Evaluation of Turf-Grass and Prairie-Vegetated 

Rain Gardens in a Clay and Sand Soil, 

Madison, Wisconsin, Water Years 2004–08 

Scientific Investigations Report 2010–5077

Prepared in cooperation with the City of Madison and Wisconsin Department of 

Natural Resources

U.S. Department of the Interior

U.S. Geological Survey
Cover: Photograph showing instrumentation used at the clay rain gardens, Madison, Wisconsin.
Evaluation of Turf-Grass and Prairie-Vegetated 

Rain Gardens in a Clay and Sand Soil, 

Madison, Wisconsin, Water Years 2004–08

By William R. Selbig, U.S. Geological Survey, and Nicholas Balster, University of

Wisconsin

Prepared in cooperation with the City of Madison and

Wisconsin Department of Natural Resources

Scientific Investigations Report 2010–5077

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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Suggested citation:

Selbig, W.R., and Balster, Nicholas, 2010, Evaluation of turf-grass and prairie-vegetated rain gardens in a clay 

and sand soil, Madison, Wisconsin, water years 2004–08: U.S. Geological Survey Scientific Investigations 

Report 2010–5077, 72 p.
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................3

Description of Study Area ...................................................................................................................3

Methods...........................................................................................................................................................4

Rain Garden Location and Construction...........................................................................................4

Hydrologic Measurements..................................................................................................................6

Precipitation..................................................................................................................................6

Evapotranspiration ......................................................................................................................6

Water Influent and Effluent........................................................................................................6

Influent..................................................................................................................................6

Effluent..................................................................................................................................8

Data Analysis................................................................................................................................8

Characterization of Soils and Vegetation .........................................................................................9

Texture and Other Soil Properties.............................................................................................9

Soil Moisture.................................................................................................................................9

Root Morphology .......................................................................................................................10

Comparison of Rain Gardens .....................................................................................................................11

Soil Properties.....................................................................................................................................11

Sand Site .....................................................................................................................................11

Clay Site.......................................................................................................................................11

Water Influent and Effluent...............................................................................................................14

Sand Site .....................................................................................................................................14

Clay Site.......................................................................................................................................16

Evapotranspiration..............................................................................................................................17

Recharge, Infiltration, and Storage .................................................................................................20

Effects of Antecedent Conditions and Precipitation Intensity on Storage ...............................22

Seasonal and Temporal Changes to Infiltration Rates .................................................................25

Sand Site .....................................................................................................................................25

Clay Site.......................................................................................................................................28

Vegetative Effects on Soil Moisture ................................................................................................31

Comparison of Soil Properties and Root Morphology ..................................................................36

Conclusions...................................................................................................................................................38

Acknowledgments.......................................................................................................................................39

References....................................................................................................................................................39

Appendix 1....................................................................................................................................................................................................................43
iv

Figures

Figure 1. Map showing location of rain garden study areas in Madison, Wisconsin ......... 3

Figure 2. Photographs showing individual plugs of various prairie species planted in

the prairie rain gardens in the A, clay site, and B, sand site ........................... 5

Figure 3. Photograph showing instrumentation used at the clay rain gardens ............... 7

Figure 4. Photograph showing instrumentation used at the sand rain gardens,

showing the turf garden setup ............................................................ 7

Figure 5. Photograph showing weather station instrumentation used for precipitation

and to estimate reference evapotranspiration .......................................... 8

Figure 6. Graph showing example calculation of average infiltration rate using

simplified falling-head technique in the sand rain gardens ........................... 9

Figure 7. Photograph showing soil-moisture sensors spaced at 20-centimeter

intervals on soil probe ..................................................................... 10

Figure 8. Cross section of soils and subsurface deposits between the turf and prairie

rain gardens in sand ........................................................................ 12

Figure 9. Cross section of soils and subsurface deposits between the turf and prairie

rain gardens in clay ........................................................................ 13

Figure 10. Graph showing precipitation totals at the clay and sand rain gardens study

sites during each study year. ............................................................ 15

Figure 11. Photograph showing accumulation of ice in downspouts draining rooftop

runoff at the clay study site ............................................................... 16

Figure 12. Graph showing annual distribution of reference evapotranspiration and

range of estimated evapotranspiration for prairie rain gardens at the sand

and clay study sites ........................................................................ 17

Figure 13. Graph showing cumulative frequency of precipitation measured at the sand

and clay study sites between water years 2004–08 .................................... 21

Figure 14A.Results of CART analysis illustrating relevant factors that determine if water

would pool in the sand rain gardens ...................................................... 23

Figure 14B.Results of CART analysis illustrating relevant factors that determine if water

would pool in the clay rain gardens ...................................................... 24

Figure 15. Boxplots showing comparison of infiltration rates by water year in the sand

rain gardens ................................................................................. 26

Figure 16. Boxplots showing comparison of infiltration rates by season in the sand rain

gardens ....................................................................................... 27

Figure 17. Boxplots showing comparison of infiltration rates by water year in the clay

rain gardens ................................................................................. 29

Figure 18. Boxplots showing comparison of infiltration rates by season in the clay soil

rain gardens ................................................................................. 30

Figure 19A.Graph showing comparison of soil moisture at 0.5, 1.25, and 2.0 feet below

land surface in the prairie-clay rain garden, May through September 2005 ......... 32

Figure 19B.Graph showing comparison of soil moisture at 0.5, 1.25, and 2.0 feet below

land surface in the turf-clay rain garden, May through September, 2005 ............ 33

Figure 20. Graph showing changes in soil moisture with increasing depth before, 1

hour, 3 days, and 6 days after flooding the prairie-clay rain garden,

September 2008.............................................................................. 34

Figure 21. Graph showing comparison of soil moisture for July 2005 and 2007 at 1.6 feet

below land surface in the turf-sand rain garden and 2.6 feet below land

surface in the prairie-sand rain garden................................................... 35
v

Tables

Table 1. List of vegetative species planted in the prairie-sand and prairie-clay rain

gardens, Madison, Wisconsin ............................................................ 4

Table 2. Summary of physical and botanical characteristics identified in the

turf-grass and prairie rain gardens in a sand soil and in a clay soil .................. 14

Table 3. Summary of influent and effluent volume measured in the turf-grass and

prairie rain gardens at the sand and clay soil study sites, water years

2004–08, Madison, Wisconsin ............................................................ 15

Table 4. Summary of water balance, after normalizing by rain-garden area, in the turf

and prairie rain gardens in sand and clay, water years 2004–08 ..................... 18

Table 5. Summary of vegetative species identified by Craig (2007) in the turf-grass

and prairie rain gardens in sand and clay and computed landscape

coefficient for estimating evapotranspiration .......................................... 19

Table 6. Comparison of observed and predicted precipitation events exceeding the

storage capacity, both above- and below-ground, in the turf- and prairie-clay

rain gardens, April through November, water years 2004–07 ........................ 20

Table 7. Statistical summary of infiltration rates in the turf-grass and prairie rain

gardens in sand and clay .................................................................. 25

Table 8. Soil-profile descriptions of the turf-clay and prairie-clay rain gardens,

October 2008 ................................................................................. 37

Table 9. Rooting dynamics below the turf-clay and prairie-clay rain gardens,

October 2008 ................................................................................. 38

Abbreviations

CART    Classification and regression tree

ET    evapotranspiration

hr    hour

K    landscape coefficient

min    minute

nmol    nanomole

NOAA   National Oceanic and Atmospheric Administration

RLD    root length density

SOM    soil organic matter

SRL    specific root length

WDNR Wisconsin Department of Natural Resources

yr    year
vi

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.09290 square meter (m2)

Volume

cubic inch (in3) 16.39 cubic centimeter

cubic foot (ft3) 0.02832 cubic meter (m3) 

Flow rate

inch per hour (in/hr) 0.0254 meter per hour (m/h)

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

Volume

cubic centimeter (cm3) 0.06102 cubic inch (in3) 

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

Density

gram per cubic centimeter (g/cm3) 62.4220 pound per cubic foot (lb/ft3) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32.

Horizontal coordinate information is referenced to the 1991 adjustment of the North American

Datum of 1983 (NAD 83/91).

Water year in USGS reports is the 12-month period October 1 through September 30. The water

year is designated by the calendar year in which it ends.
Abstract

The U.S. Geological Survey, in cooperation with a 

consortium of 19 cities, towns, and villages in Dane County, 

Wis., undertook a study to compare the capability of rain 

gardens with different vegetative species and soil types to 

infiltrate stormwater runoff from the roof of an adjacent 

structure. Two rain gardens, one planted with turf grass and 

the other with native prairie species, were constructed sideby-side in 2003 at two locations with different dominant soil 

types, either sand or clay. Each rain garden was sized to a ratio 

of approximately 5:1 contributing area to receiving area and to 

a depth of 0.5 foot. 

Each rain garden, regardless of vegetation or soil type, 

was capable of storing and infiltrating most of the runoff 

over the 5-year study period. Both rain gardens in sand, as 

well as the prairie rain garden in clay, retained and infiltrated 

100 percent of all precipitation and snowmelt events during 

water years 2004–07. The turf rain garden in clay occasionally 

had runoff exceed its confining boundaries, but was still 

able to retain 96 percent of all precipitation and snowmelt 

events during the same time period. Precipitation intensity 

and number of antecedent dry days were important variables 

that influenced when the storage capacity of underlying soils 

would become saturated, which resulted in pooled water in the 

rain gardens.

Because the rooftop area that drained runoff to each rain 

garden was approximately five times larger than the area of the 

rain garden itself, evapotranspiration was a small percentage 

of the annual water budget. For example, during water year 

2005, the maximum evapotranspiration of total influent 

volume ranged from 21 percent for the turf rain garden in clay 

to 25 percent for the turf rain garden in sand, and the minimum 

ranged from 12 percent for the prairie rain garden in clay to 19 

percent for the prairie rain garden in sand. Little to no runoff 

left each rain garden as effluent and a small percentage of 

runoff returned to the atmosphere through evapotranspiration; 

therefore, the remainder was considered recharge. During 

water year 2005, recharge was 81 to 75 percent of total 

influent volume for the prairie- and turf-rain gardens in sand 

and 87 to 78 percent for the prairie- and turf-rain gardens in 

clay, respectively. Maximum recharge volumes ranged from 

90 to 94 percent of the total influent volume in the turf and 

prairie rain gardens in sand and occurred during water year 

2004. Maximum recharge in the turf and prairie rain gardens 

in clay ranged from 89 percent during water year 2007 to 98 

percent during water year 2004. 

Median infiltration rates were an order of magnitude 

greater for rain gardens planted in sand than for those in clay, 

regardless of vegetation type. Under similar soil conditions, 

rain gardens planted with turf grass had lower median 

infiltration rates than those planted with prairie species. 

Median infiltration rates were 0.28 and 0.88 inches per hour 

in the turf and prairie rain gardens in clay, respectively, and 

2.5 and 4.2 inches per hour in the turf and prairie rain gardens 

in sand, respectively. In general, infiltration rates were greater 

during spring (April and May) and summer (June through 

August) months.

Of the six observed exceedences of the storage capacity 

of the turf rain garden in clay between April–November during 

2004–07, five were predicted by use of a combination of the 

normalized surface storage volume, the median infiltration 

rate, and an estimate of specific yield for soils under the rain 

garden to a depth equal to the uppermost limiting layer. By use 

of the same criteria, in water year 2008, when the contributing 

drainage area to the prairie rain garden in clay was doubled, 

all four observed exceedences of the total storage capacity 

were predicted. The accuracy of the predictions of when the 

total storage capacity of the rain gardens would be exceeded 

indicates that by applying measurements of the appropriate 

soil properties to rain garden design, environmental 

managers and engineers may improve the tailoring of design 

specifications of rain gardens for new or retrofitted areas.

An examination of soil structure and the root systems 

in the rain gardens in clay revealed striking differences 

between turf and prairie vegetation. Soils under the prairie rain 

garden, although they possessed the remnants of a limiting 

clay layer, appeared well-drained, whereas those under the 

turf rain garden showed marked evidence of a perched water 

table. Although roots were present in all horizons sampled 

within clay soil in the prairie rain garden, roots were limited 

to the upper A and Bt horizons within the turf rain garden. 

Collectively, these differences point to greater pedoturbation 

and soil development in the prairie rain garden in clay relative 

to the rain garden planted with turf grass. 

Evaluation of Turf-Grass and Prairie-Vegetated 

Rain Gardens in a Clay and Sand Soil, 

Madison, Wisconsin, Water Years 2004–08

By William R. Selbig, U.S. Geological Survey, and Nicholas Balster, University of Wisconsin
2 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Introduction

The adverse impacts of urbanization on stormwaterrunoff quantity and quality have been well documented (U.S. 

Environmental Protection Agency, 1983, Bannerman and 

others, 1993). When impervious area increases, precipitation 

that previously would have infiltrated into surrounding soils 

is instead collected and conveyed by hard surfaces into 

nearby receiving water bodies. Collectively, impervious 

areas introduced by traditional urban landscapes lead to more 

diverse pollutants in overland flow, reduced pollutant removal 

during overland flow, and reduced infiltration (Davis, 2005). 

By reducing the volume of runoff that would percolate into 

underlying soils under natural conditions, urban development 

can reduce the supply of groundwater that is beneficial for 

wetlands, streams, and lakes and vital for human consumption 

(Simmons and Reynolds, 1982). Traditional stormwater 

management has focused primarily on the use of detention 

ponds for reducing flood peaks and preventing localized 

flooding. Although these practices have been successful 

in reducing episodic localized flooding and improving the 

quality of runoff, they have not addressed groundwater 

recharge issues or other aspects of altered streamflow that 

negatively impact stream ecosystems and human uses (House 

and others, 1993; Pettersson, 1998; Winer, 2000; Marlin and 

others, 2002). 

As development continues to push further into our 

Nation’s landscape, controlling nonpoint sources of 

contamination, replenishing groundwater supplies, and 

protecting natural waterways have become important tasks 

for the regulatory community. Environmental managers 

are charged with developing new strategies that promote 

a balance between existing and expanding urban areas 

and the environmental challenges they impose. To this 

end, the Wisconsin Department of Natural Resources 

(WDNR) promulgated a series of performance standards 

and prohibitions with regard to nonpoint stormwater sources 

(Wisconsin Administrative Code, 2002). These standards 

are intended to be minimum benchmarks of performance 

necessary to achieve water-quantity and quality goals. 

Specifically, the standards require that new residential 

areas infiltrate 90 percent of predevelopment infiltration 

volume for an average rainfall year and that commercial 

and other nonresidential land uses infiltrate 60 percent of 

predevelopment infiltration volume (Wisconsin Administrative 

Code, 2002). 

Recent trends in urban-runoff mitigation have prompted 

technologies that focus on infiltration. One such technology, 

known as a rain garden, is a shallow depression that gathers 

runoff generated from nearby impervious surfaces and 

infiltrates that runoff into the ground. In addition to reducing 

or limiting the quantity of stormwater runoff, rain gardens 

provide some level of water-quality benefit by settling, 

filtration, adsorption, decomposition, ion exchange, and 

volatilization (Prince George’s County, 1993). Rain gardens 

are commonly used to retrofit existing urban areas, where 

land requirements often preclude larger structures. Although 

the use of rain gardens is increasing, there appears to be no 

clear consensus on how soils at a site might limit the use of 

an infiltration device. In the State of Wisconsin, an exemption 

is granted to sites that fall under the purview of infiltration 

technical standards if the infiltration rate of the soil is less 

than 0.6 in/hr (Wisconsin Administrative Code, 2002). This 

exemption limits the use of infiltration in many areas in 

Wisconsin. When expansion of the use of rain gardens and 

other infiltration devices is considered, additional information 

about soil amendments and sizing criteria is likely to reduce 

the uncertainty associated with requiring infiltration in soils 

with low infiltration rates. 

Previous studies have evaluated the infiltrative and 

water-quality benefits of rain gardens sited in various soil 

types. Results of these studies suggest rain gardens can be an 

effective way to infiltrate stormwater runoff from localized 

sources (Dietz and Clausen, 2005; Dietz and Clausen, 2006; 

Smith and Hunt, 2007). However, most of these studies 

may not have represented true field conditions, because 

underground impermeable membranes were often installed to 

seal the rain garden. This was done to capture all percolated 

water, thus ensuring accurate volumetric mass-balance 

calculations; it also disturbed the native soil structure in the 

process. Furthermore, many rain garden manuals recommend 

planting vegetation that is native to the area and do not 

consider a more commonly accepted ground cover such as turf 

grass (Prince George’s County, 1993; Wisconsin Department 

of Natural Resources, 2003; City of Lenexa, 2003). Native 

prairie vegetation has been associated with a dense root 

structure capable of growing to substantial depths below the 

ground surface. This type of vegetation is assumed to promote 

runoff interception and infiltration; however, few studies 

have verified this claim and none have examined the rooting 

character of these vegetation types within urban rain gardens. 

This lack of information about below-ground processes has 

arguably limited ability to predict the contribution of rain 

gardens to stormwater management (Eissenstat and others, 

2006). Other studies have shown that turf grasses can also 

limit overland runoff (Kussow, 1995). Steinke and others 

(2007) measured significantly lower runoff volumes from an 

experimental buffer strip planted with turf grass than those 

of an adjacent plot planted with emergent prairie vegetation; 

turf grass may be more suitable for homeowners to use due 

to cost and maintenance concerns. However, little is known 

about the interactions between the soil and the variety of plant 

species used in rain garden design. This absence of data is 

understandable given the difficulty of assessing root dynamics 

and morphology on site without destructive sampling. 

However, it limits understanding of plant-soil dynamics in rain 

gardens, including the cycling of carbon and minerals, rootwater relationships, and the thus long-term functionality of 

these bioengineered systems (Asseng and others, 1997). 

For these reasons, the U.S Geological Survey, in 

cooperation with a consortium of 19 cities, towns, and villages 

in Dane County, Wis., undertook a study to evaluate the 
Introduction 3

effectiveness of rain gardens with different soil types and 

vegetative species for infiltrating stormwater runoff. Two rain 

gardens, one planted with turf grass and the other with native 

prairie species, were constructed side-by-side in one location 

where sand was the dominant soil type and another location 

where clay was the dominant soil type. Instruments were 

installed to measure the volumetric mass balance of each rain 

garden from late 2003 through 2008. This study supports an 

ongoing effort to identify existing and new methods to reduce 

the loss of recharge to groundwater from urban areas. 

Purpose and Scope

This report documents the methods used in and the 

results from a study to determine if soil type or vegetative 

species, or both, in a rain garden have an effect on the rate 

of infiltration of stormwater runoff. Two rain gardens with 

different vegetative species and soil types were evaluated, and 

their soil and vegetative characteristics were documented. The 

controlled construction of the rain gardens and installation 

of instrumentation were important for accurate measurement 

of hydrologic, soil, and vegetative characteristics, and these 

methods are described. The capability of a water balance 

for estimating recharge at each rain garden is evaluated, and 

the storage and infiltration characteristics for different soils 

and vegetation types are compared. Finally, the results of an 

assessment of root-mass development in a limiting clay layer 

are presented. 

Description of Study Area

Madison, Wis., has a population of 208,054 (based on 

the 2000 census). The climate is typical of interior North 

America, with a large annual temperature range and frequent 

short-period temperature changes. Nearly 60 percent of the 

annual precipitation falls in May through September, and 

annual precipitation averages 31.7 in. (National Oceanic and 

Atmospheric Administration, 2005). Both rain garden study 

areas were located approximately 2 mi apart near the western 

boundaries of the city (fig. 1). 

W. Beltine Hwy

Odana Rd

Midvale Blvd

Seminole Hwy

Fish Hatchery Rd

Whitney Way

Mineral Point Rd

Cottage Grove Rd

To Milwaukee

To Sun Prairie

Commercial Ave

Winnebago To Portage To Tomah

To Janesville

CITY OF MONONA

Blair

 To Chicago Elver Park

McKenna Blvd

Williamsburg Way

Packers Ave

Northport Dr

Anderson St

Stoughton Rd

Stoughton Rd

Monona Dr

E. Washington Ave

International

Ln

To Stoughton

To Verona

Schroeder Rd 

Raymond Rd 

Dane 

County

Regional

Airport

Fordem Ave

E. Johnson St

Williamson St

E. Washington Ave

Milwaukee St

D Park St

Segoe Rd

Monroe St

Nakoma Rd

Olin Ave

Park St

John Nolen Dr

Aberg Ave

Atwood Ave

Monona

Terrace &

Convention

Center LAKE MONONA

LAKE WINGRA

CV

CV

30

90

90

90

94

94

Allen Blvd

Century Ave

W. Beltline Hwy

Whitney Way

CITY OF

MIDDLETON

 State St

To Waunakee

University of

Wisconsin

Gammon Rd

Old Sauk Rd

University Ave

Campus Dr

University Ave

University Ave University Ave

Gorham St

Q

Q

113

Pheasant Branch Rd

W. Wash. Ave

Highland

Speedway Regent St

W. Johnson St

State

Capitol

Building

LAKE MENDOTA

M

M K

W I S C O N S I N

Madison

89°30'N

43°09'W 43°03'W

89°18'N

2

2 Rain gardens in sandy soil

1

1 Rain gardens in clay soil

0 1 2 MILES

0 1 2 KILOMETERS

14

Figure 1. Location of rain garden study areas in Madison, Wisconsin.
4 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Methods

Rain Garden Location and Construction

Two geographic areas were selected in Madison, Wis., 

to represent different soil conditions. The first location had 

predominantly sandy soils and the second contained more 

clay and silt. Two rain gardens were constructed side-byside at each location in June 2003. Each rain garden received 

approximately equal amounts of runoff from the roof of a 

nearby structure. In each location, one rain garden was planted 

with turf grass and the adjacent rain garden was planted with 

native prairie vegetation. Although soils at each rain garden 

location are variable in texture, each was primarily dominated 

by soils that could be generalized as sand or clay and was 

therefore assigned a single soil type to simplify discussion. 

To clarify reference to vegetation, each rain garden will 

be referred to by vegetative species followed by the soil 

type in which it was located. The resulting rain gardens are 

subsequently called turf-sand, prairie-sand, turf-clay, and 

prairie-clay.

The city of Madison constructed the rain gardens by 

use of equipment typically available to homeowners and 

landscaping crews. Skid loaders were used to excavate all 

parent material and assisted in forming earthen berms around 

the rain garden boundaries to assure that no runoff from areas 

other than the roof entered the rain garden. Approximately 4 

to 6 in. of screened compost from the Dane County compost 

facility was mixed by use of a rototiller into parent material 

at the bottom of each rain garden. A uniform, level surface 

was approximated by use of survey equipment. Turf rain 

gardens were seeded with a grass mix of red fescue, Kentucky 

bluegrass, and perennial rye grass, then fertilized and matted. 

The prairie rain gardens were planted with dormant plugs 

spaced approximately 1 ft apart, then fertilized (fig. 2). Table 1 

details the diversity of species planted in each prairie rain 

garden.

Construction of each rain garden was completed in June 

2003; however, an extended drought during the summer of 

2003 inhibited root growth in the turf rain gardens, but by 

the following spring (2004), the grass was well established in 

both turf gardens. The prairie rain gardens did not experience 

the same retardation of vegetative growth and appeared well 

established by fall 2003. This may be a result of the use of 

dormant plantings rather than seed.

Rain gardens in sand were built next to a municipal 

maintenance garage located in the Owen Conservation Park, 

a hummocky area on the west side of Madison (fig. 1). Soils 

in this area consist of silt loam, sandy clay loam, and sandy 

loam (Natural Resources Conservation Service, 2009). The 

parent material of soils in this area consists of till typical of 

unconsolidated glacial deposits in drumlins created during 

the Wisconsin glaciation (Mickelson, 2007). Each rain garden 

received runoff from the roof of the maintenance garage. The 

total area of the roof was 1,026 ft2, and it was covered with 

asphalt composite shingles commonly found on residential 

dwellings. One-half of the total roof area (513 ft2) was directed 

into one of two downspouts draining into the turf grass or 

prairie rain gardens. Each rain garden was approximately 

100 ft2, or one-fifth the size of the roof area draining to it. 

Water was allowed to pond up to a depth of approximately 

6 in. before leaving the rain garden as discharge.

Rain gardens in clay were built next to a municipal watersupply pump house approximately 2 mi west of the sand rain 

gardens (fig. 1). Similar to the sand rain garden location, soils 

in this area range from a sandy loam to a clay loam (Natural 

Resources Conservation Service, 2009). The parent material 

of soils in this area consists of a sandy matrix of glacial 

outwash and till typical of unconsolidated glacial deposits of 

the Milton end moraine during the last part of the Wisconsin 

glaciation (Mickelson, 2007). However, excavations from 

urban development over the last decade disturbed the native 

landscape, resulting in post-construction soils that were 

heavily compacted prior to rain garden construction. Each 

rain garden received runoff from the roof of the municipal 

well house. The total area of the flat, rubber roof was 3,080 ft2

and was designed to drain equally (1,540 ft2) into one of two 

downspouts. Similar to the rain gardens in sand, the area of 

turf- and prairie-clay rain gardens was approximately one-fifth 

and one-fourth the size of the roof area draining to it (354 

and 403 ft2), respectively. Water was allowed to pond up to a 

depth of approximately 6 in. before leaving the rain garden as 

discharge.

Table 1.  List of vegetative species planted in the prairie-sand

and prairie-clay rain gardens, Madison, Wis.

