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PET < D1
DEF 30,76% (2) 5,03%
EQ 29,06%
EXC 40,18% (1) 6,05% 0,24% (3)
7,97% 33,04% 0,06%
61,93%
PET > D9 PP > D9 PP < D1
85,98% 99,70%
ABOUT CLIMATE VARIABILITY LEADING THE HYDRIC CONDITION
OF THE SOIL IN THE RAINFED REGION OF ARGENTINA.
Vanesa C. Pántano, Olga C. Penalba
LABORATORIO DE EXTREMOS
CLIMÁTICOS EN SUDAMÉRICA
[email protected], [email protected] Departamento de Ciencias de la Atmósfera y los Océanos. UBA
DISCUSSION Communities dependent on agriculture are highly sensitive to climate variability and its extremes. In the
studied region, it was showed that scarce water and heat stress contribute to the resulting hydric condition.
The response of hydric condition to high precipitation extremes is stronger than the response to low
precipitation. Extreme temperature has the weakest influence, specially towards the east. Therefore, increase
in extreme precipitation may be seen through the higher excess over the east of the region. However, when
both variables present extreme conditions the impact over the hydric condition is enhanced.
(a)
(3) P (EXC / PP<D1) (2) P (DEF / PP>D9)
HC (mm) Month Year Station
0.52 July 1993 La Plata
2.85 June 1996 Posadas
6.20 July 1975 La Plata
7.34 June 1980 Posadas
HC: Hydric Condition
TEF: Effective Temperature
PP: Accumulated Precipitation
PET: Potential Evapotranspiration
WB: Water Balance
(b)
Motivation: to evaluate how sensitive is soil moisture to water and heat stress in the region.
High variability: 4 years with more than
50% of the region under extreme conditions from
both variables.
Only 4 cases observed:
Excess condition as a consequence of high precipitation observed
the month before.
Time series of the number of stations under
extreme conditions of PP and PET
During April, the water recharge of the soil is
crucial to let the winter crops manage with the
scarce rainfalls occurring in the following months. Extreme dry condition with high thermal stress may cause severe impact on the winter crops.
Between 1996 and 2005: regional extreme condition.
HC (mm) April
1997 1998
Under PP-PET (t)<0
Estimation of monthly Water Balance (WB). Thornthwaite and Mather´s method (1957), Pascale and Damario (1977). Effective capacity of soil water is considered from Forte Lay and Spescha, 2001.
METHODOLOGY
Estimation of the monthly potential evapotranspiration values. Thornthwaite´s method (1948) modified by Camargo et al (1999) Effective temperature: Tef (t)=0.36* [3 Tmax (t) – Tmin (t)]
(a)
(b)
TEF
HC
PP PET
HC<0 DEFICIT (DEF)
HC=0 EQUILIBRIUM (EQ)
HC>0 EXCESS (EXC) Monthly scale (t)
THRESHOLDS FOR EXTREMES
Extreme event was defined when the variable is less (greater) than its 1st and 2nd (9th and 8th) Deciles:
D1, D2, D9 and D8
OBJECTIVE Analyze how the variability of rainfall
and temperature leads the hydric condition of the soil, with special
focus on extreme events
-Extreme events of temperature and rainfall have a socio-economic impact in the rainfed agriculture production region in Argentina. The magnitude of the impact can be analyzed through the water balance (WB).
-Changes observed in climate variables during the last decades affected the WB components. As a result, a displacement of the agriculture border towards the west was produced, improving the agricultural production of the region.
Data was obtained from CLARIS LPB database
(http://wp32.at.fcen.uba.ar/)
The research leading to these results has received
funding from the European Community's Seventh
Framework Programme (FP7/2007-2013) under Grant
Agreement Nº 212492: CLARIS LPB. “A Europe-South
America Network for Climate Change Assessment and
Impact Studies in La Plata Basin”.
weaker response of HC to extreme low PET
(1) P (EXC /PET>D9)
In the western region (marginal zone) extreme high PET has a stronger influence over the HC while high probabilities of deficit under high precipitation shows a limitation for agriculture production.
The response of the spatial distribution of HC is
stronger when both variables present extreme
conditions: for example 1997 and 1998.
Coupling of HC with PET and PP
-Camargo AP., Marin FR, Sentelhas PC and Giarola Piccini
A; 1999. Rev. Bras. Agrometeorología, 7, 2: 251-257.
-Forte Lay JA. and Spescha L. 2001. Rev. Arg. de
Agrometeorología 1(1): 67-74.
-Pascale JY. and Damario EA.; 1977. Rev. Fac. Agron.
La Plata (3a época), 53 (1-2): 15-34
-Thornthwaite CW.; 1948. Geog. Review. 38: 55-94
-Thornthwaite CW. and Mather JR.;1957. Drexel Institute of
technology. Climatology. Vol. X. Nº 3. 185-311.
Percentage of change for PP > D8 between 1970-1985 and 1990-2005
APRIL SEPTEMBER
PAPER
NUMBER
MOTIVATION: to evaluate how the increase in soil moisture availability (lead by changes in extreme PP events) impact different zones of the study region.
REFERENCES ACKNOWLEDGEMENTS
extreme low PP presents a strong respond from the HC.
HC(t): DEF
Under PP-PET (t)>0
Each time the storage reaches soil capacity values, the water input takes place as excess
HC (t+1): EXC HC (t+1): DEF
Since the 80`s: extreme dry events over smaller areas,
in most of the years.
HC (t): EXC
Values colored in red correspond to those in which HC sign were unexpected.
Excess is produced the following month
Excess is not produced
HC (t): EQ
DATA Daily precipitation and maximum and minimum temperatures of 33 stations located in the region of rainfed agriculture production in Argentina (Period: 1970-2006).
