Development of Geomorphological Unit Hydrograph (GUH) for Ungauged Basins

This research work significantly advances hydrological modelling in Greece by introducing Geomorphological Unit Hydrographs (GUH) tailored for ungauged basins. These GUHs, specifically adapted to the region’s intricate geomorphology and limited data resources, provide essential insights into hydrological behaviour. Utilising an innovative approach that integrates the time-area diagram method with Python’s ArcPy module, this paper examines the geomorphological metrics of 70 drainage basins and their relationships with hydrograph characteristics. Empirical relationships, expressed through simple forms like second-order polynomials and linear equations, are established and validated across 30 basins. System analysis reveals the efficacy of the 0.1–2.0 channel velocity range, supported by positive Nash–Sutcliffe Efficiency (NSE) values. Visual representations, including histograms, elucidate the intricate connections between hydrograph attributes and geomorphological parameters. Regression analysis produces predictive equations, demonstrating strong performance with models such as T-Polynomial for Q_max and Cc-Linear for other hydrograph attributes, and their precision is confirmed through validation regression analysis, enhancing forecasting across various drainage basins.