Botanical name Common name

Physostegia virginiana Obedient plant

Rudbeckia subtomentosa Sweet black-eyed susan

Iris pseudacorus Yellow flag iris

Chelone glabra White turtlehead

Lobelia cardinalis Cardinal flower

Scirpus atrovirens Dark green bulrush

Scirpus validus Great bulrush

Carex typhina Common cattail sedge

Pycnanthemum virginianum Mountain mint

Silene stellata Starry campion

Aquilegia canadensis Wild columbine

Baptisia bracteata Cream wild indigo

Aster laevis Smooth aster

Monarda Wild bergamot

Schizachyrium scoparium Little bluestem

Bouteloua curtipendula Sideoats grama grass

Asclepias incarnata Swamp milkweed

Sagittaria latifolia Narrowleaf arrowhead
Methods 5

A

B

Figure 2. Individual plugs of various prairie species planted in the prairie

rain gardens in the A, clay site, and B, sand site.
6 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Hydrologic Measurements

Stormwater runoff was measured from downspouts 

leading to each rain garden (figs. 3 and 4). The locations 

of the monitoring stations are shown in figure 1. Each 

monitoring station was equipped to measure water level, 

precipitation, subsurface soil-moisture content, and reference 

evapotranspiration. Data were measured, controlled, and 

stored by electronic dataloggers. Telephone modems allowed 

for automatic retrieval of data twice daily. Storm-event 

characteristics for runoff events at each rain garden location 

are detailed in appendix tables 1–1 and 1–2.

Precipitation

Continuous precipitation data were collected at each 

rain garden location by use of tipping-bucket rain gages 

calibrated to 0.01 in. (fig. 5). Although these rain gages were 

not designed to measure snowfall, precipitation during several 

runoff events during winter months (December-March) was 

in the form of rain instead of snow. Monthly precipitation 

totals during winter months were estimated from the National 

Oceanic and Atmospheric Administration (NOAA) weather 

station at the Dane County Regional Airport in Madison, Wis. 

(National Oceanic and Atmospheric Administration, 2003–07). 

Summaries of precipitation data from the clay and sand 

rain gardens are presented in appendix tables 1–1 and 1–2, 

respectively. 

Evapotranspiration

Estimates of evapotranspiration were computed to 

characterize the volume of water lost to the atmosphere. 

To calculate reference evapotranspiration (ETo), solar 

radiation, air temperature, relative humidity, and wind 

speed were collected by use of a pyranometer, platinum 

resistance temperature detector, capacitive relative humidity 

sensor, and anemometer, respectively (fig. 5). Reference 

evapotranspiration, in millimeters, was computed every 

5 min by use of the Penman-Monteith equation (Monteith 

and Unsworth, 1990; Allen and others, 1998) and was then 

summed into hourly and daily totals. A reference surface 

closely resembles a green, well-watered grass of uniform 

height, actively growing and completely shading the ground 

(Allen and others, 1998). Both rain gardens planted with 

turf grass closely resemble a reference surface. A landscape 

coefficient of 0.95, based on published values for cool 

season grasses (Allen and others, 1998), was applied to the 

reference evapotranspiration in the turf rain gardens.Many 

of the vegetative properties, such as ground cover, canopy, 

and aerodynamic resistance in the rain garden planted with 

prairie vegetation were likely different from those in the turf 

rain gardens. Estimates of evapotranspiration in the prairie 

rain gardens were based on a range of published landscape 

coefficients for a variety of vegetative species commonly 

used in the landscaping industry. The landscape coefficient 

uses species type, density, and microclimate to estimate a 

correction factor to reference evapotranspiration (Costello and 

others, 2000). Average landscape coefficients representing 

“low” and “high” evapotranspiration were calculated for 

many of the species in the prairie rain gardens. A landscape 

coefficient (KL) for a specific vegetative species was 

determined using the following formula:

KL = Ks × Kd × Kmc (1)

where

Ks is the species factor;

Kd is the density factor; and

Kmc is the microclimate factor.

KL is then multiplied by the reference 

evapotranspiration to determine the final 

evapotranspiration for a specific vegetative 

species. A weighted average was used to 

enhance the accuracy of the representation 

of the abundance of each species identified 

in each rain garden.

Water Influent and Effluent

Influent

Stormwater runoff influent at the turf- and prairie-clay 

rain gardens was measured by means of a prerated H-flume 

and shaft encoder (fig. 3). Rooftop runoff first traveled through 

the downspout dedicated to each rain garden into a buffer tank 

that prevented turbulent flow conditions. Water levels in the 

buffer tank would raise or lower a float and counterweight 

system connected to a shaft encoder, which was calibrated to 

the nearest 0.01 ft. The shaft encoder’s point of zero flow was 

coincident with the invert of an H-flume of 0.8 ft in height. 

Water levels in the buffer tank were used to compute an 

instantaneous discharge by use of the known H-flume rating. 

Storm-runoff volumes were computed by summing the 1-mininterval instantaneous discharge over the runoff duration. 

Stormwater runoff influent at the turf- and prairie-sand 

rain gardens was measured by means of a tipping bucket and 

magnetic reed switch (fig. 4). Rooftop runoff first traveled 

through the downspout dedicated to each rain garden into a 

buffer tank. A small funnel was attached to the buffer tank 

to focus water into the tipping bucket Each tip of the bucket 

represented a known volume of water. After passing through 

the tipping bucket, runoff would flow into a drain tube leading 

into the rain garden.
Methods    7

Figure 3.  Instrumentation used at the clay rain gardens.

Datalogger

Weather station

H-flume (influent)

Soil moisture sensors

Stilling well

H-flume (effluent)

Downspout

Buffer tank

H-flume (influent)

Figure 4.  Instrumentation used at the sand rain gardens, showing the turf garden setup. 

Tipping bucket

Soil moisture sensors

H-flume (effluent)

Stilling well

Downspout

Buffer tank
8    Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Figure 5.  Weather station instrumentation used for precipitation and to estimate 

reference evapotranspiration.

Air temperature and

relative humidity

Datalogger

Wind speed and direction

Precipitation

Solar radiation

Effluent

Water level in excess of 6 in. in each rain garden was discharged as effluent. 

A 0.6-ft prerated H-flume was used to control the rate of flow (figs. 3 and 4). Water 

levels in each rain garden were measured by means of a submersible pressure 

transducer, calibrated to 0.01 ft, placed inside a stilling well made of a smalldiameter polyvinyl chloride (“PVC”) tube (figs. 3 and 4). Water level was measured 

in 0.01-ft increments above the rain garden floor. Because the invert of the 0.6-ft 

H-flume was at a known elevation above the rain garden floor, water levels above 

the flume invert were converted to an instantaneous discharge by use of the known 

H-flume rating. Storm-runoff volumes were computed by summing the 1-mininterval instantaneous discharge over the runoff duration. 

Data Analysis

Classification and regression 

trees (CART) were used to visualize a 

relation between a dependent variable 

and a set of independent variables 

(Breiman and others, 1984). A CART 

analysis was done on each rain garden 

to understand which climatologic and 

hydrologic variables might determine 

when the rain garden would pool with 

water. The dependent variable was 

qualitatively termed “wet” or “dry” to 

describe whether or not a rain garden 

pooled with water during a discharge 

event. Quantitative independent 

variables including precipitation depth, 

total event volume, antecedent dry days, 

and 15-, 30-, and 60-min precipitation 

intensities were used to describe the 

hydrologic and climatologic conditions.

During “wet” periods, an estimate 

of the rate of infiltration was computed 

by use of a simplified falling head 

technique. Consistent with Darcy’s 

Law, infiltration rates varied with depth 

(or head) of water in the rain gardens. 

To determine if infiltration rates were 

changing over the duration of the 

study period, a fixed water depth was 

used in the computational process. 

This also provided a consistent basis 

for evaluating each rain garden. After 

cessation of rainfall, infiltration rates 

were estimated based on the rate of 

falling head in the rain garden from a 

depth of approximately 0.1 ft to when 

the rain garden was no longer covered 

by water. Figure 6 shows an example 

of the estimation of infiltration rates in 

the sand rain gardens. In some cases, 

an estimate of infiltration rate was not 

possible because of additional influent 

prior to or during recession of pooled 

water in the rain garden. Estimates 

of infiltration rates were compared 

between soil types and vegetative 

species to show seasonal and temporal 

changes. Seasonal differences were 

determined by use of the nonparametric 

Mann-Whitney statistical test for two 

groups (Helsel and Hirsch, 1992). 
Methods 9

Figure 6. Example calculation of average infiltration rate using simplified falling-head technique in the

sand rain gardens.

AAXXXX_fig 01

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0

0.05

0.1

0.15

0.2

0.25

0.3

05/23/04 00:00 05/23/04 01:30 05/23/04 03:00 05/23/04 04:15 05/23/04 05:45 05/23/04 07:15 05/23/04 08:45

CUMULATIVE PRECIPITATION, IN INCHES

DEPTH OF POOLED WATER IN RAIN GARDEN, IN FEET

DATE AND TIME

Depth of water, turf-sand garden

Depth of water, prairie-sand garden

Cumulative precipitation

AVERAGE INFILTRATION RATE:

1.2 INCHES IN 0.65 HOURS = 1.85 INCHES/HOUR

3.1 INCHES/HOUR

3.0 INCHES/HOUR

Limited sample populations precluded an evaluation of winter 

and fall infiltration rates in the prairie- and turf-sand and 

prairie-clay rain gardens. Therefore, use of the Mann-Whitney 

test was limited to a comparison of spring and summer 

infiltration rates. The infiltration rates for all four seasons 

in the turf-clay rain garden were compared by use of the 

nonparametric Kruskall-Wallis and Dunn’s statistical tests for 

multiple groups (Dunn, 1964; Helsel and Hirsch, 1992).

Characterization of Soils and Vegetation

Texture and Other Soil Properties

Selection of each study location was based upon the 

presence of either sand or clay as the dominant soil texture. 

Prior to rain garden construction, a hand-powered soil auger 

was used to identify soil texture to a depth of approximately 

1 ft at each study location. In addition, regional soils maps 

were reviewed to verify soil classification at depth (Natural 

Resources Conservation Service, 2009). Infiltration rates 

were then determined at each location by use of a doublering infiltrometer. Finally, the resulting infiltration rates were 

then compared to published values typical for sand and clay 

soils (Rawls and others, 1998). In 2003, after construction of 

each rain garden was complete, a core was extracted from the 

prairie-clay and turf- and prairie-sand rain gardens to a depth 

of approximately 20 ft by use of a Geoprobe to help provide 

a depth profile of texture changes. Additional soil cores 

were taken in 2008 at multiple locations in both the turf- and 

prairie-clay rain gardens to a depth of approximately 10 ft 

to further characterize the substrate by minimizing the large 

amount of spatial variability in soil texture. All cores were 

taken during winter months when soils were frozen and less 

prone to compaction from heavy equipment. 

Soil Moisture

Within each rain garden, volumetric soil-moisture 

profiles were measured by use of vertically oriented soilmoisture sensors (fig. 7). Soil moisture was measured at 

20-cm increments to a depth of 4 ft below the rain garden. One 

sensor and its protective access tube were installed in each 

rain garden following methods described by the manufacturer 

(Sentek Party, Ltd., 1999). Proper installation of soil-moisture 

sensors and access tubes results in no air pockets along the 

length of the access tube and causes minimal disturbance of 

the adjacent soil profile (Graczyk and Greb, 2006). 
10 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Figure 7. Soil-moisture sensors spaced at 20-centimeter intervals on soil probe. The soil probe is inserted vertically

into the access tube.

AAXXXX_fig 01

Soil-moisture sensor

Soil moisture was measured at 15 cm, 35 cm, 55 cm, 75 cm, 

95 cm, and 115 cm below the land surface in the turf-clay, 

prairie-clay, and prairie-sand rain gardens. Soil moisture in 

the turf-sand rain garden was measured at 5 cm, 15 cm, 25 

cm, 35 cm, and 45 cm below the land surface. Measurements 

of soil moisture were collected at 15-min increments from 

October 2003 to January 2006 and 5-min increments from 

February 2006 to September 2008. 

Each soil-moisture sensor was periodically calibrated by 

use of methods described by the manufacturer (Sentek Party, 

Ltd., 1999). Calibration was limited to 100 percent (water) 

and 0 percent (air) saturation. Each sensor can be calibrated 

to measure the absolute volumetric moisture content of a 

specific soil type if the physical properties of that soil are 

known across a range of moisture conditions. However, given 

the destructive nature of the calibration process to determine 

absolute soil moisture values, a generalized algorithm 

developed by the manufacturer to represent sands, loams, and 

clay loams, was used in this study. Therefore, on-site soilmoisture conditions were considered a relative, rather than 

absolute, value.

Root Morphology

In October 2008, a 4.25-ft-wide by 10-ft-long observation 

trench was excavated through the approximate center of the 

prairie- and turf-clay rain gardens. The trench in the prairieclay rain garden was dug to a depth of 5 ft, while the turf-clay 

trench was excavated to only 4 ft because of standing water 

at depth; no standing water was observed in the prairie-clay 

trench. These trenches provided profile walls that were used to 

describe the physical characteristics of each soil and quantify 

rooting dynamics within each rain garden. The south wall of 

each trench was prepared by hand for soil-profile descriptions, 

subsampling, and additional on-site root measurements; care 

was taken to avoid smearing of soil surfaces. 

Soils were described according to standard protocol 

for field observation (Schoeneberger and others, 2002). 

Measurements included master and subordinate horizons, 

any changes in parent material, texture class, rooting depth, 

color, structure, and presence of mottling. After the soil profile 

descriptions were done, six discrete soil cores were extracted 

horizontally from the approximate midpoint of each horizon 
Comparison of Rain Gardens 11

along the length of the trench by use of a 5.6-in3 cylinder 

driven into random locations along the trench wall, within 

each horizon, with a hammer-core sampler (Blake and Hartge, 

2002). These samples were bagged and transported to the 

University of Wisconsin soils laboratory for measurements of 

bulk density and root morphology. An additional sample was 

taken with a hand trowel from each horizon for determination 

of soil texture. 

Two of the six soil cores per horizon were used to 

quantify bulk density and soil organic matter (SOM). In the 

laboratory, the soil cores were dried at 105°C for 24 hours and 

then weighed. Bulk density was then calculated to the nearest 

0.01 g. Soil textures were determined by use of a hydrometer 

on samples pretreated with Calgon© solution (Gee and Or, 

2002). This analysis was performed at 30°C on samples from 

each horizon with the exception of horizons O and A, due to 

the variable proportions of organics in those samples. Soil 

organic-matter contents were determined by loss on ignition, 

by use of 10 g of oven-dried soil heated at 550°C for 3 hr in an 

Isotemp muffle furnace (Heiri and others, 2001).

Root dynamics were quantified in the lab from the 

remaining four core samples per horizon. Calculations of root 

length density (RLD), specific root length (SRL), root dry 

mass, and total length were done for each horizon. Each core 

was first soaked in distilled water for 48 hr, at which time the 

cores began to naturally disperse. The cores were then lightly 

agitated by hand to liberate the roots from the soil. All visible 

roots were extracted from the soil slurry on a 0.05-mm soil 

sieve and cleaned with distilled water. The soil slurry was run 

through the sieving process a second time to ensure all roots 

were extracted from the core samples, and the roots were then 

patted dry on a paper towel. Next, the length of each root was 

measured. Last, the roots were dried at 70°C for 48 hr in a 

convection oven before determination of dry weight. 

Comparison of Rain Gardens

Hydrologic, soil, and vegetation characteristics were 

compared for the turf-clay, prairie-clay, turf-sand, and 

prairie-sand rain gardens from December 2003 to September 

2008. During the 5-year monitoring period, the sand and 

clay gardens received runoff from more than 380 and 275 

precipitation and snowmelt events, respectively (appendix 

tables 1–1 and 1–2). Measurements of runoff volume 

(both influent and effluent), precipitation, and reference 

evapotranspiration were used to determine the water balance 

for each rain garden, which, in turn, was used to estimate 

recharge. Water depth in each rain garden was measured 

to estimate infiltration rates, which were then compared to 

determine differences between vegetative species and soil type 

as well as seasonal and temporal trends. 

Soil Properties

Sand Site

Figure 8 shows a cross section of surficial deposits based 

on the turf- and prairie-sand rain garden cores to a depth of 

20 ft. The upper 4 ft of soil in the prairie rain garden generally 

contained a greater amount of clay than the turf rain garden 

and was described as a loam to clay loam rather than a sandy 

loam. A thin clay layer was found in the prairie rain garden 

core at a depth of approximately 4.5 ft. This same clay layer 

was not found in the turf rain garden. Both gardens had sandy 

loam interspersed with occasional layers of clay loam below 

5 ft. The upper 4 ft of soil in the prairie rain garden showed 

most sediments to be classified as sandy loam with some 

gravel (fig. 8). The dissimilarity between soil profiles may be 

due, in part, to rain garden construction practices. Because the 

turf rain garden was located on a hill slope, a greater amount 

of material had to be excavated to achieve a level surface. 

This likely removed some of the surficial deposits that were 

found in the prairie rain garden. A level surface was more 

easily achieved with minimal excavation in the prairie 

rain garden. The elevation of the turf grass rain garden 

(postconstruction) was 0.77 ft lower than that of the prairie 

rain garden. 

Craig (2007) investigated soil and botanical 

characteristics of both the turf- and prairie-sand rain gardens 

and their relation with microbial community composition. 

The results were then compared to those determined from 

50 additional rain gardens and lawns surveyed around Dane 

County, Wis., and are presented in table 2. The average soil 

composition from three test plots in the turf-sand rain garden 

had a higher percentage of organic matter than other surveyed 

lawns in Dane County. Similarly, porosity was higher in the 

rain gardens than in Dane County lawns, and this may have 

been a function of the higher sand content and lower bulk 

density in the rain gardens than in the Dane County lawns 

(table 2).

Clay Site

Figure 9 shows a cross section of two cores from the clay 

rain gardens. The prairie and turf cores were taken in 2003 

and 2008, respectively. The turf- and prairie-clay rain gardens 

had variable thicknesses of sand, sand loam, clay, and silt clay 

deposits. The uppermost limiting clay layer was generally 

at shallower depths in the turf rain garden, at approximately 

1.5 ft below the soil surface, compared with approximately 

3.0 ft below the soil surface in the prairie rain garden. A 

continuous clay layer of variable thickness was distributed 

across both rain gardens at a depth of 3 ft. The upper 4 ft of 

soil in the turf-clay rain garden showed most sediments to be 

classified as sandy clay, clay loam, and clay with some fine 

layers of sand and gravel (fig. 9). 
12 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Figure 8. Cross section of soils and subsurface deposits between the turf and prairie rain 

gardens in sand. AAXXXX_fig 01

Prairie-sand Turf-sand

0 0

2 2

4 4

ACE, IN FEET

6 6

DEPTH BELOW LAND SURF

8 8

10 10

12 12

14 14

16 16

18 18

20 20

EXPLANATION

Texture Significant zones

Organic rich A horizon Silty

Sand Sandy 

Sandy loam to loamy sand Gravelly or pebbly

Loam to clay loam Stone intersected while coring

Clay Organic materials

Silty clay to silt clay loam
Comparison of Rain Gardens 13

Figure 9.  Cross section of soils and subsurface deposits between the turf and prairie rain

gardens in clay.

0

Prairie-clay

2

4

6

DEPTH BELOW LAND SURFACE, IN FEET

8

10

0

Turf-clay

2

4

6

8

10

EXPLANATION

Texture

Organic-rich A horizon

Sand

Sandy loam to loamy sand

Sandy clay to sandy clay loam

Loam to clay loam

Clay

Silty clay to silty clay loam

No soil present

Significant Zones

Silty

Sandy

Gravelly or pebbly

Stone intersected while coring

Organic materials
14 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Similar to the sand rain gardens, soil and botanical 

characteristics were examined in the clay rain gardens, and 

their characteristic were then compared to those from 50 

additional rain garden and lawn surveys around Dane County, 

Wis. (Craig, 2007). The results are presented in table 2. 

The average soil composition from three test plots in the 

prairie-clay rain garden had a higher percentage of organic 

matter than surveyed lawns in Dane County. Similarly, 

porosity was higher the prairie- and turf-clay rain gardens 

than in other Dane County rain gardens; this may have been a 

function of the high sand content and low bulk density in the 

prairie- and turf-clay rain gardens than in the Dance County 

rain gardens (table 2).

Water Influent and Effluent

The main sources of influent to the rain gardens are 

rainfall and snowmelt runoff from the roof surfaces and 

rainfall falling directly onto the gardens. The water equivalent 

for snow falling directly over the rain garden was not 

included in the computation of influent, because actual snow 

depths were not recorded at the field site. During the 5-year 

monitoring period, the annual precipitation ranged from 

24 percent below the 30-year normal of 32.95 in. in 2005 to 

35 percent above normal in 2008 (fig. 10). Monitored storms 

during the period ranged in precipitation depth from less than 

0.05 in., the amount typically required for generating rooftop 

runoff, to 4.0 in. Sixty-min precipitation intensities ranged 

from 0.01 to 1.29 in/hr.

Sand Site

Annual rainfall-runoff volumes into the turf-sand and 

prairie-sand rain gardens were nearly equal during each study 

year and showed a difference in influent of 5 percent or less 

for all years (table 3). In general, the prairie-sand rain garden 

received slightly more influent volume than the turf-sand 

rain garden. Some of the added volume can be attributed to 

preferential rainfall patterns as well as a disproportionate 

amount of snowmelt to the prairie-sand rain garden owing 

to the roof’s orientation to the sun. Annual influent volumes 

were slightly less in water year 2004 than in 2007 despite 

having a greater annual precipitation depth in 2004. Much 

of this discrepancy is due to the estimated water equivalency 

Table 2.  Summary of physical and botanical characteristics identified in the turf-grass and prairie rain gardens in a sand soil

and in a clay soil. 

[Soil characteristics represent average values from three test plots per rain garden. Comparison of features in the study rain gardens was made to other 

rain gardens surveyed around Dane County, Wis. --, data not available; nmol, nanomole]

Sand site Clay site Dane County1

Physical and biological variables Prairie Turf grass Prairie Turf grass Rain garden Lawn

Age of rain garden, in years 3 3 3 3 2 --

Area of rain garden, in square feet 92.5 85.5 403 354 280 --

Organic matter, in percent 14.3 18.5 17.6 26.4 7.5 5.4

Bulk density, in grams per cubic centimeter 0.83 0.59 0.61 0.56 1.1 1.2

Pore space, in percent 69 76 77 80 61 56

Water content, in percent 21 23 22 37 26 24

Soil air, in percent 48 52 55 43 35 33

pH 7.2 7.0 7.1 7.1 6.2 6.6

Particle size distribution, in percent

Sand 45 59 50 47 37 35

Clay 16 15 14 14 16 16

Silt 39 26 37 39 47 49

Soil texture Loam Sandy loam Loam Loam Loam Loam

Vegetation richness, in number of plant species 29 10 39 21 34 --

Vegetation cover, in percent 60–70 85 100 100 63 --

Total microbial biomass, in nmol of lipids per gram of soil 199 209 209 194 174 131

Relative abundance of bacteria, in mole percent 23 29 24 31 25 28

Relative abundance of fungi, in mole percent 20 9 21 10 20 17

1

Average value of 50 gardens in Dane County, Wis. (Craig, 2007).
Comparison of Rain Gardens 15

Figure 10. Precipitation totals at the clay and sand rain gardens study sites during each study year. The 30-year

(1971–2000) normal precipitation line shown above is based on precipitation measured at the Dane County Regional

Airport in Madison, Wis., approximately 10 miles from the study area.

Table 3.  Summary of influent and effluent volume measured in the turf-grass and prairie rain gardens at the sand and clay soil

study sites, water years 2004–08, Madison, Wis.

[--, data not available; values represent volumes into and out of rain garden from roof and direct precipitation; they include snowmelt for runoff but do 

not include water equivalent for snow falling directly on rain garden. Therefore, the volumes in this table and those presented in table 4 will be different 

because table 4 includes estimates of water equivalent for snow using available NOAA data]

Volume

(cubic feet)

Influent Effluent

Rain Garden 2004 2005 2006 2007 2008 2004 2005 2006 2007 2008

Turf-sand 1,279 749 1,142 1,341 2,1571 0 0 0 0 111

Prairie-sand 1,275 764 1,206 1,354 -- 0 0 0 0 --

Percent difference 0 -2 -5 -1 -- 0 0 0 0 --

Turf-clay 5,436 2,923 4,247 5,198 -- 191 35 10 12 --

Prairie-clay 5,859 2,423 3,608 4,437 8,3311 0 0 0 0 1381

Percent difference -7% 21% 18% 17% -- 100% 100% 100% 100% --

1

 In water year 2008, all roof runoff was directed to the turf-sand and prairie-clay rain gardens. This doubled the ratio of contributing to receiving area 

to 10 to 1 and 8 to 1, respectively.

2004 2005 2006 2007 2008

PRECIPITATION AT RAIN GARDENS AND DANE COUNTY 

REGIONAL AIRPORT, IN INCHES

WATER YEAR

Sand rain gardens

Clay rain gardens

Dane County Regional Airport

30-year normal precipitation

0

10

20

30

40

50

60
16 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Figure 11. Accumulation of ice in downspouts draining rooftop runoff at

the clay study site.

of snowmelt during winter months. If the months of the year for 

which precipitation was estimated by use of data from the NOAA 

weather station at the Dane County Regional Airport in Madison, Wis. 

(December through March) are excluded, then total precipitation in 

water year 2007 was, in fact, greater than in 2004. 

There were no monitored precipitation events during the initial 

phase (2004–07) of the study that exceeded the storage capacity 

of either the turf-sand or prairie-sand rain gardens; therefore, all 

runoff was infiltrated and stored, lost to the atmosphere through 

evapotranspiration, or recharged. In water year 2008, all runoff was 

directed to only the turf-sand rain garden. Despite this doubling of 

the contributing drainage area, only a single event on June 8, 2008, 

produced measurable effluent in the turf-sand rain garden (table 3). 

Some events prior to June 8 had similar precipitation depths and 

intensities, but they did not result in effluent discharge. The interval 

between these storms was long enough to allow soils to drain. 

Therefore, the effluent discharge that resulted from the June 8 event 

was likely due to a combination of not only high 

precipitation intensity and depth but also saturated 

soil conditions from previous events. Rainfall on 

consecutive days from June 5 through June 8 totaled 

more than 5 inches. 

