SPATIAL SCALING OF THE WATER, ENERGY, AND CARBON BUDGETS ACROSS RIVER BASINS OF THE ANDES­AMAZON SYSTEM

Abstract:

The Andes-­Amazon system exhibits complex interactions and feedbacks between hydrological, ecological, biogeochemical and climatic factors in a broad range of temporal and spatial scales. We aim to understand the coupling existing between water,energy and carbon budgets in the Andes-­Amazon system, by performing a systematic study of the system for river basins of increasing Strahler orders, from the headwaters of the Amazon River basin on the Andes (order 1 river basins) to the low­lying larger riversub­basins downstreams. To that aim, we use a 3” Digital Elevation Model (DEM),which allows defining river basins with Strahler orders from 1 to 10. The long­term water, energy, and carbon budgets are estimated for increasing values of the Strahler orders during the period 1987-­2007. Data sets pertaining to the water balance were obtained from the following sources: precipitation (P), runoff (R) and actual evapotranspiration (AET) from IDEAM (Colombia), National Water Agency (ANA,Brazil), and ORE­HYBAM (France). Data for the energy budgets were obtained fromthe Global Energy and Water Exchanges Project (GEWEX), and the ERA­Interim Reanalysis, which allowed estimating the radiative and non-­radiative fluxes of the surface energy balance and Potential Evapotranspiration (PET). Data for the Carbon budgets come from the AMAZALERT project, and to Flux Tower Data, correspondingto annual mean net primary productivity (ANPP), gross primary productivity (GPP) and respiration rates (Rr), as well as from the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA). We construct a three­dimensional parameter space in which the results of the three balances are expressed as: ψ=AET/P for the water balance,Ω=AET/PET for the energy balance and φ=AET/ANPP for the carbon balance. Ascaling function is fitted that couples this 3­parameter space linking the water, energyand carbon budgets and show their scale invariance throughout all the range of riverbasins of increasing Strahler orders in the Amazon­Andes system.