Revista Recursos Hdricos

DOI:10.5894/rh36n2-2
O texto deste artigo foi submetido para reviso e possvel publicao em fevereiro de 2015, tendo sido aceite pela Comisso de Editores Cientficos Associados em maio de 2015. Este artigo parte integrante da Revista Recursos Hdricos, Vol. 36, N 2, 17-31, novembro de 2015.

SPI e severidade da seca em cenrios de alteraes climticas. Aplicao ao sul de Portugal

SPI drought severity under climate change scenarios. Application in southern Portugal

Ana Paulo ¹, Sandra Mourato ²

---

1 - Professora Adjunta /// Instituto Politcnico de Santarm, Escola Superior Agrria, Investigadora no Centro de Engenharia dos Biossistemas /// email: ana.paulo@esa.ipsantarem.pt
2 - Professora Adjunta /// Instituto Politcnico de Leiria - Escola Superior de Tecnologia e Gesto, Investigadora no Instituto de Cincias Agrrias e Ambientais Mediterrnicas (ICAAM) /// email: sandra.mourato@ipleiria.pt 

---

RESUMO
Relatrios recentes do IPCC indicam diminuio da precipitao na regio mediterrnica. As secas podero tornar-se mais intensas e/ou mais frequentes. O ndice de seca SPI baseia-se na distribuio de probabilidades da precipitao. Valores negativos de SPI identificam uma seca e so classificados de acordo com uma escala de severidade. Iguais valores de SPI em diferentes perodos correspondem mesma severidade relativa mas a alturas de precipitao diferentes. A converso dos limiares das classes de seca do SPI em precipitao complementa a informao sobre a magnitude do fenmeno.
No Sul de Portugal estudou-se o efeito das alteraes climticas nas sries do SPI e na severidade da seca. Utilizaram-se trs modelos regionais de clima, forados por dois modelos globais e o cenrio de emisses A2 no perodo 2071-2100. Produziram-se mapas de limiares de precipitao para visualizar alteraes na severidade da seca. Os limiares de seca obtidos pelos modelos so inferiores aos equivalentes na srie 1961-90 projetando alterao do padro. Este estudo poder apoiar medidas de adaptao na gesto dos recursos hdricos e medidas de mitigao dos impactos da seca. 

Palavras-chave: ndice de seca SPI, limiares de severidade de seca, alteraes climticas, Sul de Portugal.

ABSTRACT
Late IPCC reports point out to a precipitation decrease in the Mediterranean region. Droughts may become more severe and/or more frequent. The dought index SPI is based on the probability distribution of precipitation. Negative SPI values are categorized according to a scale of drought severity. The same SPI values in distinct time periods express the same relative drought severity but different amounts of precipitation. Drought class thresholds transformed into precipitation amounts complement the information provided by SPI.
SPI and drought severity under climate change scenarios were studied for southern Portugal. SPI series were derived from precipitation projections of three regional climate models forced by two global climate models under A2 emission scenario for the period 2071-2100.
Precipitation thresholds obtained both for climate change scenarios and reference period were mapped aiming at a better visualization of the changes on drought severity. The precipitation thresholds projected by the models are consistently below the ones of the reference period. This study may contribute to support adaptation measures and to reduce drought impacts.

Keywords: SPI drought index, drought severity precipitation thresholds, climate change, Southern Portugal.

 

Arnell N.W., Reynard N.S. (1996) - The effects of climate change due to global warming on river flows of Great Britain. Journal of Hydrology, 183: 397–424.

de Lima M.I.P., Carvalho S.C.P., de Lima, J.L.M.P., Coelho, M.F.E.S. (2010) - Trends in precipitation: analysis of long annual and monthly time series from mainland Portugal, Adv. Geosci., 25, 155–160, doi:10.5194/adgeo-25-155-2010.

Dqu M, Rowell D, Schr C, Giorgi F, Christensen JH, Rockel B, Jacob D, Kjellstrom E, De Castro M, van den Hurk B. (2006) - An intercomparison of regional climate models for Europe: Assessing uncertainties in model projections. Climatic Change 81: 53-70.

Graham L.P., Andreasson J., Carlsson B. (2007) - Assessing climate change impacts on hydrology from an ensemble of regional climate models, model scales and linking methods - A case study of the Lule River basin. Climatic Change, 81 (Suppl. 1), 293-307.

Guttman N.B. (1999) - Accepting the standardized precipitation index: a calculation algorithm, J. Am. Water Resour. Assoc., 35: 311-322.

