Surface Water Index of Permanence (SWIPe) for the upper Missouri River basin, 1989-2021

With the Surface Water Index of Permanence (SWIPe), we provide a standardized metric for describing one- to five-year anomalies of the annual minimum surface water extent of streams and wetlands for multiple spatial scales including basin (4-digit hydrologic unit codes [HUCs]) to subwatersheds (12-digit HUCs). Drier conditions are represented by negative SWIPe values that range from 0 to -3 standard deviations from zero, or the normal condition. SWIPe is calculated for the upper Missouri River basin using streamflow permanence probability estimates from the Probability of Streamflow Permanence for the upper Missouri River basin (PROSPERum) model and surface-water inundation observations from the Dynamic Surface Water Extent (DSWE) dataset for years 1989-2021. The upper Missouri River basin consists of four-digit HUCs 1002-1013. Intrinsic mode functions that describe overall and interannual trends in the underlying SWIPe time series, and the significance, are provided as part of this data release. SWIPe is calculated using several different cumulative distribution functions (CDFs) including generalized normal, generalized extreme value, generalized logistic, Pearson-3, Weibull, and generalized Pareto. The CDF with p-values < 0.05 based on the Kolmogorov-Smirnov (K-S) test and the lowest Akaike Information Criterion was used to model probabilities on which SWIPe is based. An empirical CDF was applied when all of the theoretical CDFs resulted in p-values > 0.05. The probabilities were standardized to have a mean around zero and standard deviation of one.

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  "010:12"
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  "geospatial"
]