1. Surface Water Hydrology
Learning Objectives
To be able to quantify watershed attributes (7.1)
To be able to describe the role of atmospheric and ocean circulation in hydrology and the formation of precipitation (7.1)
To be able to quantify the variability of precipitation, calculate area average precipitation and determine design storm amounts (7.2)
To be able to calculate evaporation from an open water surface (7.3)

2. Watershed delineated on a topographic map

3. Streamstats

4. From Dingman, 1994

5. General Circulation of the Atmosphere, Bedient Fig 1-3a

6. Three-Cell Model
From Simon Wang

7. Three-Cell Model: Scientific evolution
Halley
Earth’s rotation and
the conservation of
linear momentum
cause the Trade Winds
Hadley
Coriolis force deflects
winds toward the east
and pulls air from south
+ Conservation of
angular momentum
Ferrel
Thermally direct
circulation forcing
air towards equator
170 years!
Slide from Simon Wang

8. Coriolis Effect

9. Formation of Precipitation
Source of moisture
Lifting mechanism (frontal, orographic, convective)
Phase change from vapor to water - Energy
Small nuclei or dust for droplet formation
Droplets must grow as they fall to earth
From Bedient

10. Lifting Mechanisms
From Bedient

11. Ralph, F. M. , P. J. Neiman, G. A. Wick, S. I. Gutman, M. D
Ralph, F. M., P. J. Neiman, G. A. Wick, S. I. Gutman, M. D. Dettinger, D. R. Cayan, and A. B. White (2006), Flooding on California's Russian River: Role of atmospheric rivers, Geophys. Res. Lett., 33, L13801, doi: /2006GL

12. Hurricane Katrina in the Gulf - 8/29/2005
From Bedient
Katrina at 17:00 UTC

13. Measuring Rainfall - Tipping
Bucket
Recording gage
Collector and Funnel
Bucket and Recorder
Accurate to .01 ft
Telemetry- computer
From Bedient

14. Shielded and Unshielded weighing Precip (Rain and Snow Gages
Snow Pillow

15. RADAR Rainfall Estimates
NEXRAD provides real-time data on a ~16 km2 (6 mi2) grid
Each estimate represents an average rainfall amount over the entire 4 x 4 km2 area
NEXRAD rainfall estimates compare well with point rain gage measurements (r2 ~ 0.9)
From Bedient

18. Normal monthly distribution of precipitation in the US in inches
From Mays, 2011, Ground and Surface Water Hydrology

19. Rainfall Averaging Methods
From Bedient
Rainfall Averaging Methods

20. NOAA Hydrometeorological Design Studies Center Precipitation Frequency Data Server (PFDS)
The standard source for design storm data
CEE 3430 – Spring 2011