Two-Gamma Reduced Analytical Hydrograph for SCS-CN Huff Design Storms

Abstract

This archive contains the code, prepared data, results, figures, and Supplemental Material S1 for A Continuous Two-Gamma Formulation for Design Hydrographs Using SCS-CN Runoff Generation and Huff Rainfall Temporal Distributions. Calculate a hydrograph for a new design case. Open supplemental_code/. The Python and MATLAB functions take total rainfall, drainage area, curve number, storm duration, time of concentration, and a Huff quartile. They return the hydrograph, the sensitivity to curve number, and a plot. Understand the calculation. Read supplement/supplemental_quartile_equations.pdf. It contains the numerical equations, coefficient tables, a worked Brazilian case, the curve number derivative, and a guide to the supplied code. Reproduce the analyses in the paper. Install the packages in requirements.txt, then run the scripts listed below from the extracted archive folder. Contents of the archive To calculate a hydrograph supplement/: Supplemental Material S1 in PDF format. supplemental_code/: standalone Python and MATLAB functions, plus a short Python example. src/: the continuous SCS-CN/Huff reference calculation, the two-gamma hydrograph, and the unit hydrograph comparison routines. To reproduce the study scripts/: scripts that fit and test the design equation, calculate the Brazilian headwater application, compare alternative hydrograph procedures, and examine the first quartile boundary case. data/: prepared inputs for 11,443 HydroBASINS level 12 headwater catchments in the Cerrado, Caatinga, Atlantic Forest, and Pampa. idf/: Sherman IDF coefficient rasters used to calculate 25-year rainfall depth. To inspect the outputs results/: numerical outputs for the design grid, curve number and time of concentration sensitivity analyses, Brazilian catchment application, and four catchment method comparison. figures/: figures in PDF, PNG, and SVG formats. SVG files can be edited in vector-graphics software. Run the analyses Install the Python dependencies once: python3 -m pip install -r requirements.txt Run the main design-grid and Brazilian headwater analysis: python3 scripts/run_huff_design_study.py Run the comparison with tabular SCS-CN procedures, the NRCS 484 unit hydrograph, and Guo's General Unit Hydrograph: python3 scripts/run_four_catchment_method_comparison.py Run the direct-use Python example: python3 supplemental_code/example_two_gamma_usage.py How the data are used The prepared catchment table contains the inputs used in the Brazilian application: catchment identifier and location, drainage area, flow length, channel slope, Kirpich time of concentration, GCN250 AMC-II curve number, local intensity-duration-frequency coefficients, and derived 25-year rainfall depth. The results files document the headwater selection, excluded cases, curve number checks, catchment coverage, and hydrograph ordinates used in the comparisons. The archive contains prepared catchment inputs and final figures. It does not redistribute the manuscript, submission documents, or the national boundary, biome, elevation, and GCN250 source layers used only to prepare map context. The manuscript identifies those external sources. README.md gives the full directory guide, data provenance, and software requirements.