Rainfall validation, runoff estimation, and drainage capacity assessment for a residential development

Abstract

Background: Rapid conversion of peri-urban land to housing increases impervious cover, accelerates runoff, and can overload small drainage corridors. This study evaluated the hydrological baseline and proposed stormwater infrastructure for the Sunville Residence development in Paccinongang, Gowa Regency, Indonesia. Methods: The assessment integrated creek geometry and velocity surveys conducted in June and December 2025, NASA Global Precipitation Measurement rainfall for 2015–2024, a 24-month comparison with nearby Meteorology, Climatology, and Geophysics Agency gauge maxima, partial-duration screening above 50 mm/day, reported Gumbel design rainfall, Mononobe rainfall intensity, the Rational Method, open-channel hydraulic checks, detention-volume calculations, and suspended-sediment loads. Satellite validation used bias, mean absolute error, root mean square error, Pearson correlation, percent bias, and Nash–Sutcliffe efficiency. Findings: Observed creek discharge ranged from 0.495 to 0.660 m³/s. NASA rainfall underestimated gauge maxima by 8.98 mm on average, with a mean absolute error of 18.13 mm, root mean square error of 24.75 mm, correlation of 0.68, percent bias of −19.82%, and Nash–Sutcliffe efficiency of 0.36. The reported 10-year design rainfall and intensity were 122.91 mm and 7.34 mm/h. Estimated runoff increased from 1.29 m³/s during construction to 1.80 m³/s during operation as the runoff coefficient rose from 0.25 to 0.35. The proposed channel capacity was 1.90 m³/s, leaving only 0.10 m³/s or 5.6% hydraulic margin. An illustrative aggregate bias adjustment increased operational runoff to 2.24 m³/s, above the stated capacity. A 13,000 m³ sedimentation pond marginally exceeded the corrected 8-hour storage requirement of 12,960 m³. Estimated sediment load increased from 1.25 t/day upstream to 1.40 t/day downstream. Conclusion: The proposed system is nominally adequate under the reported design event, but its narrow capacity and storage margins require reconciliation of input inconsistencies, sensitivity testing, clogging allowances, and integrated source-control measures before final engineering approval. Novelty/Originality of this article: The study combines hydrological calculation with a reproducibility audit that identifies numerical and documentation inconsistencies that materially affect drainage safety decisions in a fast-growing Indonesian residential catchment.