01Aqua Campus Deck

A campus roof changes where rain goes.

A visual lesson on runoff, storage, infiltration, and evaporation

Harbor Learning Studio | Introductory environmental design
Aqua Campus Deck01 / 09
02Aqua Campus Deck

We can trace rain through four possible paths.

  1. Start with a single rainfall event
  2. Follow water off the roof
  3. Compare routes through the campus
  4. Test a design choice
Aqua Campus Deck02 / 09
03Aqua Campus Deck

Rain does not disappear when it leaves the roof.

It moves into another part of the local water system. A useful design question is where it goes next.

Aqua Campus Deck03 / 09
04Aqua Campus Deck

Four pathways account for the water in our example.

Runoff

Water travels over a surface toward a drain or lower ground.

Storage

A tank holds collected water for a later, suitable use.

Infiltration

Water enters soil where the ground can absorb it.

Evaporation

Liquid water returns to the air as water vapor.

Aqua Campus Deck04 / 09
05Aqua Campus Deck

A roof-to-garden route has three design decisions.

01 Collect

Direct roof water into a gutter.

02 Slow

Hold or spread the flow before it reaches the ground.

03 Absorb

Guide water toward soil with room to infiltrate.

Aqua Campus Deck05 / 09
06Aqua Campus Deck

The surface below a roof changes the next step.

Paved edge

  • Water stays on the surface.
  • Flow may reach a drain quickly.
  • Little water can enter the ground there.

Planted bed

  • Water can spread across soil.
  • Some water may infiltrate.
  • Capacity depends on soil and rainfall.
Aqua Campus Deck06 / 09
07Aqua Campus Deck

Our illustrative rainfall splits across four pathways.

% (illustrative)
40Runoff30Storage20Infiltration10Evaporation
TakeawayThese teaching values total 100%; they are not measurements from a real campus.
Aqua Campus Deck · Sample figures, replace with sourced data07 / 09
08Aqua Campus Deck

A useful water diagram makes its assumptions visible.

The route and proportions will vary with surface, soil, weather, and design.

  • Name the area receiving the rain.
  • Show each destination with a directional line.
  • State whether values are measured or illustrative.
  • Check that the quantities account for the starting amount.
Aqua Campus Deck08 / 09
09Aqua Campus Deck

You can now trace and improve a rainwater route.

  1. Sketch a roof and two possible receiving surfaces.
  2. Mark where runoff, storage, infiltration, and evaporation may occur.
  3. Explain one design change and the path it could affect.
Aqua Campus Deck09 / 09