Hydrological Modeling of Large Scale: Initial Parameterizations in Amazon
Alailson
Venceslau
Santiago, PPGFAA, LCE-ESALQ/USP, santiago@esalq.usp.br
(Presenting)
Daniel
de Castro
Victoria, LGTI-CENA/USP, dvictori@cena.usp.br
Maria
Victoria Ramos
Ballester, LGTI-CENA/USP, vicky@cena.usp.br
Antonio
Roberto
Pereira, LCE-ESALQ/USP, arpereir@esalq.usp.br
Reynaldo
Luiz
Victória, LGTI-CENA/USP, reyna@cena.usp.br
Mariza
C.
Costa-Cabral, Department of Civil Engineering, University of Washington, cabral@hydro.washington.edu
Jeffrey
E.
Richey, School of Oceanography, University of Washington, jrichey@u.washington.edu
Anthropogenic alterations of natural ecosystems and their conversion to agricultural areas, especially in the Amazon, are changing land surface and soil characteristics (nutrient storage and cycling rates). Such processes cause alterations in the surface and sub-surface hydrological cycle. In order to quantify such alterations, we are calibrating and evaluating the performance of the Variable Infiltration Capacity model (WOOD et al., 1992), for tropical conditions in the braziliam Amazon. The model is being tested, initially, in the Ji-Paraná (RO) river basin, at a of 1/10 degree (~10 x 10 km) spatial resolution. For our first run, daily averages of the following meteorological variables were used for the years of 1994 and 1995: rainfall (mm); maximum and minimum temperature (°C) and wind velocity (m/s). Even tough the model is more suitable for large scale simulations (2 to 10 degree resolution), and we are still perfoming initial evaluation tests (with only a small numbers of observations), we observe that VIC results present a good relationship with the literature data. Mean monthly evapotranspiration rates are an example of this, showing good coherency and synchronism with the regional dry and wet seasons, varying proportionally with land use and soil texture. We also noticed that, during the first months of dry season (Ago-Set) this relationship is intensified. The evapotranspirative processes in the forest areas maintains very high rates during this period, primarily due to its large root system, maintaining the equilibrium of the regions’ microclimate. The next step is the implementation of a more detailed library for vegetation type and soil classes, especially for Amazon region, hopping to fulfill the lack information and better understand the dynamic processes in the hydrological cycle of such an heterogeneous region as the Amazon.