1. What is Subsurface Outflow?

Subsurface Outflow is the flow of water beneath earth's surface as part of the water cycle. It represents the movement of water through soil and rock layers below the ground surface.

2. How Does the Calculator Work?

The calculator uses the water balance equation:

Where:

• \( G_o \) — Subsurface Outflow (Cubic Meter per Second)
• \( P \) — Precipitation (Meter)
• \( \Delta S \) — Change in Moisture Storage (Meter)
• \( S_r \) — Surface Runoff (Cubic Meter per Second)
• \( E_{act} \) — Actual Evapotranspiration (Cubic Meter per Second)

Explanation: This equation represents the water balance where subsurface outflow is calculated as the residual of precipitation after accounting for changes in moisture storage, surface runoff, and actual evapotranspiration.

3. Importance of Subsurface Outflow Calculation

Details: Calculating subsurface outflow is crucial for understanding groundwater recharge, managing water resources, predicting flood events, and assessing the overall water balance in a watershed or catchment area.

4. Using the Calculator

Tips: Enter precipitation in meters, change in moisture storage in meters, surface runoff in cubic meters per second, and actual evapotranspiration in cubic meters per second. All values must be non-negative.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between surface runoff and subsurface outflow?
A: Surface runoff occurs over the land surface, while subsurface outflow occurs beneath the ground surface through soil and rock layers.

Q2: Why is subsurface outflow important in hydrology?
A: Subsurface outflow contributes to baseflow in streams, recharges aquifers, and plays a crucial role in maintaining water balance in watersheds.

Q3: How does change in moisture storage affect subsurface outflow?
A: An increase in moisture storage reduces subsurface outflow, while a decrease in moisture storage increases subsurface outflow, as water is either being stored or released from the system.

Q4: What factors influence actual evapotranspiration?
A: Actual evapotranspiration is influenced by temperature, humidity, wind speed, solar radiation, soil moisture, and vegetation type.

Q5: Can subsurface outflow be negative?
A: In theory, subsurface outflow should not be negative as it represents water movement. A negative result may indicate measurement errors or that the system is gaining water from other sources not accounted for in the equation.