Integrated Surface–Subsurface Hydrological Models (ISSHMs) are advanced tools for reproducing hydrological processes that are difficult to manage due to their complexity and computational cost. This paper introduces HydroCAL (Hydrological Cellular Automata Layer), an event-based spatially distributed ISSHM entirely based on the Cellular Automata (CA) paradigm through the OpenCAL software library. The primary benefit of the CA paradigm is reducing the computational burden through parallelisation and other specific optimisation features, like asynchronous functionality. HydroCAL was tested on literature benchmarks and, for the first time, considering real events in a headwater catchment, correctly reproducing streamflow (NSE = 0.86; KGE = 0.88) and providing a fully spatially distributed output of several other hydrological variables. The combined effect of parallelisation and a novel version of the asynchronous functionality accounting for spatially distributed soil hydraulic properties significantly reduces the elapsed time in real-world applications. The results suggest that HydroCAL is suitable for simulating the hydrological cycle over large watersheds while keeping a hyper-resolution detail.

综合地表-地下水文模型(ISSHM) 是用于重现水文过程的先进工具，这些过程由于其复杂性和计算成本而难以管理。本文介绍了 HydroCAL（水文元胞自动机层），这是一种基于事件的空间分布式 ISSHM，通过 OpenCAL 软件库完全基于元胞自动机 (CA) 范式。CA 范式的主要好处是通过并行化和其他特定的优化功能（例如异步功能）减少计算负担。HydroCAL 在文献基准上进行了测试，首次考虑了源头流域的真实事件，正确再现了水流（NSE = 0.86；KGE = 0.88），并提供了其他几个水文变量的完全空间分布的输出。并行化和考虑空间分布的土壤水力特性的异步功能的新颖版本的综合效果显着减少了实际应用中的耗用时间。结果表明，HydroCAL 适合模拟大流域的水文循环，同时保持超分辨率细节。