Clay Site

Annual runoff volumes into the turf-clay rain 

garden were approximately 20 percent greater than 

the prairie-clay rain garden for all but 1 study year 

(table 3). It is unclear why more rooftop runoff 

was measured in the turf-clay rain garden. One 

possible explanation is the buildup of precipitation 

due to prevailing winds. Although each downspout 

drained an equal amount of rooftop area, prevailing 

westerly winds had the potential to push some water 

from the roof area draining to the prairie-clay rain 

garden over to the roof area draining to the turfclay rain garden. Differences in measured annual 

influent volumes could also be attributed to the 

downspout design. Each downspout had an open 

face that allowed runoff to occasionally escape the 

channel walls. This small amount of runoff was 

not collected or measured by the H-flumes and, 

thus, was unaccounted for. This phenomenon was 

more pronounced during winter months when the 

downspout channel would fill with ice (fig. 11) 

than during other seasons. Much of the water 

from melting ice was not contained within the 

downspout channel walls. Although each downspout 

had this design limitation, it may have been more 

pronounced in the downspout draining to the 

prairie-clay rain garden. 

The turf-clay rain garden had one or more 

precipitation or snowmelt events or both resulting 

in a measureable volume of runoff leaving the rain 

garden during each study year (table 3). In most 

instances, effluent volume was a result of high 

precipitation intensity or depth or both. Nearly 

one-half of all effluent volume measured from the 

turf-clay rain garden was the result of two storm 

events in May 2004 that produced 4.7 in. of rain 

within 48 hours (appendix table 1–2). There were no 

monitored events during the initial phase (2004–07) 

of the study that exceeded the storage capacity of 

the prairie-clay rain garden; therefore, all runoff was 

infiltrated and stored, lost to the atmosphere through 

evapotranspiration, or recharged. During water year 

2008, all runoff was directed to only the prairieclay rain garden, thereby doubling the contributing 

drainage area. All effluent volume measured during 

this period was a result of four precipitation events, 

each with precipitation depths in excess of 2.5 in. 

(appendix table 1–2).

AAXXXX_fig 01
Comparison of Rain Gardens 17

Figure 12. Annual distribution of reference evapotranspiration and range of estimated evapotranspiration for prairie

rain gardens at the sand and clay study sites.

Evapotranspiration

In general, reference evapotranspiration followed a 

seasonal pattern of the highest monthly totals occurring during 

the warmer summer months of June and July, followed by 

gradually decreasing values with the onset of plant senescence 

in late fall (fig. 12). Because the turf grass evaluated as 

part of this study closely resembled that of a reference 

surface, estimated evapotranspiration values were only 

slightly modified (Allen and others, 1998). Several species 

identified in the prairie rain gardens were given a landscape 

coefficient ranging from “low” to “high.” Regardless of soil 

type, resulting correction coefficients for prairie vegetation 

were lower than those for turf grass; therefore, estimates of 

evapotranspiration were also lower. 

Annual evapotranspiration for turf grass ranged from 21 

to 26 in. in the sand and clay rain gardens for water years 2004 

and 2005, respectively (table 4). This accounts for more than 

one-half of direct annual precipitation. Evapotranspiration was 

greater than direct precipitation in 2005, which is a result of 

below-normal precipitation. Steuer and Hunt (2001) reported 

similar average annual evapotranspiration amounts (23.9 in) 

for the watershed in which this study was located, based on 

hydrologic model simulations from 1993 to 1998. Because 

the contributing drainage area to each rain garden was 

approximately five times greater than the receiving area, the 

percentage of turf-grass evapotranspiration, when compared 

to direct precipitation plus influent, ranged from a low of 9 in 

2004 to a high of 21 in 2005 for the clay rain garden, and from 

a low of 11 in 2004 to a high of 25 in 2005 for the sand clay 

garden (table 4). The percentage of evapotranspiration was 

reduced to 7 percent in water year 2008, when the contributing 

drainage area to the turf-sand rain garden was doubled to 

approximately 10 times the receiving area (table 4). 

Differences in leaf anatomy, stomatal characteristics, 

density, and aerodynamic properties of vegetation can 

cause differences in evapotranspiration (Allen and others, 

1998). Microclimate can also be important. Table 5 lists 

several species of vegetation identified by Craig (2007) in 

the prairie rain gardens and presents a correction coefficient 

to reference evapotranspiration based on species, density, 

and microclimate. Bare ground was the largest percentage 

of ground cover (or lack thereof) in the prairie-sand rain 

garden. Water may be lost from soil evaporation when ground 

shading is less than 100 percent. Consequently, the reference 

evapotranspiration rate for bare soils was increased by 10 to 

20 percent (Costello and others, 2000). The weighted-average 

landscape coefficient, KL, for all identified species ranged 

from 0.5 to 0.7 for the prairie-sand garden to 0.2 to 0.5 for the 

prairie-clay garden. These values agree with similar landscape 

coefficients for prairie vegetation recorded by Pitt and others 

(2008). By use of this range of landscape coefficients, the 

annual evapotranspiration for the prairie rain gardens was 

estimated to range from 2 percent in 2004 to 12 percent in 

2005 for the clay rain gardens, and from 6 percent in 2004 

to 19 percent in 2005 for the sand rain gardens (table 4). 

The percentage of evapotranspiration in the prairie-clay 

rain garden decreased in water year 2008, ranging from 1 to 

4 percent, when the contributing drainage area was doubled to 

approximately eight times the receiving area (table 4).

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

EVAPOTRANSPIRATION, IN INCHES

MONTH

AVERAGE MONTHLY PRAIRIE VEGETATION EVAPOTRANSPIRATION 

WATER YEARS 2004–2008 

Prairie-sand (low)

Prairie-sand (high)

Prairie-clay (low)

Prairie-clay (high)

Reference evapotranspiration
18 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08 Table 4.  Summary of water balance, after normalizing by rain-garden area, in the turf and prairie rain gardens in sand and clay, water years 2004–08. [Total annual outputs of evapotranspiration, effluent, and recharge are represented as a percentage of total annual inputs of precipitation and influent. <, less than; --, not measured] SAND RAIN GARDENS Volume of inputs and outputs (inches) Percentage of total inputs Influent Effluent Evapotranspiration Recharge Effluent Evapotranspiration Recharge Water Year Precipitation Turf Prairie Turf Prairie Turf Prairie Turf Prairie Turf Prairie Turf Prairie Turf Prairie 2004 43 141 127 0 0 21 11–15 165 155–159 0 0 11 6–9 90 91–94 2005 25 82 76 0 0 26 14–19 80 82–87 0 0 25 14–19 75 81–86 2006 38 127 124 0 0 24 13–18 141 144–149 0 0 15 8–11 85 89–92 2007 41 150 137 0 0 25 13–18 164 159–165 0 0 13 7–10 86 90–93 20081 43 269 -- 2 -- 23 -- 282 -- <1 -- 7 -- 91 -- CLAY RAIN GARDENS Volume of inputs and outputs (inches) Percentage of total inputs Influent Effluent Evapotranspiration Recharge Effluent Evapotranspiration Recharge Water Year Precipitation Turf Prairie Turf Prairie Turf Prairie Turf Prairie Turf Prairie Turf Prairie Turf Prairie 2004 40 184 174 7 0 21 4–10 188 204–211 3 0 9 2–4 84 95–98 2005 25 99 72 1 0 26 5–13 97 84–92 1 0 21 5–12 78 87–95 2006 38 144 107 0 0 23 5–12 158 134–141 <1 0 13 3–7 87 92–97 2007 42 176 132 0 0 23 5–12 194 162–169 <1 0 11 2–6 89 93–97 20081 44 -- 245 -- 5 -- 5–11 -- 274–281 -- 2 -- 1–4 -- 94–97

1In water year 2008, all roof runoff was directed to the turf-sand and prairie-clay rain gardens. This doubled the ratio of contributing to receiving area to 10 to 1 and 8 to 1, respectively.
Comparison of Rain Gardens 19

Table 5.  Summary of vegetative species identified by Craig (2007) in the turf-grass and prairie rain gardens in sand and clay and

computed landscape coefficient for estimating evapotranspiration (Costello and others, 2000).

[--, data not available; Ks, species factor; Kd, density factor; Kmc, microclimate factor; KL, landscape coefficient]

SAND SITE

Plant species 

in plots

Percent cover Low range High range

Plot 1 Plot 2 Plot 3 Weighted 

average

Ks Kd Kmc KL Ks Kd Kmc KL

Bare ground 64 16 32 36 -- -- -- 1.1 -- -- -- 1.2

Carex vulpinoidea 8 1 .5 2 0.4 0.5 0.5 .1 0.6 0.9 0.9 .5

Hierochloe odorata 8 0 0 2 .4 .5 .5 .1 .6 .9 .9 .5

Schizachyrium 

scoparium

0 4 8 3 .4 .5 .5 .1 .6 .9 .9 .5

Tradescantia 

ohiensis

4 2 0 1 .4 .5 .5 .1 .6 .9 .9 .5

Penstemon 

digitalis

16 16 4 11 .4 .5 .5 .1 .6 .9 .9 .5

Monarda fistulosa 4 64 16 27 .4 .5 .5 .1 .6 .9 .9 .5

Rudbeckia 

subtomentosa

8 0 8 4 .4 .5 .5 .1 .6 .9 .9 .5

Eupatorium 

perfoliatum

0 8 0 1 .4 .5 .5 .1 .6 .9 .9 .5

Cirsium arvense 1 0 4 1 .4 .5 .5 .1 .6 .9 .9 .5

Lactuca scariola 0 2 8 2 .4 .5 .5 .1 .6 .9 .9 .5

Glechoma 

heterophylla

0 4 32 11 .1 .5 .5 .0 .3 .9 .9 .2

CLAY SITE

Plant species 

in plots

Percent cover Low range High range

Plot 1 Plot 2 Plot 3 Weighted 

average

Ks Kd Kmc KL Ks Kd Kmc KL

Bare ground 0.5 0.5 1 1 -- -- 0.5 1.1 -- -- 0.9 1.2

Panicum virgatum 16 0 0 5 0.4 1.1 .5 .2 0.6 1.3 .9 .7

Iris versicolor 0 0 16 5 .1 1.1 .5 .1 .3 1.3 .9 .4

Carex lupilina 16 0 16 10 .4 1.1 .5 .2 .6 1.3 .9 .7

Scirpus atrovirens 0 8 0 3 .7 1.1 .5 .4 .9 1.3 .9 1.1

Rudbeckia 

subtomentosa

4 0 4 2 .4 1.1 .5 .2 .6 1.3 .9 .7

Physostegia virginica 7 0 0 2 .4 1.1 .5 .2 .6 1.3 .9 .7

Thalictrum 

dasycarpum

.5 .5 5 2 .4 1.1 .5 .2 .6 1.3 .9 .7

Helenium autumnale 16 64 0 26 .1 1.1 .5 .1 .3 1.3 .9 .4

Aster novae-angliae 4 2 0 2 .4 1.1 .5 .2 .6 1.3 .9 .7

Lysimachia 

quadriflora

0 0 16 5 .7 1.1 .5 .4 .9 1.3 .9 1.1

Poa pratensis 32 0 8 13 .4 1.1 .5 .2 .6 1.3 .9 .7

Erigeron 

philadelphicus

0 0 64 21 .1 1.1 .5 .1 .3 1.3 .9 .4

Lactuca serriola 1 2 0 1 .4 1.1 .5 .2 .6 1.3 .9 .7

Taraxacum officinale 8 0 0 2 .1 1.1 .5 .06 .3 1.3 .9 .4

Chenopodium album 0 0 4 1 0.4 1.1 0.5 0.2 0.6 1.3 0.9 0.7
20 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Recharge, Infiltration, and Storage

Recharge was estimated by use of the water-balance 

formula:

R = P + Vi – Vo – ET (2)

where

R is recharge, in inches;

P is precipitation, in inches;

Vi is the volume of runoff into the rain garden, 

in inches;

Vo is the volume of runoff out of the rain garden, 

in inches; and

ET is evapotranspiration, in inches. 

Table 4 shows the amount of water for each variable 

described in the formula above as well as the relative 

percentage of water outputs to inputs. For comparison, 

volumes in table 4 were normalized by rain-garden area. Rain 

gardens planted with prairie vegetation are expressed in terms 

of a range of low to high recharge to coincide with a similar 

range in evapotranspiration. At both the sand and clay study 

sites, the rain garden planted with turf grass received slightly 

more annual influent than the rain garden planted with prairie 

vegetation. Although more water was available for recharge 

in the turf-grass rain gardens, the overall percentage of annual 

recharge in the turf-grass rain gardens was slightly less than in 

the prairie rain gardens. This is largely attributable to a much 

smaller amount of evapotranspiration estimated for prairie 

species than for turf species. If rooftop runoff were equally 

distributed between the turf-grass and prairie-rain gardens, the 

difference in percent recharge between turf grass and prairie 

vegetation would become even greater. 

Differences in annual recharge between the turf-grass 

and prairie-rain gardens in clay were slightly greater than the 

differences between those vegetative species in sand. The 

average difference between percent annual recharge in the turf 

grass and prairie rain gardens in clay was 7 percent compared 

to 4 percent in sand (using the lower estimate of annual 

percent recharge for the prairie rain gardens). Differences in 

vegetation may therefore have a more pronounced effect on 

recharge given similar soil structure.

In general, each rain garden, regardless of vegetation 

or soil type, was capable of storing and infiltrating most of 

the runoff during the 5-year study period. This might suggest 

that use of a specific vegetative species in a rain garden has 

no bearing on its overall performance. However, the robust 

design of the rain gardens tested in this study may have been 

the primary reason for their success. A simple calculation was 

done to characterize the approximate size of storm required 

to exceed the storage capacity of each rain garden. Assuming 

zero infiltration, the minimum depth of precipitation required 

to fill the turf- and prairie-clay rain gardens would be 

approximately 1.4 and 1.6 in, respectively. Both rain gardens 

in sand would require approximately 1.2 in. of precipitation. 

Total storm precipitation (excluding snowfall) exceeded 

these thresholds approximately 10 percent of the time over 

4 years in both the clay and sand rain gardens (fig. 13). A rain 

garden construction by use of a 5-to-1 ratio of contributing 

to receiving area (4 to 1 for the prairie-clay rain garden) 

was, therefore, fully capable of retaining approximately 

90 percent of all precipitation events. However, because the 

water-retaining capacity of a rain garden is both a function of 

above- and below-ground storage of runoff from a source area 

as well as simultaneous infiltration of runoff, the capacity to 

store runoff from a precipitation or snowmelt event or both 

is beyond that suggested by ponding depth alone. Because 

Table 6.  Comparison of observed and predicted precipitation events exceeding the storage capacity, both above- and belowground, in the turf- and prairie-clay rain gardens, April through November, water years 2004–07.

Storage volume

(inches)

Median infiltration 

rate (inches/hour)

Number of events exceeding 

rain-garden storage

Rain garden Above ground Below ground Inches/hour Predicted Observed

Turf 1.36 0.6 0.28 6 5

Prairie 1.57 1.34 .88 1 0
Comparison of Rain Gardens 21

of infiltration, an even greater amount of precipitation would 

likely be retained and infiltrated over time if the precipitation 

intensity were equal to or less than the median infiltration rates 

listed in table 6. During April through November 2004–07, 

only 3 measured precipitation events in the prairie-clay 

rain garden and 13 in the turf-clay rain garden had 60-min 

precipitation intensities greater than the median infiltration rate 

as well as precipitation depths greater than the minimum depth 

required to exceed rain-garden storage capacity (assuming 

zero infiltration). There were no precipitation events in the 

sand rain gardens that satisfied the same criteria. 

Additional runoff volume can also be temporarily 

stored by the soils below a rain garden to a depth equal to the 

uppermost limiting layer. The volume of these void spaces in 

the soil, the drainable porosity (or specific yield), may have 

more influence on a rain garden’s ability to temporarily store 

runoff than the ponding depth. The specific yield is the ratio of 

the volume of water that drains from a saturated soil owing to 

the attraction of gravity to the total volume of the soil (Fetter, 

2001). By use of the same calculations previously described, 

an estimate was made of the volume of water needed to 

saturate the soils below the turf- and prairie-clay rain gardens. 

The volume, after normalizing by rain garden and contributing 

rooftop area, was then compared to individual precipitation 

events that equaled or exceeded the soil volume and resulted 

in pooled water. The approximate depth of soil down to the 

uppermost limiting layer, based on soil-core descriptions, 

was 1.5 and 3 ft for the turf- and prairie-clay rain gardens, 

0

0

10

20

30

40

50

60

70

80

90

100

0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5

CUMULATIVE FREQUENCY, IN PERCENT

PRECIPITATION DEPTH, IN INCHES

Sand rain gardens

Clay rain gardens

Figure 13. Cumulative frequency of precipitation measured at the sand and clay study sites between water years 2004–08.
22 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

respectively (fig. 8). Soils down to these respective depths 

ranged from sand to sandy clay. An average soil texture of silt 

was selected to approximate the full range of specific yield 

in the gardens. Specific yield for unconsolidated silt deposits 

was estimated to be 18 percent based on published values 

(Johnson, 1967). By use of these parameters, the volume of 

runoff from the rooftop combined with the amount of direct 

precipitation required to saturate the turf- and prairie-clay 

rain gardens was 0.61 and 1.34 in., respectively. The number 

of precipitation events equal to or exceeding these thresholds 

was summed for April through November 2004–07. Fortysix of the 62 precipitation events equal to or exceeding 0.61 

in. resulted in pooled water in the turf-clay rain garden. In 

the prairie-clay rain garden, 11 out of 17 precipitation events 

equal to or exceeding 1.34 in. resulted in pooled water. The 

total storage capacity of each rain garden would be a sum 

of storage both above and below ground. Table 6 details the 

quantities of each variable used to predict when the total 

storage capacity of the turf- and prairie-clay rain gardens 

would be exceeded and compares them to the observed 

number of events that exceeded storage capacity during April 

through November 2004–07. Of the six observed precipitation 

events exceeding the turf-clay rain garden total storage 

capacity, five were predicted using the values in table 6. 

Similarly, a single precipitation event was predicted to exceed 

the total storage capacity of the prairie-clay rain garden and 

none was observed. The criteria used to create table 6 were 

then applied to the prairie-clay rain garden in water year 2008, 

when the contributing drainage area was doubled. Four out of 

four predicted precipitation events exceeding the total storage 

capacity of the prairie-clay rain garden were observed.

Many design manuals promote the area of a rain garden 

as an important variable for accepting runoff, emphasizing 

the ratio of drainage area to receiving area. Oftentimes, those 

space requirements cannot be met or poor soil conditions 

preclude the location of a rain garden in an area where 

space may be available. If surficial area is unavailable, then 

storage of runoff can be created by excavating to a greater 

depth, even in the presence of clay. In the prairie-clay rain 

garden, for example, the time required to go from saturated 

to pre-event soil-moisture conditions could range from 

approximately 7 to 34 hr, well below the 48 hr commonly 

prescribed as a design specification for standing water. This 

estimate assumes an infiltration rate in the limiting clay layer 

of 0.04 to 0.20 in/hr (Hillel, 1982). Sixty-eight percent of all 

precipitation events measured during April through November 

2004–07 had an antecedent dry period greater than 34 hr. By 

applying measurements of the appropriate soil properties, 

environmental managers and engineers may improve the 

tailoring of design specifications of rain gardens for new or 

retrofitted areas.

Effects of Antecedent Conditions and 

Precipitation Intensity on Storage

The lack of appreciable effluent from the turf and prairievegetated rain gardens is a function of the above- and belowground storage capacity of the rain garden and the infiltration 

rate of the underlying soils. If the supply rate of water to the 

rain garden is greater than the infiltration rate, excess water 

will accumulate in the rain garden and eventually become 

runoff when the level of water exceeds the height of the rain 

garden berm. Although effluent discharge was rare, there 

were multiple times when influent exceeded infiltration into 

underlying soils and resulted in pooled water.

Results from the CART analysis of climatologic 

variables and the presence of pooled water indicated that 

60-min precipitation intensity largely determined whether 

or not water would pool in both the turf- and prairie-sand 

rain gardens (fig. 14A). Most discharge events that produced 

“wet” conditions were from high-intensity precipitation 

events of greater than 0.24 in/hr. The high saturated hydraulic 

conductivity of sand allows water to infiltrate quickly, 

oftentimes exceeding the rate at which water would discharge 

into the rain garden. However, as the rate of water influent to 

the rain garden exceeded the infiltration rate, water would be 

stored above ground within the rain-garden boundaries. Of the 

few discharge events producing “wet” conditions from low 

intensity events, all were a result of saturated soils from recent 

events. 

Similar to the sand rain gardens, both precipitation 

intensity and the number of antecedent dry days between 

precipitation events were important factors that controlled 

when water would pool in the turf-clay and prairie-clay rain 

gardens (fig. 14B). As in the sand rain gardens, the results of 

the CART analysis were similar for both vegetation types. 

The low saturated hydraulic conductivity of clay would 

require considerably more time between precipitation events 

to drain than sand. Subsequently, most “wet” conditions in 

both the turf-clay and prairie-clay rain gardens were a result 

of precipitation within the last 5 days. Similarly, Ishtok 

and Boersma (1986) concluded that antecedent moisture is 

more important than the magnitude or intensity of rainfall in 

controlling the occurrence of runoff. Pitt and others (1999) 

found infiltration rates in clay were affected by a strong 

interaction of compaction and moisture. Antecedent moisture 

could act as a surrogate for antecedent dry days, because 

soil moisture would decrease with increasing time between 

precipitation events. Secondary to antecedent dry days was 

precipitation intensity. All “wet” conditions in the prairie-clay 

rain garden were a result of not only a short amount of time 

between precipitation events but also precipitation intensity 

greater than approximately 0.3 in/hr. This condition was also 

true in the turf-clay rain garden, although the relation was not 

quite as strong. 
Comparison of Rain Gardens 23

Turf

SAND RAIN GARDENS

Prairie

74%

26%

60%

4%

43%

4%

17%

0%

Dry time (days)

14%

22%

10%

7%

4%

15%

60-minute precipitation 

intensity (in/hr)

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

60%

4%

48%

4%

12%

0%

Dry time (days)

20%

16%

12%

6%

Storm volume (ft3

)

Storm volume (ft3

)

80%

20%

8%

9%

60-minute precipitation 

intensity (in/hr)

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

< 0.24

> 0.24

< 5.7

> 5.7

< 0.24

> 0.24

< 6.8

> 6.8

< 24

> 24

< 25

> 25

Node: 3

Size: 101

Node: 1

Size: 280

Node: 2

Size: 179

Node: 4

Size: 131

Node: 1

Size: 232

Node: 2

Size: 149

Node: 4

Size: 122

Node: 5

Size: 27

Node: 6

Size: 43

Node: 3

Size: 83

Node: 7

Size: 40

Node: 5

Size: 48

Node: 6

Size: 48

Node: 7

Size: 53

Figure 14A. Results of CART analysis illustrating relevant factors that determine if water would pool in the sand rain gardens.

(%, percent; in/hr, inches per hour; <, less than)
24 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

< 5

< 0.29

> 0.29

< 0.29

> 0.29

< 0.3

> 0.3

< 5

> 5

< 93

> 93

> 5

Node: 1

Size: 198

Node: 2

Size: 112

Node: 3

Size: 86

Node: 7

Size: 26

Node: 6

Size: 60

Node: 5

Size: 37

Node: 1

Size: 241

Node: 2

Size: 144

Node: 4

Size: 97

Node: 5

Size: 47 Node: 6

Size: 67

Node: 7

Size: 30

Node: 3

Size: 97

Node: 4

Size: 75

CLAY RAIN GARDENS

Turf 

Prairie

63%

37%

32%

25%

29%

9%

3%

16% 

31%

12%

28%

3%

4%

10%

Storm volume (ft3

)

Dry time (days)

60 minute precipitation 

intensity (in/hr)

60 minute precipitation 

intensity (in/hr) 60 minute precipitation 

intensity (in/hr)

89%

11%

52%

8%

40%

0%

12%

8%

37%

3%

27%

1%

10%

2%

Dry time (days)

WET

DRY

WET

DRY

WET

DRY

WET

DRY

WET

DRY

Figure 14B.  Results of CART analysis illustrating relevant factors that determine if water would pool in the clay rain gardens.

(%, percent; in/hr, inches per hour; <, less than)
Comparison of Rain Gardens 25

Seasonal and Temporal Changes to Infiltration 

Rates

Infiltration rates were estimated at each rain garden 

by use of a simplified falling head technique. Estimates of 

infiltration rates for soil types and vegetative species were 

compared to discern seasonal and temporal changes. Median 

infiltration rates in sand rain gardens were greater than those 

in clay, regardless of vegetative species. Furthermore, in 

both sand and clay, prairie rain gardens had higher median 

infiltration rates than turf rain gardens. In general, infiltration 

rates were higher during spring and summer than fall and 

winter for all rain gardens.

Sand Site

Table 7 shows the number of discharge events producing 

pooled water during each water year as well as a statistical 

summary of estimated infiltration rates during the study 

period. Median infiltration rates in the prairie-sand rain 

garden are greater than in the turf-sand rain garden at 4.2 

and 2.5 in/hour, respectively. The large standard deviation 

in the prairie-sand rain garden suggests greater variability in 

infiltration rates (fig. 15). At the beginning of the study, the 

prairie-sand rain garden had a greater number of discharge 

events that resulted in pooled water than did the turf-sand 

rain garden (table 7). That may have been a function of the 

structure of the soil and immature root development of the 

prairie vegetation shortly after planting. The upper 4.5 ft of 

soil in the prairie-sand rain garden contained greater amounts 

of clay and silt than the turf-sand rain garden. Destruction of 

the natural soil matrix as well as removal of mature vegetation 

during rain-garden construction in the sand study area may 

have influenced infiltration rates during the first study year. 

In later years, as the prairie root system matured, perturbation 

of the soils may have allowed more rapid infiltration and, 

thus, fewer “wet” conditions. Improvements to soil structure 

and infiltration rates in the prairie-sand rain garden may have 

been more prevalent than in the turf-sand rain garden because 

of the abundance of sand directly beneath the turf-sand rain 

garden. Evidence of improved infiltration rates in the prairiesand rain garden is illustrated in figure 15. Median values 

for estimated infiltration rates in the prairie-sand rain garden 

steadily increased from 2004 through 2006. A slight decrease 

in 2007 may be a result of when the discharge events occurred. 

