Summary of Decadal No-Flow Fractions and Decadal L-Moments of Nonzero Streamflow Flow-Duration Curves for National Hydrography Dataset, Version 2 Catchments in the Southeastern United States, 1950 - 2010, at 12-digit Hydrologic Unit Code (HUC12) Pour Points
Description
Censored and uncensored generalized additive models (GAMs) are developed from 955 U.S. Geological Survey streamflow-gaging stations (streamgages) to predict decadal statistics of streamflow. The streamgages are located on streams draining to the Gulf of Mexico. Decadal statistics include no-flow fractions and selected L-moments of nonzero streamflow for six decades (1950s—2000s). These statistics represent metrics of decadal flow-duration curves (dFDCs) derived from about 10 million daily mean streamflows. The L-moments include the mean, coefficient of L-variation, and the third through fifth L-moment ratios. The models are fit using watershed properties such as basin area and slope, decadal precipitation and temperature and decadal values of flood storage and urban development percentages. The GAMs then estimate decadal statistics for 8,988 prediction locations (stream reaches) coincident with outlets of level-12 hydrologic unit codes. Both the entire dataset (whole model) and leave-one-watershed-out model results are reported. No-flow fractions are censored data and Tobit extensions to GAMs are effective in estimation of ephemeral streamflow conditions. Uncensored GAMs conversely were used for estimation of the L-moments. The R language was used to pull and process the streamflow data, and the scripts can be found online at https://code.usgs.gov/water/restore/fdclmrpplo.