A New Urban Runoff Research Facility At Texas A&M University.

Efficient use of landscape irrigation water and retention of applied nutrients and pesticides are critical components of sustainable urban landscapes.  A 1,000 m² facility containing 24 individual 33.6 m² field plots at a slope of 3.6% was constructed atop non-disturbed native soil and instrumented for measuring total runoff volumes with time, and collection of runoff water subsamples at selected intervals.  Half the plots were sodded with Raleigh St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze) on 8-Aug-2012 and the remaining plots on 12-Sept-2012. 

Preliminary data from an initial runoff event 24 hr after planting shows reasonable uniformity between plots in terms of runoff volume and nutrient concentrations in the runoff water.  Runoff volumes from the two planting dates had coefficient of variability (CV) values of 28.7 and 38.2%.  The pH values for all water samples collected after the first runoff event the morning after laying sod on 8-Aug-2012 averaged 8.4 standard units with a CV of 1.5%.  The electrical conductivity and sodium concentration of the runoff samples had fairly large means and CV values below 10%.  Concentrations of DOC, TDN, DON, PO₄-P, K, Mg and Ca had CV values in the range of 10.3 to 32.9%.  Concentrations of NO₃-N and NH₄-N had means of 0.58 and 0.12 mg/L and were the most variable with CV values of 85.0 and 63.5%, respectively.

Overall, the runoff facility has numerous benefits for future research concerning runoff from turf covered areas such as home lawns, sports fields, parks and similar green spaces.  Primary among these is that the facility is large enough to be maintained on a long term basis using full sized equipment common to the turf industry.  The large size of the individual plots should help include similar amounts of natural variability and microclimate effects in each.  Runoff measurement and sampling is automated allowing data and sample collection from unscheduled storm events.  Future studies at this facility will provide scientific data to help shape best management procedures for urban landscape irrigation, fertilization and pest control to minimize off site transport of water and applied materials.