Transcript HYDROLOGIC CYCLE - Purdue Agriculture

Forest Watershed Management
Course Objective:
Understand the impact of forest management
activities on water yield and quality. Become
familiar with best management practices
(BMP’s), the specific BMP programs of
several states, and the role of foresters in
BMP implementation and watershed
management.
Grading
• Grades are based on:
• Four quizzes - 30%
• Final examination - 30%
• Project - 30%
• Class participation - 10%
Research Paper
• Due Date: December 8, 2000
• Length: 1,200 words
• Topic:You may write about anything related to the course
or watershed management in general. I suggest selecting a
topic of particular interst to you. Prof. Hoover is available
to discuss possible topics.
• Format: This is to be a research paper. This means all
factual statements must be based on published research.
Any conclusions should be based on the evidence available
in the literature, not mere opinion.
• Number of citations: Provide a minimum of six citations
for sources of information included in your paper.
What Is A Watershed?
Also referred to as a “catchment”
• Topographically delineated area drained by a stream
system
– No specific scale implied
• Total land area above a designated point on a stream
or river that drains past that point
• For planning and management purposes it’s a
– Physical-biologic unit
– Socioeconomic-political unit
Why Study Forest Watershed
Management?
• Historically focus was
forest hydrology
– Hydrological effects of
vegetation and land
management practices
on water quantity and
quality, erosion, and
sedimentation at
specific sites
• Hydrology – science
of water concerned
with the origin,
circulation,
distribution, and
properties of the
waters of the earth.
Sources of Soil Erosion –
“It’s All Relative Folks”
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Construction sites
Cropland
Forest roads
Forest land
12T/A/Yr
Soil Erosion on Forest Land
Piedmont Region of Southeastern U.S.
= 0.4 tons/acre/year
= 0.04 tons/acre/year
Source: John D. Hewlett. 1982. Principles of Forest Hydrology, Univ. Ga. Press, p. 150
Forest Activities & Soil Erosion
(in order of contribution to erosion)
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Roads and skid trails
Channel encroachment
Site preparation
Harvesting activities
Fire prevention and suppression
Recreation activities
Flatwoods drainage
Wildlife management activities
Source: John D. Hewlett. 1982. Principles of Forest Hydrology, Univ. Ga. Press, p. 149
Hydrologic Affects of
Silvicultural Practices
• Clearcut
– Expose mineral soil
– Increase soil
temperatures
– Reduce
evapotransporation
– Increase exposure to
wind and associated
evaporation
– Increase erosion and
stream sedimentation
Hydrologic Affects of
Road Systems
• Creates impermeable surface
– Increases surface flow
– Channelizes surface water flow
– May channelize shallow subsurface flow
Forest Watershed Management
• Clean Water Act
– Sec. 1329 focuses attention
of forest land through
nonpoint source pollution
requirements
• Citizen interest
– Poor practices would cause
shutdowns of forest
operations
• Best management
practices (BMP) adopted
in most states
An Issue in All States
• Areas of
abundant
rainfall
– Impacts of
storm events
• Droughty areas
– Capture and
allocation of
available water
Best Management Practices
• Focus of forestry and forest products community
• BMP’s are either regulations or guidelines for silvicultural
activities
– Planting
– Harvesting
– Roads
• Usually emphasize water quality
Focus of Course: Knowledge to
Implement Forest BMP Practices
• Understand action of
water in forest
environments
• Knowledge of
applicable BMP’s
• Skill to apply BMP’s
to a specific project on
a specific site
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
Knowledge of 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
Become familiar with
precipitation patterns
• Sources of data
– NOAA
– NWS
– State climatologist
• Usually at Land
Grant University
• Vast amount of data
available on line
National Climatic Data Center
National Climatic Data Center
National Weather Service
National Weather Service
Indiana Climate Page
http://shadow.agry.purdue.edu/index.html
Variation in Precipitation
• Random
• Seasonal
• Proximity to water
body (lake affect)
• Prevailing winds
with moisture
• Topographic
Seasonal Variation
Indiana Total Precipitation
5
NC
SC
State
3
2
1
Month
No
v.
Se
p.
Ju
ly
M
ay
M
ar
.
0
Ja
n.
Inches
4
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 onehalf (20 inches) of the normal rainfall for the rest of the
region.
Puget Sound Area, Washington
20
18
16
14
12
10
8
6
4
2
0
Clearwater 118.5”
Coupeville 21.14”
Ja
n.
Fe
b.
M
ar
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Ap
r.
M
ay
Ju
ne
Ju
ly
Au
g.
Se
p.
O
ct
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No
v.
D
ec
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Inches
Avg. Monthly Rainfall 1931-1998
Month
3/26/99
3/19/99
3/12/99
3/5/99
2/26/99
2/19/99
2/12/99
2/5/99
1/29/99
1/22/99
1/15/99
1/8/99
1/1/99
Inches
Storm Events, 1st Qtr.
Daily Precipitation, Bedford, IN, 1998
1
0.8
0.6
0.4
0.2
0
6/24/99
6/17/99
6/10/99
6/3/99
5/27/99
5/20/99
5/13/99
5/6/99
4/29/99
4/22/99
4/15/99
4/8/99
4/1/99
Inches
Storm Events, 2nd Qtr.
Daily Precipitation, 1998, Bedford, IN
5
4
3
2
1
0
9/30/99
9/23/99
9/16/99
9/9/99
9/2/99
8/26/99
8/19/99
8/12/99
8/5/99
7/29/99
7/22/99
7/15/99
7/8/99
7/1/99
Inches
Storm Events, 3rd Qtr.
Daily Precipitation, 1998, Bedford, IN
1.2
1
0.8
0.6
0.4
0.2
0
12/31/99
12/24/99
12/17/99
12/10/99
12/3/99
11/26/99
11/19/99
11/12/99
11/5/99
10/29/99
10/22/99
10/15/99
10/8/99
10/1/99
Inches
Storm Events, 4th Qtr.
Daily Precipitation, 1998, Bedford, IN
2.5
2
1.5
1
0.5
0
Monroe County Airport, April 15-16, 1998
.03
1053
.26
1158
.00
1253
.01
1353
.0
1453
.04
1553
.0
0.3
1953
.14
0.2
2053
.12
0.1
2153
.10
2253
.36
2353
.17
0053
.32
0153
.22
0253
.25
0353
.08
Hourly Precipitation
0.4
Series1
16 53
-00
5
16
-02 3
53
2
-22
53
15
-20
53
15
-15
53
15
-13
58
15
15
-11
53
0
-09
16th
0953
15
15th
Some Basic Hydrologic Concepts
Weir are used to measure volume
of water flowing past a point.
What Happens to Precipitation?
• Hydrologic cycle
P = RO + ET + S,
Where,
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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
Source: http://www.agric.gov.ab.ca/agdex/500/72000003.html
Sheet erosion of cropland
resulting from surface runoff
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:
Hot Link to Website
What We’ll Look At
• Erosion
– Impacts of
• Roads
• Harvests
• Water flows
– Storm events
– Storage
• Water yield
– Amount
– Timing
Montgemory Reservoir, Clearfield, PA, WLH