Five discharge events resulted in pooled water in the prairiesand rain garden in 2007, and three of them were in August. 

By comparison, in 2006, three of the four discharge events that 

produced “wet” conditions were in May. Spring in this case 

is defined as March through May and summer is defined as 

June through August. Although results of the Mann-Whitney 

test indicated no difference in infiltration rate in the prairiesand rain garden between spring and summer (at the 5-percent 

significance level), many of the estimated infiltration rates 

in the prairie-sand rain garden were greater in spring than in 

summer, especially during 2006 and 2007 (fig. 16). Diamond 

and Shanley (1998) found a similar seasonal pattern when 

assessing the spatial and temporal variability of infiltration 

capacity of major soil types in Ireland. This pattern was not 

reproduced in the turf-sand rain garden, which showed a 

similar range of infiltration rates in the summer and spring. 

Unlike the prairie-sand rain garden, infiltration rates in the 

turf-sand rain garden remained relatively consistent, ranging 

from 2 to 4 in/hr, except in 2005 when a single infiltration 

rate of nearly 10 in/hr was estimated. It is unclear why this 

single infiltration rate is much larger than all the others, but it 

was included when changes to infiltration rates over time and 

season in the turf-sand rain garden were compared.

Winter and fall were excluded from statistical tests due 

to a limited sample population. Water pooled in the prairiesand rain garden only twice during winter, in February 2004 

and January 2005, resulting in an estimated infiltration rate of 

0.75 and 2.28 in/hr, respectively. There were no pooled water 

events during winter in the turf-sand rain garden. Muthanna 

and others (2006) found the hydraulic performance of an 

experimental rain garden in Norway was not impacted by the 

climatic factors experienced during the cold season. Given the 

paucity of pooled water conditions in the sand rain gardens 

during winter months, it is likely their hydraulic function was 

not appreciably altered by frozen soils.

Table 7.  Statistical summary of infiltration rates in the turf-grass and prairie rain gardens in sand and clay. 

[Precipitation events resulting in pooled water were used to estimate an infiltration rate by use of the falling head technique. --, not measured; SD, 

standard deviation; COV, coefficient of variation; in/hr, inches per hour]

Number of events with pooled water Estimated infiltration rate (in/hr)

Water year All water years

Rain Garden 2004 2005 2006 2007 2008 Mean Median SD COV

Turf-sand 16 7 14 18 25 3.00 2.50 1.60 0.50

Prairie-sand 24 4 7 14 -- 6.50 4.20 4.70 0.70

Turf-clay 25 11 20 18 -- 0.31 0.28 0.19 0.60

Prairie-clay 5 3 3 7 10 1.00 0.88 0.55 0.54
26 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Turf-sand rain garden

Prairie-sand rain garden

INFILTRATION RATE, IN INCHES PER HOUR INFILTRATION RATE, IN INCHES PER HOUR

2003 2004 2005 2006 2007 2008

(1) (7) (2) (5) (5) (14)

(2) (11) (3) (4) (5)

0

2

4

6

8

10

12

14

16

18

20

2003 2004 2005 2006 2007

0

2

4

6

8

10

12

14

16

18

20

EXPLANATION:

(10) Number of values

Upper limit

75th percentile

Mean

Median

25th percentile

Lower limit

Minimum/Maximum

WATER YEAR

Figure 15. Comparison of infiltration rates by water year in the

sand rain gardens. Infiltration rates are based on falling-head

technique during events with pooled water.
Comparison of Rain Gardens 27

Turf-sand rain garden

Prairie-sand rain garden

EXPLANATION:

(10) Number of values

Upper limit

75th percentile

Mean

Median

25th percentile

Lower limit

Minimum/Maximum

(4) (15) (15)

(3) (10) (10) (2)

INFILTRATION RATE, IN INCHES PER HOUR INFILTRATION RATE, IN INCHES PER HOUR

Fall Spring Summer

0

2

4

6

8

10

12

14

16

18

20

Fall Spring Summer Winter

0

2

4

6

8

10

12

14

16

18

20

SEASON

Figure 16. Comparison of infiltration rates by season in the sand rain

gardens. Infiltration rates are based on falling-head technique during events

with pooled water.
28 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Clay Site

Table 7 shows the number of discharge events producing 

pooled water during each water year as well as a statistical 

summary of estimated infiltration rates during the study 

period in the clay rain gardens. Median infiltration rates in the 

prairie-clay rain garden are more than three times greater than 

in the turf-clay rain garden at 0.88 and 0.28 in/hr, respectively. 

Despite the disparity between overall median infiltration 

rates, the turf-clay rain garden exhibited a general increase 

in annual median infiltration rates from 2004 through 2007, 

ranging from less than 0.2 in/hr in 2004 and 2005 to more than 

0.4 in/hr in 2006 and 2007 (fig. 17). Although the increase in 

infiltration rates appears modest, it represents an appreciable 

improvement over those measured prior to rain-garden 

construction. Infiltration rates of approximately 0.1 in/hr were 

measured by use of a double-ring infiltrometer at the clay 

rain-garden site prior to rain-garden construction. Destruction 

of the natural soil matrix by excavation and compaction can 

decrease hydraulic conductivity (Pitt and others, 1999; Legg 

and others, 1996). Because the soil structure prior to this study 

was likely degraded from construction activities, it would not 

be unusual to see an increase in infiltration rates regardless 

of vegetation type. Hino and Shutto (1987) found the growth 

of grass altered the structure of soils within 2 months of 

establishment, and they measured increases in saturated 

hydraulic conductivity from 0.24 in/hr in bare soil to nearly 

4.0 in/hr for grass-covered soil. Despite annual differences 

in median infiltration rates, seasonal differences were not as 

apparent. Comparison of seasonal infiltration rates by use of 

a combination of the Kruskal-Wallis test for multiple groups 

and Dunn’s test suggested that infiltration rates in the turf 

garden were greatest during summer months, at the 5-percent 

significance level. Winter infiltration rates in the turf-clay 

rain garden were the lowest of all seasons and had a median 

value of 0.11 in/hr, which is the same as the infiltration rate 

measured prior to rain-garden construction. Furthermore, 

infiltration rates increased by season, with winter rates the 

lowest, then spring, fall, and finally, summer the highest 

(fig. 18).

Similar to the turf-clay rain garden, an increase in annual 

median infiltration rates was also measured in the prairie-clay 

rain garden (fig. 17). Rates ranged from 0.6 in/hr to more 

than 1.0 in/hr in 2004 and 2008, respectively. As with turf 

grass, prairie vegetation can improve hydraulic conductivity 

by creating or improving macropores or both from extensive 

root growth (Beven and Germann, 1982). Under favorable 

circumstances, macropore systems can be developed in as 

little as 1 to 2 years (Beven and Germann, 1982). Little can 

be inferred about the direction of median infiltration rates in 

2005 and 2006 because of the lack of data. Because a lack of 

pooled water would preclude estimation of an infiltration rate, 

as was often the case in the prairie-clay rain garden, the rate 

at which water infiltrated into the soil was likely greater than 

the rate water flowed into the rain garden. Therefore, fewer 

rather than more data points in figure 17 would qualitatively 

suggest improved infiltration rates given similar precipitation 

characteristics to other study years. Results of the MannWhitney test indicate no difference between spring and 

summer infiltration rates at the 5-percent significance level 

for the prairie-clay rain garden. Because the prairie-clay rain 

garden lacked “wet” conditions during the fall and winter, an 

evaluation of seasonal differences was limited to only spring 

and summer. 
Comparison of Rain Gardens 29

Turf-clay rain garden

Prairie-clay rain garden

INFILTRATION RATE, IN INCHESPER HOUR INFILTRATION RATE, IN INCHES PER HOUR

EXPLANATION:

(10) Number of values

Upper limit

75th percentile

Mean

Median

25th percentile

Lower limit

Minimum/Maximum

YEAR

2003 2004 2005 2006 2007

0

0.5

1

1.5

2

2.5

3

3.5

2004 2005 2006 2007 2008

0

0.5

1

1.5

2

2.5

3

3.5

(2) (25) (17) (22) (17)

(6) (2) (2) (7) (11)

Figure 17. Comparison of infiltration rates by water year in the clay rain

gardens. Infiltration rates are based on falling-head technique during

events with pooled water.
30 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Turf-clay rain garden

Prairie-clay rain garden

INFILTRATION RATE, IN INCHES PER HOUR INFILTRATION RATE, IN INCHES PER HOUR

EXPLANATION:

(10) Number of values

Upper limit

75th percentile

Mean

Median

25th percentile

Lower limit

Minimum/Maximum

SEASON

Fall Spring Summer Winter

0

0.5

1

1.5

2

2.5

3

3.5

Fall Spring Summer Winter

0

0.5

1

1.5

2

2.5

3

3.5

(11)

(2) (12) (12) (2)

(36) (25) (11)

Figure 18. Comparison of infiltration rates by season in the clay soil rain

gardens. Infiltration rates are based on falling-head technique during events

with pooled water.
Comparison of Rain Gardens 31

Vegetative Effects on Soil Moisture

Analysis of the temporal variation of soil moisture 

can be qualitatively useful in estimating the timing, depth, 

and duration of recharge events (Delin and Herkelrath, 

1999). Interpretation of fluctuations in soil moisture in the 

unsaturated zone is based on the premise that water in the 

soil above the vegetative-rooting depth travels upward in 

response to evapotranspiration. Water below that depth 

drains downward to the water table as recharge. This 

evapotranspiration/drainage boundary is further described by 

Delin and others (2000) who used soil moisture as a means to 

compute a volumetric mass balance of the unsaturated zone. 

Time-lapse imagery in conjunction with the vertical soilmoisture profile illustrates the combined effect of root systems 

and evapotranspiration on soil moisture in the prairie-clay 

rain garden during an extended dry period in 2005 (fig. 19A). 

In figure 19A, a diurnal fluctuation in soil moisture with 

increasing depth becomes more evident from May through 

August 2005. Multiple days with no precipitation force the 

prairie root system to tap into deeper sources of soil moisture. 

The development of root systems into deeper soil depths may 

increase the infiltrative capacity of a rain garden by creating 

macropores and other fissures that allow for rapid water 

movement. This might also explain, in part, the larger median 

infiltration rate measured in the prairie-clay rain garden 

compared with that in the turf-clay rain garden (table 7). The 

diurnal fluctuation in soil moisture over the same time period 

is not as prominent in the turf-clay rain garden (fig. 19B). This 

is likely due to the shallow root depth of turf grass. Only the 

uppermost soil layer (0.5 feet below land surface) showed 

appreciable decline in soil moisture.

 In September 2008, an effort was made to track the 

temporal changes in soil moisture after artificially flooding 

the prairie-clay rain garden. Because there was evidence of a 

limiting clay layer approximately 3 ft below the land surface 

(fig. 8), water was expected to pool and accumulate at or near 

this depth. However, if the prairie root system was capable of 

penetrating through the limiting layer, then water could slowly 

percolate downward. Soil moisture was measured vertically by 

use of a neutron logger at four intervals: before flooding, 1 hr 

after flooding, and 3 and 6 days after flooding. As expected, 

soil moisture rapidly increased in the uppermost soil layers 

shortly after flooding of the rain garden began (fig. 20). After 

1 hr, modest increases in moisture levels continued down 

to a depth of approximately 8 ft, which is 5 ft below the 

demarcation of the upper limiting layer. Soil moisture returned 

to pre-flooding levels from the uppermost layer to a depth of 

approximately 6 ft after 3 days; however, moisture from 6 

to 8 ft remained high even after 6 days. It is likely a second, 

thinner layer at approximately 8 to 9 ft was limiting the 

downward movement of water and causing a perching effect, 

and, thus, elevated moisture levels above 8 ft for an extended 

period of time. Despite the lower limiting layer, water still 

advanced downward as recharge, as is evident by the increase 

in soil moisture after 3 and 6 days post rain garden flooding to 

depths below 10 ft. An increase in soil moisture in the upper 

limiting layer, although small, might indicate perturbation of 

the soil by prairie roots. The clay rain gardens were excavated 

shortly after the flood test to verify the extent of soil structure 

and root morphology. The results are discussed later in this 

report. 

Additional evidence of deep penetrating prairie root 

systems is further illustrated in the prairie-sand rain garden 

(fig. 21). In 2005, there was little change in soil-moisture 

levels after extended periods of no precipitation in the turfsand rain garden at 1.6 feet below land surface and the prairiesand rain garden at 2.6 feet below land surface. In 2007, 

however, soil moisture in the prairie-sand rain garden began 

to display a diurnal fluctuation during extended dry periods, 

which is an indication of the effect of evapotranspiration. In 

contrast, the turf-sand moisture levels showed a steady decline 

in soil-moisture levels, and this is more likely a function 

of evaporation and drainage than the water needs of a root 

system. 
32 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

SOIL MOISTURE, IN PERCENT

4/30/2005 5/31/2005

SENSOR 2—0.5 FEETSENSOR 3—1.25 FEETSENSOR 4—2.0 FEET

7/31/2005

DATE

8/31/2005 9/30/2005 6/30/2005

605040302010

Figure 19

A. Comparison of soil moisture at 0.5, 1.25, and 2.0 feet below land surface in the prairie-clay rain garden, May through September 2005.
Comparison of Rain Gardens 33

SOIL MOISTURE, IN PERCENT

4/30/2005

50

40302010

5/31/2005

SENSOR 2—0.5 FEET

SENSOR 3—1.25 FEETSENSOR 4—2.0 FEET

7/31/2005 8/31/2005 9/30/2005 6/30/2005

DATE

Figure 19B. Comparison of soil moisture at 0.5, 1.25, and 2.0 feet below land surface in the turf-clay rain garden, May through September, 2005.
34 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

0

02468101214

5 10 15 20

VOLUMETRIC WATER CONTENT, IN PERCENT

DEPTH BELOW LAND SURFACE, IN FEET

25 30 35 40

Before flooding1 hour after flooding3 days after flooding6 days after flooding

Figure 20. Changes in soil moisture with increasing depth before, 1 hour, 3 days, and 6 days after flooding the prairie-clay rain garden, September2008. Explanation of soil texture can be found in figure 8.
Comparison of Rain Gardens 35

SOIL MOISTURE, IN PERCENT

06/30

12:00 AM

07/07

12:00 AM

07/14

12:00 AM

07/21

12:00 AM

07/29

12:00 AM

605040302010

Prairie-sand 2005Prairie-sand 2007Turf-sand 2005Turf-sand 2007

DATE AND TIME

Figure 21. Comparison of soil moisture for July 2005 and 2007 at 1.6 feet below land surface in the turf-sand rain garden and 2.6 feet below land surface in theprairie-sand rain garden.
36 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

Comparison of Soil Properties and Root 

Morphology

In October 2008, 5 years after planting the rain gardens, 

an observation trench was excavated through the approximate 

center of the prairie- and turf-clay rain gardens to characterize 

differences in soil properties and rooting between vegetation 

types. Although the turf- and prairie-clay rain gardens had 

similar soil textures and soil-horizon designations, there were 

striking differences in soil characteristics between the two 

clay gardens. Table 8 details physical characteristics of the soil 

profiles in the turf- and prairie-clay rain gardens. 

The differences in soil properties were associated 

with water and air movement within the two rain gardens. 

The soil under the prairie-vegetated rain garden, although 

possessing the remnants of a limiting clay layer, appeared 

well-drained. At no time during field sampling did water enter 

the prairie-clay trench from the profile wall or its bottom. 

Conversely, there was clear evidence of a perched water table 

at approximately 0.7–1.0 ft below the surface of the turfplanted rain garden. Water not only seeped into the turf-clay 

trench during sampling, but a strongly gleyed horizon was 

present from 1.05–2.95 ft and was indicative of an anaerobic, 

saturated environment; a weakly gleyed horizon in the prairieclay garden (0.66 ft in thickness) ended at 1.51 ft below the 

surface. Oxidized mottles and other redox features within 

the master B horizon of the turf-clay rain garden further 

indicated a fluctuating perched water table. Moreover, the Bt 

horizon above the gleyed layer in the turf-clay soil possessed 

a large enough clay fraction that it was classified as a silt 

loam relative to the Bt horizon in the prairie-clay soil. This 

observation may indicate a transfer of the finer clay fraction to 

lower horizons in the prairie-clay profile. Finally, a substantial 

clay fraction was found in the lower B horizons of both rain 

gardens as shown by an angular, blocky to somewhat platey 

structure as well as the laboratory particle-size classification of 

silty clay loams.

The 2008 soil-profile descriptions also indicated 

differences in flora and fauna activity between the prairie- and 

turf-clay rain gardens (table 8). Many fine roots extended 

from the surface down to 0.46 ft in the turf-clay rain garden 

(absolute rooting depth in the turf-clay garden was 0.56 ft), 

but roots extended to a depth of 4.7 ft in the prairie-clay 

rain garden. Moreover, many roots were found within the 

Btg horizon of the prairie-clay garden but they were absent 

from the Btg horizon of the turf-clay rain garden. The greater 

amount and depth of rooting in the prairie-clay rain garden 

coincided with greater macrofauna activity, indicated by many 

earthworms, along with many abandoned worm channels and 

cavities once occupied by roots. These channels were either 

lined with organic matter or were redox features indicating the 

movement of water and air into lower horizons of the prairieclay rain garden. Conversely, there was little evidence of 

macrofauna activity in the soil under the turf. This biological 

activity was also evident in the horizon boundaries of the 

prairie-clay soil which were wavy, irregular, and clear. In 

contrast, the horizon boundaries of the turf-clay soil were 

largely smooth and abrupt. Collectively, these differences in 

soil properties point to greater pedoturbation in the prairie-clay 

rain garden than in the turf-clay rain garden. 

Although the absolute values of dry root mass were 

low relative to mature turf and prairie systems, differences 

were evident between the prairie-clay and turf-clay gardens 

(table 8). The root number and dry mass in each rain garden 

mirrored the differences of organic matter throughout each 

profile, in that the prairie-clay garden had more dry root mass 

than the turf-clay rain garden. Although both soils had an Oi 

and an A horizon, the organic accumulation of the prairie-clay 

rain garden was 0.4 in thicker in the Oi horizon and 4 percent 

greater in the A horizon relative to the turf-clay soil. This 

percent difference in organic matter between gardens carried 

into the B horizons, where the prairie soil averaged 1 percent 

greater organic matter than the turf-clay garden. These bioticderived differences appear to also correlate with differences 

in soil bulk density between the two rain gardens. Both rain 

gardens displayed the typical increase in bulk density with 

depth; however, the soil of the prairie-clay rain garden was 

less dense overall than the turf-clay soil, particularly in the A 

and Btg horizons..

Similar to the differences in dry root mass, rooting 

behavior also varied between the prairie- and turf-clay rain 

gardens. Roots were present in all horizons sampled within the 

prairie-clay soil, where the absolute rooting depth extended 

to 4.7 ft; in contrast, roots were found only in the A and Bt 

horizons within the turf-clay rain garden. The absence of 

roots below 1.05 ft in the turf-clay soil may be explained by 

the interaction between the shallow-rooting turf grass and 

the saturated, anaerobic character of the thick Btg horizon. 

Conversely, the prairie-vegetation species appeared to 

penetrate the “limiting layer” and allowed mixing of surface 

organics, macrofauna, water, and air deeper into the profile.

There were marked differences in rooting morphology 

(for example, in length, density, and amount) between the 

prairie- and turf-clay rain gardens (table 9). The mean dry 

root mass per volume of soil within the A horizon of the 

prairie-clay rain garden was almost double that of the turfclay rain garden; root mass within the Bt was similar between 

rain gardens. The SRL was 23 percent lower and 14 percent 

greater in the A and Bt horizons, respectively, of the prairieclay soil than in the same horizons in the turf-clay soil. 

Conversely, the RLD was 75 percent greater in the A horizon 

of the prairie-clay rain garden relative to the turf-clay soil, and 

the RLD in the Bt horizon was similar in both rain gardens. 

These differences in rooting morphology concurred with the 

differences in SOM and bulk density between the two rain 

gardens, where greater root mass equated with higher SOM 

and lower bulk density. Moreover, these quantitative measures 

capture the interaction between vegetation types and soil that 

controls rain-garden function. 
Comparison of Rain Gardens 37

Table 8.  Soil-profile descriptions of the turf-clay and prairie-clay rain gardens, October 2008. [--, not measured; >, greater than; <, less than; cm2, square centimeters; %, percent; g/cm3, grams per cubic centimeter]

Turf-clay rain garden

Horizon Depth (ft) Lower boundary 

(topography, distinctness)

Dominant structure 

(type)

Roots (quantity class, 

estimated size class)

Presence of 

mottles

Texture class Organic matter 

(%)

Bulk density 

(g/cm3)

Oi 0–0.03 Smooth, abrupt -- -- -- -- -- --

A .03–.46 Smooth, abrupt Granular >5 per cm2, 1–2 mm None -- 16.0 1.11

Bt .46–1.05 Wavy, clear Angular blocky to 

somewhat platey

<0.2 per cm2, < 1mm None Silty clay loam 3.6 1.65

Btg 1.05–2.95 Smooth, clear Angular blocky to 

massive

None Common Silty clay loam 3.1 1.56

Additional soil properties for turf-clay rain garden

• Color of the Bt = 4/4 7.5YR; Btg = 3/10Y Gley1; mottles 4/6 2.5YR (Munsell Color, 1990)• Root amounts given as an average of counts per 5, 1-cm2 patches on profile wall• No roots observed in gleyed horizon; a few roots observed in Btg horizon, but belonged to an adjacent maple tree• Maximum rooting depth observed was 0.56 ft• Redox features common in B horizon; no worm evidence throughout B horizon• Perched water table at approximately 0.7–1.0 ft below the surface

Prairie-clay rain garden

Horizon Depth (ft) Lower boundary 

(topography, distinctness)

Dominant structure 

(type)

Roots (quantity class, 

estimated size class)

Presence of 

mottles

Texture class Organic matter 

(%)

Bulk density 

(g/cm3)

Oi 0–0.07 Wavy, abrupt -- -- -- -- -- --

A .07–.33 Wavy, abrupt Granular >5 per cm2, 1–2 mm None -- 20.0 0.89

Bt .33–.85 Wavy, clear Angular blocky 1-5 per cm2,1–2mm None Silt loam 4.1 1.63

Btg .85–1.51 Irregular, clear Angular blocky to 

somewhat platey 

>5 per cm2, 1–2mm None Silty clay loam 4.3 1.44

Bt2 1.51–3.28 Wavy, clear Angular to subangular 

blocky

1–5 per cm2, <1mm Slight Silty clay loam 3.7 1.49

Additional soil properties for prairie-clay rain garden

• Color of the Bt = 5/8 7.5YR, Btg = 7/10B Gley2 (Gleyed horizon much lighter than turf-clay Btg)• Root amounts given as an average of counts per 5, 1-cm2 patches on profile wall• Maximum rooting depth was 4.7 ft; many former root channels lined with organics and redox features• Visible signs of pedoturbation and pedotransfer processes to a depth of 2.26 ft• Abundant worm evidence including many live worms• No perched water table or standing water at trench bottom
38 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

The length of a plant’s root system largely controls its 

acquisition of water and nutrients, as well as the development 

of soil structure. Although species vary widely in their specific 

root length, the relative differences observed between the 

two rain gardens studied here helps explain the differences 

observed in soil development (Fitter, 1985). Species with 

a relatively small investment in root biomass per unit root 

length, high SRL, may possess an advantage for exploiting 

pulses of water in the soil by quickly increasing root length 

(Eissenstat and Caldwell, 1989; Chapin, 1989). Moreover, a 

lower energy cost per unit length of root may facilitate soil 

development, as the plant can afford to explore a greater 

volume of soil and typically turn over roots at higher rates 

(Grime and others, 1986). In a study of orange trees grown in 

disturbed soil, rootstocks with higher SRL and greater RLD 

were able to extract water more rapidly than those with lower 

SRL (Eissenstat, 1991). 

This interaction between roots and soil may explain the 

greater soil development in the prairie-clay rain garden than 

in the turf-clay rain garden. Within the A horizon, the prairie 

roots not only had a greater mass of roots per volume of soil, 

but also a lower mass investment per length of root such that 

there was almost double the rooting length per volume of soil 

in the prairie-clay rain garden relative to the turf-clay rain 

garden. This trend between rain gardens carried into the Bt 

horizon, although the differences were much less pronounced 

than in the A horizon. Therefore, the ability of the prairie 

vegetation to build an energetically less-expensive root system 

may have facilitated higher rates of root proliferation, leading 

to greater soil development and improved infiltration for water 

and air, than in the turf-clay rain garden. The 2008 profile 

observations in table 8 support this hypothesis. 

Finally, the absolute values of root mass, SRL, and RLD 

for these rain gardens were low relative to published values 

for grasses. The relative immaturity of these systems and the 

one-time sampling late in the growing season may help explain 

this difference. Moreover, the differences in soil development 

reported here are based on two rain gardens. Sequential 

coring and additional treatment replication would increase the 

reproducibility of these data.

Conclusions

Recent trends in urban runoff mitigation have resulted in 

technologies that focus on infiltration. One such technology, 

known as a rain garden, is a shallow depression that accepts 

runoff generated from nearby impervious surfaces and 

infiltrates that runoff back into the underlying soil. In addition, 

rain gardens may provide some level of water-quality 

benefit by settling, filtration, adsorption, decomposition, ion 

exchange, and volatilization. Rain gardens range in size but 

are commonly used as a way to retrofit existing urban areas 

where land requirements often preclude larger structures. 

Although the use of rain gardens is increasing, there appears to 

be no clear consensus on how soils at the site might limit the 

use of an infiltration device. The use of rain gardens and other 

infiltration devices could be expanded if additional information 

about soil amendments and sizing criteria was available to 

mitigate the uncertainty of requiring infiltration in soils that 

have low infiltration rates. 

