Rivers

Rivers  Many originate from snowmelt in mountains  Runoff provides rivers with nutrients  Three “stages”, varying in temperature and velocity Youthful (erosion zone)Youthful (erosion zone) Mature (transport zone)Mature (transport zone) Senile (deposition zone)Senile (deposition zone)

Youthful stage (Upper course)

Senile Stage (Lower course)

THREATS TO RIVERS  Drainage for agricultural use  Drainage for manufacturing use  Redirection  Damns  Pollution

Wetlands What are they? Why are they important?

What are wetlands?  The U.S. Fish and Wildlife Service defines wetlands as the “…lands transitional between terrestrial and aquatic systems where the water table is usually at or near the land surface or the land is covered by shallow water.” (Cowardin et al., 1979)  Wetlands must have all of the following characteristics: Hydric soil Hydric soil Hydrology Hydrology Hydrophytic vegetation Hydrophytic vegetation Standing water for at least part of the year Standing water for at least part of the year

Types of wetlands Marsh

Forested wetland

Wet Meadow

Bog and fen

 Brackish marshes – variable salinity  Tidal salt marshes - saltier water  Everglades largest freshwater marsh in U.S. largest freshwater marsh in U.S.

Historical perspective on wetlands  The U.S. total of natural wetlands is estimated at 127 million acres  By million acres (35%) had already been drained  Presently only 10-19% of the area are wetlands (see figures)  Most wetlands were lost to agricultural expansion  Some were lost to development due to population growth  They were considered wastelands and destroyed until recent scientific research and environmental awareness stressed their importance

Why are they important?  Hydrologic value —refers to the distribution and movement of water on or below the earth’s surface -wetlands are capable of slowing down and retaining water (especially important during floods or heavy rain) -wetlands play an important role in groundwater recharge -plants along bodies of water slow down sediment deposits in streams and lakes (process called erosion) thus improving water quality

Wetland importance…  Habitat value —wetlands are some of the most biologically rich ecosystems in the world comparable to tropical rainforests and coral reefs -wetlands provide habitats for amphibians, fish, wildlife, birds and plants -some of the species can only survive in the wetland environment -there are 500 species of plants and animals threatened with extinction in Illinois; 55% of these depend on wetlands or other aquatic habitats for survival (spotted turtle, Illinois chorus frog, four-toed salamander, black- crowned night heron and many more)

Wetland importance…  Direct use value --ecotourism--fishing --production of saw timber and pulpwood --environmental education

Wetland importance…  Water quality --wetlands remove pollutants from surface runoff and streams --wetland plants reduce algae bloom and fish kills by transforming nitrogen and phosphorus into available forms

Did you know that…?  Wetlands are often referred to as “the kidneys of the landscape” because they filter out harmful materials  One acre of wetland can store million gallons of floodwater  Wetlands comprise only 5% of the contiguous U.S., although they are home to 31% of all plant species  As many as 50% of North American bird species either nest or feed in wetlands

Threats to Wetlands  “Improvement” of wetlands - drained and cleared 20% of the wetlands (1 Million acres!) around New Orleans have been lost over the last 100 years 20% of the wetlands (1 Million acres!) around New Orleans have been lost over the last 100 years Read more about it at: m/ngm/0410/feature5/?fs=www3.nati onalgeographic.com Read more about it at: m/ngm/0410/feature5/?fs=www3.nati onalgeographic.com m/ngm/0410/feature5/?fs=www3.nati onalgeographic.com m/ngm/0410/feature5/?fs=www3.nati onalgeographic.com  Residential & Commercial development  Federal regulations now in place to prohibit destruction of wetlands

New Orleans : Areas Below Sea Level

Erosion of Lake Ponchartrain (meters per yr)

River System

Protection Against Hurricanes  Floods replenish land and soil and build new land from sediments and deposits  Mississippi Delta and Barrier Islands act as a buffers that slow down storm surges  Marshes, swamps, bayous and wetlands act as sponges absorbing energy and water from hurricanes

Sedimentation

Freshwater Wetlands

Healthy Marsh

Marsh

Atchafalaya Bayou

Chandeleurs Prior Katrina

Barrier Island

Chandeleur Barrier Islands

History That Contributed to Tragedy  1879: Congress authorized ACE to build levees to prevent Spring flooding  Oil Industry and other development drained, dredged, and built channels and canals throughout wetlands and marshes  Mississippi River was channeled to empty at continental shelf

Effects of Levees on Mississippi: in Missouri

Results  New Orleans sank further below sea level as earlier sediments and deposits compacted and sank (no new sediments deposited)  Mississippi Delta and Barrier Islands began to disappear – erosion and subsidence  Wetlands and marshes were fragmented, ripped up, and destroyed, leading to recession of coastline

Historic Deltas

Channeled Mississippi Delta

Dredging Marshes and Wetlands

Levees to Prevent Flooding

Canals Protecting Neighborhoods

Delta Community

Human-Made Channels

Sand Mining

Oil and Agriculture

Petro Channels Through Marsh

Environmental Impact Prior to Katrina  Rate of disappearance of wetlands:  1 acre every 24 minutes 60 acres per day 60 acres per day 25 to 30 square miles per year 25 to 30 square miles per year By 2050 Louisiana would lose another 1000 square miles of marshes By 2050 Louisiana would lose another 1000 square miles of marshes By 2090, some estimates predict that New Orleans will have sunk to approximately 10 to 15 feet below sea level and that the coastline may have receded to a point north of New Orleans By 2090, some estimates predict that New Orleans will have sunk to approximately 10 to 15 feet below sea level and that the coastline may have receded to a point north of New Orleans

Erosion on Barrier Islands

Erosion of Delta and Barrier Islands

Disappearing and Sinking Wetlands

Disappearing Marsh

Erosion: Louisiana Coast

Recent History  1980s: 5 federal agencies & 6 state agencies have jurisdiction: turf wars  LSU scientists model Katrina disaster  1990s: $40 million per year for remediation  1998: Hurricane Georges; New Orleans escapes  Result: “Plan 2050” Cost: 14 billion “prohibitive”  2000 – 2005: little money allocated to Plan 2050; significant funds diverted to Iraq war; ACE remediation/restoration budget slashed

Other Contributing Factors  Global warming well underway (but debate about causes continues)  2000: US refuses to sign Kyoto Accord  Wetlands “redefined” at times to allow more development (i.e. more habitat destruction )  Atlantic Ocean and Gulf of Mexico waters extremely warm  Two fold increase in category 4 and 5 hurricanes in last 30 years

Katrina Strikes!  Flooding in New Orleans and Surrounding Communities  Further Erosion of Marshes and Wetlands  Destruction of Barrier Islands

Levee Breach: Katrina

New Orleans Levees

Katrina Flood

Further Destruction of Marshlands

Chandeleurs: Pre & Post Katrina

End Result:  New Orleans, surrounding parishes, and much of coastal Louisiana are now even more vulnerable to hurricanes (as exemplified by Rita).

Sources  Scientific American:  “Drowning New Orleans”. October 2001  National Geographic:  “Gone with the Water”. October 2004