Rivers：練習題

In the study of a drainage basin, what is the specific term used to describe the boundary that separates one drainage basin from another?

Which of the following describes the typical change in a river's cross-section as it moves from its upper course to its lower course?

Compare the efficiency of two river channels:
Channel A has a cross-sectional area of \(24\text{ m}^2\) and a wetted perimeter of \(12\text{ m}\).
Channel B has a cross-sectional area of \(30\text{ m}^2\) and a wetted perimeter of \(20\text{ m}\).
Which channel is more efficient and why?

Which of the following processes in the hydrological cycle involves water moving vertically downwards from the land surface into the soil?

In a meander, where is the water velocity typically the highest, and what is the primary process occurring there?

Define the term watershed and name the area of land that is drained by a river and its tributaries.

Explain how infiltration is affected by soil saturation and describe the role of this process in maintaining groundwater flow.

Explain how channel efficiency is determined by the hydraulic radius and describe why velocity often increases downstream despite a decrease in the river's gradient.

Drainage basins function as open systems with various inputs, outputs, and transfers within the hydrological cycle.

(a) Define the term confluence.

(b) Identify the specific term used to describe the total volume of water passing a given point in a river channel at a specific time, usually measured in cubic metres per second (\(m^{3}/s\)).

(c) Identify two processes in the hydrological cycle where water is transferred from the Earth's surface or plants back into the atmosphere.

Rivers provide both opportunities and hazards for people living near them.
(a) Explain why flood plains are often used for intensive agriculture.
(b) Describe how afforestation (planting trees) in the upper course of a drainage basin can help to manage the risk of flooding in the lower course.