Monitoring Agricultural Drought in Mainland Portugal - Monitoring and Predicting Agricultural Drought: A Global Study - page 192

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effects using an approximate analytical solution to the radiative transfer
equation.
The volume scattering formulation is similar to the G-function and
Hot Spot model. However, the probability between the crown and gap
is formulated in terms of the FVC and a geometric variable ( η ) associated
with the shape of plants. The canopy model can be coupled with a leaf-level
radiative transfer model, which provides a stronger connection between
leaf optical properties and biochemical and structural parameters. The
model can be inverted to estimate both FVC and LAI.

Ea rly Warning Systems

In Portugal an early warning system is being developed involving data
acquisition, analysis leading to drought monitoring, and prediction using a
software application (Pires, 2003). Such a system will help planners devise
the best strategy for drought management. In the near future this product
will be available on the Web for direct access by users.
A project is also being developed to identify, characterize, and predict
local and regional droughts (INTERREG IIIB, 2002) using general circu-
lation models, soil water balancing, and drought indices (e.g., PDSI, SPI)
and probabilistic and stochastic modeling of regional droughts.

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C rop Growth Models

In Portugal, crop growth simulation models have been used to assess the
impacts of climate variability on agriculture. The models used are CERES
models included in the Decision Support System for Agrotechnology Trans-
fer series (Pinto and Brand ao, 2002; Jones et al., 2003) and, more recently,
the World Food Studies model (Supit and van der Goot, 2002). These mod-
els will be used for yield estimation, together with seasonal and annual
forecasting, to complete the early warning system.

[192

D rought-Mitigating Measures
Portugal is reducing risks associated with the occurrence of droughts using
mitigation measures and early warning systems. Portugal is in the process
of building dams and artificial lakes to store water and develop irrigation
techniques to cope with water shortage, especially during drought periods.
Alqueva Dam in Alentejo will create a large artificial lake. Other methods
for drought mitigation include carefully choosing appropriate crops for
a given region and local climate, developing crop varieties that are better
adapted to higher temperatures and water stress (in the southern regions of
Portugal, introduction of subtropical and tropical plants is an important
strategy), improving carbon sink capacity of Portuguese forests through
aforestation/reforestation, avoiding land degradation, and improving irri-
gation and drainage systems.