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1

Surface water hydrology

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

2

a stream is

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

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

a body of running water of any size

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

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

5

Rills form during

precipitation events

6

Rills form during precipitation events and gather

downhill to form a brook

7

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

creek

8

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

large or small.

9

watershed

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

10

water shed is also called

a river basin, drainage basin, and catchment

11

Watersheds can be as small as a

parcel of ground that drains into a pond

12

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

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

13

A watershed is delineated by a

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

14

All surface water runoff below a ridge line will flow

downhill within the watershed

15

The incline of terrain is generally downhill toward

the main channel of a river

16

The boundaries of a watershed can be delineated by

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

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

a ridge, or high point, is identified

18

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

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.

19

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

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

20

Surface water flows can also be predicted based on

various potential precipitation events

21

Hydrologists-

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

22

The aspect of a watershed is the

direction of exposure of sloping lands

23

orientation is the

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

24

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

north-south in aspect

25

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

one of three general directions

26

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

evaporate back into the atmosphere.

27

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

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

28

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

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

29

overland flow

. Runoff water that is moving toward a river or stream

30

Some overland flow may become stored in

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