A device for simulating overland flow

A Flow Simulation Applicator (FSA) was heloped to create even-sheet overland flow of water into a vegetative filter strip. The FSA, constructed from easily-obtained materials, is adaptable to various applications, portable, easily calibrated and delivers reproducible flow rates. Variability among replications was quite small with Coefficient of Variability (CV) of less than 1.5%. Water flowed as a sheet onto the test surface at application rates of 4 L min−1 (1.1 gal) or greater. In initial field tests, the device was used to apply a 0.1 mg kg1 (0.1 PPM) atrazine solution to 1 × 5-m (3.3 × 16.4-ft) sections of buffalograss (Buchloë dactyloides Nutt. Engelm.)sod at a rate equivalent to run of occurring from a 30-m (38.4-ft) wide field directly upslope with a 5.1 cm (2 in) rain. The outflow atrazine concentration from the sod was reduced in the first 15 min, and then increased, stabilizing at 85% of the input concentration. With minor modifications, the FSA can provide inflow for concentrated flow experiments.