Quantifying the integrated water and carbon cycle in a data-limited karst basin using a process-based hydrologic model

Abstract

Quantitative estimation of the terrestrial hydrologic fluxes in a karst basin is difficult due to the wide distribution of karst pores, the strong water conductivity of aquifer medium, and the complex groundwater dynamics. In this work, we attempt to estimate the water and carbon budgets of a data scarce karst basin using a process-based hydrological model. Without the knowledge of subsurface structure and rock medium, the karst pipes were simply treated as open channels. The model can generally predict the stream discharge and evapotranspiration, and reproduce the seasonal trend of the gross primary production (GPP) and net primary production (NPP) of the basin, with this simplification. The main hydrologic budgets were estimated and reveal how water partitions in the hydrologic cycle in this karst basin. The simulated results also indicate the main source (either baseflow or surface runoff) of the stream flow in different seasons. However, the simulation of the surface/subsurface hydrologic interactions, groundwater/stream flow exchange, and the vegetation root zone dynamics could be improved if the karst groundwater dynamics, especially for the area with complicated karst pipe system, are depicted in detail.