Transcript Managing Water Quality in Sustainable Forestry Programs

Issues in Urban Water Quality
C. Rhett Jackson, Professor of Hydrology
Warnell School of Forestry and Natural Resources, UGA
Are you sure you know what water quality is?
Would you take your child fishing here?
Water Quality has three aspects:
• Physical Water Quality. E.g. temperature,
pool frequency and volume, large woody
debris, particle size distribution.
• Biological Water Quality. E.g. composition
and structure of biological community (fish,
macroinvertebrates, amphibians, birds),
amount of algae, non-native species.
• Chemical Water Quality. Concentrations of
pollutants. In forestry: nutrients, suspended
sediments, pesticides.
The 1972 Clean Water Act
protects physical, chemical, and
biological integrity of the nation’s
waters.
This is the basic standard for regulation
and monitoring.
BMPs and sustainable forestry programs
must address all water quality aspects.
Horton
overland flow
Interflow
Variable
source area
runoff
Groundwater
Direct
precipitation
Jackson, C.R.
(2006),
Adapted from
Atkinson
(1978)
Dunne et al.
1975.
Hydrol. Sci.
Bull.
Unpublished Data. Dry Creek Paired
Watershed Study, South Georgia, USA.
0
1
2
pt(m)
3
4
5
7
0
6
0
5
0
B
4
0
Flow(L/s)
C
3
0
A
2
0
D
1
0
0
9
/
1
5
/
0
2
D
a
t
e
9
/
1
6
/
0
2
Water,
Nutrients,
Stream
sediment
Groundwater
Light
CPOM,
LWD
Algae
Microbes
Macroinverts
Fish
Hyporheic
exchange
The Stream as a Factory
Terrestrial
sediment
Insects
Amphibians
Water, CPOM,
FPOM, Fish,
Sediment,
Organisms
Geology
Climate
Topography/Topology
Soils
Flows
Vegetation
Sediment
Loading
Woody
Debris
Loading
Channel Habitat Structure, Chemistry,
Physical Conditions, & Biota
Keystone Species:
Humans & Beavers
Largely
unmodified by
watershed
activities.
Time since
disturbance*
Biogeographic
Setting
*Major disturbances
include fires, hurricanes,
glaciation, epidemics,
keystone episodes, etc.
11 Major Landscape Factors That Determine Stream Morphology, Habitat, & Biota
Unit Area Flow Comparison;
Peachtree (Urban) v. Falling (Forested) Creeks
Unit Area Flow (cfs/mi2)
100
10
1
0.1
0.01
Sep-95
Dec-95
Apr-96
Jul-96
Date, water year 1996
Falling Creek
Peachtree Creek
Figure 1. Changes in Peak Flow Recurrence Over Tim e Peachtree Creek at
Northside Drive (USGS gage 02336300)
12000
Flow (cfs)
10000
50's & 60's
8000
70's
6000
80's
1990-2002
4000
2000
0
1
10
Return Interval (years)
100
What makes forest soils so
different?
Macropores
Root Morphology
Soil fauna (invertebrates,
salamanders, microbes)
Soil structure (blocky, columnar,
etc.)
Irregularities in subsurface
topography
Roots rot, make macropores.
Critters move in.
Flow maintains macropores.
Edward Gilman, Dept. of Horticulture, Univ. of Florida
F ie ld K s a t (0 -2 5 cm )
100
n=15
K s a t (cm /h )
10
1
0 .1
A llu viu m
F o re s t
A llu viu m
Lawn
A llu viu m
P a s tu re
S a p ro lite
F o re s t
S a p ro lite
Lawn
S a p ro lite
P a s tu re
TIA vs. IBI
Studies from Coweeta
area (Franklin and Otto,
North Carolina)
Scott and Helfman
(2001)
How does urbanization alter the biology of
streams?
Increased size and frequency of peak flows.
Increased channel erosion and bed mobility.
Direct channel alteration.
Channel simplification.
Increased concentrations of toxic substances.
Increased concentrations of nutrients.
Food web alteration.
From
USGS
ACF
NAWQA
Study
From
USGS
ACF
NAWQA
Study
Prior to 1972 Clean
Water Act, US Rivers
were very polluted.
Clean Water Act Goal:
Make all rivers safe for fishing,
swimming, and drinking water supply.
The Clean Water Act focused first on reducing point source pollution.
- Federal taxpayers invested $66 Billion (1996 dollars) in
municipal wastewater treatment.
- 15,986 municipal wastewater treatment plants now in operation.
- also created regulatory system for industrial discharges
Population Served (millions)
250
200
No discharge
Tertiary
150
Secondary
100
Primary
Raw discharge
50
0
1968
1996
Year
The Clean Water Act has greatly reduced point-source
pollution in the United States, and U.S. Rivers are now
much cleaner than they were 35 years ago..
Structural Stormwater Management BMPs:
Detention Facilities
Infiltration Facilities
Constructed Wetlands
Bioswales
Rain Gardens
Pervious Pavements
Cisterns for Collecting Roof Runoff
Green Roofs
Detention Pond for Highway Runoff Under Construction
Brand New California Bioswale
Streamside Management Zone (SMZ)
Buffer of vegetation left along a stream to
protect water quality.
Multiple roles of streamside
management zones (SMZs):
Bank stability
Shade (water
temperature)
Organic debris
input
Narrow, 25 feet Tree roots
will suffice
critical to bank
stability
30’ generally
More important
sufficient.
on small
Benefit
streams
increases to
100’
Narrow, 25 feet Leaves, twigs,
will suffice
needles drive
stream ecology
More SMZ functions:
Large woody
debris
recruitment
Sediment,
nutrient,
pesticide
filtration
½ a mature tree Wood creates
height (40-60
pools, sorts
feet).
sediment,
provides cover
and food.
Width depends SMZs filter
on upslope
>95% of
conditions.
sediment,
More is better. phosphorus.
(40-100 feet).
Little affect on
pesticides.
More SMZ functions:
Wildlife habitat
Benefits
Many songbirds
increase to 300 and amphibians
feet and beyond dependent on
riparian forests
Aesthetics
Eye of the
beholder
This is a major
issue for large
rivers, estuaries.
Georgia’s Major
River Basins
Basic Basin Water Balance
sources
rainfall
groundwater inflow
Human import
losses
evapotranspiration (ET)
streamflow (Runoff)
groundwater outflow
human withdrawals
Conservation of mass;
inputs = outputs + changes in storage
P + GWin = ET + R + GWout + changes in storage
Usually, P = ET + R
average)
(Long term
In Ga, a typical partitioning of the water budget is:
P
= 50" - 55"/yr
R
= 15" - 18"/yr
ET
= 35" - 40"/yr
Some major or important rivers that routinely fail
to reach the sea:
1. The Colorado River - diversion to Los Angeles,
Arizona, San Diego, Imperial Valley
2. The Rio Grande - irrigation, cities
3. Yellow River, China - mostly irrigation
4. Indus River, Pakistan
5. Murray-Darling River, Australia
6. Limpopo River, southern Africa
7. Aral Sea - Amu Darya and the Syr Darya
8. The Jordan River
9. The Nile (nearly dried up at the mouth, but not quite).
What’s a drought?
• Period of below average rainfall (precipitation
drought)
• Period of low soil moisture (agricultural
drought)
• Period of low water tables
• Period of low stream flows
• Period of low reservoir or lake levels
• Period when available water supply does not
meet demand under usual pricing structures
Population (in Millions)
Georgia's Population Over Time
10
8
6
4
2
0
1880
1900
1920
1940
1960
Year
1980
2000
2020
Thanks!
Rhett Jackson
[email protected]