meteorology – storm events. knowledge of precipitation amounts and patterns plan drainage...
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Meteorology – Storm Events
Knowledge of Precipitation Amounts and Patterns
• Plan drainage structures– Size temporary
culverts to handle storm events during period of operations
– Size permanent drainage structure to handle 100 year storms
Know Precipitation Amounts and Patterns
• Time operations– Expose soil during dry periods
if possible– Establish vegetative cover as
soon as possible– Use native vegetation
whenever possible
What’s Wrong?
Become familiar with precipitation
patterns• Sources of data
– NOAA
– NWS
– State climatologist• Usually at Land Grant
University
• Vast amount of data available on line
Ochocos Mountains of Central Oregon
National Climatic Data Center
http://www.ncdc.noaa.gov/oa/ncdc.html
National Weather Servicehttp://www.weather.gov/view/national.php?thumbs=on
National Oceanic and Atmospheric Administration's
National Weather Service
Indiana State Climatologist
http://www.agry.purdue.edu/climate/
Variation in Precipitation
• Random• Seasonal• Proximity to water
body (lake affect)• Prevailing winds
with moisture• Topographic
Seasonal Variation
Indiana Total Precipitation
0
1
2
3
4
5
Jan.
Mar.
May
July
Sep.
Nov.
Month
Inch
es
NC
SC
State
Proximity to Water Body
Prevailing Winds
Topographic Affect
• Rising air cools• Dew point reached• Water vapor
condenses to form clouds
• Precipitation may occur
• Cloud patterns induced by passage of air current over mountains
• Precipitation concentrated on windward side of mountain, and mountain top
• Tends to be rain shadow on leeward side
• Fidalgo Island in rain shadow of the Olympic Mountains.
• Rainforests with up to 200 inches of precipitation on the west side.
• Rain shadow area northeast of the Peninsula with only one-half (20 inches) of the normal rainfall for the rest of the region.
Avg. Monthly Rainfall 1931-1998
02468101214161820
Month
Inch
es
Clearwater 118.5”
Coupeville 21.14”
Puget Sound Area, Washington
Storm Events, 1st Qtr.
Daily Precipitation, Bedford, IN, 1998
00.20.40.60.81
1/1/99
1/8/99
1/15/99
1/22/99
1/29/99
2/5/99
2/12/99
2/19/99
2/26/99
3/5/99
3/12/99
3/19/99
3/26/99
Inch
es
Storm Events, 2nd Qtr.
Daily Precipitation, 1998, Bedford, IN
012345
4/1/99
4/8/99
4/15/99
4/22/99
4/29/99
5/6/99
5/13/99
5/20/99
5/27/99
6/3/99
6/10/99
6/17/99
6/24/99
Inch
es
Storm Events, 3rd Qtr.
Daily Precipitation, 1998, Bedford, IN
00.20.40.60.81
1.2
7/1/99
7/8/99
7/15/99
7/22/99
7/29/99
8/5/99
8/12/99
8/19/99
8/26/99
9/2/99
9/9/99
9/16/99
9/23/99
9/30/99
Inch
es
Storm Events, 4th Qtr.
Daily Precipitation, 1998, Bedford, IN
00.51
1.52
2.5
10/1/99
10/8/99
10/15/99
10/22/99
10/29/99
11/5/99
11/12/99
11/19/99
11/26/99
12/3/99
12/10/99
12/17/99
12/24/99
12/31/99
Inch
es
Monroe County Airport, April 15-16, 1998
15th 0953 .03
1053 .26
1158 .00
1253 .01
1353 .0
1453 .04
1553 .0
1953 .14
2053 .12
2153 .10
2253 .36
2353 .17
16th 0053 .32
0153 .22
0253 .25
0353 .08
Hourly Precipitation
0
0.1
0.2
0.3
0.4
Series1
Some Basic Hydrologic Concepts
Weirs are used to measure volume of water flowing past a point.
What Happens to Precipitation?
• Hydrologic cycleP = RO + ET + S,
Where,• P ≡ precipitation
• RO ≡ runoff
• ET ≡ evapotranspiration
• S ≡ storage
Evapotranspiration
• Loss of water from a given area during a specified time by evaporation from the soil surface and by transpiration from the plants.
• Supports plant life• Reduces water yield
Runoff Provides Major Benefits RO = P – ET
Moose Creek, Clearfield County, PA (WLH)
Where does runoff go to?
• RO = CI + SRO + SSF + BF, – where,
• CI ≡ channel interception• SRO ≡ surface run off • SSF ≡ subsurface flow• BF ≡ base flow
Where does runoff go to?
– CI ≡ channel interception• Precipitation falling directly into
channel
Susquehanna River, Clearfield, PA, (WLH)
Where does runoff go to?– SRO ≡ surface runoff or overland flow
• Precipitation not infiltrating soil
Sheet erosion of cropland resulting from surface runoff
Source: http://www.agric.gov.ab.ca/agdex/500/72000003.html
Where does runoff go to?
– SSF ≡ subsurface flow, or interflow• Infiltrating precipitation intercepted by hardpan or
bedrock before entering groundwater pool
Where does runoff go to?– BF ≡ base flow or ground water flow
• Precipitation entering water table
Research results come from experimental watersheds such as:
What We’ll Look At
• Erosion– Impacts of
• Roads• Harvests
• Water flows– Storm events– Storage
• Water yield– Amount– Timing Montgemory Reservoir, Clearfield, PA, WLH