To that end, the U.S Geological Survey, in cooperation 

with a consortium of 19 cities, towns, and villages in Dane 

County, Wis., evaluated the effectiveness of rain gardens with 

different soil types and vegetative species for stormwater 

infiltration. Two rain gardens, one planted with turf grass and 

the other with native prairie species, were constructed sideby-side in two locations of different soil types, sand and clay. 

Instruments were installed to measure the volumetric mass 

balance of each rain garden from late 2003 through 2008. 

Root morphology, soil texture, and other subsurface properties 

were characterized so that differences in storage capacity and 

infiltration rates between vegetation and soil type could be 

understood.

Results of the study show that each rain garden, regardless 

of vegetation or soil type, was capable of storing and 

infiltrating most of the runoff during the 5-year study period. 

Median infiltration rates for rain gardens in sand were greater 

than those in clay. Within each soil type, rain gardens with 

prairie vegetation had greater median infiltration rates than 

those with turf grass. Infiltration was generally highest during 

spring and summer and lowest during winter. Despite reduced 

infiltration rates during months when soils were likely frozen, 

the hydraulic function of the rain gardens did not appear to be 

appreciably altered. 

Table 9.  Rooting dynamics below the turf-clay and prairie-clay

rain gardens, October 2008.

[SRL, specific root length; RLD, root length density. mg/cm3, milligrams of 

root per volume of dry soil; m/g, meters of root length per weight of dry root; 

cm/cm3, centimeters of root length per volume of dry soil; --, not measured]

Turf-clay rain garden

Horizon Depth (ft) Mean root 

dry mass 

(mg/cm3

)

Total SRL 

(m/g)

RLD 

(cm/cm3

)

Oi 0–0.03 -- -- --

A 0.03–0.46 0.10 38.0 0.48

Bt 0.46–1.05 .03 61.3 .19

Btg 1.05–2.95 -- -- --

Prairie-clay rain garden

Horizon Depth (ft) Mean root 

dry mass

(mg/cm3

)

Total SRL 

(m/g) 

RLD

(cm/cm3

)

Oi 0–0.07 -- -- --

A 0.07–0.33 0.18 46.9 0.84

Bt 0.33–0.85 .04 70.3 .20

Btg 0.85–1.51 .02 68.9 .19 

Bt2 1.51–3.28 .01 30.2 .07
References 39

The success of the rain gardens was primarily because 

the 5 to 1 ratio of contributing area to receiving area (4 to 1 for 

the prairie-clay rain garden) and 0.5 ft depth were capable of 

storing and infiltrating nearly all the stormwater. Even when 

the contributing area was doubled to 10 to 1 in the turf-sand 

rain garden and 8 to 1 in the prairie-clay rain garden, only a 

limited amount of outflow from the rain garden was generated. 

Approximately 90 percent of all precipitation measured over 

the 4-year study was capable of being stored in the gardens 

(assuming an infiltration rate of zero). The percentage of 

precipitation events fully retained by each rain garden 

increased to nearly 100 percent when the median infiltration 

rate and specific yield of subsurface soils were included in the 

estimates. Precipitation intensity and antecedent dry days were 

the dominant secondary controlling factors in determining 

when the storage capacity of a rain garden might be exceeded 

and result in pooled water above ground. 

Because of the large area of rooftop contributing runoff 

to each rain garden, evapotranspiration was a small percentage 

of the overall water balance. Therefore, most of the annual 

runoff volume influent to each rain garden, regardless of 

vegetation or soil type , was recharged back into groundwater. 

However, differences in annual recharge between the turf 

grass and prairie rain gardens in clay were slightly greater than 

the differences between rain gardens planted with the same 

vegetative species in sand. This is largely because a much 

smaller amount of evapotranspiration was estimated for prairie 

species than for turf grass.

Examination of soil development and root morphology in 

the rain gardens 5 years after planting clearly showed greater 

biological activity of flora and fauna in the prairie-clay rain 

garden than in the turf-clay rain garden. Roots in the prairieclay garden were found to a depth of 4.7 ft compared with 

0.46 ft in the turf-clay rain garden. The greater amount and 

depth of rooting in the prairie-clay rain garden coincided with 

greater earthworm activity along abandoned worm channels 

and cavities once occupied with roots. These channels were 

either lined with organic matter or redox features, indicating 

the movement of water and air into lower horizons within 

the prairie-clay rain garden. Moreover, the prairie roots had 

a lower mass investment per length of root such that there 

was almost double the rooting length per volume of soil in 

the prairie-clay soil relative to the turf-clay soil. Collectively, 

these differences point to greater pedoturbation and soil 

development in the prairie-clay rain garden relative to the turfclay rain garden, and this may result in greater capacity of the 

prairie-clay rain garden to store and infiltrate stormwater than 

the turf-clay rain garden. 

By applying measurements of the appropriate soil 

properties to rain-garden design, environmental managers and 

engineers may improve the tailoring of design specifications 

of rain gardens for new or retrofitted areas. If surficial area 

is unavailable to temporarily store runoff above ground, then 

storage can be created by excavating to a greater depth, even 

in the presence of clay.

Acknowledgments

The authors would like to thank Eric Booth, Justin 

Haasch, and Kristian Corby of the U.S. Geological Survey for 

their tireless efforts installing, calibrating, and maintaining the 

diversity of equipment used in this study; Roger Bannerman 

of the Wisconsin Department of Natural Resources for insight 

on the big-picture perspective behind rain gardens; and Greg 

Fries of the city of Madison for providing personnel and 

equipment when needed. Without their cooperation and effort, 

this study would not have been possible.

References

Allen, R.G., Pereira, L.S., Raes, D., and Smith, M., 1998, 

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42 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil, Madison, Wisconsin, Water Years 2004–08

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Appendix 1 43

Appendix 1
44 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

10/03/2003 08:59 10/03/2003 13:40 4.7 0.06 0.12 0.10 0.05 -- 1.8 2.4 0.0 0.010/11/2003 19:53 10/12/2003 08:38 12.8 0.27 0.16 0.12 0.11 8.3 11.2 11.0 0.0 0.010/13/2003 20:57 10/14/2003 15:56 19.0 0.60 0.08 0.06 0.05 1.5 23.8 25.7 0.0 0.010/24/2003 16:37 10/24/2003 22:04 5.4 0.54 0.40 0.32 0.29 10.0 21.9 21.9 0.0 0.010/28/2003 01:23 10/28/2003 12:16 10.9 0.04 0.04 0.04 0.02 3.1 1.9 1.6 0.0 0.0

10/29/2003 18:21 10/29/2003 21:44 3.4 0.09 0.12 0.08 0.07 1.3 3.6 3.6 0.0 0.011/01/2003 19:59 11/02/2003 20:53 24.9 1.50 0.36 0.30 0.27 2.9 58.0 61.1 0.0 0.011/03/2003 05:57 11/04/2003 10:57 29.0 4.00 1.76 1.60 1.22 0.4 127.9 135.3 0.0 0.011/17/2003 19:38 11/18/2003 17:00 21.4 0.36 0.16 0.12 0.09 13.4 17.0 15.7 0.0 0.011/22/2003 17:52 11/23/2003 10:00 16.1 2.23 1.52 1.14 0.72 4.0 70.4 74.0 0.0 0.012/05/2003 11:15 12/05/2003 15:53 4.6 0.14 0.16 0.14 0.12 12.1 3.3 5.1 0.0 0.012/09/2003 11:50 12/10/2003 17:00 29.2 1.51 0.32 0.28 0.23 3.8 55.8 64.0 0.0 0.012/27/2003 21:58 12/28/2003 16:35 18.6 0.18 0.24 0.16 0.10 17.2 7.1 3.5 0.0 0.002/18/2004 11:21 02/21/2004 00:46 61.4 0.34a 0.20 0.14 0.12 51.8 28.0 22.4 0.0 0.0

02/21/2004 11:15 02/21/2004 19:17 8.0 0.21 0.28 0.26 0.19 0.4 5.7 6.4 0.0 0.002/22/2004 09:30 02/24/2004 21:32 60.0 0.08a 0.08 0.08 0.05 0.6 12.9 1.9 0.0 0.002/25/2004 11:00 02/25/2004 19:21 8.3 snowmelt -- -- -- 0.6 2.0 0.0 0.0 0.002/29/2004 23:19 03/01/2004 09:00 9.7 0.12 0.16 0.14 0.08 4.2 5.2 4.6 0.0 0.003/01/2004 14:59 03/02/2004 08:00 17.0 0.13 0.16 0.08 0.05 0.2 6.0 5.1 0.0 0.003/04/2004 17:50 03/05/2004 10:42 16.9 1.28 0.48 0.28 0.24 2.4 49.3 52.2 0.0 0.003/10/2004 19:59 03/11/2004 00:47 4.8 snowmelt -- -- -- 5.4 2.1 2.6 0.0 0.003/13/2004 20:55 03/14/2004 02:12 5.3 0.13 0.08 0.06 0.04 2.8 5.6 1.8 0.0 0.003/17/2004 11:23 03/17/2004 17:05 5.7 0.11 0.28 0.20 3.4 5.9 1.8 0.0 0.003/18/2004 09:30 03/18/2004 13:06 3.6 snowmelt -- -- -- 0.7 2.1 2.1 0.0 0.0

03/24/2004 01:15 03/24/2004 05:51 4.6 0.16 0.16 0.10 0.08 5.5 6.8 6.9 0.0 0.0

.
Appendix 1 45

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

03/25/2004 14:34 03/26/2004 12:10 21.6 1.42 1.32 0.96 0.80 1.4 50.3 31.5 0.0 0.003/28/2004 12:15 03/28/2004 19:15 7.0 0.39 0.24 0.18 0.16 2.0 15.7 12.2 0.0 0.003/30/2004 15:49 03/31/2004 13:15 21.4 snowmelt -- -- -- 1.9 1.5 1.5 0.0 0.004/15/2004 18:49 04/16/2004 01:53 7.1 snowmelt -- -- -- 15.2 1.3 1.3 0.0 0.004/16/2004 23:45 04/17/2004 09:42 9.9 0.52 0.48 0.34 0.27 0.9 18.1 19.6 0.0 0.0

04/18/2004 01:35 04/18/2004 07:49 6.2 0.15 0.56 -- -- 0.7 5.2 5.7 0.0 0.004/20/2004 14:47 04/21/2004 07:59 17.2 0.56 0.32 0.18 0.15 2.3 22.6 26.0 0.0 0.004/24/2004 19:14 04/25/2004 15:30 20.3 0.32 0.16 0.08 0.07 3.5 13.5 16.0 0.0 0.005/02/2004 10:32 05/02/2004 13:04 2.5 0.07 0.24 -- -- 6.8 2.5 2.8 0.0 0.005/08/2004 20:25 05/09/2004 14:22 18.0 0.52 1.08 0.60 0.33 6.3 17.2 19.8 0.0 0.005/10/2004 02:36 05/10/2004 19:32 16.9 0.44 0.72 0.44 0.29 0.5 16.5 18.5 0.0 0.005/13/2004 09:18 05/13/2004 23:01 13.7 0.42 0.56 0.32 0.21 2.6 16.8 17.5 0.0 0.005/14/2004 05:29 05/14/2004 23:42 18.2 0.34 0.12 0.12 0.09 0.3 13.0 16.2 0.0 0.005/17/2004 20:08 05/18/2004 13:25 17.3 0.81 2.08 1.34 0.75 2.9 21.1 22.1 0.0 0.005/21/2004 07:27 05/21/2004 11:00 3.6 0.75 1.68 1.08 0.70 2.8 22.2 20.3 0.0 0.0

05/21/2004 16:07 05/22/2004 09:00 16.9 2.79 2.00 1.32 0.89 0.2 78.2 78.5 0.0 0.005/22/2004 17:59 05/23/2004 08:00 14.0 1.54 0.96 0.64 0.46 0.4 45.2 43.3 0.0 0.005/25/2004 00:43 05/25/2004 06:52 6.1 0.13 0.36 0.22 0.12 1.7 4.2 5.3 0.0 0.005/29/2004 07:33 05/29/2004 14:58 7.4 0.45 0.24 0.18 0.17 4.0 13.5 16.0 0.0 0.005/30/2004 07:57 05/30/2004 18:00 10.0 0.65 0.80 0.54 0.42 0.7 14.0 16.4 0.0 0.005/31/2004 06:50 06/01/2004 00:00 17.2 0.32 0.20 0.14 0.12 0.5 10.2 12.2 0.0 0.006/09/2004 16:59 06/10/2004 16:51 23.9 1.54 0.52 0.42 0.35 8.7 29.1 34.5 0.0 0.006/12/2004 00:12 06/12/2004 01:16 1.1 0.16 0.32 0.18 0.15 1.3 3.7 4.6 0.0 0.006/16/2004 20:42 06/17/2004 04:49 8.1 0.56 0.56 0.46 0.32 4.8 12.3 16.1 0.0 0.006/21/2004 08:52 06/21/2004 20:00 11.1 0.19 0.16 0.12 0.09 4.2 5.1 6.8 0.0 0.0

—Continued.
46 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

06/23/2004 20:31 06/24/2004 13:00 16.5 0.54 0.68 0.20 0.15 2.0 12.2 15.9 0.0 0.006/27/2004 16:59 06/28/2004 02:00 9.0 0.10 0.20 0.14 0.07 3.2 3.3 3.6 0.0 0.007/03/2004 14:59 07/04/2004 12:00 21.0 2.25 2.32 1.70 1.10 5.5 73.8 57.5 0.0 0.007/05/2004 22:19 07/06/2004 06:00 7.7 0.16 0.44 0.22 0.11 1.4 3.7 4.7 0.0 0.007/06/2004 20:05 07/07/2004 06:00 9.9 0.10 0.16 0.12 0.08 0.6 4.0 4.0 0.0 0.0

07/09/2004 11:36 07/09/2004 14:00 2.4 0.30 0.88 0.50 0.29 2.2 10.2 8.4 0.0 0.007/11/2004 15:17 07/11/2004 18:00 2.7 0.08 0.12 0.12 -- 2.1 2.9 3.1 0.0 0.007/16/2004 10:21 07/17/2004 07:00 20.6 0.74 1.52 0.84 0.44 4.7 12.4 17.9 0.0 0.007/21/2004 08:01 07/21/2004 15:00 7.0 0.35 0.32 0.22 0.17 4.0 13.3 15.2 0.0 0.007/29/2004 14:30 07/29/2004 22:00 7.5 0.68 1.16 0.90 0.64 8.0 29.5 22.7 0.0 0.007/30/2004 02:33 07/30/2004 14:00 11.5 0.59 0.68 0.38 0.19 0.2 22.9 22.2 0.0 0.008/02/2004 10:28 08/02/2004 14:00 3.5 0.14 0.20 0.16 0.11 2.9 4.9 4.9 0.0 0.008/03/2004 18:02 08/04/2004 07:00 13.0 1.06 3.16 1.72 0.94 1.2 17.1 18.5 0.0 0.008/16/2004 20:16 08/17/2004 07:00 10.7 0.14 0.20 0.20 0.10 12.6 4.9 4.1 0.0 0.008/18/2004 17:23 08/19/2004 01:00 7.6 0.48 1.48 0.88 -- 1.4 9.3 9.7 0.0 0.0

08/24/2004 10:30 08/24/2004 14:00 3.5 0.14 0.24 0.18 0.11 5.4 4.9 5.4 0.0 0.008/26/2004 23:58 08/27/2004 06:00 6.0 0.38 0.96 0.56 0.35 2.4 11.3 11.1 0.0 0.008/28/2004 07:58 08/28/2004 10:00 2.0 0.12 0.20 0.18 -- 1.1 4.4 4.8 0.0 0.008/28/2004 15:47 08/28/2004 21:00 5.2 0.15 0.28 0.18 0.11 0.2 4.9 5.3 0.0 0.009/01/2004 04:24 09/01/2004 09:00 4.6 0.45 0.80 0.58 0.36 3.3 15.9 15.2 0.0 0.009/06/2004 03:02 09/06/2004 10:00 7.0 0.15 0.24 0.14 0.08 4.8 5.3 5.2 0.0 0.009/15/2004 09:27 09/16/2004 08:00 22.5 0.61 0.56 0.42 0.26 9.0 19.8 18.5 0.0 0.010/01/2004 16:16 10/02/2004 02:00 9.7 0.80 1.64 0.98 0.59 15.3 20.3 23.1 0.0 0.010/07/2004 23:50 10/08/2004 10:00 10.2 0.74 0.48 0.46 0.35 5.9 26.1 26.5 0.0 0.010/19/2004 00:56 10/19/2004 10:00 9.1 0.19 0.20 0.14 0.09 10.6 6.3 7.5 0.0 0.0

—Continued.
Appendix 1 47

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

10/22/2004 17:03 10/23/2004 11:00 18.0 1.02 0.36 0.32 0.29 3.3 32.3 36.7 0.0 0.010/26/2004 13:15 10/27/2004 00:00 10.7 0.19 0.12 0.08 0.07 3.1 6.2 7.5 0.0 0.010/29/2004 22:53 10/30/2004 12:00 13.1 0.20 0.52 0.32 0.19 3.0 5.7 6.6 0.0 0.011/01/2004 08:57 11/02/2004 10:00 25.0 0.53 0.12 0.10 0.08 1.9 16.9 20.2 0.0 0.011/04/2004 01:32 11/04/2004 11:00 9.5 0.23 0.20 0.14 0.11 1.6 7.0 7.9 0.0 0.0

11/10/2004 20:47 11/11/2004 00:00 3.2 0.08 0.12 0.08 0.07 6.4 3.1 3.2 0.0 0.011/15/2004 10:03 11/16/2004 01:00 15.0 0.11 0.12 0.08 0.05 4.4 3.3 4.1 0.0 0.011/18/2004 20:40 11/20/2004 09:00 36.3 0.36 0.12 0.08 0.06 2.8 14.0 17.6 0.0 0.011/26/2004 23:27 11/27/2004 20:00 20.6 0.47 0.12 0.08 0.08 6.6 18.1 20.5 0.0 0.012/05/2004 21:50 12/06/2004 16:00 18.2 0.43 0.16 0.14 0.14 8.1 14.4 18.0 0.0 0.012/06/2004 23:03 12/07/2004 16:00 16.9 0.76 0.32 0.24 0.22 0.3 28.8 30.4 0.0 0.012/09/2004 19:02 12/11/2004 04:00 33.0 0.31 0.08 0.06 0.05 2.1 10.9 12.3 0.0 0.012/30/2004 20:06 12/31/2004 09:00 12.9 snowmelt -- -- -- 19.7 1.9 1.2 0.0 0.001/12/2005 13:48 01/13/2005 16:00 26.2 0.79 0.40 0.32 0.29 12.2 12.3 29.1 0.0 0.002/04/2005 10:59 02/05/2005 11:00 24.0 snowmelt -- -- -- 21.8 3.8 3.8 0.0 0.0

02/06/2005 18:19 02/07/2005 13:00 18.7 0.35 0.12 0.08 0.08 1.3 21.0 21.3 0.0 0.002/09/2005 08:59 02/09/2005 17:00 8.0 snowmelt -- -- -- 1.8 0.5 2.2 0.0 0.002/10/2005 09:59 02/10/2005 19:00 9.0 snowmelt -- -- -- 0.7 1.0 1.5 0.0 0.002/11/2005 08:59 02/11/2005 20:00 11.0 0.10 0.16 0.14 0.09 0.6 2.7 2.1 0.0 0.002/12/2005 11:59 02/12/2005 22:00 10.0 snowmelt -- -- -- 0.7 1.8 0.0 0.0 0.002/13/2005 11:00 02/14/2005 13:00 26.0 0.52 0.20 0.14 0.12 0.5 19.6 21.7 0.0 0.002/15/2005 02:19 02/15/2005 07:00 4.7 snowmelt -- -- -- 0.6 1.7 1.5 0.0 0.002/21/2005 09:00 02/22/2005 04:00 19.0 0.32 0.12 0.10 0.08 6.1 7.1 8.5 0.0 0.002/22/2005 10:18 02/22/2005 22:00 11.7 0.07 0.12 0.08 -- 0.3 2.5 2.6 0.0 0.002/23/2005 11:59 02/23/2005 18:00 6.0 snowmelt -- -- -- 0.6 2.1 2.1 0.0 0.0

—Continued.
48 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

02/24/2005 12:59 02/24/2005 18:00 5.0 snowmelt -- -- -- 0.8 2.3 2.3 0.0 0.002/25/2005 10:59 02/25/2005 19:00 8.0 snowmelt -- -- -- 0.7 2.5 2.5 0.0 0.002/27/2005 12:59 02/28/2005 02:00 13.0 snowmelt -- -- -- 1.7 2.2 2.2 0.0 0.002/28/2005 11:59 02/28/2005 17:00 5.0 snowmelt -- -- -- 0.4 1.0 1.0 0.0 0.003/01/2005 11:54 03/01/2005 15:00 3.1 0.08 0.08 0.06 0.04 0.8 0.9 0.9 0.0 0.0

03/04/2005 10:59 03/04/2005 20:00 9.0 snowmelt -- -- -- 2.8 2.2 2.2 0.0 0.003/05/2005 10:59 03/05/2005 17:00 6.0 snowmelt -- -- -- 0.6 1.4 1.4 0.0 0.003/07/2005 00:17 03/07/2005 09:00 8.7 0.17 0.32 0.20 0.13 1.3 7.0 7.1 0.0 0.003/10/2005 12:55 03/10/2005 23:00 10.1 0.19 0.12 0.10 0.10 3.2 3.7 3.8 0.0 0.003/11/2005 09:59 03/11/2005 18:00 8.0 snowmelt -- -- -- 0.5 2.5 0.1 0.0 0.003/12/2005 10:49 03/12/2005 16:00 5.2 snowmelt -- -- -- 0.7 0.8 1.6 0.0 0.003/14/2005 10:59 03/14/2005 17:00 6.0 snowmelt -- -- -- 1.8 1.2 0.0 0.0 0.003/18/2005 13:07 03/21/2005 00:05 59.0 0.83a 0.44 0.38 0.32 3.8 16.7 25.5 0.0 0.0

03/21/2005 07:59 03/21/2005 23:00 15.0 snowmelt -- -- -- 0.3 2.2 1.6 0.0 0.003/22/2005 07:59 03/23/2005 03:00 19.0 snowmelt -- -- -- 0.4 2.1 2.7 0.0 0.003/23/2005 09:59 03/23/2005 20:00 10.0 snowmelt -- -- -- 0.3 2.0 1.0 0.0 0.003/24/2005 08:59 03/25/2005 18:00 33.0 snowmelt -- -- -- 0.5 5.3 0.0 0.0 0.003/30/2005 14:09 03/31/2005 08:00 17.9 0.73 1.52 0.76 0.38 4.8 18.4 19.0 0.0 0.004/06/2005 19:09 04/07/2005 01:00 5.8 0.74 0.96 0.84 0.52 6.5 28.7 26.2 0.0 0.004/12/2005 06:18 04/12/2005 18:00 11.7 0.43 0.28 0.24 0.19 5.2 14.9 17.5 0.0 0.004/19/2005 22:59 04/20/2005 03:00 4.0 0.15 0.28 0.22 0.14 7.2 6.0 5.2 0.0 0.004/22/2005 19:42 04/22/2005 22:00 2.3 0.06 0.12 0.08 0.05 2.7 2.3 2.1 0.0 0.004/25/2005 18:12 04/26/2005 01:00 6.8 0.15 0.20 0.16 0.10 2.8 5.8 5.0 0.0 0.005/06/2005 05:58 05/06/2005 10:00 4.0 0.39 0.72 0.44 0.32 10.2 15.2 11.5 0.0 0.0

05/11/2005 03:17 05/11/2005 12:00 8.7 0.88 0.40 0.32 0.29 4.7 37.0 27.9 0.0 0.0

—Continued.
Appendix 1 49

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

05/13/2005 01:11 05/13/2005 10:00 8.8 0.45 0.52 0.36 0.34 1.5 20.2 14.8 0.0 0.005/14/2005 13:54 05/14/2005 18:00 4.1 0.07 0.12 0.06 0.04 1.2 1.8 1.4 0.0 0.005/18/2005 21:55 05/19/2005 07:00 9.1 0.61 0.44 0.32 0.25 4.2 25.6 20.5 0.0 0.005/19/2005 15:53 05/19/2005 21:00 5.1 1.17 4.44 -- -- 0.4 11.0 11.0 0.0 0.005/22/2005 05:24 05/22/2005 08:00 2.6 0.10 -- -- -- 2.3 1.7 2.6 0.0 0.0

05/27/2005 02:06 05/27/2005 07:00 4.9 0.16 0.60 -- -- 4.8 5.9 3.4 0.0 0.006/04/2005 23:59 06/05/2005 08:00 8.0 0.37 0.32 0.26 0.22 8.7 16.3 7.0 0.0 0.006/09/2005 17:27 06/09/2005 19:00 1.5 0.15 -- -- -- 4.4 3.6 3.3 0.0 0.006/13/2005 12:58 06/13/2005 14:00 1.0 0.10 -- -- -- 3.7 3.3 2.5 0.0 0.006/24/2005 23:18 06/25/2005 07:00 7.7 0.22 0.12 0.10 0.07 11.4 9.0 8.9 0.0 0.006/25/2005 20:36 06/26/2005 09:00 12.4 0.36 0.56 0.34 0.18 0.6 12.5 13.0 0.0 0.007/04/2005 02:59 07/04/2005 18:00 15.0 0.07 0.04 0.04 0.02 7.7 2.4 2.6 0.0 0.007/12/2005 23:58 07/13/2005 04:00 4.0 0.21 0.36 0.28 0.20 8.2 8.3 8.1 0.0 0.007/20/2005 09:17 07/20/2005 17:00 7.7 0.68 1.32 0.88 0.62 7.2 16.4 17.5 0.0 0.007/21/2005 08:59 07/21/2005 13:00 4.0 1.06 2.92 1.94 1.00 0.7 13.8 13.6 0.0 0.0

