Design and Construction of an Urban Runoff Research Facility

Summary

This paper describes the design, construction, and function of a 1,000 m² facility containing 24 individual 33.6 m² field plots equipped for measuring total runoff volumes with time and collection of runoff subsamples at selected intervals for quantification of chemical constituents in the runoff water from simulated home lawns.

Abstract

As the urban population increases, so does the area of irrigated urban landscape. Summer water use in urban areas can be 2-3x winter base line water use due to increased demand for landscape irrigation. Improper irrigation practices and large rainfall events can result in runoff from urban landscapes which has potential to carry nutrients and sediments into local streams and lakes where they may contribute to eutrophication. A 1,000 m² facility was constructed which consists of 24 individual 33.6 m² field plots, each equipped for measuring total runoff volumes with time and collection of runoff subsamples at selected intervals for quantification of chemical constituents in the runoff water from simulated urban landscapes. Runoff volumes from the first and second trials had coefficient of variability (CV) values of 38.2 and 28.7%, respectively. CV values for runoff pH, EC, and Na concentration for both trials were all under 10%. Concentrations of DOC, TDN, DON, PO₄-P, K⁺, Mg²⁺, and Ca²⁺ had CV values less than 50% in both trials. Overall, the results of testing performed after sod installation at the facility indicated good uniformity between plots for runoff volumes and chemical constituents. The large plot size is sufficient to include much of the natural variability and therefore provides better simulation of urban landscape ecosystems.

Introduction

Four of the most rapidly growing, highly populated metropolitan areas are located in the southern U.S. in subtropical climates¹. In addition, the largest percent change in urbanized land between 1982 and 1997 occurred in southern USA¹. With increased urban areas comes a concomitant demand for potable water, much of which is used for outdoor use during summer months². With new construction, programmable in-ground irrigation systems are often installed. Unfortunately, these systems are often programmed to deliver irrigation to urban landscaping more frequently and/or in volumes that exceed evapotranspiration demands of the landscape....

Protocol

1. Site Selection

1. Locate a suitably-sized area of undisturbed soil having a uniform 3-4% slope.
2. Conduct a topographic survey and delineate an area approximately 10 m x 100 m having an average 3.7±0.5% slope.
3. Divide the 10 m x 100 m area into three blocks, each approximately 10 m x 33.3 m (Figure 1).
4. Subdivide each block into 8 field plots, each 4.1 m wide by 8.2 m long.
5. Identify and document the soil series present in the study area. Note: this location had a Booneville series fine sandy loam but other soil series and textures may be used.

2. Retai....

Results

Plot characteristics
The average slope for all 24 plots was 3.7% and ranged from a low of 3.2% for plot 17 to a high of 4.1% for plot 2 (Table 1). Average topsoil thickness was 36 cm and ranged from a low of 25.0 cm for plot 24 to a high of 51.5 cm for plot 10 (Table 1).

Runoff volumes
Runoff volumes from the first trial on 09 August 2012 had a mean of 213.5 L and ranged from a low of 95.6 L to a high of 391 L with a coefficient of variability (CV) of .......

Discussion

Water flow over, into, and through soils is greatly affected by the topography, vegetative cover, and the soil physical properties. Excessively compacted soils and soils with high clay contents will exhibit reduced infiltration rates and increased amounts of runoff. Therefore, when building a facility of this nature, every effort should be made to use native soils with uniform slopes and minimize compaction from all types of traffic on the experimental areas during construction. In addition, compaction from post construc.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Flow Meter	Teledyne Isco	Model 4230	Bubbling flow meter that measures and records water flow through flume
Portable Sampler	Teledyne Isco	Model 6712	Works in conjunction with the flow meter to collect water samples at predetermined intervals.
Flow Link Software to collect data	Teledyne Isco	Ver 5.0	Allows communication between flow meter and computer
Presloped trench drain	Zurn Industries, LLC	Z-886
Irrigation Controller	Toro Company	VP Satellite	Controls irrigation to each plot individually
Electric Valves	Hunter	2.5 cm PGV	Opens or closes water flow to individual plots based on signal from irrigation controller
Irrigation heads	Hunter	Pro Spray 4	4 in pop up spray heads
6 in Slotted Drain Pipe	Advanced Drainage Systems	6410100	Single wall corrugated HDPE - slotted
6 in Plain Drain Pipe	Advanced Drainage Systems	6400100	Single wall corrugated HDPE - plain
Filter Paper	Whatman GF/F	1825-047	47 mm diameter, binder-free, glass microfiber filter
pH Meter	Fisher	Accumet XL20
Combination pH Probe	Fisher	13-620-130
Automatic Temperature Compensating Probe	Fisher	13-602-19
Electrical Conductivity Probe	Fisher	13-620-100	Cell constant of 1.0
TOC-VCSH with total nitrogen unit TMN-1	Shimadzu Corp	TOC-VCSH with TMN-1	Dissolved C and N analyzer
Smartchem 200	Unity Scientific	200	Discrete Analyzer for P measurement
ICS 1000	Dionex	ICS 1000	Ion Chromatography for Ca, Mg, K, and Na measurement
Portable Soil Moisture Meter	Spectrum	FieldScout TDR 300	7.5 cm long probes
Totallizing Water Meters	Badger	3/4 inch water meters	Standard homeowner water meters