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This paper develops a tsunami inundation model, filling the current void between industry applied simplified methods (bathtub and attenuation) and comprehensive numerical modeling. The proposed model utilizes two‐dimensional equations established on hydraulic principles (energy conservation and friction loss) to produce the finite‐difference, two‐dimensional model. While the sophistication of depth‐averaged numerical modeling has not been entirely replicated, the incorporation of hydraulic roughness and gravitational effects (slope) through the Bernoulli energy equation, accompanied by suitable assumptions, significantly improves performance over simplified bathtub and attenuation methods. This improvement not only retains excellent efficiency (completing case studies in under 100 s) but also yields inundation results comparable to traditional numerical modeling, which typically takes multiple hours to days. This is the first application of such equations to a two‐dimensional tsunami inundation model, leading to simulations at Gisborne and Christchurch, New Zealand, for validation against the numerical model, COMCOT. F1 scores produced from inundation extent comparisons were upwards of 84%. Inundation depth discrepancies recorded 77% within a ±$\pm$1 m range, while over 93% within a ±$\pm$2 m range. [ABSTRACT FROM AUTHOR]

With recent acknowledgment that New Zealand requires updated guidelines in predicting rainfall and runoff, this case study compares three approaches in forming flood regions for the North Island of New Zealand. With comparison to regions in the literature, new regions are delineated on the basis of administrative boundaries, similar catchment climate and dominant topographies, and comparable linear moment ratios of the coefficient of variation (L-CV) of the annual maximum flow series. Across 204 individual flow gauging sites, the regions on the basis of L-CV were observed to provide the best predictors of flood discharges when compared with those derived using at-site analyses, with relative errors of 6.9 and 21% for 10- and 100-year peak discharges, respectively. Although these regions are delineated on the basis of spatial proximity and similar hydrologic flood flow regimes, concerns are raised regarding the homogeneity of these regions as a whole. Although further breakdowns of regions could be beneficial, these regions are still recommended for use in ungauged catchments over those previously published. [ABSTRACT FROM AUTHOR]

Summary As a case study for the Auckland Region of New Zealand, this paper investigates the potential use of gene-expression programming (GEP) in predicting specific return period events in comparison to the established and widely used Regional Flood Estimation (RFE) method. Initially calibrated to 14 gauged sites, the GEP derived model was further validated to 10 and 100 year flood events with a relative errors of 29% and 18%, respectively. This is compared to the RFE method providing 48% and 44% errors for the same flood events. While the effectiveness of GEP in predicting specific return period events is made apparent, it is argued that the derived equations should be used in conjunction with those existing methodologies rather than as a replacement. [ABSTRACT FROM AUTHOR]