Tools and Methodologies in Agrometeorology

47 Pages·2008·0.68 MB·English

Tools and Methodologies in
Agrometeorology
Adrian R. Trotman
Caribbean Institute for
Meteorology and Hydrology
21-24 October, Nairobi, Kenya
Outline
(cid:122) Statistical Analysis
(cid:122) Evapotranspiration, Soil Water Balance
and Irrigation Estimation
(cid:122) Growing Seasons
(cid:122) Rainfall Monitoring and Forecasting
(cid:122) Crop Simulation
(cid:122) Land Evaluation
Statistical Analysis
(cid:122) For agroclimatic studies/maps – simple and more
complicated
(cid:122) Instat
(cid:122) Genstat
(cid:122) Excel
(cid:122) Sigmastat
(cid:122) Systat
(cid:122) SPSS
(cid:122) Combined with GIS can map output
(cid:122) Agroclimatic maps for examples using
Arcview
(cid:122) Rainfall totals
(cid:122) Dry spells/drought
(cid:122) Probabilities
(cid:122) Percentiles
(cid:122) Potential flood rains
(cid:122) Extreme value analysis/return periods

Evapotranspiration, Soil Water
Balance and Irrigation Estimation
(cid:122) Potential water loss using Penman- Monteith
(cid:122) Potential water loss using evaporation pan
(cid:122) Combined with rainfall, runoff and drainage gives
water storage change
(cid:122) Irrigation estimation
Box : Water Balance Equation and its parameters
P = Q + D+E + ∆ S
Where:
P precipitation received
Q runoff (influenced by the slope of the land)
D drainage
E evaporation
∆ S change in water storage in the soil
Software
(cid:122) Instat
(cid:122) Cropwat
(cid:122) WINISAREG, SIMDualKc
(cid:122) Excel
The Windows version of the model used in this study,
WINISAREG (Pereira et al., 2003), includes programs
for ETo computation and crop parameterization following the
FAO methodology described by Allen et al. (1998). It
also includes an algorithm to consider soil salinity impacts on
ETc and yield (Pereira et al., 2007) and parametric
functions for computation of the groundwater contribution and
percolation (Liu et al., 2006). The water stress
impacts on crop yields are evaluated by estimating the relative
yield losses as a function of the relative
evapotranspiration deficit through the water–yield response
factor Ky (Stewart et al., 1977).