Procedure for Estimating Flow-Duration Curves for Ungaged Mountainous and High Plains Streams in Montana

摘要

A procedure for estimating shape and magnitude of flow-duration curves for ungaged stream locations in Montana has been developed. This procedure utilizes a dimensionless flow-duration curve which is determined based on streamflow records from a particular hydrologic region. The dimensionless curve is 'scaled' to an ungaged site using drainage area and mean annual precipitation as determined from suitable maps. Methodology requires that individual judgment be used in selecting flow-duration curve shape--especially if spring flow and/or regulation exist above the chosen site. Accuracy of this procedure will vary depending on the degree of hydrologic similarity between the ungaged site and the gaged streams used to develop dimensionless curves.