Evaporation-Induced Hysteresis in Surface Water-Groundwater Exchange in Wetlands

Abstract

Evaporation is a major pathway of surface water loss in wetlands, yet its influence on subsurface feedbacks remains poorly understood. Using an integrated surface–subsurface hydrologic and solute transport model, we show that evaporation can induce hysteresis between evaporative demand and the upwelling of groundwater and solutes, with the strength of this feedback governed by sediment permeability and shaped by site-specific hydrologic and topographic conditions. Under low-permeability (<1 × 10−12 m2) conditions, evaporation leads to lagged and prolonged groundwater and tracer upwelling, whereas high-permeability sediments respond more directly to evaporative forcing. Ponded water depth, land surface slope, and evaporation rate regulate the magnitude of upwelling fluxes, while rainfall and fluctuating groundwater levels can reverse flow direction. These findings highlight evaporation as an indirect yet critical driver of wetland water and solute exchange, with important implications for biogeochemical cycling and the hydrologic resilience of wetland ecosystems under a changing climate.