Module 8 Criteria for Success

1. Be able to identify components of the Water Cycle

precipitation, runoff, evaporation, transpiration (the release of water vapor by plant and animal cells), infiltration, evapotranspiration, groundwater

1. Be able to identify components of the Water Cycle: precipitation

any form of water (rain, snow, sleet, hail) that falls from clouds to Earth’s surface

1. Be able to identify components of the Water Cycle: evaporation

the crucial process where liquid water from oceans, lakes, rivers, and even plants turn into invisible water vapor (a gas) and rises into the atmosphere, driven primarily by the sun’s heat, acting as the main way water enters the air before forming clouds and returning as precipitation

1. Be able to identify components of the Water Cycle: runoff

precipitation (rain, snowmelt) that flows over land into streams, rivers, lakes and oceans, rather than soaking into the ground

1. Be able to identify components of the Water Cycle: infiltration

the crucial process where precipitation (rain, snowmelt) soaks downward from the Earth’s surface into the soil and subsurface layers, replenishing soil moisture and groundwater

1. Be able to identify components of the Water Cycle: groundwater flow

the slow, continuous movement of water through underground soil and rock layers driven by gravity and pressure

2. Identify stream drainage patterns, and identify how the geology/topography controls these patterns

dendritic pattern - develops on relatively uniform bedrock (common)

radial pattern - develops on isolated volcanic cones or domes

rectangular pattern - develops on highly jointed bedrock

trellis pattern develops in areas of alternating weak and resistant bedrock

3. Describe the processes that lead to river erosion

Hydraulic Action: the sheer force of water dislodges rock and soil from banks and beds

Abrasion (Corrasion): rocks carried by the river grind against the beds and banks, wearing them down

Attrition: rocks and pebbles carried by the river collide with each other, becoming smaller and smother

Solution (Corrosion): slightly acidic river water dissolves soluble minerals in rocks, carrying them away invisibly

3. Describe the processes that lead to deposition of sediment

Decreased Gradient: moving from steep to flat land, slowing the water

Meanders: faster water erodes the outside bend (cut bank), depositing finer sediment on the inside bend (point bar)

Floodplains: water overtops banks during floods, slows, and drops larger sediment first, building levees

River Mouth/Delta: velocity drops significantly as a river meets a larger body of water (sea/lake)

3. Be able to identify cut bank

the steep, eroded outer bank of a river’s meander (curve) where faster water undercuts the land, creating a cliff-like slope

3. Be able to identify point bars

a crescent-shaped, sandy deposit of sediment that forms the inside curve of a meandering river where water slows down

4. Be able to describe how stream landscapes change as they mature

1. Fluvial landscape is uplifted, raising stream channels (young stream)

• steep slopes

• v-shaped valley

• straight channels

2. Main streams cut channels downward, drainage networks form

• moderate slopes

• little flat ground (narrow floodplain)

3. Stream erosion has lowered land surface to base level (mature stream)

• gentle slope

• significant meandering

• broad floodplain

5. Have familiarity with the formation of deltas

Form when a river deposits sediment as it enters a larger body of water, causing its flow to slow down. The river’s carrying capacity decreases, so it drops the mud, silt, and sand it has been transporting. Over time, this accumulation of sediment builds up and extends into the ocean or lake, creating new land and often forming a network of branching channels called distributaries.

5. Be able to distinguish between arcuate and birds foot deltas and know why they differ: arcuate

longshore drift > stream flow

curving shoreline (e.g. Nile River Delta)

most common delta shape

deposits tend to be more gravelly (finer material gets eroded)

Be be able to distinguish between arcuate and birds foot deltas and know why they differ: birds foot

stream flow > longshore drift

distributaries are able to deposit and lobes build out (e.g. Mississippi River Delta)

sediments tend to be very fine

6. Know how flood frequency is calculated

100 yr flood - 100-yr-reoccurence interval - 1% chance of occurring in any given year

500-yr flood - 0.2% chance