6/20/11!
Drought!
Agricultural Reference Index
for Drought - ARID!
Southeast Climate Consortium!
C. W. Fraisse and E. Gelcer!
Agricultural and Biological Engineering!
University of Florida!
Types of Drought!
•! Slow-onset natural hazard, its effects
accumulate slowly over a substantial
period of time!
•! Beginning and end difficult to determine!
•! First evidence of drought is based on
rainfall records, while the next piece of
evidence to appear is often an effect on
vegetation!
Types of Drought!
•! Agricultural
•! Meteorological
drought is
characterized by a
shortage of moisture in
the root zone of crops
and does not depend
only on the amount of
precipitation!
drought is
characterized by rainfall
being significantly lower
than the climatologically
expected over a wide
area!
Rainfall (in) - Year to date departure from normal.
(Source: NWS - Advanced hydrologic Prediction Service)!
1!
6/20/11!
Types of Drought!
•! Hydrological drought is characterized
by decreased flows in rivers and streams
and below-average water levels in lakes,
reservoirs, and groundwater!
•! Socio-economic associates the supply
and demand of economic goods (e.g.,
water, grains, hydro-electrical power) with
elements of meteorological, hydrological,
or agricultural droughts!
ARID: Agricultural
Reference Index for Drought!
Grass!
15 inches!
Deep drainage!
Daily Soil Water Balance !
Woli, P. et al., 2010!
onset and intensity of an agricultural
drought!
•! Relate this index to biomass production
(grass)!
•! Develop a web-based tool for monitoring
and forecasting the index (and therefore
biomass) !
ARID!
and stress (water) using grass as the
reference crop!
Run-off!
Soil!
•! Develop an index that helps monitoring the
•! Daily indicator of soil moisture conditions
Rainfall +!
Irrigation!
Evapotranspiration!
What are our
objectives?!
If there is enough soil moisture in the
profile: T = ETo !
ARID = 0 (no stress)!
If there is no soil moisture available for
the plant: ET = 0!
ARID = 1 (full stress)!
•! Will vary with soil type !
•! ARID = 0 indicates no stress!
•! ARID = 1 indicates full stress!
Grass is used as a
reference crop!
2!
6/20/11!
Evaluation of ARID"
Data Collection!
UF Plant Science Research and Educatoin
Unit - Citra, FL!
•! Weather!
•! Soil moisture (3
locations across FL)!
•! Biomass every 28
days (Bahiagrass &
Tifton 85)!
•! Root length density!
Biomass - Citra, FL 2009"
Can we relate biomass production to water stress?!
Biomass production (lbs/acre) of Bahiagrass in Citra, FL during season of
2009 as effected by irrigation and fertilizer management. Biomass
sampling interval of 27±1 days.
3!
6/20/11!
How do we compare current
ARID trends with what is
expected?!
Marianna, FL!
•! We are calculating typical average
values of ARID for selected
weather stations in FL and GA:!
•! FL: Jay, Live Oak, Marianna!
•! GA: Plains, Tifton, Vidalia!
U.S. Drought Monitor!
June 12, 2007!
Tifton, GA!
June 14, 2011!
4!
6/20/11!
Tift County"
Plains, GA!
Tifton Station!
2004!
2005!
2006!
2007!
2008!
2009!
Questions about the tool!
1.! Time scales: short term weather forecast, for the next 7-10
days directed towards hay cutting and seasonal going back 2
months and looking ahead 1 month that could be used for
deciding about how much to invest in fertilizer and also for
planting decisions of winter forages
2.!
Is a station-based product of interest giving the fact that rainfall is "spotty"
during the summer?!
3.!
Is a web-based dynamic tool of interest or would you prefer a more
descriptive, outlook style information?!
4.!
Is there interest in information available or delivered via cellular phones?!
5.!
Are the colors a problem? Should we break it down in more categories (5)?!
5!