Risk of erosion

It's a global phenomenon 

• Damages areas where runoff ends up
• degrades land that is eroded
• reduces crop yields
• eroded soil damages dams, rivers, lakes, buildings and roads
• Occurs particularly on steeper slopes, on eroidable soils under crops vulnerable to erosion and where unwise farming methods are practised
• In uplands caused by overgrazing and footpaths

Very High Risk:
Rills likely to form in most years and gullies may develop in very wet periods

High Risk:
Rills are likely to develop in most seasons during wet periods

Moderate:
Sediment may be seen running to roads, ditches or watercourses
Rills may develop in some seasons during very wet periods

Lower:
Sediment is rarely seen to move but polluting runoff may enter ditches or watercourses


Crops' susceptibility to erosion:

High: Winter cereals, potatoes, maize, sugar beet
Moderate: Winter forage crops eg turnips, oil-seed rape
Low: Permanent grass, woodland

Submergent Fettures: Rias

A Ria is an irregular coastal inlet caused by a relative rise in sea levels resulting in the submergence of a former valley system.

Types of Ecosystems

from the Millenium Ecosystem Assessment reporting catergories

Marine - Ocean deeper than 50m

Coastal - Interface between ocean and land

Inland Water - Permanent water bodies and areas dominated by regular flooding that are inland from the coast

Forest - Land that is at least 40% covered by woody plants taller than 5m

Dryland - Land where annual precipitation is less than two thirds of potential evaporation

Islands -Land surrounded by water with a high proportion of coast to hinterland

Mountains - Land surrounded by water and with a high proportion of coast to hinterland

Polar - High Latitude systems frozen for most of the year

Cultivated - Land dominated by agriculture including orchards or forestry

Urban - Built environments with high human density and population of 5000 or more

Case Study: Mount St Helens

Reasons for growth in Volcanic Tourism industry:

• Improvements in air travel made places like Hawaii more accessible
• Global media coverage has increased public awareness of these events
• World Heritage sites raise profile of places like Giant's causeway

Mt St Helens:

• Strato volcano in Cascade mountain range
• Before 1980 it attracted people to hunt, ski and hike
• Spirit Lake at its base was popular area for fishing, boating and swimming
• Forests were commercially logged
• 1980 people flocked to see eruption
• Vechicles blocked road to spirit lake
• Souvenir trade: ash in glass vials, tshirts, mugs
• Forestry service sought safe spots where people could view eruption
• Mobile trailers set up to show film footage
• More violent than predicted
• Claimed 57 lives

Recovery:

Economic:

• Spirit Lake Memorial Highway
• Large bridges
• Five visitor centres

Social:

• Mt St Helens Volcanic Monument established

Environmental:

• Several interpretative trails
• sediment retention structure
• Pumice plain receeded
• Outlets cut to release water from lakes created when avalanches dammed streams to decrease flood risk
• Tunnel constructed at Spirit Lake to maintain safe water level

Tourism Issues:

Conservation: 

• Only one road leads to site

• pressure on observatory
• other attractions help
• Erosion - hardened park area with 420 vehicle capacity
• Destruction by vistors
• trampling can damage pioneer speicies
• $100 fine for stepping on or picking wildflowers