predicting water use in urban residential...

Predicting Water Use Predicting Water Use in Urban Residential in Urban Residential

LandscapesLandscapes

R. D. Havlak, R. H. White, D. R. Chalmers, W. A. Mackay,J. C. Thomas

During the summer, it is estimated that 25 During the summer, it is estimated that 25 to 60 % of the water used by residential to 60 % of the water used by residential customers is applied to the landscape.customers is applied to the landscape.

9478

6250

3429

196

4

0 10 20 30 40 50 60 70 80 90 100

Percentage

Act

ivit

y

Aeration

Soil testing

Disease Control

Dethatching

Clippings removal

Weed Control

Insect Control

Fertilizer

Irrigation

Texas Single Family Home LawnsTexas Single Family Home LawnsMaintenance PracticesMaintenance Practices

Source: The Economic Impact of the Texas Turfgrass IndustrySource: The Economic Impact of the Texas Turfgrass Industry

Take a Look at theTake a Look at the“Whole Landscape”“Whole Landscape”

üü In urban landscapes, irrigation In urban landscapes, irrigation requirements have been determined for requirements have been determined for turfgrasses but turfgrasses but notnot for most landscape for most landscape species. (Costello et al, 2000)species. (Costello et al, 2000)

üü Evidence that homeowner irrigation Evidence that homeowner irrigation practices did practices did notnot change substantially with change substantially with changes in landscape design. changes in landscape design. (Peterson et al, 1999)(Peterson et al, 1999)

PROGRAM GOALS

• To Replace water-thirsty turf with trees and shrubs • To save time by installing low maintenance shrubs and mulch• To choose the right plant for the right place• To reduce future demand on the water utility and create

beautiful, drought tolerant landscapes.

Austin, Texas

WaterWise Landscape Rebate Program

Do Trees and Shrubs Do Trees and Shrubs Influence Water Use?Influence Water Use?

üü In typical clayIn typical clay--loam soils, most tree roots loam soils, most tree roots are usually located less than 8 to 12 are usually located less than 8 to 12 inches below the surface and grow inches below the surface and grow outward far beyond the branch tips of the outward far beyond the branch tips of the tree. (Perry, 1982)tree. (Perry, 1982)

üü Does actual landscape water use change Does actual landscape water use change substantially when trees and shrubs are substantially when trees and shrubs are added? Does actual homeowner water added? Does actual homeowner water use change?use change?

00

5050

100100

150150

200200

250250

300300

MONTHMONTH

EV

AP

OT

RA

NS

PIR

AT

ION

EV

AP

OT

RA

NS

PIR

AT

ION

Bermuda/RyegrassBermuda/Ryegrass

MesquiteMesquite

OakOak

WillowWillowF

ebFeb

Apr

Apr

Jun

Jun

Aug

Aug

Oct

Oct

Dec

Dec

FebFeb

Apr

Apr

Jun

Jun

Aug

Aug

Oct

Oct

Dec

Dec

Devitt et al. 1995Devitt et al. 1995

J. of Turfgrass Management 1:47J. of Turfgrass Management 1:47--6262

Research ObjectivesResearch Objectives

1.1. Determine if correlations exist for water Determine if correlations exist for water use between 6 landscape speciesuse between 6 landscape species

2.2. Identify water use patterns for a Identify water use patterns for a landscape and its plant componentslandscape and its plant components

3.3. Compare daily water use versus Compare daily water use versus potential evapotranspiration for a multiple potential evapotranspiration for a multiple plant species landscapeplant species landscape

Research Objectives (cont.)Research Objectives (cont.)

4.4. Establish seasonal water use coefficients Establish seasonal water use coefficients for a landscape and its plant componentsfor a landscape and its plant components

5.5. Evaluate actual water use between xeric Evaluate actual water use between xeric and mesic landscapes, trained and and mesic landscapes, trained and untrained homeowners, and 2 untrained homeowners, and 2 –– 5, 5, 8 8 –– 12, and 20+ year old landscapes 12, and 20+ year old landscapes

Research LocationsResearch Locations

Brazos County

Hidalgo County

ResearchResearchMaterials and MethodsMaterials and Methods

1.1. Texas Texas ELITEELITE ProgramProgram””EEfficient fficient LLandscape andscape IIrrigation rrigation TThrough hrough EEducation”ducation”

•• Collaborative effort with Hidalgo Co. CEACollaborative effort with Hidalgo Co. CEA--Hort and Master Gardener volunteersHort and Master Gardener volunteers

