Update on the use of the RORA program for recharge estimation.

An update on the use of the RORA program is provided to supplement information given in the initial description of the program in Ground Water in 1994. The method estimates ground water recharge on the basis of streamflow records. Important considerations in the use of the automated approach are described that should improve the reliability of recharge estimates and avoid misapplication of the technique. Topics include the recession index, errors caused by direct surface runoff, the time scale for reporting results, comparisons with results of manual calculations, and errors caused by gradual recharge and discharge. The use of ground water levels for independent assessment of results from RORA is also described. RORA results are compared and contrasted with results from other base flow separation techniques.