Supplementary data and code for "Distribution-Based Method-Selection Framework for Reservoir Storage Estimation in a Semi-Arid Snow-Fed Basin" (Water, MDPI, 2026)

Supplementary Material S1 (annual streamflow series of gauging stations 2119, 2151, 2154 and 2156 in the Karasu sub-basin of the Upper Euphrates, Türkiye; water years, Mm³) and S2 (Python scripts s00–s23 with their numerical outputs and README) of the article "Distribution-Based Method-Selection Framework for Reservoir Storage Estimation in a Semi-Arid Snow-Fed Basin", Water (MDPI), 2026 (manuscript water-4572251). The scripts reproduce the data compilation, the fitting of the Normal, Log-Normal and Gamma distributions, goodness-of-fit tests and Akaike weights, the closed-form storage estimators (Gould–Dincer, Alexander, McMahon–Mein), the behaviour analysis, the 50,000-year synthetic-record simulations, the model-conditional reference capacity with its bootstrap uncertainty, and the checks of the tables and text. Software versions and random seeds are listed in the README; every numerical output was reproduced from the scripts. The monthly DSİ records are not redistributed (available from DSİ on request).