•• Evaluating actual water use by trained vs. Evaluating actual water use by trained vs. untrained homeowners with xeric and untrained homeowners with xeric and mesic landscape typesmesic landscape types


1.1. Texas Texas ELITEELITE Program (cont.)Program (cont.)””EEfficient fficient LLandscape andscape IIrrigation rrigation TThrough hrough EEducation”ducation”

Twelve (12) LandscapesTwelve (12) Landscapes

6 xeric landscapes and 6 mesic landscapes6 xeric landscapes and 6 mesic landscapes

3 response unit sites (trained)3 response unit sites (trained)3 standard practice sites (untrained) 3 standard practice sites (untrained)


2.2. Effects of Landscape Maturity on Effects of Landscape Maturity on Homeowner Water UseHomeowner Water Use

•• Collaborative effort with City of College Collaborative effort with City of College Station Station -- Water Conservation personnelWater Conservation personnel

•• Evaluate 1997 Evaluate 1997 -- 2002 water use data2002 water use dataüü 2 2 –– 5 year old landscapes5 year old landscapesüü 8 8 –– 12 year old landscapes12 year old landscapesüü 20+ year old landscapes20+ year old landscapes

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10 11 12

MONTH

WA

TER

US

E (

1000

gal

lons

)

0

5

10

15

20

25

30

35

40

PE

T (

1000

gal

lon

s) 2 - 5

8 - 12

20+

PET

Water Use Data Comparisons for 2-5, 8-12,and 20+ Year Old Landscapes (2000)

(Based on a 7000 sq. ft. landscapeand a 0.6 landscape coefficient)


3.3. Rainfall Interception by Tree CanopiesRainfall Interception by Tree Canopies

•• 3 Post Oak and 3 Live Oak trees3 Post Oak and 3 Live Oak treesüü 6 rainfall gauges randomly placed 6 rainfall gauges randomly placed

beneath canopybeneath canopyüü Data collected and gauges randomly Data collected and gauges randomly

rearranged after each rainfall eventrearranged after each rainfall eventüü 3 rainfall gauges in non3 rainfall gauges in non--canopy areascanopy areas


4.4. Soil Water Dynamics in a Landscape Soil Water Dynamics in a Landscape With Multiple Vegetation TypesWith Multiple Vegetation Types•• Location: Weslaco Ext. & Res. CenterLocation: Weslaco Ext. & Res. Center•• Soil type: Willacy fine sandy loam Soil type: Willacy fine sandy loam •• Nov. 2002: Installed 192 ECHO volumetric Nov. 2002: Installed 192 ECHO volumetric

soil moisture sensorssoil moisture sensorsØØ 64 sensor locations64 sensor locations——3 sensors/location3 sensors/locationüü 0” 0” –– 8” depth8” depth (A) (A) üü 8” 8” –– 16” depth16” depth (B)(B)üü 16” 16” –– 24” depth24” depth (C)(C)

Landscape Vegetation Types Landscape Vegetation Types EvaluatedEvaluated

üü Mature Walnut Tree/St. AugustinegrassMature Walnut Tree/St. Augustinegrass–– Measurements from 10’, 20’, and 30’ from Measurements from 10’, 20’, and 30’ from

the base of the treethe base of the tree

üü Crepe Myrtles/St. AugustinegrassCrepe Myrtles/St. Augustinegrassüü St. AugustinegrassSt. Augustinegrassüü Rose BushesRose Bushesüü Ficus HedgeFicus Hedgeüü Dwarf Yaupon HedgeDwarf Yaupon Hedge


Data Collection and AnalysisData Collection and Analysis

•• Daily soil water content (inches)Daily soil water content (inches)•• Daily soil water loss (inches)Daily soil water loss (inches)

--Soil depths = A, B, C, A+B, B+C, TotalSoil depths = A, B, C, A+B, B+C, Total--LLcc values = actual ET/potential ETvalues = actual ET/potential ET

•• Daily PET and rainfall data collected from Daily PET and rainfall data collected from nearby weather stationnearby weather station

Sensor Response to a 1.0" Rainfall Event

15

20

25

30

35

0 800 1600 2400

Time (Hours)

Vo

lum

etri

c W

ater

C

on

ten

t (%

)

Sensor #40Measurements

Sensor Response to Soil Moisture Fluctuations

2424.224.424.624.8

2525.225.425.625.8

26

0 8 16 24 32 40 48

Time (Hours)

Vo

lum

etri

c W

ater

C

on

ten

t (%

) Sensor #30Measurements

Total Increase in Soil Moisture vs.

