Relation between precipitation deficiency and low streamflow

Abstract

A study was made to determine whether low-flow frequency distributions in Illinois could be reliably estimated from meteorological data and geologic factors. The development of such a method is desirable because of the general lack of long-term streamflow records. In this study, use was made of 50-year records of precipitation from 62 locations and data from 12 stream-gage stations with 45-year or longer records. When the state was divided into six different geomorphic regions it was found that the low-flow frequencies for any basin in each region could be reliably estimated by the precipitation frequency distribution and a geomorphic index. The regional geomorphic indices were developed through use of data from the 12 basins with long streamflow records. The method developed is applicable for basins of any size, for recurrence intervals of five years or longer, and for drought durations of 12 months or longer. Although based upon Illinois data, the method should be applicable to other regions in the United States and other parts of the world.