Step 1: Define the Hydrologic Cycle.
The hydrologic cycle is the continuous movement of water on, above, and below Earth's surface. It can be conceptualized as a system with inputs, outputs, and storage changes, applicable at any scale from a small watershed to the globe.
Step 2: Analyze Relevant Equations/Principles.
- Bernoulli's Equation: Describes the relationship between pressure, velocity, and elevation in a moving fluid, based on energy conservation.
- Dalton's Law: Pertains to partial pressures in gas mixtures, applicable to evaporation.
- Continuity Equation: A mass balance equation, known in hydrology as the water balance equation: Inflow - Outflow = Change in Storage (\( I - O = \Delta S \)). This equation fundamentally governs the entire hydrologic cycle.
- Darcy's Law: Explains fluid flow through porous media, relevant to groundwater movement.
Step 3: Identify the Governing Equation.
Although Dalton's and Darcy's laws describe specific hydrological processes, the overarching principle governing the hydrologic cycle is mass conservation, as expressed by the Continuity Equation.