Warmup 3/24/15 What is erosion? How do we use land? (What do you think?)

Explain needs and consequences for land use 2.2.1a

Urbanization: What is it? Urbanization, is the physical growth of urban areas as a result of rural migration and even suburban concentration into cities, particularly the very largest ones.

US and World Population Clock Why is it needed? – People need places to live. Many move to big cities. The United Nations projected that half of the world's population would live in urban areas at the end of – As the human population increases, the need for urbanization also increases.

Consequences of Urbanization Urban sprawl is a multifaceted concept centered around the expansion of low-density development. – In the last 50 years, the greatest percentage of population growth in the US has occurred in two classes: suburban and exurban With more people moving to the suburbs…you need to remove trees and build houses! Overpopulation, less land available, etc

Alternatives? Greener cities: – Green rooftops – Water collection – Green pavement – Alternative energy

Deforestation Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a non-forest use. – Clear Cutting – Selective Cutting

Why is deforestation needed? Forests provide paper and wood that we use for many common things We need more land for other uses – Conversion of forestland to farms, ranches, or urban use.

Consequences of Deforestation Deforestation can cause more erosion/landslides – Roots held soil together, now gone

About half of the world's original forests had been destroyed by 2011, the majority during the previous 50 years. Since 1990 half of the world's rain forests have been destroyed. More than half of the animal and plant species in the world live in tropical forests. Consequences: Habitat loss

Alternatives? Reduce, reuse, recycle Sustainable forestry

Agriculture The use of land for growing crops (plants or animals for food and other uses)

Why is Agricultural Land Needed? With the world population growing, there is a need to produce more food.

Why is Agricultural Land Needed? Therefore, we maximize the land use for farming. – Due to this urban sprawl, houses are taking the place where agricultural lands have been. Commercial agriculture is large-scale production of crops for sale, intended for widespread distribution to wholesalers or retail outlets

Consequences of Agriculture Traditional (small-scale) agricultural practices are being replaced by massive farming operations using chemical fertilizers, pesticides, etc. Again, there is a need for the removal of forest land to produce agriculture land. However, this might take away from the land needed for housing… What do you do?

Alternatives: Sustainable agriculture Preserving fertile topsoil is essential to feeding the world’s rapidly growing population. This can be done through: (1) Windbreaks (2) Terracing hillsides (3) Contour plowing (4) Crop rotation

WINDBREAKS Windbreaks are located along crop field borders or within the field itself How do windbreaks help to reduce erosion rates?

TERRACING HILLSIDES Terracing is the building of wide flat rows of terraces on mountainside and hillsides. The terraces look like big staircases. They hold rainwater so that it will not wash away the soil.

CONTOUR PLOWING Instead of plowing up and down, farmers plow across a slope. In this way, the soil forms a ridge that slows down the flow of water, so soil is not carried away.

CROP ROTATION Crop rotation is the practice of growing a series of different types of crops in the same area in back to back seasons. It maintains a balance of nutrients in the soil.

Overall: There is a global need to use land for human use. More people need more homes and like the suburban feel. As a result, there is an increase in deforestation and more of a need for agriculture land.

Effect of development on shoreline Construction along the shoreline increases the rate of erosion beyond the already high rate of erosion experienced along shorelines due to the ocean.

Artificial stabilization: Shoreline structures Structures can be built to protect a coast from erosion or to prevent movement of sand along a beach: Groins Breakwaters Seawalls

Artificial stabilization: groins Groins are barriers built at right angles to the beach to trap sand that is moving parallel to the shore. Groins are built to maintain or widen beaches that are losing sand.

Artificial stabilization: breakwaters Breakwaters are built parallel to the shoreline off the coast to limit the force of oncoming waves.

Artificial stabilization: SEAWALLS Structure designed to prevent impact of tides and waves on property, built directly along the shoreline.

Artificial stabilization: SEAWALLS Structure designed to prevent impact of tides and waves on property, built directly along the shoreline.

Artificial stabilization: beach nourishment Beach nourishment projects add large quantities of sand to the beach system. It is an attempt to stabilize shorelines without adding protective features.

Beach nourishment: disadvantages Temporary fix; waves will eventually erode the replacement sand as well Expensive: costs lots of money to transport sand to the beach from offshore areas Negative effects on marine life: dredging sand off the coast replaces natural, coarse sand with softer, muddier sand that increases the cloudiness (turbidity) of the water and can kill offshore coral reefs

Effect of development on mountainsides Construction along mountainsides can decrease the stability of the land, allowing for a greater rate of erosion. Mass movements (ex: rockslides) are more probable.

Artificial stabilization: slope revetment Screen mesh (called slope revetment) draped over a steep slope keeps loosened rocks from entering roadways.slope revetment

Artificial stabilization: retaining walls Human activities or natural processes can remove some soil from the base of a slope, making the remaining upper part of the slope less stable and more prone to mass movement. Construction of a retaining wall can support the upper part of a slope.

Artificial stabilization: slope vegetationstabilization: slope vegetation While harvesting trees, leave enough mature trees to anchor the slope and protect soil from excessive erosion due to runoff.