Chapter 13 Reading Quizlet

13.3 Summarize the factors that influence flow velocity.

- channel slope or gradient - channel size and cross-sectional shape - channel roughness - amount of water flowing in the channel

13.3 Contrast laminar and turbulent flow.

-Laminar flow, the water particles move in roughly straight-line paths that parallel the stream channel -Turbulent flow, the water moves in an erratic fashion that can be characterized as a swirling motion

13.2 Prepare a simple sketch of the four drainage patterns discussed in this section. Briefly describe why streams exhibit each pattern.

1) Dendrite patterns which are formed on surface of the materials that are uniform 2) Rectangular patterns are formed on joints of the bedrocks. 3) Radial pattern develops on isolated cones of volcano or domes. 4) Trellis pattern forms in areas of bedrocks that are weak and resistant. **Look at the blue drawings on page 343

13.6 What is a graded stream?

A stream has just energy, not extra nor deficit, to transit a load. The processes are balanced.

13.3 What is longitudinal profile?

Cross section view from source to mouth reveals how channels are cut Example is on page 346 that graph that is labeled 13.11

13.4 In what three ways does a stream transport its load? Which part of the load moves most slowly?

Dissolved load Suspended load Bed load

13.6 Describe or sketch how an erosional floodplain develops.

Figure 13.24 on Page 355

*13.4 Outline the ways in which streams erode, transport, and deposit sediment.

Streams erode when turbulent water lifts loose particles from the stream bed. The focused "drilling" of the stream armed with swirling particles also creates potholes in solid rock. Streams transport their load of sediment in solution, in suspension, and along the bottom (bed) of the channel. A stream 's ability to transport solid particles is described using two criteria: Capacity refers to how much sediment a stream is transporting, and competence refers to the particle sizes the stream is capable of moving. Streams deposit sediment when velocity slows and competence is reduced. This results in sorting, the process by which like-size particles are deposited together.

13.7 Explain why the Mississippi delta consists of seven coalescing subdeltas.

Subdeltas are created when the main flow is diverted from one channel to the shorter and more direct path that heads to the Gulf of Mexico. Each subdetla intertwines together and makes a complex structure.

13.3 What typically happens to channel width, channel depth, flow velocity, and discharge between the headwaters and the mouth of a stream? Briefly explain why these changes occur.

The channel slope decreases toward a stream's mouth, the flow velocity increases; increases in channel size and discharge and decreases in channel roughness that occur downstream

*13.3 Discuss streamflow and the factors that cause it to change.

The flow of water in a stream may be laminar or turbulent. A stream's flow velocity is influenced by channel gradient; size, shape, and roughness of the channel; and discharge.

13.1 Over the oceans, evaporation exceeds precipitation, yet sea level does not drop. Explain why.

The runoff from continents is about the same as the lost evaporation

13.2 Draw a simple sketch of a drainage basin and a divide and label each.

Top left picture on page 342

*13.8 Summarize the various categories of floods and the common measures of flood control.

Part 1: Regional floods - seasonal, take place because of heavy rain or fast melting of snow when it is spring Flash floods - small warning, deadly, very quick rise in water level and high speeds Ice jam floods - happen in frozen rivers. Increase level of streams, ice will break and flow and accumulate Dam failure floods - when a dam or artificial levee fails. Part 2: Artificial levees: earthen mounds build on the banks of a river to increase the volume of water the channel can hold Flood-control dams: build to store floodwater and then let it out slowly Channelization: involves altering a stream channel in order to speed the flow of water to prevent it from reaching flood height

13.4 Describe two processes by which streams cut channels in bedrock.

Quarrying - removal blocks from the channel bed. Abrasion - process where bed and bank of a bed rock channel are hit constantly by particles that are carried in the flow.

13.6 Explain why V-shaped valleys often contain rapids and/or waterfalls.

Rapids and waterfalls occur where the stream's gradient increases significantly, and V-shaped valleys have steep sides

13.8 List and distinguish among four types of floods.

Regional floods - seasonal, take place because of heavy rain or fast melting of snow when it is spring Flash floods - small warning, deadly, very quick rise in water level and high speeds Ice jam floods - happen in frozen rivers. Increase level of streams, ice will break and flow and accumulate Dam failure floods - when a dam or artificial levee fails.

13.2 List several factors that cause infiltration and runoff to vary from place to place and time to time.

1-the intensity and duration of the rainfall 2-the amount of water already in the soil 3-the nature of the surface material 4-the slope of the land 5-the extent and type of vegetation *when surface material is highly impermeable or when it becomes saturated - runoff is the dominant process

13.2 What are the three main parts (zones) of a river system?

1.sediment production 2. sediment transport 3. sediment deposition

13.5 Describe a situation that might cause a stream channel to become braided.

A stream that experiences a high degree of variability in discharge

*13.6 Contrast narrow V-shaped valleys, broad valleys with floodplains, and valleys that display incised meanders or stream terraces.

