Spatial trends in Pearson Type III statistical parameters

Spatial trends in the statistical parameters (mean, standard deviation, and skewness coefficient) of a Pearson Type III distribution of the logarithms of annual flood peaks for small rural basins (less than 90 km 2 ) are delineated using a climate factor, C T ( T = 2-, 25-, and 100-yr recurrence intervals) which quantifies the effects of long-term climatic data (rainfall and pan evaporation) on observed T -yr floods. The statistical parameters are computed from gridded estimates of the geographically varying climate factors and regression models relating at-site T -yr floods as a function of drainage area, climate factor, hydrograph shape, and infiltration. Spatial portrayals, covering a large part of the United States east of the 105th meridian, are presented for averaged statistical parameters and their variability obtained using data from a sample of 200 small basins scattered over 12 states. Maps showing trends in average parameter values demonstrate the geographically varying influence of climate on ...