SOIL WATER SURPLUS AND ENSO EVENTS DURING THE LAST HUMID PERIOD IN ARGENTINE PAMPEAN FLATLANDS

SCARPATI O. E, J. A FORTE LAY Y A. D CAPRIOLO

International Journal of Water (IJW)

Indersciences Publishe

Lugar: Geneve- Switzerland; Año: 2008

1465-6620

The main argentine agricultural region is located in the Pampean flatlands. Daily soil water balances are estimated for the period 1951 – 2006. Daily soil water surplus is employed as the major output with their annual trends. Soil water surpluses are analyzed because of their harmful effects on the harvest of the cultivations of the precedent summer and also partially control the risk of floods in the important agriculture and urban areas. Soil water surplus trends were analyzed at 8 stations in the area, in all cases found positive trends, although only 2 of them were statistically significant trends at the probability level of 95%. Differing phases of ENSO -identified using the multivariate ENSO index (MEI) - have differing impacts on rain and soil moisture conditions across the study area. The probabilities of occurrence of predetermined soil water surplus and hence risk are calculated and mapped. The south and south western areas are generally free of risk during all ENSO events, while the north eastern area reveals high risks of saturated soils and floods especially during El Niño years. There are differences between El Niño years (higher surplus) and La Niña (minor surplus) but only 2 of 3 stations analyzed in the centre of the area were statistically significant, denoting the existence of a signal that, in the region, is manifested as weak but that must be taken into account.