The Potential for Beneficial Use The Potential for Beneficial Use - - PowerPoint PPT Presentation

The Potential for Beneficial Use The Potential for Beneficial Use

• f
• f Stormwater

Stormwater in Pima County in Pima County

Findings of the City/County Findings of the City/County Study on the Use of Study on the Use of Stormwater Stormwater

Evan Canfield PhD, PE Evan Canfield PhD, PE Dave Stewart EIT Dave Stewart EIT Pima County Regional Flood Control Pima County Regional Flood Control District District

‘ ‘Harvestable Harvestable’ ’ Water Water (Rainwater/ (Rainwater/Stormwater Stormwater) )

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000 10000

Area (sq mi) Harvestable Stormwater

WRRC Data USGS Gage USDA ARS Data Model Developed Model Undeveloped Regression for Developed Regression for Undeveloped

Lot Scale (< 2 ac) Neighborhood Scale (2 ac to 64 ac) Tributary Watercourse (0.1 mi

2 to ~100 mi 2)

Regional Watercourse (> ~100 mi

2)

y = 0.0734e-0.5845 log (A) R2 = 0.90 y = 0.0334e-0.3366 log (A) R2 = 0.85

Mean Monthly Rainfall Tucson Airport Mean Monthly Rainfall Tucson Airport

(Western Regional Climatic Center) (Western Regional Climatic Center)

0.5 1 1.5 2 2.5 3 Mean Monthly Rainfall (inches) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1996-2008 1961-1990

Tree Water Use Tree Water Use

Annual Estimate of Plant Water Use Annual Estimate of Plant Water Use

• Annual Water Requirement

Annual Water Requirement

• City of Tucson

City of Tucson – – Water Harvesting Water Harvesting Development Standard Development Standard

• Velvet Mesquite (30

Velvet Mesquite (30’ ’ canopy) canopy) – – 9,000 gal/yr 9,000 gal/yr

• Low Water Use Plant

Low Water Use Plant – – 20.2 inches/yr 20.2 inches/yr

• Orange Tree (Wright, U of A Extension 2000)

Orange Tree (Wright, U of A Extension 2000)

• 20

20’ ’ Canopy Canopy -

• 11,300 gal/yr

11,300 gal/yr

• 30

30’ ’ Canopy Canopy – – 25,500 gal/yr 25,500 gal/yr

Active Rainwater Harvesting Active Rainwater Harvesting

Root Zone Storage Root Zone Storage

Caliche

Water Volume in Tree Root Zone Water Volume in Tree Root Zone (3' root depth) (3' root depth)

1000 2000 3000 4000 5000 6000 7000 8000 5 10 15 20 25 30 Tree Diameter (feet)

Volume in Root Zone (gallons)

Saturation - Sandy Soils (42%) Saturation - Loamy Soils (44%) Available Water - Sandy Soils (8%) Available Water - Loamy Soils (16%)

Lot Scale Evaluation Lot Scale Evaluation (1/5 acre lot example) (1/5 acre lot example)

Right of Way

Length Lot Width Directly Connected Impervious Area Unconnected Impervious Area Pervious Area R

• a

d w a y Directly Connected Impervious Area Water Harvesting Basin

Evaluate Effectiveness of Water Harvesting Features

Conceptual Model Conceptual Model

Pervious Area (PA) Directly Connected Impervious Area (DCA) Water Harvesting Basin Unconnected Impervious Area (UA)

Storage Accounting in Basin: Storage i Storage i Storage Conceptual Representation Δ + − = ) 1 ( ) (

i

ET Rainwater Storage

i −

= Δ

(EToAZmet * Kc)

Mathematical Representation

) 8 . ( ) 2 . (

2

S P S P Q + − =

Q is the total depth of runoff (inches); P is the daily rainfall depth of precipitation (inches); S is the potential abstraction (inches) CN is the Curve Number.

10 1000 − = CN S

DCA i DCA i i DCA

xArea P CN f Q Vol )] ( (

, ) (

=

Rainwater off lot from Directly Connected:

UA i UA i i UA

xArea P CN f Q Vol )] ( (

, ) (

=

PA i PA i i PA

xArea P CN f Q Vol )] ( (

, ) (

=

Rainwater in to Water Harvesting Basin:

Data Sets Data Sets

• Daily Rainfall Data

Daily Rainfall Data – – 108 years of data 108 years of data gathered at U of A. gathered at U of A.

• Mean Daily Reference ET (

Mean Daily Reference ET (ETo ETo) ) – – from from Campbell Avenue Farm Campbell Avenue Farm

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0-Jan 30-Jan 29- Feb 30- Mar 29- Apr 29- May 28-Jun 28-Jul 27- Aug 26- Sep 26-Oct 25- Nov 25- Dec Day of Year Penman Monteith ETo (in/day)

Supplemental Water Supplied, and Supplemental Water Supplied, and Harvested Harvested Stormwater Stormwater from a from a Lotside Lotside Swale Swale

• n a 1/5 acre lot
• n a 1/5 acre lot

5 10 15 20 25 30 35 40 45 50 < 1 9 9 2

• 3

9 9 4

• 5

9 9 6

• 7

9 9 8

• 9

9 9 1

• 1

1 9 9 1 2

• 1

3 9 9 1 4

• 1

5 9 9 1 6

• 1

7 9 9 1 8

• 1

9 9 9 2

• 2

1 9 9 > 2 2

Annual Volume (cubic ft) Number of Years

Supplemental Water Provided Stormwater Harvested Range of Supplemental Water Required