A stream valley includes the channel itself, the adjacent floodplain, and the relatively steep valley walls. Streams erode downward until they approach base level, the lowest point to which a stream can erode its channel. A river flowing toward the ocean (the ultimate base level) may encounter several local base levels along its route. These could be lakes or resistant rock layers that retard downcutting by the stream. A stream valley is widened through the meandering action of the stream, which erodes the valley walls and widens the floodplain. If base level were to drop or if the land were uplifted, a meandering stream might start downcutting and develop incised meanders.

13.7 Describe the formation of an alluvial fan.

Alluvial fans form where water flowing in a confined channel abruptly spreads out on an unconfined valley floor. While a delta is just the landform produced by deposition of sediment where a stream enters a lake, reservoir, or sea.

13.8 Describe three basic flood-control strategies. What are some drawbacks of each?

Artificial levees: earthen mounds build on the banks of a river to increase the volume of water the channel can hold Flood-control dams: build to store floodwater and then let it out slowly Channelization: involves altering a stream channel in order to speed the flow of water to prevent it from reaching flood height

13.1 What is meant by the term evapotranspiration?

Because both evaporation and transpiration involve the transfer of water from the surface directly to the atmosphere, they are often considered together as the combined process of evapotranspiration

*13.5 Contrast bedrock and alluvial stream channels. Distinguish between two to types of alluvial channels.

Bedrock channels are cut into solid rock and are most common in headwaters areas where gradients are steep. Rapids and waterfalls are common features. Alluvial channels are dominated by stream flow through alluvium previously deposited by the stream. A floodplain usually covers the valley floor, with the river meandering or moving through braided channels. Meanders change shape through erosion at the cut bank (the outer edge of the meander) and deposition of sediment on point bars (the inside of a meander). A meander may become cut off and form an oxbow lake.

13.5 Are bedrock channels more likely to be found near the head or the mouth of a stream?

Bedrock channels are more likely to be found at the head of a stream where gradient is steep.

13.4 Explain the difference between capacity and competency.

Capacity is the maximum load of solid particles a stream can transport per unit time Competence refers to the stream's ability to transport particles by size and not quantity.

*13.7 List the major despositional landforms associated with streams and describe the formation of these features.

Delta - form where a river deposits sediment in another water body at its mouth. The partitioning of stream flow into multiple distributaries spreads sediment in different directions. Natural Levees - result from sediment deposited along the margins of a stream channel by many flooding events. Because the levees slope gently away from the channel, the adjacent floodplain is poorly drained, resulting in back swamps and yazoo tributaries flowing parallel to the main river. Alluvial fans - fan-shaped deposits of alluvium that form where steep mountain fronts drop down into adjacent valleys.

13.5 Describe or sketch the evolution of a meander, including how an oxbow lake forms.

Figure 13.18 pictures (Geologist's Sketch) on Page 352

13.7 Sketch a cross section of a simple delta and distinguish among the three types of beds that compose it.

Figure 13.7 on Page 357. Those "five" pictures illustrate the formation.

13.7 Briefly describe the formation of a natural levee. How is this feature related to back swamps and yazoo tributaries?

Natural levees are formed by successive floods over many years. When a stream overflows its banks, its velocity immediately diminishes, leaving coarse sediment deposited in strips bordering the channel. As the water spreads out over the valley, a lesser amount of fine sediment is deposited over the valley floor, which produces the gentle slope of the natural levee. Blackswamps result in the poorly drained area behind a levee Yazoo tributaries can't enter a river because of the levee

13.8 What is meant by a nonstructural approach to flood control?

Nonstructural approach to flood control encourages changes in how people occupy/use floodplains in order to reduce the number of people at risk in floods. Also tries to decrease the damages associated with floods.

*13.1 List the hydrosphere's major reservoirs and describe the different paths that water takes through the hydrologic cycle.

Oceans, glaciers, rivers, lakes, air, soil, and living tissue Water evaporates from the ocean, plants, and soil; moves through the atmosphere, and eventually falls as precipitation

13.6 Describe two situations that would trigger the formation of incised meanders.

Originally, the meanders probably developed on the floodplain of a stream that was in balance with its base level. then, a change in base level cause the stream to begin downcutting. One of two events likely occurred: Either the base level dropped or the land on which the river was flowing was uplifted.

13.4 What is settling velocity? What factors influence settling velocity? Does settling velocity affect the dissolved load?

Settling velocity is defined as the speed at which a particle falls through a still fluid Factors that influence settling velocity are particle size, particle shape, and the specific gravity of particles

13.1 Describe or sketch the movement of water through the hydrologic cycle. b) Once precipitation has fallen on land, what paths might the water take?

Sketch is on page 341 b) Either soaks into the ground or flows on the ground surface and eventually joins the rivers or evaporates into the atmosphere.

*13.2 Describe the nature of drainage basins and river systems. Sketch and briefly explain four basic drainage patterns.

The land area that contributes water to a stream is its drainage basin. Drainage basins are separated by imaginary lines called divides. As a generalization, river systems tend to erode at the upstream end, transport sediment through the middle section, and deposit sediment at the downstream end. Page 343 Sketches

13.6 Define base level and distinguish between ultimate base level and distinguish between ultimate base level and local, or temporary, ase level.

Ultimate base level: "grand base level" or sea level Local (or temporary) base level: include lakes, resistant layers of rock, and rivers that act as base levels for their tributaries