IPCC (2001) - Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K.Maskell and C.A. Johnson, Eds., Cambridge University Press, Cambridge, pp. 881.

Keyantash, J., Dracup, J.A. (2002) - The quantification of drought: an evaluation of drought indices. Bull. Am. Meteorol. Soc. 83: 1167–1180.

Lopez-Moreno J, Goyette S, Beniston A. (2007) - Climate change prediction over complex areas: spatial variability of uncertainties and predictions over the Pyrenees from a set of regional climate models. International Journal of Climatology 28(11): 1535-1550.

Martins D.S., Raziei T., Paulo A.A., Pereira L.S. (2012) - Spatial and temporal variability of precipitation and drought in Portugal, Nat. Hazards Earth Syst. Sci., 12, 1493–1501.
DOI: 10.5194/nhess-12-1493-2012.

McKee T.B., Doesken N.J., Kleist J. (1993) - The relationship of drought frequency and duration to time scales, in Proceedings of the 8th Conference on Applied Climatology, American Meteorology Society, 179-184.

McKee T.B., Doesken N.J., Kleist J. (1995) - Drought monitoring with multiple time scales. In: 9th Conference on Applied Climatology, Am. Meteor. Soc, Boston, pp. 233-236.

Mishra A.K., Singh V.P. (2011). Drought modelling – a review. J. Hydrology, 403: 157-175.

Mourato S., Moreira M., Corte-Real J. (2010) - Interannual variability of precipitation distribution patterns in Southern Portugal, Int. J. Climatol. 30: 1784–1794.

Mourato S., Moreira M., Corte-Real J. (2014) - Water availability in southern Portugal for different climate change scenarios subjected to bias correction. Journal of Urban and Environmental Engineering, 8 (1) 09-117.

Mourato S. (2010) - Modelao do Impacte das Alteraes Climticas e do Uso do Solo nas Bacias Hidrogrficas do Alentejo. Tese de doutoramento. Universidade de vora.

Nakicenovic N, Alcamo J, Davis G, de Vries HJM, Fenhann J, Gaffin S, Gregory K, Grubler A, Jung TY, Kram T, La Rovere EL, Michaelis L, Mori S, Morita T, Papper W, Pitcher H, Price L, Riahi K, Roehrl A, Rogner H-H, Sankovski A, Schlesinger M, Shukla P, Smith S, Swart R, van Rooijen S, Victor N, Dadi Z. (2000) - Special Report on Emissions Scenarios. Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge.

Nez, J., Rivera, D., Oyarzn, R., Arum, J.L. (2014) - On the use of Standardized Drought Indices under decadal climate variability: Critical assessment and drought policy implications. Journal of Hydrology, 517: 458–470.

Paulo A.A., Pereira L.S. (2006) - Drought Concepts and Characterization. Comparing Drought Indices, Water International, 31: 37-49.

Paulo A.A., Pereira L.S. (2008a) - Stochastic prediction of drought class transitions, Water Resour Manage 22: 1277-1296.

Paulo A.A., Pereira L.S. (2008b) - Secas e gesto do risco: caracterizao e predio de secas e sua aplicao ao Sul de Portugal, Recursos Hdricos 29(01) 73-86.

Paulo A. A., Rosa R. D., Pereira L. S. (2012) - Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal. Nat. Hazards Earth Syst. Sci., 12: 1481–1491.

Portela M.M., Santos J.F.F., Naghettini N., Matos J.P., Silva A.T. (2012) - Superfcies de limiares de precipitao para identificao de secas em portugal continental: uma aplicao complementar do ndice de precipitao padronizada, SPI, Recursos Hdricos 33(02), 5-23.

Santos J.F., Pulido-Calvo I., Portela M.M. (2010) - Spatial and Temporal Variability of Droughts in Portugal, Journal of Water Resources Research, 46, W03503. ISSN 0043–1397 (IF: 2.957).

Sienz F., Bothe O., Fraedrich K. (2011) - Monitoring and quantifying future climate projections of dryness and wetness extremes: SPI bias, Hydrol. Earth Syst. Sci. Discuss., 8: 10635–10677.

WMO (2012) - Standardized precipitation index user guide. No. 1090.

Wu H., Svoboda M., Hayes M.J., Wilhite, D.A.,Wen, F. (2007) - Appropriate application of the Standardized Precipitation Index in arid locations and dry seasons. Int. J. Climatol. 27: 65–79.

.