The letters following each Review Question refer to the corresponding Learning Objective from the Chapter Opener. How does discharge vary according to the stream's length, the climate, and position along the stream course? (C)

As the stream's length increases, its discharge generally increases as well. This is because, as the stream flows longer distances, it gains more water from tributaries (smaller streams and rivers joining the main stream), precipitation, and other sources, resulting in a higher flow volume. Additionally, longer streams generally drain larger areas and are more likely to capture water from various sources, contributing to increased discharge.

Climate plays a significant role in the variation of discharge in a stream. In regions with high precipitation, streams tend to have a higher discharge due to the increased input of water. Conversely, in arid regions or areas with low precipitation, there might be less water available to contribute to the stream flow, leading to lower discharge values. Moreover, the seasonality of precipitation can also affect discharge, as streams in areas with distinct wet and dry seasons might experience significant fluctuations in discharge throughout the year.

The position along the stream course also affects the discharge. Near the headwaters (the start of a stream), discharge will be low because the stream has only just begun to accumulate water. As the stream flows downstream, it will receive more water from tributaries, ground seepage, and precipitation, gradually increasing in discharge. Also, the stream's slope can influence the discharge; steeper inclines speed up the flow of water, while gentler slopes may slow it down. In conclusion, the discharge of a stream varies according to its length, the climate, and position along the stream course. Longer streams with abundant water sources and a higher amount of precipitation tend to have a higher discharge, while short streams and those in drier regions have lower discharge values. The position along the stream course also plays a critical role, with discharge typically increasing as it moves downstream from its source.