US EPA

Calculation of time of travel from dye-tracing studies in karstic aquifers is critical to establishing pollutant arrival times from points of inflow to resurgences, calculation of subsurface flow velocities, and determining other important transport parameters such as longitudinal dispersion. In addition, breakthrough curve modeling demands accurate time of travel calculations if model results are to have any realistic meaning. However, accurate time of travel calculations are very difficult for long tracer tests in which sampling schedules are not consistent or when there are major disruptions such as may occur when adverse weather conditions cause automatic sampling equipment to fail. Long and inconsistent sampling times may be accurately converted to decimal times of travel by converting the conventionally recorded Gregorian sampling date and time event to a baseline time standard similar to astronomer’s use of Julian time. By converting to a baseline time standard, all recorded dates and times are linked to the established baseline standard so that each succeeding sampling date and time is correctly determined relative to the previous sampling date and time and to the injection date and time.

Journal Article

FIELD, M. S. Calculation Of Elapsed Decimal Time For Dye-Tracing Studies: Application Of A Baseline Time Standard (Journal Article). GROUND WATER. National Ground Water Association, Westerville, OH, 46(1):156-159, (2008).