moving water-are also concerned with the aspect and orientation of a watershed.

Question 22

The aspect of a watershed is the

Answer 22

direction of exposure of sloping lands

Question 23

orientation is the

Answer 23

general direction of the main portion of a river as it moves down a watershed.

Question 24

A river with an east-west orientation will probably have slopes that are generally

Answer 24

north-south in aspect

Question 25

Rain that falls on the land surface within a watershed will immediately move in

Answer 25

one of three general directions

Question 26

Rain that falls on the land surface within a watershed will immediately move in one of three general directions. First, rain may

Answer 26

evaporate back into the atmosphere.

Question 27

First, rain may evaporate back into the atmosphere. Second, precipitation may

Answer 27

percolate, or seep, down into the soil and eventually become groundwater

Question 28

. First, rain may evaporate back into the atmosphere. Second, precipitation may percolate, or seep, down into the soil and eventually become groundwater. Third,

Answer 28

rain may move along the land surface as runoff during and after a storm event.

Question 29

overland flow

Answer 29

. Runoff water that is moving toward a river or stream

Question 30

Some overland flow may become stored in

Answer 30

small ponds, wetlands, or lakes before reaching a flowing stream

Question 31

Overland flow ................. and ........................ are very dependent on

Answer 31

rates volumes precipitation rates, duration of a storm event, and the spatial distribution of precipitation.

Question 32

A second feature of surface water runoff, called

Answer 32

interflow

Question 33

interflow, occurs when

Answer 33

precipitation percolates just below the land surface and moves in the same direction as overland flow.

Question 34

. Interflow moves in

Answer 34

subsurface materials at a slower rate than moving water on the surface and will arrive at a river later than overland flow.

Question 35

A heavy 45-minute downpour typically generates a

Answer 35

more rapid overland flow than calm, soaking shower over a 48-hour period that generates interflow.

Question 36

A heavy 45-minute downpour typically generates a more rapid overland flow than calm, soaking shower over a 48-hour period that generates interflow. This variation in surface water runoff is an important reason why

Answer 36

accurate precipitation measurement is so important in water resources management.

Question 37

Both overland flow and interflow are greatly affected by

Answer 37

human development

Question 38

Hard surfaces, such as parking lots, roads, and rooftops act as

Answer 38

funnels to drainage pathways

Question 39

Hard surfaces, such as parking lots, roads, and rooftops act as funnels to drainage pathways that ultimately empty into

Answer 39

rivers, streams, ponds, and lakes.

Question 40

Impervious barriers created by development also

Answer 40

inhibit interflow and percolation into the soil.

Question 41

By contrast, forests, cultivated ground, open space, parks, and other vegetated areas are relatively

Answer 41

porous and slow the runoff of precipitation and promote percolation into the soil.

Question 42

Rivers contain less than

Answer 42

0.01 percent of the Earth's water but originate in several possible sources

Question 43

Rivers contain less than 0.01 percent of the Earth's water but originate in several possible sources. Some are fed by

Answer 43

springs or small streams coming together to create larger rivers of water

Question 44

Some are fed by springs or small streams coming together to create larger rivers of water. Some originate in

Answer 44

lakes, such as the Mississippi River at Lake Itasca in northern Minnesota

Question 45

Other rivers, such as the Colorado River in the Rocky Mountains of Colorado, begin as

Answer 45

trickles of melted snow water

Question 46

A river consists of

Answer 46

of a main channel and all tributaries that flow into it

Question 47

The beginning of a river is called its

Answer 47

headwaters or source

Question 48

................................ are smaller streams that combine to form larger streams and ultimately rivers

Answer 48

Tributaries

Question 49

When viewed from above or on an aerial or satellite photo, tributaries often look like

Answer 49

the branches of a tree

Question 50

The site at which a tributary joins the main river channel is called the

Answer 50

confluence of a river

Question 51

.................................... denotes a location toward the headwaters of a river or tributary

Answer 51

Upstream

Question 52

Upstream denotes a location toward the headwaters of a river or tributary, whereas downstream is

Answer 52

is toward the direction of a confluence with a larger stream, mouth, or other end point of a river.

Question 53

The imaginary line that connects the deepest points of a river channel is called the

Answer 53

thalweg of a river

Question 54

Overland flow and interflow are

Answer 54

important sources of water for many rivers

Question 55

After a rainstorm, water levels in rivers often

Answer 55

rise

Question 56

. After a rainstorm, water levels in rivers often rise and cause

Answer 56

some water to percolate into the banks (sides) of a river

Question 57

. After a rainstorm, water levels in rivers often rise and cause some water to percolate into the banks (sides) of a river (called..................)

Answer 57

bank storage

Question 58

). As local conditions become drier, this bank storage will

Answer 58

slowly move back into the river as flow decreases.

Question 59

Porous riverbanks allow significant amounts of storm runoff to be

Answer 59

temporarily held as bank storage and can reduce the threat of flooding downstream.

Question 60

The zone beneath a river is called the

Answer 60

hyporheic

Question 61

The zone beneath a river is called the hyporheic (from the Greek meaning "...........................................") zone

Answer 61

to flow beneath

Question 62

The zone beneath a river is called the hyporheic (from the Greek meaning "to flow beneath") zone and varies in

Answer 62

depth depending on the composition and size of a river bottom

Question 63

The hyporheic zone can extend

Answer 63

beneath a riverbed to a depth of a few inches (less than 10 cm) or down to several feet (1 m or more).

Question 64

Oxygen is the limiting factor that determines

Answer 64

what type of organisms can survive in this area

Question 65

). Oxygen is the limiting factor that determines what type of organisms can survive in this area, with the ................... waters of ........................ altitudes supporting the most life.

Answer 65

colder | high

Question 66

Geomorphology is the study of

Answer 66

forces that shape the surface of the Earth

Question 67

Geomorphology is the study of forces that shape the surface of the Earth. The greatest force in the

Answer 67

the alteration of land is moving water, and its effects can easily be seen along rivers.

Question 68

. Rivers develop many features after

Answer 68

years of traveling the same course.

Question 69

A "young" river has a ........ valley

Answer 69

V-shaped

Question 70

A "young" river has a V-shaped valley, with some rivers having

Answer 70

almost vertical walls and swift-flowing water

Question 71

As a river continues toward its mouth and seeks a base level, the slope of the river channel generally

Answer 71

decreases

Question 72

As a river continues toward its mouth and seeks a base level, the slope of the river channel generally decreases. Eventually, the river valley

Answer 72

widens and becomes more U-shaped where silt and sand have created a wide plain caused by previous floods.

Question 73

Playfair's Law

Answer 73

Every river appears to consist of a main trunk, fed from a variety of branches, each running in a valley proportional to its size, and all of them together forming a system of valleys connecting with one another