Variations in streamflow among watersheds of the Cumberland Plateau, Tennessee

The purpose of this study is to evaluate the differences in streamflow characteristics among the streams of the Cumberland Plateau of Tennessee and to account for those differences. The study is limited to those gaged basins on the Plateau with water shed areas of 50 to 1000 square miles in order to avoid the extreme variations found in very small basins as well as the moderating effect of large basins.

Stream discharges at low and peak flows were obtained from published sources. In order to compare flows from watersheds of varying size, all flows were standarized to units of cubic feet per second per square mile. Graphic display of the results in the form of flow duration curves and flood flow recurrence curves reveals major differences in the hydrologic response of streams in the study area. Water budget analysis and recalculation of flood peaks using a standard time interval indicates that differences in the streamflow regimes of the various watersheds are not attributable to long-term differences in climatic factors or to chance variations of individual large storms.

Factors found to be most significant in influencing watershed runoff rates are: (1) basin storage capacity for transient surplus water; (2) the nature of groundwater storage systems; (3) slope factors; and (4) minor factors such as basin shape and land use.