Abstract |
Base-flow recession curves of nineteen Illinois streams were analyzed to determine the most significant factors which affected the base-flow recession rate. The eight most significant factors were (in order): number of days since the last major storm, average minimum daily temperature, average daily temperature, average maximum daily temperature, discharge at beginning of recession, average daily evaporation for one to five days preceeding the beginning of the recession, average daily evaporation for the duration of the recession and total runoff. A regression equation for these variations was derived. The relationship between base-flow and the water depth in various wells was studied. Significant correlations were obtained for dry weather flow for some wells but the relationships were found to be invalid during periods of storm runoff. Tritium analyses of eight water samples from two different watersheds were made. The results indicated that a normal gravity flow system exists with shallow groundwater moving toward the streams rather than leaking to underlying aquifers. (Author) |