Describe the components of a basin water budget and its primary use.

• A. Inputs: precipitation; losses: evapotranspiration, runoff; changes in storage; used to assess water resources and flood risk.
• B. It describes precipitation without losses.
• C. It only considers soil moisture.
• D. It forecasts weather patterns.

Answer: (A)

A basin water budget tracks the balance of water in a watershed over a given time, showing how much water enters, leaves, and is stored. The main input is precipitation. The main outputs are evapotranspiration and runoff. Changes in storage account for water that accumulates or is depleted in soil moisture, groundwater, and surface water bodies between periods. This balance—inputs minus outputs equals the change in storage—lets us quantify how much water is available for use and how the system might respond to varying conditions. Its primary use is to assess water resources and flood risk, guiding resource management, planning, and flood mitigation decisions.