Question 1

The primary stream fed by tributaries within a drainage basin is termed a ____________.

Accepted Answer

The primary stream that is fed by tributaries within a drainage basin is called the trunk stream. It is the main river or stream that receives water from smaller tributaries or streams within the basin. The other choices (lead stream, taproot stream, pirate stream) are not commonly used terms in geography or hydrology.

Question 2

How would the competency of an arid versus a temperate-region stream vary,in a downstream direction?

Accepted Answer

In arid regions, streams often experience flash floods, which can significantly increase their competency downstream as they carry larger sediments.

Question 3

In uniform sediments with a relatively constant slope at the surface,a ____________ drainage network is expected.

Accepted Answer

In uniform sediments with a relatively constant slope, dendritic drainage network is expected as it represents a random pattern of streams that resemble the veins of a leaf. It is the most common drainage network pattern and usually forms in areas where the underlying rock is relatively uniform, and lacks any structural control on the direction of flow.

Question 4

The discharge of a river traveling through a humid region will typically ____________ downstream; the discharge of a river traveling through an arid region will typically ____________ downstream.

Accepted Answer

In a humid region, there is usually more rainfall, which leads to higher levels of soil moisture and groundwater. This extra water is continually fed into the river, causing the river's discharge to increase downstream.

On the other hand, in an arid region, there is minimal rainfall, and water is either quickly evaporated or absorbed into the soil. As a result, there is less water available to feed into the river, leading to a decrease in discharge downstream.

Question 5

In a region characterized by a parallel series of ridges and valleys,a ____________ drainage network is expected.

Accepted Answer

The trellis drainage pattern is typically found in regions with parallel ridges and valleys. The streams flow down the valleys and join together at right angles to form a trellis-like pattern. This pattern is the most efficient for drainage in these types of landscapes. The other options (dendritic, radial, and rectangular) would not be expected in this type of terrain.

Question 6

With time,a river may erode terrain to produce a low-lying plain termed a(n)____________.

Accepted Answer

A peneplain is a low-lying plain produced by erosion of a river over time. Astral plain is not a geological term and is not related to erosion or rivers. Antedeluvial plain refers to a plain that existed before the biblical flood and is not related to erosion. Plateau is a term for a flat-topped area that is elevated above the surrounding terrain and is not necessarily the result of river erosion.

Question 7

Which sediment load carries electrically charged ions?

Accepted Answer

The dissolved load carries electrically charged ions, as they are in a solution with water and not physically suspended in the water. The bed load, suspended load, and bank load do not typically carry electrically charged ions in the same way as the dissolved load.

Question 8

The deepest part of a mature river channel is where the water usually flows the fastest.

Accepted Answer

The deepest part of a mature river channel is called the thalweg and it usually follows the path of fastest current flow, as it has been eroded the most by the water. Therefore, the water usually flows the fastest in that part of the channel.

Question 9

Which two of these factors set the stage for the 1889 Johnstown flood?

Accepted Answer

The answer of Which two of these factors set the...

Question 10

Although the Nile River is longer,the Amazon River has the greatest discharge of any stream on Earth.

Accepted Answer

The Amazon River has the largest discharge of any stream on Earth, despite being shorter than the Nile River.

Question 11

Which three geologic terms are used to describe the course of an ephemeral stream?

Accepted Answer

Wash, arroyo, and wadi are all terms used to describe the course of an ephemeral stream in various regions around the world. A wash is a dry stream bed that fills with water during heavy rains. An arroyo is a steep-sided gully or canyon created by erosion from flowing water. A wadi is a dry riverbed that fills with water seasonally or after heavy rains. Together, these terms encompass the various types of ephemeral streams found in different geologic settings.

Question 12

All flowing water on the continents' surfaces is confined to stream channels.

Accepted Answer

While most flowing water on continents is in stream channels, it is not confined to them. Water can also flow in rivers, lakes, ponds, and wetlands, among other places.

Question 13

Which has greater competence?

Accepted Answer

The answer of Which has greater competence?
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Question 14

In the region immediately surrounding an isolated volcano,a ____________ drainage network is expected.

Accepted Answer

A radial drainage network is characterized by streams and rivers that radiate outwards from a central high point, such as an isolated volcano. This type of drainage pattern is common around volcanic cones, where surface water accumulates and flows away in all directions. The other three choices are not typically found in such an environment – dendritic patterns develop on flat, uniform landscapes; rectangular patterns tend to form in jointed or fractured bedrock; and trellis patterns are associated with folded and faulted topography.

Question 15

All the water in rivers and streams arrives directly from rainfall runoff.

Accepted Answer

The answer of All the water in rivers and streams...

Question 16

The sediment load of a stream consists of only those grains that are fine enough to stay in suspension.

Accepted Answer

The answer of The sediment load of a stream consists...

Question 17

Ephemeral streams ____________.

Accepted Answer

Ephemeral streams have flowing water either episodically or during a portion of the year. The other options do not accurately describe ephemeral streams.

Question 18

As the velocity of flow decreases,____________.

Accepted Answer

As the velocity of flow decreases, the flow tends to become more laminar due to decreased turbulence. Additionally, the maximum flow velocity decreases, leading to a decrease in the ability of the flow to transport sediment. This can cause suspended sediment to start to be deposited, especially in areas of low energy such as the bottom of a watercourse. Therefore, all of the above options are correct.

Question 19

Which sediment load is likely to move the least,in between periods of flood?

Accepted Answer

Bed load consists of larger particles that roll, slide, or bounce along the bottom of a riverbed and are less likely to be transported during periods of low flow compared to suspended or dissolved loads.

Question 20

In a region with prominent orthogonal sets of joints,a ____________ drainage network is expected.

Accepted Answer

In regions with prominent orthogonal sets of joints, a rectangular drainage network is expected because the rivers and streams tend to follow the paths of least resistance, which are often the fractures or joints in the rock. These joints typically intersect at right angles, leading to a rectangular pattern in the drainage network.

Quiz 14: Streams and Floods: the Geology of Running Water