07/23/2005 10:47 07/23/2005 17:00 6.2 0.25 0.68 0.40 0.21 1.9 8.1 7.0 0.0 0.007/25/2005 01:09 07/25/2005 08:00 6.8 0.97 0.96 0.70 0.42 1.3 9.0 9.5 0.0 0.007/25/2005 14:55 07/26/2005 16:00 25.1 0.07 0.12 0.08 0.06 0.3 25.3 23.7 0.0 0.008/04/2005 02:45 08/04/2005 07:00 4.2 0.09 0.16 0.08 0.05 8.4 3.3 3.4 0.0 0.008/09/2005 22:59 08/10/2005 09:00 10.0 0.06 0.12 0.08 0.05 5.7 1.7 2.1 0.0 0.008/11/2005 07:55 08/11/2005 16:00 8.1 0.10 0.08 0.06 0.04 1.0 3.8 3.7 0.0 0.008/11/2005 22:32 08/12/2005 07:00 8.5 0.20 0.40 0.28 0.18 0.3 7.3 8.3 0.0 0.008/18/2005 06:48 08/18/2005 12:01 5.2 0.39 0.48 0.32 0.19 6.0 14.2 16.1 0.0 0.008/18/2005 17:56 08/19/2005 08:00 14.1 0.27 0.24 0.20 0.16 0.2 9.2 9.7 0.0 0.008/26/2005 19:38 08/27/2005 04:00 8.4 0.13 0.12 0.10 0.09 7.5 4.4 4.3 0.0 0.0

—Continued.
50 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

09/13/2005 16:38 09/13/2005 19:00 2.4 0.08 0.12 0.10 -- 17.5 1.5 1.2 0.0 0.009/19/2005 05:14 09/19/2005 10:00 4.8 0.27 0.12 0.10 0.10 5.4 6.0 6.1 0.0 0.009/22/2005 03:42 09/22/2005 15:00 11.3 0.15 0.08 0.06 0.06 2.7 3.4 2.1 0.0 0.009/25/2005 09:08 09/26/2005 17:00 31.9 0.89 0.24 0.20 0.17 2.8 16.9 17.0 0.0 0.009/28/2005 12:53 09/29/2005 09:00 20.1 0.28 0.16 0.12 0.11 1.8 7.3 9.4 0.0 0.0

10/05/2005 19:15 10/06/2005 07:00 11.7 0.40 0.16 0.10 0.08 6.4 7.0 5.9 0.0 0.010/17/2005 06:26 10/17/2005 10:51 4.4 0.11 0.08 0.06 0.04 11.0 2.8 2.5 0.0 0.010/23/2005 08:37 10/23/2005 12:00 3.4 0.09 0.04 0.04 0.02 5.9 1.8 1.4 0.0 0.010/30/2005 14:28 10/31/2005 00:00 9.5 0.13 0.08 0.06 0.04 7.1 4.1 4.1 0.0 0.011/05/2005 13:11 11/06/2005 10:59 21.8 1.18 0.64 0.36 0.25 5.5 42.3 66.6 0.0 0.011/12/2005 16:17 11/13/2005 15:00 22.7 0.22 0.52 0.30 0.16 6.2 7.2 8.8 0.0 0.011/15/2005 13:06 11/16/2005 04:00 14.9 0.64 0.28 0.24 0.21 1.9 18.8 37.7 0.0 0.011/23/2005 06:59 11/23/2005 20:00 13.0 0.07 0.20 0.12 -- 7.1 1.7 0.6 0.0 0.011/26/2005 11:12 11/26/2005 17:00 5.8 0.08 0.12 0.08 0.07 2.6 1.1 1.7 0.0 0.011/27/2005 07:07 11/28/2005 18:00 34.9 0.67 0.40 0.32 0.22 0.6 20.3 28.7 0.0 0.0

12/02/2005 09:59 12/02/2005 15:00 5.0 snowmelt -- -- -- 3.7 0.1 1.3 0.0 0.012/04/2005 09:59 12/04/2005 17:00 7.0 snowmelt -- -- -- 1.8 0.2 1.4 0.0 0.012/11/2005 11:59 12/11/2005 17:00 5.0 snowmelt -- -- -- 6.8 1.3 0.0 0.0 0.012/14/2005 11:59 12/15/2005 22:00 34.0 snowmelt -- -- -- 2.8 2.8 1.7 0.0 0.012/22/2005 15:12 01/01/2006 01:00 225.8 0.77a 0.16 0.12 0.12 6.7 31.5 15.9 0.0 0.0

01/01/2006 20:04 01/04/2006 17:00 68.9 0.68 0.28 0.20 0.17 0.8 37.4 31.3 0.0 0.001/20/2006 22:59 01/21/2006 01:00 2.0 0.13a 0.12 0.08 0.07 16.2 1.1 1.1 0.0 0.001/21/2006 08:59 01/21/2006 17:00 8.0 snowmelt -- -- -- 0.3 1.3 1.1 0.0 0.001/24/2006 09:59 01/24/2006 21:00 11.0 snowmelt -- -- -- 2.7 1.8 0.0 0.0 0.0

01/28/2006 05:15 01/28/2006 14:00 8.8 0.25 0.16 0.12 0.08 3.3 8.0 10.0 0.0 0.0

—Continued.
Appendix 1 51

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

01/30/2006 10:22 01/31/2006 17:00 30.6 snowmelt -- -- -- 1.8 0.4 1.5 0.0 0.002/03/2006 04:59 02/03/2006 11:00 6.0 snowmelt -- -- -- 2.5 3.0 3.0 0.0 0.002/17/2006 08:59 02/17/2006 16:00 7.0 snowmelt -- -- -- 13.9 0.2 1.7 0.0 0.002/21/2006 12:28 02/21/2006 17:00 4.5 0.29 0.28 0.24 0.21 3.9 2.2 4.8 0.0 0.002/22/2006 08:59 02/23/2006 00:00 15.0 snowmelt -- -- -- 0.7 2.5 1.6 0.0 0.0

02/23/2006 09:59 02/23/2006 19:00 9.0 snowmelt -- -- -- 0.4 1.5 1.6 0.0 0.002/24/2006 11:59 02/25/2006 02:00 14.0 snowmelt -- -- -- 0.7 1.7 0.6 0.0 0.002/25/2006 09:59 02/25/2006 18:00 8.0 snowmelt -- -- -- 0.3 1.0 1.4 0.0 0.002/28/2006 09:59 02/28/2006 21:00 11.0 snowmelt -- -- -- 2.7 1.6 0.8 0.0 0.003/01/2006 10:59 03/02/2006 00:00 13.0 snowmelt -- -- -- 0.6 1.7 0.4 0.0 0.003/02/2006 11:56 03/02/2006 18:00 6.1 snowmelt -- -- -- 0.5 0.8 1.2 0.0 0.003/04/2006 07:59 03/04/2006 19:00 11.0 snowmelt -- -- -- 1.6 1.5 0.8 0.0 0.003/06/2006 09:25 03/07/2006 01:00 15.6 0.34 0.28 0.18 0.13 1.6 5.3 6.9 0.0 0.003/08/2006 17:41 03/10/2006 15:00 45.3 0.68 0.36 0.32 0.27 1.7 39.4 29.0 0.0 0.003/11/2006 19:41 03/12/2006 02:00 6.3 0.19 0.72 0.36 -- 1.2 3.7 4.3 0.0 0.0

03/12/2006 16:15 03/13/2006 16:36 24.3 0.45 0.24 0.22 0.17 0.6 17.4 17.1 0.0 0.003/17/2006 10:52 03/17/2006 19:00 8.1 0.37 0.28 0.26 0.23 3.8 5.4 9.7 0.0 0.003/23/2006 14:17 03/23/2006 23:00 8.7 0.11 0.16 0.14 0.09 5.8 2.3 2.2 0.0 0.003/30/2006 22:03 03/31/2006 04:00 6.0 0.20 0.16 0.12 0.10 7.0 6.9 8.8 0.0 0.003/31/2006 12:51 03/31/2006 21:00 8.2 0.06 0.12 0.10 -- 0.4 2.3 2.2 0.0 0.004/02/2006 10:49 04/03/2006 09:00 22.2 1.40 1.00 0.60 0.43 1.6 53.7 51.9 0.0 0.004/06/2006 18:24 04/07/2006 12:00 17.6 1.12 0.56 0.46 0.26 3.4 41.7 39.9 0.0 0.004/12/2006 05:15 04/12/2006 10:00 4.7 0.35 0.40 0.34 0.26 4.7 13.6 12.2 0.0 0.004/16/2006 02:05 04/17/2006 03:00 24.9 1.20 2.04 1.12 0.69 3.7 34.4 33.0 0.0 0.004/19/2006 02:36 04/19/2006 10:00 7.4 0.08 0.16 0.08 0.07 2.0 3.5 3.6 0.0 0.0

—Continued.
52 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

04/22/2006 01:15 04/22/2006 09:00 7.7 0.13 0.48 -- -- 2.6 5.1 4.4 0.0 0.004/29/2006 14:20 04/30/2006 19:00 28.7 1.45 0.28 0.22 0.22 7.2 49.5 67.2 0.0 0.005/01/2006 17:38 05/03/2006 14:00 44.4 0.43 1.28 0.74 0.38 0.9 12.4 13.2 0.0 0.005/09/2006 10:53 05/09/2006 23:00 12.1 0.45 0.20 0.16 0.13 5.9 17.5 20.6 0.0 0.005/11/2006 06:49 05/12/2006 15:00 32.2 0.84 0.16 0.10 0.08 1.3 27.2 30.4 0.0 0.0

05/13/2006 00:59 05/15/2006 04:00 51.0 0.06 0.04 0.02 0.01 0.4 5.7 6.4 0.0 0.005/15/2006 10:12 05/17/2006 19:00 56.8 0.32 0.08 0.04 0.02 0.3 15.6 17.1 0.0 0.005/24/2006 18:30 05/25/2006 04:50 10.3 1.11 4.16 2.10 1.05 7.0 24.6 24.7 0.0 0.005/25/2006 12:02 05/26/2006 01:00 13.0 0.47 1.04 0.70 0.38 0.3 19.4 20.1 0.0 0.005/30/2006 12:55 05/31/2006 11:15 22.3 0.28 0.64 0.34 0.17 4.5 17.5 16.3 0.0 0.006/06/2006 05:02 06/06/2006 10:00 5.0 0.18 0.16 0.12 0.10 5.7 6.2 6.6 0.0 0.006/10/2006 00:25 06/10/2006 09:00 8.6 0.71 0.28 0.24 0.22 3.6 26.9 27.9 0.0 0.006/14/2006 11:13 06/14/2006 13:00 1.8 0.16 0.52 -- -- 4.1 5.8 5.6 0.0 0.006/18/2006 04:53 06/18/2006 15:00 10.1 0.30 0.40 0.28 0.18 3.7 11.2 11.1 0.0 0.006/21/2006 05:44 06/21/2006 18:00 12.3 0.10 0.28 0.16 0.08 2.6 3.1 2.4 0.0 0.0

06/24/2006 23:13 06/25/2006 09:00 9.8 0.11 0.20 0.14 0.10 3.2 3.3 3.1 0.0 0.006/25/2006 15:50 06/26/2006 11:00 19.2 0.08 0.08 0.08 0.05 0.3 3.2 3.3 0.0 0.007/09/2006 19:31 07/09/2006 22:00 2.5 0.39 -- -- -- 13.4 11.9 12.3 0.0 0.007/11/2006 07:53 07/11/2006 16:00 8.1 1.60 0.84 0.66 0.49 1.4 60.9 64.1 0.0 0.007/20/2006 02:29 07/20/2006 13:00 10.5 0.88 1.60 0.94 0.53 8.4 26.7 26.2 0.0 0.007/21/2006 12:25 07/21/2006 21:00 8.6 0.13 0.36 0.20 0.11 1.0 4.3 3.7 0.0 0.007/22/2006 03:59 07/23/2006 09:00 29.0 0.06 0.12 0.08 0.04 0.3 1.9 2.2 0.0 0.007/25/2006 23:09 07/26/2006 10:00 10.8 0.13 0.24 0.12 0.08 2.6 4.3 3.5 0.0 0.007/27/2006 11:50 07/27/2006 18:00 6.2 0.74 1.04 0.66 0.42 1.1 17.2 19.1 0.0 0.008/06/2006 05:40 08/06/2006 15:00 9.3 0.92 0.52 0.34 0.26 9.5 34.1 35.8 0.0 0.0

—Continued.
Appendix 1 53

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

08/17/2006 15:16 08/18/2006 07:00 15.7 0.18 0.36 0.28 0.15 11.0 6.2 7.2 0.0 0.008/18/2006 15:01 08/18/2006 21:00 6.0 0.06 0.12 0.06 0.04 0.3 2.4 2.5 0.0 0.008/23/2006 22:19 08/24/2006 11:00 12.7 1.67 2.36 1.30 0.67 5.1 49.9 52.4 0.0 0.008/24/2006 13:07 08/24/2006 17:00 3.9 1.44 2.80 1.60 1.23 0.1 40.1 40.9 0.0 0.008/25/2006 05:09 08/26/2006 06:00 24.8 0.98 1.40 0.70 0.35 0.5 25.7 26.3 0.0 0.0

08/28/2006 08:53 08/28/2006 19:00 10.1 0.11 0.12 0.08 0.06 2.1 3.7 4.2 0.0 0.009/03/2006 18:09 09/04/2006 00:55 6.8 0.39 0.40 0.32 0.20 6.0 15.0 14.6 0.0 0.009/04/2006 05:19 09/04/2006 09:40 4.4 0.35 0.40 0.32 0.24 0.2 13.1 13.1 0.0 0.009/08/2006 22:00 09/09/2006 13:50 15.8 0.08 0.12 0.10 0.07 4.5 3.1 3.3 0.0 0.009/10/2006 05:48 09/13/2006 09:52 76.1 2.96 1.08 0.84 0.54 0.7 114.1 118.3 0.0 0.009/21/2006 21:39 09/22/2006 10:00 12.3 0.08 0.12 0.10 0.07 8.5 4.9 6.2 0.0 0.009/23/2006 13:26 09/24/2006 10:00 20.6 0.18 0.12 0.10 0.08 1.1 6.9 7.4 0.0 0.010/04/2006 05:30 10/04/2006 16:00 10.5 0.35 0.52 0.36 0.25 9.8 11.1 11.2 0.0 0.010/10/2006 19:41 10/11/2006 19:33 23.9 0.46 0.12 0.08 0.08 6.2 16.3 17.8 0.0 0.010/16/2006 15:37 10/17/2006 10:20 18.7 0.78 0.28 0.22 0.19 4.8 30.6 34.6 0.0 0.0

10/18/2006 14:31 10/19/2006 01:36 11.1 0.16 0.12 0.10 0.07 1.2 6.2 6.3 0.0 0.010/21/2006 09:15 10/21/2006 21:15 12.0 0.41 0.16 0.14 0.09 2.3 15.5 15.8 0.0 0.010/22/2006 12:32 10/22/2006 20:10 7.6 0.40 0.36 0.30 0.26 0.6 9.3 12.6 0.0 0.010/26/2006 16:31 10/27/2006 17:10 24.7 0.07 0.04 0.04 0.02 3.8 3.1 3.8 0.0 0.011/10/2006 11:50 11/10/2006 23:00 11.2 0.37 0.32 0.26 0.24 13.8 17.0 21.1 0.0 0.011/11/2006 10:00 11/11/2006 19:03 9.0 0.24 0.16 0.12 0.11 0.5 1.7 1.9 0.0 0.011/12/2006 09:25 11/14/2006 20:00 58.6 0.45 0.16 0.12 0.10 0.6 12.6 13.2 0.0 0.011/26/2006 20:15 11/27/2006 08:00 11.8 0.30 0.36 0.20 0.13 12.0 8.7 11.3 0.0 0.011/27/2006 17:33 11/28/2006 10:00 16.5 0.95 0.28 0.22 0.18 0.4 33.6 39.6 0.0 0.011/29/2006 02:43 11/29/2006 22:00 19.3 0.23 0.12 0.10 0.06 0.7 8.5 9.2 0.0 0.0

—Continued.
54 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

12/10/2006 09:51 12/10/2006 17:00 7.2 0.07 0.04 0.04 0.02 10.5 2.7 0.7 0.0 0.012/11/2006 09:59 12/12/2006 09:00 23.0 0.07 0.24 0.12 0.06 0.7 3.3 3.2 0.0 0.012/20/2006 19:48 12/22/2006 08:00 36.2 0.86 0.32 0.22 0.16 8.4 30.4 36.1 0.0 0.012/22/2006 10:21 12/22/2006 22:00 11.6 0.37 0.40 0.38 0.33 0.1 14.6 13.2 0.0 0.012/31/2006 07:18 12/31/2006 21:00 13.7 0.28 0.28 0.26 0.18 8.4 9.1 13.0 0.0 0.0

01/21/2007 23:59 01/22/2007 19:00 19.0 snowmelt -- -- -- 21.1 1.4 0.0 0.0 0.001/26/2007 11:59 01/27/2007 00:00 12.0 snowmelt -- -- -- 3.7 2.4 0.2 0.0 0.001/27/2007 09:59 01/27/2007 18:00 8.0 snowmelt -- -- -- 0.4 0.4 1.6 0.0 0.002/19/2007 10:59 02/23/2007 16:00 101.0 snowmelt -- -- -- 22.7 10.3 4.9 0.0 0.002/25/2007 11:55 03/02/2007 17:00 125.1 1.04a 0.36 0.28 0.19 1.8 27.8 31.1 0.0 0.0

03/03/2007 09:59 03/03/2007 18:00 8.0 0.07 0.12 0.08 0.05 0.7 1.4 2.8 0.0 0.003/05/2007 10:59 03/05/2007 19:00 8.0 snowmelt -- -- -- 1.7 1.2 0.0 0.0 0.003/09/2007 14:26 03/09/2007 21:04 6.6 0.26a 0.12 0.10 0.08 3.8 20.3 9.5 0.0 0.003/14/2007 16:55 03/14/2007 23:00 6.1 snowmelt -- -- -- 4.8 1.3 1.6 0.0 0.003/21/2007 03:43 03/22/2007 08:00 28.3 1.08 1.76 1.22 0.72 6.2 26.4 30.8 0.0 0.0

03/28/2007 11:35 03/28/2007 18:15 6.7 0.19 0.20 0.14 0.10 6.1 7.4 8.2 0.0 0.003/30/2007 12:27 03/30/2007 20:00 7.5 snowmelt -- -- -- 1.8 1.3 1.5 0.0 0.003/31/2007 08:23 04/01/2007 03:00 18.6 1.09 0.92 0.66 0.48 0.5 38.6 39.4 0.0 0.004/01/2007 10:46 04/01/2007 11:00 0.2 0.09 0.20 0.10 0.05 0.3 1.9 1.7 0.0 0.004/02/2007 23:48 04/03/2007 07:10 7.4 1.68 0.60 0.52 0.39 1.5 38.4 39.4 0.0 0.004/12/2007 11:13 04/13/2007 11:00 35.8 snowmelt -- -- -- 9.2 19.2 13.9 0.0 0.004/22/2007 20:03 04/23/2007 23:00 13.9 0.82 0.64 0.40 0.29 8.9 30.8 29.6 0.0 0.004/24/2007 13:10 04/25/2007 07:21 18.2 0.86 0.20 0.14 0.13 1.1 32.2 33.8 0.0 0.004/25/2007 20:17 04/27/2007 05:00 32.7 0.72 0.24 0.20 0.16 0.5 29.5 30.4 0.0 0.0

04/29/2007 21:59 04/30/2007 03:00 5.0 snowmelt -- -- -- 2.7 1.2 1.2 0.0 0.0

—Continued.
Appendix 1 55

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

05/13/2007 06:04 05/13/2007 11:00 4.9 0.43 0.28 0.24 0.18 13.1 15.2 16.4 0.0 0.005/15/2007 12:14 05/15/2007 22:00 9.8 0.54 0.56 0.40 0.28 2.1 20.3 19.3 0.0 0.005/16/2007 15:31 05/16/2007 19:00 3.5 0.13 0.48 0.24 0.12 0.7 4.3 4.0 0.0 0.005/24/2007 16:30 05/24/2007 21:00 4.5 0.42 1.40 0.72 0.38 7.9 9.1 9.6 0.0 0.006/01/2007 16:30 06/01/2007 20:00 3.5 0.35 0.88 0.46 0.25 7.8 12.8 12.2 0.0 0.0

06/02/2007 06:46 06/02/2007 13:00 6.2 0.43 0.92 0.54 0.35 0.4 15.5 14.6 0.0 0.006/03/2007 17:21 06/04/2007 15:00 21.7 1.40 1.24 0.68 0.39 1.2 43.0 43.4 0.0 0.006/06/2007 14:58 06/06/2007 17:00 2.0 0.07 0.12 0.08 0.06 2.0 2.9 3.4 0.0 0.006/18/2007 15:48 06/19/2007 08:00 16.2 0.50 1.04 0.52 0.28 11.9 14.9 14.9 0.0 0.006/21/2007 11:32 06/22/2007 02:00 14.5 0.79 0.52 0.44 0.28 2.1 28.1 28.2 0.0 0.007/03/2007 05:57 07/03/2007 09:00 3.0 0.08 0.24 -- -- 11.2 3.2 3.0 0.0 0.007/03/2007 19:58 07/04/2007 05:00 9.0 0.43 0.44 0.34 0.29 0.5 16.6 15.8 0.0 0.007/26/2007 23:05 07/27/2007 09:00 9.9 1.00 1.44 1.24 0.82 22.8 26.7 29.9 0.0 0.008/04/2007 13:32 08/05/2007 12:00 22.5 2.19 0.64 0.50 0.37 8.2 86.7 88.4 0.0 0.008/06/2007 22:24 08/07/2007 11:00 12.6 0.46 0.32 0.24 0.18 1.4 15.8 17.0 0.0 0.0

08/09/2007 03:46 08/09/2007 11:00 7.2 0.70 1.04 0.72 0.59 1.7 23.4 24.0 0.0 0.008/12/2007 00:57 08/12/2007 05:00 4.1 0.39 1.12 0.70 0.38 2.6 13.8 12.9 0.0 0.008/14/2007 02:15 08/14/2007 08:00 5.8 1.67 1.76 1.72 0.98 1.9 38.3 39.3 0.0 0.008/15/2007 07:08 08/15/2007 20:00 12.9 0.52 0.32 0.24 0.16 1.0 19.5 19.2 0.0 0.008/18/2007 09:22 08/19/2007 11:49 26.4 3.36 1.52 1.10 0.57 2.6 129.7 133.6 0.0 0.008/19/2007 18:41 08/20/2007 04:49 10.1 0.41 0.20 0.14 0.13 0.3 16.7 18.5 0.0 0.008/22/2007 01:21 08/22/2007 10:00 8.6 0.36 0.60 0.34 0.18 1.9 13.9 12.5 0.0 0.008/22/2007 15:31 08/23/2007 02:00 10.5 1.64 2.32 1.78 0.94 0.2 51.2 46.0 0.0 0.008/23/2007 04:00 08/23/2007 11:00 7.0 0.25 0.36 0.20 0.11 0.1 10.4 9.7 0.0 0.008/23/2007 14:20 08/23/2007 18:02 3.7 0.14 0.36 0.20 0.11 0.1 5.4 4.7 0.0 0.0

—Continued.
56 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

08/24/2007 02:53 08/24/2007 11:00 8.1 0.74 1.24 0.88 0.73 0.4 29.3 24.5 0.0 0.008/24/2007 16:08 08/24/2007 19:39 3.5 0.60 1.92 1.18 0.59 0.2 21.4 19.2 0.0 0.008/27/2007 08:55 08/27/2007 13:00 4.1 0.48 0.48 0.32 0.28 2.6 18.9 18.1 0.0 0.009/06/2007 17:57 09/07/2007 09:00 15.0 0.71 1.32 0.74 0.38 10.2 17.8 18.1 0.0 0.009/10/2007 06:54 09/11/2007 08:00 25.1 0.92 0.28 0.26 0.25 2.9 36.9 35.5 0.0 0.0

09/21/2007 19:08 09/22/2007 08:00 12.9 0.64 1.60 0.82 0.46 10.5 12.9 12.9 0.0 0.009/25/2007 13:23 09/26/2007 09:00 19.6 0.23 0.36 0.28 0.16 3.2 7.4 8.8 0.0 0.009/30/2007 21:41 10/01/2007 12:00 14.3 0.82 0.60 0.30 0.20 4.5 31.9 30.1 0.0 0.010/02/2007 17:17 10/03/2007 08:18 15.0 0.48 0.80 0.42 0.23 1.2 18.7 -- 0.0 --10/08/2007 12:09 10/08/2007 14:00 1.9 0.11 -- -- -- 5.2 4.4 -- 0.0 --10/14/2007 02:52 10/14/2007 23:00 20.1 0.22 0.12 0.08 0.05 5.5 6.3 -- 0.0 --10/15/2007 19:24 10/16/2007 11:00 15.6 0.45 0.32 0.26 0.16 0.8 15.0 -- 0.0 --10/17/2007 20:48 10/18/2007 10:00 13.2 1.23 0.84 0.60 0.48 1.4 46.2 -- 0.0 --10/19/2007 00:47 10/19/2007 13:00 12.2 0.07 0.04 0.04 0.02 0.6 2.4 -- 0.0 --11/20/2007 11:33 11/21/2007 02:00 14.5 0.18 0.12 0.08 0.04 31.9 8.2 -- 0.0 --

11/22/2007 10:09 11/22/2007 16:00 5.8 0.07 0.04 0.04 0.03 1.3 2.1 -- 0.0 --12/02/2007 02:19 12/02/2007 18:00 15.7 0.19 0.12 0.08 0.06 9.4 7.6 -- 0.0 --12/03/2007 10:33 12/03/2007 12:00 1.5 snowmelt -- -- -- 0.7 2.4 -- 0.0 --12/20/2007 12:07 12/23/2007 01:30 61.4 snowmelt -- -- -- 17.0 66.9 -- 0.0 --01/04/2008 13:49 01/09/2008 01:00 107.2 snowmelt -- -- -- 12.5 124.7 -- 0.0 --01/10/2008 11:00 01/11/2008 18:00 31.0 snowmelt -- -- -- 1.4 5.5 -- 0.0 --01/12/2008 11:20 01/13/2008 17:00 29.7 snowmelt -- -- -- 0.7 4.3 -- 0.0 --01/16/2008 13:00 01/17/2008 16:00 27.0 snowmelt -- -- -- 2.8 3.1 -- 0.0 --01/27/2008 13:48 01/29/2008 15:00 49.2 0.35a 0.12 0.08 0.07 9.9 7.8 -- 0.0 --