Modeled Mesquite Water Requirements (ET) and Modeled Mesquite Water Requirements (ET) and Water Harvested in a Water Harvested in a Lotside Lotside Swale on a 1/5 Swale on a 1/5 acre acre-

• lot

lot

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month Average Depth (in)

Stormwater Harvested ET

Supplemental Water Supplied, and Supplemental Water Supplied, and Harvested Harvested Stormwater Stormwater from a from a Lotside Lotside Swale Swale

• n a 1/5 acre lot
• n a 1/5 acre lot

5 10 15 20 25 30 35 40 45 50 < 1 9 9 2

• 3

9 9 4

• 5

9 9 6

• 7

9 9 8

• 9

9 9 1

• 1

1 9 9 1 2

• 1

3 9 9 1 4

• 1

5 9 9 1 6

• 1

7 9 9 1 8

• 1

9 9 9 2

• 2

1 9 9 > 2 2

Annual Volume (cubic ft) Number of Years

Supplemental Water Provided Stormwater Harvested Range of Supplemental Water Required

Potential Root Zone Potential Root Zone Stormwater Stormwater Storage (for illustration purposes only) Storage (for illustration purposes only)

Acres #Lots Ret Vol (ac-ft) Ret Vol (gallons) # Trees (1) Tree/Lot 4.8 17 0.35 114,040 22.8 1.3 3.8 9 0.24 78,199 15.6 1.7 4.4 13 0.25 81,457 16.3 1.3

1 Assumes 30’ Velvet Mesquite with 5000 gallons potential storage in root zone

Low Impact Development (LID) Low Impact Development (LID)

• LID Planning

LID Planning

• Disconnect and minimize

Disconnect and minimize impervious surfaces. impervious surfaces.

• Maintain pre

Maintain pre-

• development

development waterways. waterways.

• LID Flow Paths

LID Flow Paths

• Lengthen and roughen

Lengthen and roughen

• verland flow paths.
• verland flow paths.
• LID Infiltration/ Features

LID Infiltration/ Features

• Pervious pavement.

Pervious pavement.

• Swales, filter strips.

Swales, filter strips.

• Bioretention

Bioretention. .

• Rainwater catchment

Rainwater catchment systems. systems.

• Detention basins.

Detention basins.

Source: Low Impact Development Center

Stormwater Stormwater Quality BMPS in Practice Quality BMPS in Practice at Rincon Heights Neighborhood at Rincon Heights Neighborhood

Photo: Watershed Management Group (WMG)

Native Vegetation Irrigated with Harvested Native Vegetation Irrigated with Harvested Stormwater Stormwater at Highland Vista Park at Highland Vista Park

Stormwater Stormwater Harvesting at Harvesting at KERP KERP

Water Demand and Harvested Water Demand and Harvested Stormwater Stormwater at KERP at KERP

2004 2004 2005 2005 2006 2006 2007 2007 2008 2008 Demand Demand (in acre (in acre-

• feet)

feet) 582 582 582 582 582 582 582 582 582 582 Reclaimed Water Reclaimed Water 330 330 180 180 395 395 160 160 188 188 Harvested Water Harvested Water 252 252 402 402 187 187 422 422 394 394 Annual Rainfall Annual Rainfall (in inches) (in inches) 7.60 7.60 9.57 9.57 11.81 11.81 9.78 9.78 8.67 8.67

Summary Summary

• The City/County

The City/County stormwater stormwater study found that the study found that the greatest potential for beneficial use of greatest potential for beneficial use of stormwater stormwater was at the lot and neighborhood was at the lot and neighborhood scales scales. .

• Storage is the greatest limiting factor

Storage is the greatest limiting factor in in beneficial use of beneficial use of stormwater stormwater. .

• Passive

Passive stormwater stormwater harvesting can be an harvesting can be an excellent strategy excellent strategy to supply water requirements to supply water requirements for deep for deep-

• rooted drought

rooted drought-

• tolerant plants.

tolerant plants.

• Stormwater

Stormwater harvesting is harvesting is best evaluated in terms best evaluated in terms

• f a strategy that achieves multiple benefits
• f a strategy that achieves multiple benefits

including flood control, including flood control, stormwater stormwater water quality water quality management, habitat preservation and management, habitat preservation and mitigating urban heat island effects. mitigating urban heat island effects.

Next Steps Next Steps ‘ ‘Develop Design Guidelines for Develop Design Guidelines for Neighborhood Rainwater to Neighborhood Rainwater to Encourage the Creation of Habitat Encourage the Creation of Habitat and Water Efficient Landscapes and Water Efficient Landscapes

(Demand Management Action Plan 5.1) (Demand Management Action Plan 5.1)

Next Steps Next Steps Evaluation of Street Tree Water Use Evaluation of Street Tree Water Use

Acknowledgements Acknowledgements

• Dave Stewart

Dave Stewart developed the current developed the current version of the lot scale water harvesting version of the lot scale water harvesting model and assisted with evaluation. model and assisted with evaluation.

• Irene Ogata

Irene Ogata is the City of Tucson is the City of Tucson counterpart on this study. counterpart on this study.

Questions? Questions?

http:// http://www.tucsonpimawaterstudy.com www.tucsonpimawaterstudy.com /Reports/Phase2/Stormwater.Mgt.Tech.Paper.pdf /Reports/Phase2/Stormwater.Mgt.Tech.Paper.pdf Evan Canfield Evan Canfield

evan.canfield@rfcd.pima.gov