Runoff Given Change in Moisture Storage Calculator

Surface Runoff Formula:

\[ S_r = -(\Delta S - P + G_o + E_{act}) \]

Change in Moisture Storage (ΔS):

Precipitation (P):

Subsurface Outflow (Gₒ):

m³/s

Actual Evapotranspiration (Eₐcₜ):

m³/s

Surface Runoff (Sᵣ):

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1. What is Surface Runoff?

Surface runoff is water from rain, snowmelt, or other sources that flows over the land surface, and is a major component of the water cycle. It occurs when the soil is saturated or when precipitation falls faster than the soil can absorb it.

2. How Does the Calculator Work?

The calculator uses the surface runoff formula:

\[ S_r = -(\Delta S - P + G_o + E_{act}) \]

Where:

\( S_r \) — Surface Runoff (m³/s)
\( \Delta S \) — Change in Moisture Storage (m)
\( P \) — Precipitation (m)
\( G_o \) — Subsurface Outflow (m³/s)
\( E_{act} \) — Actual Evapotranspiration (m³/s)

Explanation: The formula calculates surface runoff by considering the water balance components including changes in moisture storage, precipitation input, subsurface water movement, and water loss through evapotranspiration.

3. Importance of Surface Runoff Calculation

Details: Accurate surface runoff calculation is crucial for flood prediction, water resource management, urban planning, and environmental impact assessments. It helps in designing drainage systems and managing watersheds effectively.

4. Using the Calculator

Tips: Enter all values in their respective units. Change in Moisture Storage and Precipitation should be in meters, while Subsurface Outflow and Actual Evapotranspiration should be in cubic meters per second. Ensure all values are valid and consistent.

5. Frequently Asked Questions (FAQ)

Q1: What factors affect surface runoff?
A: Surface runoff is influenced by rainfall intensity, soil type, land slope, vegetation cover, and land use patterns.

Q2: How is surface runoff measured in practice?
A: Surface runoff is typically measured using flow gauges, weirs, or through hydrological modeling based on precipitation and watershed characteristics.

Q3: Why is surface runoff important in urban areas?
A: In urban areas, impervious surfaces increase runoff, which can lead to flooding, erosion, and water pollution if not properly managed.

Q4: How does vegetation affect surface runoff?
A: Vegetation reduces surface runoff by intercepting rainfall, increasing infiltration, and slowing water movement across the surface.

Q5: What's the difference between surface runoff and subsurface flow?
A: Surface runoff occurs over the land surface, while subsurface flow moves through soil and rock layers beneath the surface.