Running Water

Running water Water as an agent of erosion; water in streams, tributaries (larger streams) and rivers that flow down hill therefore changing the landscape (erosion)

Running water Abrasion – wearing away of rock by grinding action

3 ways rock is carried by water Solution – mineral matter dissolved from bedrock is carried in a river (25%)

3 ways rock is carried by water Suspension – small rock materials, silt and clay, carried by a river are stirred up & kept from sinking by the turbulence of stream flow (50%)

3 ways rock is carried by water Bed Load – sand, gravel, pebbles, and boulders that are moved along the bed of a stream & that are too heavy to be carried in suspension (25%)

Carrying Power – how much total sediments a stream can carry and the size of the particles being carried by the stream at given time and stream velocity

Discharge – volume of water flowing past a given point in a stream at a given time

Stream features depend on 3 major things 1. The type of rock being eroded. 2. The amount of water & sediment 3. The climate of the area

Base Level – the level of the body of water into which a stream flows

Gully – a miniature valley formed by erosion from heavy rains

Headward Erosion – wearing away of land at the head of a gully or a stream valley

More Headward Erosion

Divide – the higher land separating two adjacent drainage basins

Continental Divide made of Rocky Mountains and Sierra Madre Occidental Mountains Streams on the East drain into the Atlantic Ocean or Gulf of Mexico Streams to the West drain into the Pacific

Stream Velocity – the speed of water at a given point at a given time Drainage system - Streams flow into larger streams (tributaries), which flow into rivers, which flow into oceans … cumulative denotes a “drainage system”

Drainage Basin (watershed) – an area of land who’s runoff supplies water to the stream of a drainage system - area drained by a river system

Stream Piracy – the diversion of the upper part of one stream by the headward growth of another stream

Water Gap – a pass in a mountain ridge through which a stream flows, created by resistant rock layers

Life of a River A Youthful Stream Narrow V-shaped valley Down cutting Swift water Steep gradient Erosion is dominant

Mature Stream Lateral Erosion begins Meanders develop Floodplains develop Gradient lowers

Old Age Wide meanders and oxbow lakes Wide floodplain Low velocity Low gradient Dynamic equilibrium between erosion and deposition

Flow speed High velocity (erosion): Outside of curve Middle of surface Well below the surface Increase in discharge Increases with increase in gradient

Flow speed Low velocity (deposition): Inside of curve Edges of river surface Decrease in discharge Decreases with decrease in gradient

Flash Flood – a sudden rush of water, usually caused by a single cloudburst over the narrow valley of a young mountain stream

3 Common types of natural dams A. landslides B. ice jams  C. volcanoes

3 Common types of artificial flood control A. build up levees B. pump rising water into back swamp reservoirs C. build a series of dams and control the overall flow of the river

Features… Meander – a curve in a mature or old stream

Mississippi River

Features… Oxbow Lake – crescent- shaped lake formed when a river meander gets cut off from the river and the ends of the original bend have ‘silted up’ Erosion on the outside bend of a river Deposition of the inside bend of a river

Features… Floodplain – the broad flat valley floor carved by a meandering stream and often covered with water when a stream floods Levee – a natural or artificial bank confining a stream or river channel

Pothole – deep oval or circular holes cut into a stream bed by abrasion from swirling sand & pebbles. Very large ones are called plunge pools

Delta – a fan-shaped deposit of sediment formed at the mouth of a stream or river when it flows into a quiet body of water, such as a lake, gulf, or inland sea (ex. Mississippi & Nile river deltas)

Laizhou Bay (Laizhou Wan) is the southern arm of the Bohai Sea (also Known as the Bohai Bay, or just Bo Hai), which is a large relatively shallow extension of the Korea Bay

Nile River Delta

Alluvial Fan – sloping triangular deposits of sediment located where a mountain stream reaches level land (ex. At the foot of the Rocky Mountains and the Sierra Nevada’s)

Online quiz… http://www.uh.edu/~jbutler/physical/chap13mult.html