What are the two main sources of stream flow?

The two main sources of stream flow are indeed stormflow and base flow. Stormflow refers to the increased discharge that occurs in streams and rivers following rainfall events or snowmelt. It is characterized by rapid increases in flow caused by surface runoff or overland flow, where water moves over the land surface into water bodies. This typically occurs during and shortly after precipitation events when the ground becomes saturated or when rainfall exceeds the infiltration capacity.

Base flow, on the other hand, is the portion of stream flow that comes from groundwater. It contributes a steady flow to a stream throughout dry periods when there is little to no precipitation. Base flow results from groundwater discharging into the stream, maintaining flow levels during times of low rainfall, which is essential for the ecological health of stream ecosystems.

The combination of these two sources ensures that streams and rivers have a consistent flow regardless of immediate weather conditions, making them vital for maintaining habitat and water availability. Thus, recognizing that stormflow and base flow together account for the primary contributions to stream flow is crucial for understanding hydrology and water resource management.