Recent in-flight instances of aircraft engine power loss involving hail ingestion have forced the manufacturers to demonstrate successful engine operation whilst ingesting hail. The main objective of this research project has been to obtain an understanding of the basic characteristics of hailstone impacts. A hail gun was designed to fire simulated hailstones at speeds up to 175 m/s. Three measurement techniques were used to determine the impact characteristics of the hailstones, i.e: patternator, high speed cine-photography, and still photography with short duration flashes. Using these techniques, the basic impact characteristics in terms of post-impact particle size, velocity and mass distribution were obtained for a variety of target configurations. The influence of seemingly important parameters on the impact characteristics were investigated, including approach angle and velocity, target curvature, and target rotation. Studies were further made into multiple impacts, and the effect of target curvature and rotation on the impact characteristics. Based on the experimental results, a set of empirical rules and a mathematical model describing hailstone break-up were defined.

Escherichia coli changes in Sinking Creek, an impaired water body in the Watauga watershed of northeast Tennessee, were assessed during storm events using water samples collected with ISCO automated samplers during eight storms at two locations. Turbidity and electrical conductivity (EC) data loggers were deployed in the creek, and dissolved oxygen (DO) was measured in situ to test the stream’s water quality and reaction to inclement weather. Cotton fabric was deployed at both locations and sent to an external lab to test for the presence of Optical Brighteners (OB), which are indicators of residential wastewater. E. coli and turbidity at the creek generally increased within 2.5 hours of a rain event, remaining above the single sample standard for several hours during the storm. At the spring, E. coli became elevated within 30 minutes of precipitation onset, but generally decreased below the standard during the event.

Sinking Creek (HUC 06010103046), in the Watauga watershed of northeast Tennessee, is impaired due to Escherichia coli. To assess how E. coli and other water quality parameters fluctuated during storm events, water samples were collected with automated samplers during eight storms at two locations: Sinking Creek and a feeder spring. Turbidity and electrical conductivity data loggers were deployed in the creek, and dissolved oxygen (DO) was measured in situ. The presence of optical brighteners, used in detergents and an indicator of residential wastewater, was assessed using cotton fabric deployed at both sites and analyzed by an external laboratory. The Colilert Quanti-Tray method was used to process water samples for E. coli. Relationships between water quality parameters and lagged precipitation were assessed using cross-correlation. At the creek, E. coli and turbidity increased within 2 h of precipitation, exceeding the single sample water quality standard of 941 cfu 100 ml−1 during the storm. At the spring, E. coli became elevated more quickly than at the stream, within 30 min of precipitation, and decreased below the standard during the event. Electrical conductivity decreased within 1.5 h of the storm at the creek, and DO levels were higher at the creek than at the spring. Optical brightener analysis indicated possible presence of residential wastewater during one of two sampled storms. Targeted sampling and dye tracing are recommended to validate this hypothesis. These results may be used to inform field methods in similar storm sampling studies and will be useful in watershed restoration efforts in Sinking Creek.

No description available.