Stormwater Harvesting

Information and resources for the transition from shedding to infiltration of stormwater.

On this page

Amazing Stormwater Infiltration Demo —December 7th 2015 San Marcos Pass
Mulch Basins Catch a Stormwater Rain Bomb (video)
California State Stormwater Strategy
Water Observations: Inside a Fissured Bedrock Aquifer
Water Observations: Kayaking the Santa Ynez River in August
Stormwater articles
More info —and resources

Amazing Stormwater Infiltration Demo

Optimizing stormwater management is the perfect gateway for government systems thinking and collaboration across numerous departments (for more on this see the Event Handout).

This was a demonstration of the under-appreciated potential for small-scale, distributed catchment in developed areas to:

transform the hydrology of the landscape
increase water supply
reduce downstream flooding
increase dry season creek flows
increase readiness and resiliency for both flood and drought

The demonstration was attended by 30 professionals including our state congressional delegation, the heads of several local water-related agencies, local non-profits, educators and students.

Short version (below) full version

Mulch Basins Catch a Stormwater Rain Bomb (video)

Short version (below), full version

Video of a 2.5" storm on Jan 31st, 2016, which included a 3 inch/ hour burst for 15 min. That's a 10 year storm; the biggest of the season.
The video has synchronized time lapse of the inlet, storm radar, gutter cam, and graphs of rainfall intensity, gpm of rain income, run-on from roof, road, and hillside, infiltration and the mere trace of runoff. Yes, this took forever to dial in. The water income peaked at 1500 gpm, infiltration at about 1000 gpm (!). We infiltrated about 67,000 gallons in six hours…equal to 9 months consumption for the house. The whole thing was pretty amazing. I had high expectations and the performance exceeded them. Learned a lot about best practices for stormwater infiltration. Check it out:

(please subscribe to our channel, "like" and share this video; that will help enable us to keep producing original designs and content...or purchase the full version)

System specs

(preliminary numbers)

100,000 ft2 of catchment
3,500 gpm peak inflow
1,000 ft2 of simple, mulch-filled infiltration terraces, basins, and swales of a variety of designs, on a 10,000 ft2 (quarter acre) lot
Monitoring wells 8' below the surface and about 30'± horizontally from the upper infiltration basins
500-1,000± gpm of continuous infiltration capacity
12,000± gallons of surge capacity above ground
100,000± gallons of surge capacity in three feet of sandy topsoil
35,000±gallons of long term storage in the topsoil
Target capacity: infiltrate 100% of a 400-year peak rain intensity event ("rain bomb") like this one below, from an area six times the size of the property

The hydrograph for the most intense rainfall in the Flood Control Historical record for our area (1.2" in 15 minutes), on December 11th 2014. The expected recurrence interval based on pre-climate change patterns is once every 400 years. Vertical axis is inches per five minute interval.

Objectives

Help develop engineering values and best practice details for small scale, infill stormwater infiltration suitable for developed areas of California
Help increase the accuracy of estimates of possible contributions to local water and state water budgets, 1) for conservation downstream of the meter by offsetting the need for irrigation with metered water 2) for increased groundwater recharge upstream of the meter
Help increase the accuracy of estimates for the possible contribution to flood control, dry season habitat flows, etc.

Water at 177 gpm fills the first three terraces, then overflows with a two-second surge of 2000± gpm.
1240 gallons in 7 minutes only wet the first 15% of the infiltration basins. (Note: this makes 2000 gallons we've added to this small area in a week and there is still no moisture in the monitoring wells twenty feet away and 8 feet deep, indicating that the water is going down rather than sideways.)

Discussing the implications...

Later, in the rain--

Stormwater Log

Home water budget before/ after water makeover, impacts on water and climate commons (excerpt from Oasis greywater-book

California State Stormwater Strategy-Agency and Public Input Solicited

The California Water Resources Control Board is developing a strategy to optimize the management of stormwater in California: Draft Strategy to Optimize Management of Stormwater.

We suggest you e-mailthe SWRCB and ask that:
1) the SWRCB support the filling of data and best practice information gaps for simple, small scale groundwater recharge projects
2) investigate the potential benefits for development and statewide deployment of software tools to identify and prioritize stormwater management opportunities

Water Observations: Inside a Fissured Bedrock Aquifer

An accurate mental model is the basis for good design...and the best way to improve a mental model is by direct observation of water systems, natural and man made. As soon as it starts raining, head outside and observe. Be sure to poke through the surface of the leaf litter and soil. Based in part on spending a month inside a fissured bedrock aquifer in Spain, I think that most of the recharge in such formations may come from a tiny % of the area where the water concentrates, is detained, and has a high perk pathway to get underground...

Most of the increase in groundwater flow due to medium rain from countless bedrock fissures in a 400 year old horizontal well that goes 500' into the mountainside was from just one fissure (The special fissure is behind the brick dam I made above).

Water Observations: Kayaking the Santa Ynez River in August

Not many flow surges to see recently...except for the 56,000 gpm surge on the Santa Ynez we kayaked this August (!)

Stunning and surreal to see sad pond Cachuma with a pipe to pump the water over the spillway several stories above the water level…then kayak/ paddle board the river for miles on the release of a staggering quantity of crystal clear, warm drinking water…