Spatially distributed tracer‐aided modelling to explore water and isotope transport, storage and mixing in a pristine, humid tropical catchment
artículo original
Fecha
2018Autor
Dehaspe, Joni
Tetzlaff, Doerthe
Sánchez Murillo, Ricardo
Durán Quesada, Ana María
Soulsby, Chris
Birkel Dostal, Christian
Metadatos
Mostrar el registro completo del ítemResumen
Rapidly transforming headwater catchments in the humid tropics provide important
resources for drinking water, irrigation, hydropower, and ecosystem connectivity.
However, such resources for downstream use remain unstudied. To improve under standing of the behaviour and influence of pristine rainforests on water and tracer
fluxes, we adapted the relatively parsimonious, spatially distributed tracer‐aided rain fall–runoff (STARR) model using event‐based stable isotope data for the 3.2‐km2 San
Lorencito catchment in Costa Rica. STARR was used to simulate rainforest intercep tion of water and stable isotopes, which showed a significant isotopic enrichment in
throughfall compared with gross rainfall. Acceptable concurrent simulations of dis charge (Kling–Gupta efficiency [KGE] ~0.8) and stable isotopes in stream water
(KGE ~0.6) at high spatial (10 m) and temporal (hourly) resolution indicated a rapidly
responding system. Around 90% of average annual streamflow (2,099 mm) was com posed of quick, near‐surface runoff components, whereas only ~10% originated from
groundwater in deeper layers. Simulated actual evapotranspiration (ET) from intercep tion and soil storage were low (~420 mm/year) due to high relative humidity (average
96%) and cloud cover limiting radiation inputs. Modelling suggested a highly variable
groundwater storage (~10 to 500 mm) in this steep, fractured volcanic catchment that
sustains dry season baseflows. This groundwater is concentrated in riparian areas as
an alluvial–colluvial aquifer connected to the stream. This was supported by rain fall–runoff isotope simulations, showing a “flashy” stream response to rainfall with
only a moderate damping effect and a constant isotope signature from deeper
groundwater (~400‐mm additional mixing volume) during baseflow. The work serves
as a first attempt to apply a spatially distributed tracer‐aided model to a tropical
rainforest environment exploring the hydrological functioning of a steep, fractured‐
volcanic catchment. We also highlight limitations and propose a roadmap for future
data collection and spatially distributed tracer‐aided model development in tropical
headwater catchments
External link to the item
10.1002/hyp.13258Colecciones
- Meteorología [504]