Data for manuscript 'An analytical approach to ascertain saturation-excess versus infiltration-excess overland flow in urban and reference landscapes'

Uncontrolled overland flow drives flooding, erosion, and contaminant transport, with the severity of these outcomes often amplified in urban areas. In pervious media such as urban soils, overland flow is initiated via either infiltration‐excess (where precipitation rate exceeds infiltration capacity) or saturation‐excess (when precipitation volume exceeds soil profile storage) mechanisms. These processes call for different management strategies, making it important for municipalities to discern between them. In this study, we derived a generalized one‐dimensional model that distinguishes between infiltration‐excess overland flow (IEOF) and saturation‐excess overland flow (SEOF) using Green–Ampt infiltration concepts. Next, we applied this model to estimate overland flow generation from pervious areas in 11 U.S. cities. We used rainfall forcing that represented low‐ and high‐intensity events and compared responses among measured urban versus predevelopment reference soil hydraulic properties. The derivation showed that the propensity for IEOF versus SEOF is related to the equivalence between two nondimensional ratios: (a) precipitation rate to depth‐weighted hydraulic conductivity and (b) depth of soil profile restrictive layer to soil capillary potential. Across all cities, reference soil profiles were associated with greater IEOF for the high‐intensity set of storms, and urbanized soil profiles tended towards production of SEOF during the lower intensity set of storms. Urban soils produced more cumulative overland flow as a fraction of cumulative precipitation than did reference soils, particularly under conditions associated with SEOF. These results will assist cities in identifying the type and extent of interventions needed to manage storm water produced from pervious areas.

无控制的陆面径流导致洪水、侵蚀和污染物迁移，其影响之严重性在城市地区往往更为加剧。在城市土壤等透水性介质中，陆面径流的产生通过渗透过剩（降水速率超过渗透能力）或饱和过剩（当降水量超过土壤剖面存储量时）机制实现。这些过程需要不同的管理策略，因此对于市政当局来说，区分它们至关重要。在本研究中，我们基于Green–Ampt渗透概念，推导出一个通用的单维模型，用以区分渗透过剩陆面径流（IEOF）和饱和过剩陆面径流（SEOF）。随后，我们将该模型应用于估算11个美国城市透水区域的陆面径流产生。我们使用了代表低强度和高强度事件的降雨强迫，并比较了测量得到的城市土壤与未开发参考土壤的水力特性的响应。推导结果显示，IEOF与SEOF的倾向性与两个无量纲比值的等价性相关：（a）降水速率与深度加权水力导率；（b）土壤剖面限制层深度与土壤毛管势。在所有城市中，对于高强度风暴，参考土壤剖面与较大的IEOF相关联，而城市土壤剖面在低强度风暴期间倾向于产生SEOF。城市土壤产生的累积陆面径流占累积降水量的比例，比参考土壤更多，尤其是在与SEOF相关的条件下。这些结果将有助于城市确定管理从透水区域产生的城市雨水的干预类型和程度。