PHYSICAL HYDROLOGY

All the rivers run into the sea; yet the sea is not full; unto the place from whence the rivers come, thither theyreturn again”

(Ecclesiastes 1:7)

PHYSICAL HYDROLOGY

• Why should we be concerned with the complexity of the many relationships that affect various phases of the hydro. cycle?

 • Arguably, hydrologic science wasn’t as

important 20 years ago, so why is it now? 

PHYSICAL HYDROLOGY

“Multiple demands for the use of the same gallon of water and prospects for even greater demands tomorrow indicate that more and more people of different disciplines need to have a knowledge of hydrology”

PHYSICAL HYDROLOGY

PHYSICAL HYDROLOGY

Employment of environmental scientists is expected to grow about as fast as the average for all occupations through 2014, while employment of hydrologists should grow much faster than average. Job growth for environmental scientists and hydrologists should be strongest at private-sector consulting firms. Demand for environmental scientists and hydrologists will be spurred largely by public policy, which will oblige companies and organizations to comply with complex environmental laws and regulations, particularly those regarding ground-water decontamination, clean air, and flood control.Job opportunities also will be spurred by a continued general awareness regarding the need to monitor the quality of the environment, to interpret the impact of human actions on terrestrial and aquatic ecosystems, and to develop strategies for restoring ecosystems.

PHYSICAL HYDROLOGY

PHYSICAL HYDROLOGY

Agriculture

Undeveloped

Existing Development

Undeveloped

UnderConstruction

Developed

Developed

Center for Watershed Protection

Impervious Cover Can Transform a Watershed in Just a Few Years

1940s1950s1960s1970s1990s

PHYSICAL HYDROLOGY

More Frequent FloodingCenter for Watershed Protection

Higher Flood Levels

The large amount of stormwater runoff in the stream system can cause:

PHYSICAL HYDROLOGY

PHYSICAL HYDROLOGY

“Today’s student will be tomorrow’s water management decision maker”

PHYSICAL HYDROLOGY

• The spatial and temporal variations of water substance in the terrestrial, oceanic, and atmospheric compartments of the global water system

• The movement of water on and under the earth’s land surfaces, the physical and chemical processes accompanying that movement, and the biological processes that conduct or affect that movement

 

What Is a Watershed?

A watershed is the area of land that drains to a particular point along a stream

Center for Watershed Protection

PHYSICAL HYDROLOGY

PHYSICAL HYDROLOGY

• Many hydrologic processes are non-linear 

0

500

1000

1500

2000

2500

0 50 100 150 200 250

Time (seconds)

Infi

ltra

tio

n (

mm

/hr)

PHYSICAL HYDROLOGY

• e.g. preferential flow

PHYSICAL HYDROLOGY

• e.g. turbulence

PHYSICAL HYDROLOGY

• Conditions vary enormously in space and time and it is difficult to obtain data to characterize this variability

00 100 200 300

FIELD A

Sep Oct Nov Dec Jan Feb Mar Apr May

1992 1993

Frozen ground

010203040

-1R

ainfall (mm

day )

Vehicle wheeling

Time (days)

Soi

l moi

stur

e (g

g

)-1

10

20

30

40

50

PHYSICAL HYDROLOGY

PHYSICAL HYDROLOGY

18 oct 19 oct

22 oct

< 80%

80-90%

90-100%

Saturated