ABSTRACT
The method presented in this chapter may be used to adjust a peak-discharge time series that is nonstationary because of changing land use within the gaged watershed over the gaging period. The method has several parts. First, the method focuses on deriving a spatially sensitive time series of land use. This step requires resourcefulness and creativity on the part of the hydrologist to obtain relevant data and to organize these data into a format, most likely using making use of geographic information systems (GIS) technology, that can be readily used to generate the values necessary as input to the hydrologic model. The next step is to calibrate the hydrologic model over the gaging period being studied, while taking into account the spatially and temporally varying land use. The final step is to use the calibrated model to generate a synthetic time series of peak discharge, related to the observed time series, but adjusted to reflect a single land use condition such as the current or ultimate land use. This chapter examines the differences in derived flood-frequency behavior between the observed (nonstationary) and adjusted (stationary) peakdischarge time series.
