Transcript PowerPoint slides

228.22
Municipal uses – Examined costs in 2 major urban areas: Southern
California (Los Angeles south to San Diego) & Central Arizona
(Phoenix)
Recreation – $0.03 – 0.13 billion
Limited data availability
Some uses are not valuable, but rafting and kayaking are valuable
For Green River and Colorado River above Lake Mead, value of
lost water for boating estimated at $0.5 – 2.3 million per year
Underestimates total value because only considers part of system
Flood control – $2.9 billion
Tamarisk stand trap sediments, which leads to a narrowing river
channel, and narrowing of the flood plain
Narrower channels means channel can hold less water, which
means floods at lower volumes of water
Plus the dense vegetation backs-up the water , spreading it out
over a larger area
Thus get more frequent and large floods
Used Army Corps of Engineer’s conservative estimates of extra
flood damage due to Tamarisk of $52 million per year times 55
years
1953
CHANGES IN RIPARIAN VEGETATION IN
THE SOUTHWESTERN UNITED STATES:
Floods and Riparian Vegetation on the San
Juan River, Southeastern Utah-- USGS
1998
Sedimentation – Benefits of $0.07 billion
Tamarisk traps sediments, and hence increases lifetime of
reservoirs
Dove hunting – Benefits of $0.02 billion
Doves like Tamarisk thickets
Increases value for hunting
Add up the total losses & benefits
• Municipal uses
$1.4 – 3.7 billion
• Agricultural uses
$2.1 – 6.7 billion
• Hydroelectric power
$0.8 – 2.4 billion
• Recreation
$0.03 – 0.13 billion
• Flood control
$2.9 billion
• Wildlife
$0.09 – 0.37 billion
• Sedimentation
- $0.07 billion
• Dove hunting
- $0.02 billion
________________
TOTAL
$7.3 – 16.1 billion loss
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California
late 1800’s
• Extremely invasive; toxic
• By early 1940’s: 5 million acres of infested rangeland
• Biological control in California
1945/1946: 2 leaf feeders introduced
1950: root feeder introduced
Total Cost: $750,000
• By early 1960’s in California, insects had reduced
Klamath weed acreage to <1% of peak acreage
• Annual benefits estimated @ $3,500,000 per year in
California
Total Benefits (1965 – 2005): $140 million
Benefit : Cost ratio = 187 : 1 (not adjusted for
inflation)
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Aquatic weed that forms dense, floating mats
• Introduced to Chesapeake Bay in 1880’s; now widespread throughout US
• Spreads primarily by plant fragments
• Population reported at Lake Tahoe since 1960’s
• Economic impacts include
↓ recreational activities (fishing, boating, swimming, etc.)
Clog irrigation canals, gates, etc.
↓hydroelectric generation by clogging intake pipes
Non-use value: degradation of Lake Tahoe
Study only focused on recreational uses
• Low & high economic values for 4 sites in
Lake Tahoe – Truckee – Pyramid watershed
If 100% infestation, lose $30-45 million per year
If 5% infestation, lose >$1 million per year
South African fynbos
Eucalypts, pines, Acacias, and other species have invaded the
fynbos of South Africa’s Cape Province
Neotropical shrub Lantana camara is invading east Africa
Parthinium weed (Parthenium hysterophorus) in Pakistan and Australia