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Impacts of subgrid elevation bands on hydrological portrayals: insights from a suite of hydroclimatically diverse mountainous catchments
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  • Octavio Murillo,
  • Pablo A. Mendoza,
  • Nicolás Vásquez,
  • Naoki Mizukami,
  • Álvaro Ayala
Octavio Murillo
Universidad de Chile
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Pablo A. Mendoza
Universidad de Chile

Corresponding Author:[email protected]

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Nicolás Vásquez
Universidad de Chile
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Naoki Mizukami
National Center for Atmospheric Research
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Álvaro Ayala
Centre for Advanced Studies in Arid Zones (CEAZA)
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Abstract

The implementation of elevation bands is a common strategy to account for vertical heterogeneity in hydrology and land surface models; however, there is no consensus guidelines for their delineation. We characterize hydrological implications of this choice by configuring the Variable Infiltration Capacity (VIC) model in nine mountainous basins of the Andes Cordillera, central Chile, using six different setups: no elevation bands (benchmark model), and elevation bands with vertical discretizations of 1000, 750, 500, 200 and 100 m. The analyses are conducted in a wet period (April/1982-March/1987), dry period (April/2010-March/2015) and a climatological period April/1982-March/2015). The results show that adding elevation bands yield little variations in simulated monthly or daily streamflow; however, there are important effects on the partitioning of precipitation between snowfall and rainfall, snowmelt, sublimation, and the spatial variability in September 1 SWE, suggesting a model-structure equifinality. Incorporating elevation bands generally yields less basin-averaged snowmelt, and more (less) catchment-scale sublimation across water-limited (energy-limited) basins. Further, the implications of elevation bands vary with the analysis period: fluxes are more affected during the wet period, while variations in September 1 SWE are more noticeable during the dry period. In general, the effects of adding elevation bands are reduced with increasing vertical discretization, and can differ among catchments. Finally, the grid cells that yield the largest sensitivities to vertical discretization have relatively lower mean altitude, elevation ranges >1000 m, steep slopes (>15°) and annual precipitation amounts <1000 mm, with large intra-annual variations in the water/energy budget.