Daily Rainfall

-1.5-1

-0.50

0.51

1.5

35 45 55 65 75

Time (Days)

So

il W

ater

L

oss

/Gai

n (I

nch

es)

LandscapeRainfall

Total Soil Water Loss vs. Potential Evapotranspiration (PET)

0

0.05

0.1

0.15

0.2

89 90 91 92 93 94 95 96 97

Time (Days)

So

il W

ater

Lo

ss (I

nch

es)

TR-10

TR-20

TR-30

SA

Landscape

PET

Total Daily Water Loss Compared to PET (Between Rainfall Events)

May 2 - May 14

0.00

0.05

0.10

0.15

0.20

0.25

0.30

122 124 126 128 130 132 134

Time (Days)

So

il W

ater

Lo

ss (I

nch

es)

TR-10

TR-20

TR-30

SA

PET


June 8 - June 13

0.00

0.05

0.10

0.15

0.20

0.25

0.30

159 160 161 162 163 164 165

Time (Days)

So

il W

ater

Lo

ss (

Inch

es)

TR-10

TR-20

TR-30

SA

PET

Soil Water Loss by Depth for St. Augustinegrass (June 8-13)

0

0.05

0.1

0.15

0.2

0.25

0.3

159 160 161 162 163 164 165

Time (Days)

So

il W

ater

Lo

ss (I

nch

es)

0"-8"

8"-16"

16"-24"

Total

PET

Soil Water Loss by Depth for Tree-30 (June 8-13)

0

0.05

0.1

0.15

0.2

0.25

0.3

159 160 161 162 163 164 165

Time (Days)

So

il W

ater

Lo

ss (

Inch

es)

0"-8"

8"-16"

16"-24"

Total

PET


June 8 - June 13

0

0.05

0.1

0.15

0.2

0.25

0.3

159 160 161 162 163 164 165

Time (Days)

Soi

l Wat

er L

oss

(Inc

hes)

FI

DY

RB

CM

PET

Landscape Coefficient Compared to PET(May 31 - June 13)

00.10.20.30.40.50.60.70.80.9

1

1 3 5 7 9 11 13

Time (Days)

PE

T (

Inch

es)

Lc

(Per

cen

t)

Lc

PET

Weekly Summation of Soil Water Loss

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

0.00 5.00 10.00 15.00 20.00 25.00

Time (Weeks)

So

il W

ater

Lo

ss (I

nch

es)

Landscape

PET

Monthly Summation of Soil Water Loss(February and March)

0

0.5

1

1.5

2

2.5

3

3.5

February March

Time (Months)

So

il W

ater

Lo

ss (

Inch

es)

TR-10TR-20

TR-30SAFI

DYRBCM

LandscapePET

Monthly Summation of Soil Water Loss(April and May)

00.5

11.5

22.5

33.5

44.5

55.5

April May

Time (Months)

So

il W

ater

Lo

ss (

Inch

es)

TR-10

TR-20

TR-30

SA

FI

DY

RB

CM

Landscape

PET

April 12, 2003April 12, 2003

Total Actual ETTotal Actual ET

April 12, 2003April 12, 2003

Actual ET 4Actual ET 4--6 pm6 pm

June 8, 2003Total ET

AcknowledgementsAcknowledgements

Funding:Funding:

üü USDAUSDA--Cooperative State Research, Cooperative State Research, Education, and Extension ServiceEducation, and Extension Service

--Rio Grande Basin Initiative Rio Grande Basin Initiative üü Texas Water Resource InstituteTexas Water Resource Instituteüü Texas Texas TurfgrassTurfgrass AssociationAssociation

AcknowledgementsAcknowledgements

Collaborations:Collaborations:

üü Weslaco Ext. and Res. Center personnelWeslaco Ext. and Res. Center personnelüü Hidalgo Co. Master Gardener volunteersHidalgo Co. Master Gardener volunteersüü Hidalgo Co. CEAHidalgo Co. CEA--HortHort (Barbara (Barbara StorzStorz))üü City of College Station personnelCity of College Station personnelüü TurfgrassTurfgrass Staff Staff –– Texas A&M UniversityTexas A&M University

predicting water use in urban residential...

Documents