Necessity to consider hydrological controls of biogeochemical cycling when developing a catchment-scale ecosystem model

Abstract

In order to model the stream water chemistry in a forest catchment, the model should include functions describing both the biogeochemical cycle and the hydrological pathways as the transportation system for solutes and suspended substances. Although several catchment-scale models have been developed based mainly on the data collected under non-monsoon climate corditions in the northeastern United States and northern Europe, it is questionable whether these models are able to simulate the seasonal changes in streamwater chemistry in a forest catchment under monsoon climate conditions. This is because the monsoon-driven precipitation seasonality affects subsurface-groundwater mixing, and this in turn strongly influences the seasonal variation in streamwater chemistry. To simulate this effect in a catchment-scale response, it is important to combine biogeochemical and hydrological models that will be able to express the effects by soil and groundwater storage and their mixing.