A unified physically based recession model reveals contrasting functioning of monsoon and Mediterranean karst aquifers

作者：Liangjie Zhao, yang yang, Stefano Fazi, Song Luan, Cheng Chao Li, Ning Zhang, Elisabetta Preziosi · 年份：2026 · DOI：10.5194/egusphere-2025-6044 · 研究领域：Karst Systems and Hydrogeology、Hydrology and Watershed Management Studies、Geology and Paleoclimatology Research

Abstract. Karst aquifers supply drinking water to hundreds of millions of people but remain among the least understood freshwater systems because of their strongly heterogeneous conduit–matrix structure. Spring recession analysis is widely used to infer karst storage dynamics, yet most existing models either treat different parts of the hydrograph separately or rely on empirical formulations with limited physical interpretability. Here we derive a unified analytical model for karst spring recession by combining turbulent conduit flow, represented by a Forchheimer-type relationship, with linear drainage from a porous matrix. The resulting governing equation, dQ/dt = -αQn + γe-λt, simultaneously describes nonlinear conduit depletion and delayed conduit–matrix exchange. The parameters α, n, γ and λ can be related to aquifer properties, reflecting conduit drainage efficiency, flow nonlinearity, and the magnitude and timescale of matrix drainage.We apply the model to hourly discharge records (2013–2023) from climatically and geologically contrasting karst systems in monsoon-influenced southwest China and Mediterranean central Italy. Event-based calibration shows that the unified recession model reproduces complete recession limbs and consistently outperforms a classical dual-reservoir benchmark. Beyond goodness of fit, the inferred parameter patterns reveal systematic regional contrasts: Chinese spring exhibits higher nonlinear exponents (n = 2) and larger α, indicating strongly t...