02/04/2008 13:09 02/06/2008 03:00 37.8 0.32a 0.12 0.08 0.06 5.9 15.5 -- 0.0 --

—Continued.
Appendix 1 57

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

02/07/2008 11:04 02/07/2008 16:00 4.9 snowmelt -- -- -- 1.3 0.5 -- 0.0 --02/08/2008 11:00 02/09/2008 17:00 30.0 snowmelt -- -- -- 0.8 3.5 -- 0.0 --02/17/2008 09:51 02/18/2008 06:00 20.2 0.38a 0.96 0.52 0.29 7.7 19.7 -- 0.0 --

02/23/2008 10:12 02/23/2008 17:00 6.8 snowmelt -- -- -- 5.2 0.5 -- 0.0 --02/24/2008 09:32 02/26/2008 18:00 56.5 snowmelt -- -- -- 0.7 8.8 -- 0.0 --

02/27/2008 13:00 02/27/2008 17:00 4.0 snowmelt -- -- -- 0.8 0.9 -- 0.0 --02/29/2008 11:05 02/29/2008 21:00 9.9 snowmelt -- -- -- 1.8 3.3 -- 0.0 --03/02/2008 07:40 03/02/2008 18:00 10.3 0.62a 0.32 0.30 0.18 1.4 103.8 -- 0.0 --

03/04/2008 10:31 03/04/2008 17:00 6.5 snowmelt -- -- -- 1.7 2.5 -- 0.0 --03/05/2008 12:44 03/05/2008 20:00 7.3 snowmelt -- -- -- 0.8 0.8 -- 0.0 --03/06/2008 11:00 03/06/2008 17:00 6.0 snowmelt -- -- -- 0.6 0.6 -- 0.0 --03/10/2008 10:49 03/10/2008 20:00 9.2 snowmelt -- -- -- 3.7 1.1 -- 0.0 --03/11/2008 11:00 03/12/2008 02:00 15.0 snowmelt -- -- -- 0.6 3.4 -- 0.0 --03/12/2008 10:00 03/14/2008 21:00 59.0 snowmelt -- -- -- 0.3 21.8 -- 0.0 --03/15/2008 14:00 03/15/2008 19:00 5.0 snowmelt -- -- -- 0.7 0.7 -- 0.0 --

03/17/2008 14:00 03/18/2008 23:00 33.0 0.11 0.08 0.04 0.04 1.8 10.0 -- 0.0 --03/22/2008 12:42 03/23/2008 03:00 14.3 0.58 0.44 0.44 0.39 3.6 16.8 -- 0.0 --03/23/2008 10:00 03/25/2008 19:00 57.0 snowmelt -- -- -- 0.3 21.4 -- 0.0 --03/27/2008 01:47 03/27/2008 17:00 15.2 snowmelt -- -- -- 1.3 3.8 -- 0.0 --03/31/2008 02:08 04/01/2008 03:00 24.9 0.94 0.48 0.46 0.33 3.4 52.9 -- 0.0 --04/03/2008 18:40 04/04/2008 02:00 7.3 0.20 0.16 0.12 0.09 2.7 11.9 -- 0.0 --04/06/2008 21:21 04/07/2008 06:00 8.7 0.15 0.16 0.14 0.11 2.8 9.1 -- 0.0 --04/08/2008 12:36 04/09/2008 11:00 22.4 1.06 0.32 0.24 0.21 1.3 66.5 -- 0.0 --04/10/2008 08:41 04/11/2008 07:00 22.3 2.26 1.32 1.08 0.65 0.9 142.2 -- 0.0 --

04/11/2008 17:32 04/12/2008 12:00 18.5 0.17 0.12 0.10 0.07 0.4 9.1 -- 0.0 --

—Continued.
58 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turf- sand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/ yyyy) Start time (hh:mm) End date (mm/dd/ yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity (in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event

Volume

Prairie 

Influent

(ft3

)

Total 

Event

Volume

Turf 

Effluent

(ft3

)

Total 

Event

Volume

Prairie 

Effluent

(ft3

)

04/17/2008 21:09 04/18/2008 04:13 7.1 0.46 0.32 0.26 0.22 5.4 28.6 -- 0.0 --04/18/2008 15:26 04/19/2008 01:00 9.6 0.51 0.64 0.42 0.29 0.5 33.6 -- 0.0 --04/22/2008 10:31 04/22/2008 12:00 1.5 0.06 0.16 0.10 -- 3.4 3.3 -- 0.0 --04/24/2008 14:46 04/25/2008 11:48 21.0 2.12 1.84 1.22 0.98 2.1 119.3 -- 0.0 --04/28/2008 14:46 04/28/2008 17:00 2.2 0.08 0.16 0.10 0.06 3.1 5.7 -- 0.0 --

05/02/2008 03:18 05/02/2008 12:00 8.7 0.49 0.92 0.52 -- 3.4 29.1 -- 0.0 --05/06/2008 23:21 05/07/2008 10:00 10.6 0.41 0.36 0.34 0.29 4.5 27.7 -- 0.0 --05/10/2008 20:28 05/11/2008 12:00 15.5 0.32 0.12 0.08 0.06 3.4 20.1 -- 0.0 --05/17/2008 20:07 05/18/2008 08:00 11.9 0.05 0.12 0.08 0.04 6.3 4.3 -- 0.0 --05/25/2008 19:49 05/26/2008 01:00 5.2 0.42 0.52 0.38 0.28 7.5 26.4 -- 0.0 --05/29/2008 12:55 05/30/2008 12:00 23.1 1.36 0.64 0.60 0.48 3.5 86.7 -- 0.0 --06/02/2008 18:30 06/03/2008 04:00 9.5 0.11 0.08 0.06 0.04 3.3 7.0 -- 0.0 --06/05/2008 03:34 06/05/2008 10:00 6.4 1.23 2.48 1.42 0.84 2.0 56.5 -- 0.0 --06/06/2008 05:26 06/06/2008 09:00 3.6 0.09 0.20 0.10 0.05 0.8 5.1 -- 0.0 --06/07/2008 15:33 06/08/2008 11:24 19.8 2.44 2.88 2.16 1.29 1.3 114.5 -- 0.0 --

06/08/2008 17:06 06/09/2008 06:00 12.9 1.53 2.64 1.90 1.17 0.2 58.9 -- 11.3 --06/12/2008 10:15 06/13/2008 06:00 19.7 2.02 1.56 1.04 0.65 3.2 115.8 -- 0.0 --06/14/2008 15:11 06/15/2008 08:00 16.8 0.33 0.68 0.34 0.17 1.4 19.8 -- 0.0 --06/21/2008 03:11 06/21/2008 09:00 5.8 0.06 0.16 0.10 -- 5.8 3.9 -- 0.0 --06/28/2008 14:20 06/28/2008 16:00 1.7 0.11 0.40 -- -- 7.2 5.8 -- 0.0 --07/06/2008 22:29 07/07/2008 10:00 11.5 0.13 0.20 0.10 0.06 8.3 7.8 -- 0.0 --07/07/2008 20:02 07/08/2008 02:45 6.7 1.69 3.36 1.98 1.24 0.4 63.8 -- 0.0 --07/08/2008 16:32 07/08/2008 21:00 4.5 0.05 -- -- -- 0.6 3.2 -- 0.0 --07/10/2008 17:25 07/10/2008 20:00 2.6 0.21 0.72 0.38 -- 1.9 11.9 -- 0.0 --07/11/2008 01:07 07/12/2008 08:00 30.9 2.76 2.44 1.82 1.14 0.2 135.0 -- 0.0 --

—Continued.
Appendix 1 59

Appendix table 1–1.  Hydrologic and precipitation characteristics of discharge events in the sand rain gardens. In water year 2008, all roof runoff was directed to the turfsand rain garden, doubling the ratio of contributing to receiving area from 5:1 to 10:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date

(mm/dd/

yyyy)

Start 

time

(hh:mm)

End date

(mm/dd/

yyyy)

End 

time

(hh:mm)

Duration 

(h)

Precipitation

depth

(in)

15-minute

precipitation

intensity

(in/h)

30-minute

precipitation

intensity

(in/h)

60-minute

precipitation

intensity

(in/h)

Antecedent 

dry time

(days)

Total Event

Volume

Turf Influent

(ft3)

Total 

Event

Volume

Prairie 

Influent

(ft3)

Total 

Event

Volume

Turf 

Effluent

(ft3)

Total 

Event

Volume

Prairie 

Effluent

(ft3)

07/19/2008 23:24 07/20/2008 04:00 4.6 0.23 0.28 0.24 0.20 7.6 14.8 -- 0.0 --07/29/2008 20:25 07/30/2008 08:00 11.6 0.09 -- -- -- 9.7 5.2 -- 0.0 --08/04/2008 04:48 08/04/2008 15:00 10.2 0.93 2.32 1.46 -- 4.9 46.6 -- 0.0 --08/13/2008 10:57 08/13/2008 15:00 4.0 0.31 1.16 0.58 0.29 8.8 17.7 -- 0.0 --08/28/2008 04:26 08/28/2008 10:00 5.6 0.11 0.12 0.10 0.08 14.6 6.5 -- 0.0 --

08/28/2008 20:28 08/29/2008 09:00 12.5 0.15 0.56 0.28 0.14 0.4 8.5 -- 0.0 --09/04/2008 00:58 09/05/2008 11:00 34.0 1.30 0.68 0.48 0.34 5.7 90.3 -- 0.0 --09/08/2008 09:13 09/08/2008 19:00 9.8 0.16 0.08 0.06 0.04 2.9 10.5 -- 0.0 --09/11/2008 07:53 09/11/2008 13:00 5.1 0.12 0.16 0.12 0.07 2.5 8.2 -- 0.0 --09/12/2008 21:05 09/14/2008 10:00 36.9 1.16 0.40 0.26 0.21 1.3 83.1 -- 0.0 --09/14/2008 19:34 09/15/2008 06:00 10.4 0.11 0.16 0.08 0.06 0.4 8.0 -- 0.0 --09/24/2008 06:52 09/24/2008 10:00 3.1 0.11 0.24 0.20 -- 9.0 7.0 -- 0.0 --

a Combination rainfall and snowmelt event

—Continued.
60 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairie- clay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/yyyy) Start time (hh:mm) End date (mm/dd/yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity(in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3

)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3

)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3

)

12/09/2003 11:50 12/10/2003 17:36 29.8 1.49 0.32 0.28 0.23 -- 228 89 0 0

12/15/2003 18:44 12/16/2003 17:53 23.2 0.17 0.08 0.06 0.04 5.0 157 84 0 0

12/27/2003 21:05 12/28/2003 07:52 10.8 0.30 0.28 0.18 0.13 11.1 106 50 0 0

02/18/2004 12:43 02/21/2004 01:14 76.7 snowmelt -- -- -- 52.2 550 1,096 0 0

02/22/2004 15:27 02/22/2004 21:25 6.0 0.11 0.08 0.06 0.05 0.9 10 11 0 0

02/29/2004 23:09 03/01/2004 04:44 5.6 0.14 0.20 0.14 0.10 7.1 52 112 0 0

03/01/2004 14:57 03/01/2004 22:16 7.3 0.20 0.40 0.20 0.11 0.4 140 247 0 0

03/04/2004 17:46 03/05/2004 18:41 24.9 1.45 0.40 0.30 0.28 2.8 348 335 32 0

03/13/2004 21:00 03/14/2004 03:11 6.2 0.11 0.08 0.06 0.04 8.1 15 14 0 0

03/17/2004 10:55 03/18/2004 20:53 34.0 0.16 0.32 0.28 -- 3.3 20 21 0 0

03/24/2004 01:13 03/24/2004 21:57 20.7 0.18 0.12 0.10 0.09 5.2 59 71 0 0

03/25/2004 20:28 03/26/2004 09:37 13.1 1.31 1.28 0.98 0.74 0.9 812 982 0 0

03/28/2004 11:48 03/28/2004 18:58 7.2 0.33 0.20 0.16 0.11 2.1 149 182 0 0

04/16/2004 23:42 04/17/2004 04:36 4.9 0.62 0.56 0.40 0.32 19.2 66 59 0 0

04/18/2004 01:32 04/18/2004 02:35 1.1 0.18 0.64 -- -- 0.9 19 22 0 0

04/20/2004 14:43 04/20/2004 22:40 8.0 0.78 0.32 0.24 0.22 2.5 81 84 0 0

04/21/2004 04:37 04/21/2004 05:26 0.8 0.11 -- -- -- 0.2 14 15 0 0

04/24/2004 19:00 04/25/2004 13:20 18.3 0.48 0.16 0.08 0.08 3.6 52 58 0 0

05/08/2004 20:19 05/09/2004 03:16 6.9 0.36 0.44 0.26 0.17 13.3 36 38 0 0

05/10/2004 02:30 05/10/2004 16:19 13.8 0.37 0.52 0.32 0.21 1.0 43 43 0 0

05/13/2004 10:46 05/13/2004 16:44 6.0 0.41 0.60 0.32 0.16 2.8 45 48 0 0

05/14/2004 05:40 05/14/2004 12:46 7.1 0.30 0.12 0.08 0.07 0.5 30 33 0 0

05/17/2004 20:04 05/18/2004 05:02 9.0 0.75 1.36 1.16 0.68 3.3 107 83 0 0

05/21/2004 07:25 05/21/2004 09:33 2.1 0.52 0.84 0.54 0.44 3.1 67 62 0 0

05/21/2004 16:10 05/22/2004 08:42 16.5 3.05 2.08 1.34 0.92 0.3 408 351 115 0

.
Appendix 1 61

Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairieclay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date 

(mm/dd/yyyy)

Start 

time 

(hh:mm)

End date 

(mm/dd/yyyy)

End 

time 

(hh:mm)

Duration 

(h)

Precipitation 

depth (in)

15-minute 

precipitation 

intensity(in/h)

30-minute 

precipitation 

intensity

(in/h)

60-minute 

precipitation 

intensity 

(in/h)

Antecedent 

dry time 

(days)

Total Event 

Volume Turf 

Influent (ft3)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3)

05/22/2004 18:13 05/23/2004 09:45 15.5 1.65 1.52 0.92 0.56 0.4 197 209 33 0

05/25/2004 00:39 05/25/2004 11:07 10.5 0.18 0.32 0.28 0.16 1.6 17 19 0 0

05/29/2004 07:15 05/29/2004 14:43 7.5 0.54 0.24 0.22 0.18 3.8 58 61 0 0

05/30/2004 07:56 05/30/2004 11:48 3.9 0.92 1.72 1.00 0.65 0.7 119 113 0 0

05/31/2004 06:53 05/31/2004 15:59 9.1 0.32 0.32 0.16 0.11 0.8 31 31 0 0

06/09/2004 23:52 06/11/2004 11:25 35.6 1.33 1.68 0.88 0.44 9.3 136 147 0 0

06/12/2004 00:09 06/12/2004 05:28 5.3 0.37 0.72 0.36 0.34 0.5 47 45 0 0

06/16/2004 20:39 06/17/2004 06:12 9.5 0.69 0.88 0.74 0.47 4.6 86 74 0 0

06/21/2004 09:34 06/21/2004 13:08 3.6 0.18 0.12 0.10 0.07 4.1 18 22 0 0

06/23/2004 20:31 06/23/2004 21:33 1.0 0.17 -- -- -- 2.3 21 20 0 0

06/24/2004 06:23 06/24/2004 13:37 7.2 0.33 0.32 0.20 0.14 0.4 37 40 0 0

07/03/2004 14:41 07/04/2004 06:57 16.3 1.44 0.84 0.64 0.51 9.0 167 168 0 0

07/06/2004 19:53 07/07/2004 04:38 8.8 0.11 0.16 0.14 0.08 2.5 10 8 0 0

07/09/2004 11:37 07/09/2004 14:27 2.8 0.20 0.48 0.28 0.17 2.3 25 22 0 0

07/16/2004 10:19 07/16/2004 18:56 8.6 1.07 2.12 1.14 0.59 6.8 136 129 0 0

07/21/2004 07:57 07/21/2004 11:49 3.9 0.53 0.80 0.54 0.30 4.5 68 48 0 0

07/29/2004 12:59 07/29/2004 15:43 2.7 0.44 4.56 2.28 1.14 8.0 55 48 0 0

07/30/2004 02:42 07/30/2004 18:11 15.5 0.37 0.40 0.24 0.20 0.5 40 37 0 0

08/02/2004 10:16 08/02/2004 13:12 2.9 0.16 0.16 0.12 0.10 2.7 14 11 0 0

08/03/2004 17:54 08/03/2004 21:20 3.4 1.47 3.24 1.74 0.94 1.2 224 153 11 0

08/16/2004 20:41 08/17/2004 00:00 3.3 0.18 0.28 0.24 0.13 13.0 17 14 0 0

08/18/2004 17:24 08/18/2004 19:58 2.6 0.48 1.40 0.82 -- 1.7 70 46 0 0

08/24/2004 10:24 08/25/2004 13:00 26.6 0.18 0.20 0.16 0.10 5.6 21 18 0 0

08/26/2004 23:57 08/27/2004 00:03 0.1 0.30 0.60 0.34 0.25 1.5 40 33 0 0

08/28/2004 15:57 08/28/2004 19:08 3.2 0.14 0.20 0.14 0.10 1.7 14 10 0 0

—Continued.
62 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairie- clay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/yyyy) Start time (hh:mm) End date (mm/dd/yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity(in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3

)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3

)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3

)

09/01/2004 04:18 09/01/2004 07:05 2.8 0.56 1.12 0.74 0.41 3.4 70 63 0 0

09/06/2004 02:54 09/06/2004 10:00 7.1 0.14 0.36 0.18 0.09 4.8 15 16 0 0

09/15/2004 09:21 09/15/2004 19:01 9.7 0.62 0.40 0.28 0.20 9.0 73 65 0 0

10/01/2004 16:07 10/01/2004 23:04 6.9 0.71 1.08 0.76 0.45 15.9 99 82 0 0

10/07/2004 23:53 10/08/2004 15:01 15.1 0.80 0.80 0.54 0.40 6.0 95 81 0 0

10/19/2004 00:51 10/19/2004 10:00 9.1 0.26 0.20 0.16 0.12 10.4 29 28 0 0

10/22/2004 16:57 10/23/2004 06:56 14.0 1.07 0.40 0.32 0.27 3.3 129 137 0 0

10/26/2004 13:11 10/27/2004 04:00 14.8 0.20 0.08 0.06 0.05 3.3 18 18 0 0

10/29/2004 22:33 10/30/2004 08:01 9.5 0.26 0.52 0.34 0.22 2.8 31 27 0 0

11/01/2004 08:48 11/02/2004 06:59 22.2 0.50 0.12 0.08 0.06 2.0 66 62 0 0

11/04/2004 01:40 11/04/2004 10:01 8.3 0.21 0.16 0.12 0.11 1.8 23 23 0 0

11/15/2004 10:05 11/15/2004 23:01 12.9 0.14 0.08 0.06 0.05 11.0 9 8 0 0

11/18/2004 20:38 11/20/2004 12:00 39.4 0.37 0.08 0.06 0.06 2.9 41 40 0 0

11/26/2004 23:23 11/27/2004 14:16 14.9 0.45 0.16 0.12 0.09 6.5 25 48 0 0

12/05/2004 21:42 12/06/2004 10:57 13.3 0.65 0.24 0.20 0.19 8.3 55 74 0 0

12/06/2004 22:18 12/07/2004 00:57 2.6 0.63 0.24 0.18 0.14 0.5 70 75 0 0

12/09/2004 20:55 12/10/2004 23:12 26.3 0.32 0.08 0.06 0.05 2.8 20 18 0 0

01/12/2005 06:52 01/13/2005 12:03 29.2 0.82a 0.36 0.30 0.27 32.3 201 192 9 0

01/31/2005 10:36 02/01/2005 12:03 25.5 0.17a 0.12 0.06 0.05 17.9 23 23 0 002/06/2005 18:09 02/07/2005 14:08 20.0 0.37a 0.12 0.10 0.08 5.3 11 11 0 002/13/2005 10:28 02/14/2005 13:07 26.6 0.77a 0.16 0.14 0.11 5.8 44 44 0 003/07/2005 00:49 03/07/2005 09:07 8.3 0.15a 0.32 0.22 0.13 20.5 32 31 0 003/30/2005 14:01 03/31/2005 10:05 20.1 0.72a 1.20 0.64 0.32 23.2 140 117 26 004/06/2005 19:09 04/07/2005 05:14 10.1 1.02 1.12 0.96 0.80 6.4 125 119 0 0

04/12/2005 03:19 04/12/2005 21:53 18.6 0.49 0.32 0.26 0.18 4.9 46 43 0 0

—Continued.
Appendix 1 63

Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairieclay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date 

(mm/dd/yyyy)

Start 

time 

(hh:mm)

End date 

(mm/dd/yyyy)

End 

time 

(hh:mm)

Duration 

(h)

Precipitation 

depth (in)

15-minute 

precipitation 

intensity(in/h)

30-minute 

precipitation 

intensity

(in/h)

60-minute 

precipitation 

intensity 

(in/h)

Antecedent 

dry time 

(days)

Total Event 

Volume Turf 

Influent (ft3)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3)

04/19/2005 22:56 04/20/2005 12:35 13.6 0.16 0.32 0.20 0.14 7.0 18 18 0 0

04/22/2005 19:35 04/22/2005 20:54 20.9 0.08 0.12 0.10 -- 1.5 9 6 0 0

04/25/2005 18:15 04/26/2005 10:25 16.2 0.15 0.16 0.14 0.10 2.9 16 16 0 0

05/06/2005 05:54 05/06/2005 09:44 3.8 0.41 0.60 0.36 0.33 9.8 48 37 0 0

05/11/2005 03:14 05/11/2005 11:12 8.0 1.12 0.44 0.40 0.32 4.7 123 91 0 0

05/13/2005 01:18 05/13/2005 08:40 7.4 0.48 0.48 0.38 0.32 1.6 49 37 0 0

05/18/2005 21:52 05/19/2005 05:05 7.2 0.73 0.52 0.42 0.31 5.6 76 59 0 0

05/19/2005 11:40 05/19/2005 17:59 6.3 0.47 1.68 0.86 0.43 0.3 69 42 0 0

05/27/2005 02:02 05/27/2005 03:33 1.5 0.27 0.96 0.48 0.24 7.3 32 26 0 0

06/05/2005 01:09 06/05/2005 08:56 7.8 0.32 0.32 0.20 0.19 8.9 37 36 0 0

06/09/2005 17:25 06/09/2005 17:45 0.3 0.64 -- -- -- 4.4 96 63 0 0

06/10/2005 20:57 06/10/2005 22:05 1.1 0.18 -- -- -- 1.1 25 20 0 0

06/13/2005 12:50 06/13/2005 13:52 1.0 0.28 -- -- -- 2.6 44 31 0 0

06/14/2005 20:21 06/15/2005 04:47 8.4 0.11 0.36 0.18 0.10 1.3 14 13 0 0

06/24/2005 23:18 06/25/2005 08:25 9.1 0.26 0.16 0.10 0.06 9.8 35 27 0 0

06/25/2005 20:55 06/26/2005 09:16 12.3 0.22 0.16 0.14 0.12 0.5 30 25 0 0

07/12/2005 23:00 07/14/2005 08:11 33.2 0.57 0.72 0.62 0.43 16.6 82 60 0 0

07/20/2005 09:33 07/20/2005 12:25 2.9 0.64 1.12 0.92 0.59 6.1 90 62 0 0

07/21/2005 08:56 07/21/2005 14:03 5.1 0.83 2.20 1.38 0.74 0.9 136 76 0 0

07/23/2005 10:38 07/23/2005 14:37 4.0 0.12 0.28 0.16 0.08 1.9 15 12 0 0

07/25/2005 00:56 07/25/2005 03:26 2.5 0.14 0.24 0.14 0.10 1.4 18 12 0 0

07/25/2005 14:53 07/26/2005 04:23 13.5 0.97 0.84 0.64 0.36 0.5 140 98 0 0

08/04/2005 02:38 08/04/2005 13:22 10.7 0.11 0.20 0.10 0.07 8.9 17 12 0 0

08/11/2005 22:42 08/12/2005 03:04 4.4 0.22 0.40 0.28 0.19 7.4 30 21 0 0

08/18/2005 06:46 08/18/2005 11:20 4.6 0.31 0.24 0.22 0.14 6.2 41 30 0 0

—Continued.
64 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairie- clay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/yyyy) Start time (hh:mm) End date (mm/dd/yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity(in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3

)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3

)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3

)

