6. Title: The Impact of Land Cover and Land Use Changes on the Hydroclimate of the La Plata Basin
PI: Ernesto H. Berbery
Period: 1-Apr-2008 to 30-Jun-2011
Total budget: USD $526,670
Funding Agency: IAI
Summary:
Vast areas of the La Plata Basin have experienced
changes in land cover conditions due to the expansion of the
agriculture (replacing natural vegetation), but also due to changes in
crop types. In particular, a notable increase in soybean production has
replaced other crops like rye and sorghum. In addition, pastures with a
typical cycle of 4-5 years are being replaced by crops that have an
annual cycle (Paruelo et al. 2005). Crop changes have also taken
place in Brazil, where, among others, the planted area of sugar cane
has increased from 1×106 hectares in 1970 to more than
5×106 hectares at present. Further significant changes could be
expected as a result of biofuel, paper and cellulose and thermoelectric
energy production that require specific types of crops such as sugar
cane, palm trees and eucalyptus.
Modeling studies have shown that surface conditions
have a significant impact on weather and climate as changes in
vegetation types imply changes in albedo and evapotranspiration,
significantly altering the physical conditions of a region and thus
affecting the overlying atmospheric state and the processes that
modulate precipitation (e.g., Pielke and Avissar 1990; Pielke et al.
1999). Changes in vegetation types (e.g., from forests to different
kinds of crops) also involve changes in the root depth and thus in the
deeper ground characteristics that affect the soil moisture content,
the infiltration, subsurface and groundwater outflow, leading to
changes in the volume, timing and quality of the water available at
catchment scales.
These changes have not been systematically included
in studies of the Hydroclimate System, and in particular for the La
Plata Basin. The proposed research will seek to determine the extent of
the impact of land cover and land use changes (LCLUC) in the La Plata
Basin hydroclimate and specifically assess the consequences for the
duration and magnitude of extreme events, including seasonal floods and
droughts. The research team will work in collaboration with PIs of
IAI’s CRN-2031 to help them interpret the potential feedbacks between
climate forcings and LCLU changes.
The project will (a) Develop 25-year (1980-2005)
datasets employing a Land Data Assimilation System at adequate
resolutions with all possible in situ and remotely sensed observations
including land use and land cover changes, useful for agricultural and
hydrological assessments and applications. (b) Assess the impact of
LCLU changes on the hydroclimate of the La Plata Basin, and the
physical mechanisms by which the impacts take effect, by means of
regional model simulations. (c) Investigate the role of LCLU changes in
the intensity and length of extreme events (floods and droughts). (d)
Investigate the potential changes in the hydrological character (soil
moisture, infiltration, and runoff) of the La Plata Basin due to the
changes in LCLU.