08/18/2005 17:52 08/18/2005 19:30 1.6 0.24 0.84 0.44 -- 0.3 34 23 0 0

08/26/2005 19:34 08/26/2005 22:42 3.1 0.15 0.16 0.12 0.09 8.0 20 16 0 0

09/19/2005 05:14 09/19/2005 18:10 12.9 0.39 0.52 0.34 0.19 23.3 55 39 0 0

09/25/2005 09:07 09/25/2005 14:35 5.5 0.73 1.12 0.64 0.38 5.6 108 67 0 0

09/25/2005 19:52 09/26/2005 01:41 5.8 0.29 0.52 0.36 0.22 0.2 45 25 0 0

09/28/2005 12:54 09/29/2005 10:02 21.1 0.28 0.20 0.18 0.15 2.5 38 22 0 0

10/05/2005 19:17 10/06/2005 09:13 13.9 0.39 0.52 0.30 0.22 6.4 54 34 0 0

10/17/2005 06:17 10/17/2005 17:57 11.7 0.14 0.20 0.14 0.07 10.9 15 16 0 0

11/05/2005 12:43 11/06/2005 08:15 19.5 1.62 0.64 0.36 0.25 18.8 218 145 0 0

11/12/2005 16:27 11/13/2005 00:12 7.7 0.16 0.32 0.18 0.10 6.3 22 18 0 0

11/15/2005 13:00 11/15/2005 20:10 7.2 0.66 0.28 0.24 0.21 2.5 89 54 0 0

11/27/2005 02:03 11/28/2005 20:31 42.5 0.83 0.40 0.30 0.22 11.2 121 78 0 0

01/01/2006 20:20 01/04/2006 13:07 64.8 0.76 0.40 0.32 0.23 34.0 88 67 0 0

01/24/2006 09:24 01/24/2006 14:19 4.9 0.16a 0.20 0.16 0.13 19.8 7 9 0 0

01/28/2006 05:14 01/29/2006 23:32 42.3 1.03 0.16 0.14 0.10 3.6 107 112 0 0

03/07/2006 11:54 03/08/2006 01:30 13.6 0.19a 0.12 0.06 0.05 36.5 16 34 0 0

03/08/2006 17:37 03/09/2006 18:38 25.0 0.68a 0.32 0.26 0.25 0.7 61 60 0 003/12/2006 15:52 03/13/2006 11:06 19.2 0.53 0.28 0.24 0.20 2.9 70 65 0 0

03/17/2006 09:18 03/17/2006 18:39 9.4 0.27a 0.12 0.10 0.07 3.9 15 24 0 0

03/30/2006 22:44 03/31/2006 05:24 6.7 0.19 0.20 0.14 0.09 13.2 18 18 0 0

03/31/2006 12:43 03/31/2006 14:00 1.3 0.07 -- -- -- 0.3 9 9 0 0

04/02/2006 10:44 04/03/2006 07:01 20.3 1.21 0.72 0.42 0.31 1.9 143 130 0 0

04/06/2006 18:14 04/07/2006 10:02 15.8 0.88 0.44 0.34 0.20 3.5 103 83 0 0

04/12/2006 05:19 04/12/2006 09:18 4.0 0.30 0.36 0.30 0.24 4.8 37 30 0 0

04/16/2006 02:04 04/16/2006 20:56 18.9 1.16 1.32 0.88 0.56 3.7 144 121 0 0

—Continued.
Appendix 1 65

Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairieclay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date 

(mm/dd/yyyy)

Start 

time 

(hh:mm)

End date 

(mm/dd/yyyy)

End 

time 

(hh:mm)

Duration 

(h)

Precipitation 

depth (in)

15-minute 

precipitation 

intensity(in/h)

30-minute 

precipitation 

intensity

(in/h)

60-minute 

precipitation 

intensity 

(in/h)

Antecedent 

dry time 

(days)

Total Event 

Volume Turf 

Influent (ft3)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3)

04/22/2006 01:11 04/22/2006 08:28 7.3 0.12 0.40 -- -- 5.2 16 14 0 0

04/29/2006 14:23 04/30/2006 18:29 28.1 1.78 0.32 0.26 0.22 7.2 190 210 0 0

05/01/2006 18:17 05/02/2006 09:56 15.7 0.29 0.72 0.38 0.19 1.0 36 37 0 0

05/09/2006 10:28 05/10/2006 11:40 25.2 0.47 0.24 0.18 0.12 7.0 46 60 0 0

05/11/2006 06:49 05/12/2006 14:20 31.5 0.83 0.12 0.10 0.10 0.8 95 104 0 0

05/13/2006 19:40 05/14/2006 15:30 19.8 0.25 0.28 0.16 0.08 1.2 30 27 0 0

05/15/2006 13:39 05/16/2006 09:37 20.0 0.14 0.20 0.12 0.06 0.9 16 15 0 0

05/16/2006 15:29 05/17/2006 09:47 18.3 0.71 2.04 1.24 0.65 0.2 101 80 0 0

05/17/2006 15:53 05/17/2006 22:49 6.9 0.15 0.32 -- -- 0.3 20 16 0 0

05/24/2006 18:27 05/24/2006 22:37 4.2 1.11 4.16 2.10 1.05 6.8 150 64 0 0

05/25/2006 12:02 05/26/2006 01:01 13.0 0.47 1.04 0.70 0.38 0.6 57 45 0 0

05/30/2006 12:55 05/30/2006 18:14 5.3 0.28 0.64 0.34 0.17 4.5 37 28 0 0

05/31/2006 05:58 05/31/2006 09:02 3.1 0.77 0.96 0.82 0.68 0.5 112 77 0 0

06/06/2006 05:20 06/06/2006 10:02 4.7 0.17 0.16 0.12 0.10 5.8 16 21 0 0

06/10/2006 00:23 06/10/2006 08:00 7.6 0.80 0.36 0.30 0.26 3.6 103 97 0 0

06/14/2006 10:22 06/14/2006 13:03 2.7 0.19 0.44 0.24 0.14 4.1 20 16 0 0

06/17/2006 19:32 06/17/2006 21:15 1.7 0.14 -- -- -- 3.3 20 16 0 0

06/18/2006 05:29 06/18/2006 15:07 9.6 0.31 0.28 0.26 0.15 0.3 32 33 0 0

06/25/2006 15:36 06/25/2006 19:04 3.5 0.49 1.04 0.82 0.44 7.0 58 53 0 0

06/26/2006 00:21 06/26/2006 11:00 10.7 0.50 0.44 0.28 0.15 0.2 52 56 0 0

07/09/2006 19:28 07/10/2006 01:02 5.6 0.34 -- -- -- 13.4 51 33 0 0

07/11/2006 07:56 07/11/2006 19:04 11.1 1.37 0.76 0.58 0.44 1.3 154 131 0 0

07/20/2006 02:33 07/20/2006 11:09 8.6 0.85 1.24 0.74 0.42 8.3 106 97 0 0

07/25/2006 23:26 07/26/2006 13:01 13.6 0.17 0.40 0.22 0.11 5.5 21 18 0 0

07/27/2006 11:46 07/27/2006 17:01 5.3 0.76 0.80 0.76 0.46 0.9 98 78 0 0

—Continued.
66 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairie- clay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/yyyy) Start time (hh:mm) End date (mm/dd/yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity(in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3

)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3

)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3

)

08/06/2006 05:33 08/06/2006 13:02 7.5 0.97 0.36 0.30 0.27 9.5 114 111 0 0

08/17/2006 14:51 08/17/2006 21:04 6.2 0.17 0.24 0.22 0.11 11.1 18 15 0 0

08/23/2006 22:18 08/24/2006 09:24 11.1 1.95 2.20 1.16 0.62 6.1 271 205 0 0

08/24/2006 12:55 08/24/2006 21:38 8.7 1.51 2.88 1.64 1.23 0.1 206 128 10 0

08/25/2006 05:13 08/25/2006 12:34 7.3 0.74 0.72 0.40 0.30 0.3 88 82 0 0

09/03/2006 17:58 09/03/2006 21:44 3.8 0.42 0.36 0.26 0.23 9.2 51 49 0 0

09/04/2006 05:14 09/04/2006 09:29 4.3 0.28 0.24 0.18 0.16 0.3 32 29 0 0

09/10/2006 05:55 09/12/2006 23:14 65.3 3.61 1.00 0.88 0.56 5.9 464 427 0 0

09/21/2006 21:29 09/22/2006 08:09 10.7 0.17 0.12 0.10 0.07 8.9 14 14 0 0

09/23/2006 13:23 09/23/2006 18:15 4.9 0.21 0.16 0.12 0.09 1.2 16 17 0 0

10/04/2006 05:47 10/04/2006 14:06 8.3 0.45 0.80 0.54 0.35 10.5 60 49 0 0

10/10/2006 19:29 10/11/2006 14:08 18.7 0.55 0.16 0.10 0.09 6.2 50 59 0 0

10/16/2006 15:30 10/17/2006 09:11 17.7 0.87 0.32 0.24 0.21 5.1 100 74 0 0

10/18/2006 14:36 10/18/2006 23:05 8.5 0.19 0.16 0.12 0.08 1.2 24 22 0 0

10/21/2006 09:24 10/22/2006 01:53 16.5 0.45 0.16 0.10 0.09 2.4 43 49 0 0

10/22/2006 04:22 10/22/2006 19:11 14.8 0.23 0.12 0.08 0.07 0.1 29 27 0 0

11/10/2006 11:46 11/10/2006 15:30 3.7 0.32 0.28 0.22 0.19 18.7 39 34 0 0

11/12/2006 09:37 11/13/2006 14:29 28.9 0.45 0.12 0.08 0.06 1.8 51 42 0 0

11/26/2006 20:15 11/27/2006 02:11 5.9 0.31 0.32 0.20 0.15 13.2 42 34 0 0

11/27/2006 18:09 11/28/2006 07:58 13.8 1.02 0.32 0.26 0.19 0.7 141 100 0 0

11/29/2006 02:26 11/29/2006 23:15 20.8 0.22 0.12 0.08 0.06 0.8 20 17 0 0

12/20/2006 19:45 12/21/2006 13:56 18.2 1.03 0.20 0.18 0.17 20.9 111 95 0 0

12/22/2006 05:58 12/22/2006 15:02 9.1 0.37 0.44 0.38 0.32 0.7 43 40 0 0

12/31/2006 07:17 01/01/2007 08:17 25.0 0.42 0.40 0.36 0.25 8.7 54 53 0 0

02/19/2007 09:53 02/22/2007 04:12 66.3 snowmelt -- -- -- 49.1 118 170 0 0

—Continued.
Appendix 1 67

Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairieclay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date 

(mm/dd/yyyy)

Start 

time 

(hh:mm)

End date 

(mm/dd/yyyy)

End 

time 

(hh:mm)

Duration 

(h)

Precipitation 

depth (in)

15-minute 

precipitation 

intensity(in/h)

30-minute 

precipitation 

intensity

(in/h)

60-minute 

precipitation 

intensity 

(in/h)

Antecedent 

dry time 

(days)

Total Event 

Volume Turf 

Influent (ft3)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3)

02/25/2007 08:05 02/25/2007 16:58 8.9 0.25a 0.12 0.08 0.07 3.2 16 13 0 0

03/01/2007 10:50 03/02/2007 06:15 19.4 0.61a 0.48 0.36 0.23 3.7 35 77 0 003/09/2007 09:29 03/09/2007 20:14 10.7 0.31a 0.12 0.10 0.08 7.1 38 50 0 003/21/2007 03:42 03/22/2007 04:15 24.6 1.15 1.88 1.24 0.77 11.3 152 121 0 0

03/28/2007 05:32 03/28/2007 18:16 12.7 0.22 0.28 0.18 0.13 6.1 19 20 0 0

03/31/2007 08:24 04/01/2007 01:09 16.8 1.40 1.32 0.90 0.71 2.6 184 130 0 0

04/02/2007 23:48 04/03/2007 08:05 8.3 1.75 0.60 0.54 0.38 1.9 214 181 0 0

04/12/2007 09:03 04/12/2007 22:15 13.2 snowmelt -- -- -- 9.0 17 25 0 0

04/13/2007 08:55 04/13/2007 09:29 0.6 snowmelt -- -- -- 0.4 1 22 0 0

04/22/2007 20:05 04/23/2007 08:24 12.3 0.90 0.80 0.46 0.31 9.4 122 99 0 0

04/24/2007 13:15 04/25/2007 12:10 22.9 0.33 0.16 0.14 0.12 1.2 43 34 0 0

04/25/2007 17:18 04/27/2007 01:13 31.9 0.65 0.20 0.16 0.13 0.2 69 58 0 0

05/05/2007 01:06 05/07/2007 18:11 65.1 0.12 0.08 0.06 0.04 8.0 9 11 0 0

05/13/2007 06:06 05/13/2007 11:11 5.1 0.39 0.28 0.24 0.19 5.5 42 38 0 0

05/15/2007 09:57 05/16/2007 03:12 17.3 0.53 0.48 0.34 0.24 1.9 70 48 0 0

05/16/2007 15:24 05/16/2007 18:12 2.8 0.12 0.36 0.18 0.09 0.5 15 13 0 0

05/24/2007 16:00 05/24/2007 21:03 5.1 0.27 0.52 0.28 0.20 7.9 42 26 0 0

06/01/2007 16:23 06/01/2007 20:12 3.8 0.64 1.92 0.98 0.52 7.8 96 67 0 0

06/02/2007 06:53 06/02/2007 17:09 10.3 0.46 1.00 0.56 0.38 0.4 63 53 0 0

06/03/2007 19:04 06/04/2007 11:07 16.0 2.27 1.96 1.52 1.09 1.1 304 223 0 0

06/07/2007 19:15 06/07/2007 20:40 1.4 0.14 0.48 -- -- 3.3 21 13 0 0

06/18/2007 15:45 06/20/2007 12:07 44.4 0.40 0.40 0.28 0.19 10.8 58 40 0 0

06/21/2007 11:28 06/22/2007 02:11 14.7 1.16 0.84 0.60 0.45 1.0 144 124 0 0

07/03/2007 16:08 07/04/2007 09:20 17.2 0.47 0.44 0.38 0.29 11.6 69 51 0 0

07/26/2007 23:05 07/27/2007 11:15 12.2 1.27 1.72 1.60 1.02 22.6 189 136 0 0

—Continued.
68 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairie- clay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/yyyy) Start time (hh:mm) End date (mm/dd/yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity(in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3

)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3

)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3

)

08/04/2007 13:28 08/05/2007 09:37 20.1 2.64 0.68 0.56 0.45 8.1 341 214 0 0

08/07/2007 02:44 08/07/2007 13:22 10.6 0.38 0.28 0.22 0.17 1.7 46 29 0 0

08/09/2007 03:39 08/09/2007 10:58 7.3 0.64 0.84 0.62 0.49 1.6 79 54 0 0

08/12/2007 00:55 08/12/2007 11:17 10.4 0.41 1.16 0.70 -- 2.6 56 46 0 0

08/14/2007 02:09 08/14/2007 07:24 5.3 2.10 2.40 1.80 1.05 1.6 276 249 12 0

08/15/2007 07:17 08/16/2007 04:06 20.8 0.55 0.28 0.22 0.15 1.0 68 65 0 0

08/18/2007 09:19 08/19/2007 12:50 27.5 3.81 1.44 1.04 0.56 2.2 459 430 0 0

08/19/2007 18:35 08/20/2007 16:59 22.4 0.57 0.44 0.26 0.17 0.2 61 57 0 0

08/22/2007 01:18 08/22/2007 08:51 7.5 0.37 0.56 0.30 0.18 1.3 43 41 0 0

08/22/2007 15:36 08/22/2007 21:22 5.8 1.35 2.48 1.56 0.82 0.3 179 162 0 0

08/23/2007 04:12 08/23/2007 11:17 7.1 0.19 0.28 0.20 0.12 0.3 19 19 0 0

08/23/2007 14:17 08/23/2007 18:23 4.1 0.15 0.36 0.22 0.11 0.1 14 13 0 0

08/24/2007 02:58 08/24/2007 10:41 7.7 0.82 1.20 1.00 0.77 0.4 102 93 0 0

08/24/2007 16:02 08/24/2007 19:03 3.0 0.34 1.08 -- -- 0.2 40 41 0 0

08/27/2007 08:47 08/27/2007 13:03 4.3 0.70 0.68 0.46 0.37 2.6 90 84 0 0

09/06/2007 18:05 09/07/2007 08:04 14.0 0.43 0.56 0.34 0.18 10.2 55 45 0 0

09/10/2007 06:51 09/10/2007 17:52 11.0 0.97 0.32 0.30 0.25 2.9 109 107 0 0

09/21/2007 19:05 09/21/2007 22:19 3.2 0.59 1.28 0.70 0.40 11.1 82 68 0 0

09/25/2007 13:10 09/25/2007 19:11 6.0 0.28 0.36 0.30 0.18 3.6 40 31 0 0

09/30/2007 21:38 10/01/2007 10:54 13.3 0.76 0.40 0.24 0.23 5.1 82 55 0 0

10/02/2007 17:13 10/02/2007 22:00 4.8 0.46 0.80 0.40 0.22 1.3 -- 45 -- 0

10/08/2007 12:04 10/08/2007 14:00 1.9 0.06 -- -- -- 5.6 -- 6 -- 0

10/14/2007 02:57 10/14/2007 15:10 12.2 0.23 0.20 0.10 0.05 5.5 -- 13 -- 0

10/15/2007 15:43 10/16/2007 04:20 12.6 0.47 0.24 0.20 0.14 1.0 -- 32 -- 0

10/17/2007 20:26 10/18/2007 06:15 9.8 1.50 0.92 0.70 0.59 1.7 -- 151 -- 0

—Continued.
Appendix 1 69

Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairieclay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date 

(mm/dd/yyyy)

Start 

time 

(hh:mm)

End date 

(mm/dd/yyyy)

End 

time 

(hh:mm)

Duration 

(h)

Precipitation 

depth (in)

15-minute 

precipitation 

intensity(in/h)

30-minute 

precipitation 

intensity

(in/h)

60-minute 

precipitation 

intensity 

(in/h)

Antecedent 

dry time 

(days)

Total Event 

Volume Turf 

Influent (ft3)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3)

11/20/2007 11:28 11/21/2007 11:00 23.5 0.14a 0.08 0.06 0.03 33.2 -- 65 -- 0

12/20/2007 14:39 12/23/2007 02:35 59.9 snowmelt -- -- -- 29.2 -- 722 -- 0

01/05/2008 18:52 01/05/2008 21:45 2.9 snowmelt -- -- -- 13.7 -- 108 -- 0

01/07/2008 07:25 01/07/2008 16:45 9.3 0.74a 1.80 0.92 0.48 1.4 -- 276 -- 0

01/08/2008 02:09 01/08/2008 19:25 17.3 0.45a 0.48 0.28 0.20 0.4 -- 191 -- 0

01/13/2008 12:00 01/13/2008 17:25 5.4 snowmelt -- -- -- 4.7 -- 15 -- 0

01/28/2008 07:22 01/29/2008 16:45 33.4 snowmelt -- -- -- 14.6 -- 72 -- 0

02/04/2008 13:33 02/05/2008 22:00 32.4 0.32a 0.12 0.08 0.07 5.9 -- 112 -- 0

03/02/2008 09:42 03/03/2008 05:15 19.5 1.21 0.36 0.30 0.19 25.5 -- 274 -- 0

03/17/2008 22:59 03/18/2008 04:20 5.3 0.16 0.12 0.08 0.07 14.7 -- 22 -- 0

03/22/2008 13:32 03/25/2008 17:00 75.5 snowmelt -- -- -- 4.4 -- 76 -- 0

03/31/2008 02:04 04/01/2008 04:45 26.7 1.02 0.56 0.48 0.33 5.4 -- 240 -- 0

04/03/2008 18:20 04/04/2008 05:30 11.2 0.25 0.16 0.14 0.11 2.6 -- 44 -- 0

04/06/2008 21:16 04/07/2008 02:15 5.0 0.13 0.16 0.12 0.10 2.7 -- 28 -- 0

04/08/2008 12:44 04/09/2008 09:00 20.3 1.15 0.28 0.22 0.20 1.4 -- 211 -- 0

04/10/2008 07:08 04/11/2008 11:50 28.7 3.07 2.04 1.42 0.85 0.9 -- 580 -- 39

04/11/2008 16:58 04/12/2008 12:00 19.0 0.15 0.08 0.04 0.03 0.2 -- 38 -- 0

04/17/2008 21:07 04/18/2008 05:35 8.5 0.45 0.28 0.24 0.21 5.4 -- 85 -- 0

04/18/2008 09:44 04/19/2008 00:24 14.7 0.45 0.44 0.30 0.23 0.2 -- 91 -- 0

04/22/2008 10:07 04/22/2008 13:55 3.8 0.08 0.16 0.14 -- 3.4 -- 16 -- 0

04/24/2008 14:42 04/25/2008 17:15 26.5 2.61 2.04 1.36 1.17 2.0 -- 559 -- 3

04/28/2008 14:47 04/28/2008 17:15 2.5 0.11 0.16 0.12 0.10 2.9 -- 12 -- 0

05/02/2008 03:16 05/02/2008 04:45 1.5 0.26 0.96 -- -- 3.4 -- 54 -- 0

05/02/2008 10:12 05/02/2008 12:00 1.8 0.29 0.92 0.52 -- 0.2 -- 55 -- 0

05/06/2008 23:25 05/07/2008 02:00 2.6 0.32 0.32 0.28 0.23 4.5 -- 40 -- 0

—Continued.
70 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08 Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairie- clay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1 [mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured] Start date (mm/dd/yyyy) Start time (hh:mm) End date (mm/dd/yyyy) End time (hh:mm) Duration (h) Precipitation depth (in) 15-minute precipitation intensity(in/h) 30-minute precipitation intensity (in/h) 60-minute precipitation intensity (in/h) Antecedent dry time (days) Total Event Volume Turf Influent (ft3

)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3

)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3

)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3

)

05/10/2008 20:27 05/11/2008 10:30 14.1 0.30 0.08 0.06 0.05 3.8 -- 20 -- 0

05/25/2008 19:44 05/25/2008 22:30 2.8 0.47 0.60 0.50 0.36 14.4 -- 75 -- 0

05/29/2008 12:51 05/30/2008 09:00 20.2 1.44 0.60 0.48 0.36 3.6 -- 215 -- 0

06/02/2008 17:49 06/02/2008 19:20 1.5 0.15 0.12 0.08 0.05 3.4 -- 9 -- 0

06/05/2008 03:34 06/05/2008 09:25 5.9 1.23 2.48 1.42 0.84 2.3 -- 312 -- 0

06/06/2008 05:26 06/06/2008 08:00 2.6 0.09 0.20 0.10 0.05 0.8 -- 9 -- 0

06/07/2008 15:33 06/09/2008 01:00 33.4 3.97 2.88 2.16 1.29 1.3 -- 865 -- 74

06/12/2008 10:04 06/13/2008 04:15 18.2 1.64 1.20 0.62 0.43 3.4 -- 316 -- 0

06/14/2008 15:09 06/14/2008 19:00 3.8 0.31 0.64 0.32 0.16 1.5 -- 74 -- 0

06/22/2008 15:10 06/22/2008 18:50 3.7 0.26 0.88 0.44 0.22 7.8 -- 57 -- 0

06/27/2008 10:20 06/27/2008 10:55 0.6 0.09 -- -- -- 4.6 -- 25 -- 0

07/06/2008 22:22 07/07/2008 02:20 4.0 0.10 0.12 0.06 0.03 9.5 -- 16 -- 0

07/07/2008 19:58 07/08/2008 00:07 4.2 1.52 2.04 1.40 1.01 0.7 -- 362 -- 0

07/08/2008 16:28 07/08/2008 17:00 0.5 0.11 -- -- -- 0.7 -- 24 -- 0

07/10/2008 17:23 07/10/2008 17:55 0.5 0.21 0.72 0.38 -- 2.0 -- 48 -- 0

07/11/2008 01:07 07/12/2008 10:15 33.1 3.10 1.24 1.18 1.06 0.3 -- 768 -- 22

07/19/2008 23:21 07/20/2008 00:55 1.6 0.24 0.24 0.24 0.21 7.5 -- 38 -- 0

07/29/2008 20:20 07/29/2008 22:00 1.7 0.16 0.60 -- -- 9.8 -- 36 -- 0

08/04/2008 04:50 08/04/2008 13:00 8.2 0.70 1.36 1.00 0.67 5.3 -- 149 -- 0

08/06/2008 18:25 08/06/2008 19:20 0.9 0.12 0.44 0.22 -- 2.2 -- 20 -- 0

08/13/2008 10:56 08/13/2008 14:25 3.5 0.56 2.16 1.08 0.55 6.7 -- 122 -- 0

08/28/2008 04:16 08/28/2008 07:55 3.7 0.16 0.28 0.14 0.09 14.6 -- 27 -- 0

08/28/2008 20:23 08/28/2008 21:30 1.1 0.15 -- -- -- 0.5 -- 30 -- 0

09/04/2008 01:22 09/04/2008 20:35 19.2 1.04 0.20 0.18 0.18 6.2 -- 156 -- 0

09/08/2008 09:03 09/08/2008 17:30 8.4 0.16 0.08 0.06 0.04 3.5 -- 17 -- 0

—Continued.
Appendix 1 71

Appendix table 1–2.  Hydrologic and precipitation characteristics of discharge events in the clay rain gardens. In water year 2008, all roof runoff was directed to the prairieclay rain garden, doubling the ratio of contributing to receiving area from 4:1 to 8:1[mm/dd/yyyy, month/day/year; hh:mm, hour:minute; in, inch; h, hour; in/h, inch per hour; ft3, cubic feet; --, not computed or measured]

Start date 

(mm/dd/yyyy)

Start 

time 

(hh:mm)

End date 

(mm/dd/yyyy)

End 

time 

(hh:mm)

Duration 

(h)

Precipitation 

depth (in)

15-minute 

precipitation 

intensity(in/h)

30-minute 

precipitation 

intensity

(in/h)

60-minute 

precipitation 

intensity 

(in/h)

Antecedent 

dry time 

(days)

Total Event 

Volume Turf 

Influent (ft3)

Total 

Event 

Volume 

Prairie 

Influent 

(ft3)

Total 

Event 

Volume 

Turf 

Effluent 

(ft3)

Total 

Event 

Volume 

Prairie 

Effluent 

(ft3)

09/11/2008 07:49 09/11/2008 13:30 5.7 0.11 0.12 0.08 0.06 2.6 -- 20 -- 0

09/12/2008 20:55 09/13/2008 20:00 23.1 1.16 0.40 0.28 0.19 1.3 -- 247 -- 0

09/14/2008 15:34 09/15/2008 02:34 11.0 0.12 0.16 0.10 0.07 0.8 -- 20 -- 0

09/24/2008 06:40 09/24/2008 07:20 0.7 0.14 0.24 0.22 -- 9.2 -- 20 -- 0

a Combination rainfall and snowmelt event

—Continued.
72 Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sandy Soil: Madison, Wisconsin, Water Years 2004–08

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Selbig and Balster— Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sand Soil, Madison, Wisconsin, Water Years 2004–08—Scientific Investigations Report 2010–5077