Maria Elizabeth Carbone

Residual Flow Structure at a Scour-hole in Bahia Blanca Estuary, Argentina

Abstract Two-dimensional data of mean and sediment flow collected at a natural confluence of channels in the inner Bahía Blanca Estuary are presented. We describe the two-dimensional flow field to assess the role of changes in bed morphology occurring during transport-effective events on the structure of flow at a confluence; and to examine how the flow structure varies with changes in the ratio of momentum flux. At each station, vertical profiles of velocity, salinity, temperature and suspended sediment were obtained during the whole tidal cycle and residual fluxes were obtained. Lagrangean flux is higher than possible fresh water input, denoting an extra output of water which is the flux over the tidal flats along the southern and northern coasts of the channel. The effect of the junction produces a distortion of the vertical profile flow and in the suspended sediment transport. The effect of the particular conformation of the system makes necessary for consider the lateral effect of the tidal flats in the circulation of the estuary which exerts a significant influence.

IMPACTO DE LOS EVENTOS DE SEQUÍA EN LA REGIÓN DE LA CUENCA HIDROGRÁFICA DE LA LAGUNA SAUCE GRANDE (PROVINCIA DE BUENOS AIRES, ARGENTINA)

Drought impact in the region of the watershed the Sauce Grande lagoon (Buenos Aires province, Argentina) The distribution and intensity of extreme water causes a direct impact on human activities. Dry and wet events in the region of the watershed of the Sauce Grande lagoon during the period 1971 - 2010 are analyzed through the application of Index of Palmer drought severity, 49% of the cases analyzed corresponded to weak, and emerging drought . The most extreme dry events values (-4.31) caused irreparable damage yields, which decreased by 19 % compared to the current average . During the summer months the severe and extreme (12 %) cases were observed. Dry periods had greater influence on livestock far ming in the region, occurring during the years 2008 and 2009, the relationship between this values of the indices and severe extremes in the morphometry of the lagoon and the Sauce Grande estuary were identified.

ZONIFICACIÓN AMBIENTAL DE LA RESERVA NATURAL BAHÍA SAN ANTONIO, ARGENTINA. APLICACIÓN DEL ÍNDICE DE CALIDAD AMBIENTAL

Human activities and natural processes are needed in changes affect different environments in coastal Patagonia. The aim of this study is to determine the current environmental quality places that make San Antonio Bay reserve. Applying the Environmental Quality Index (EQI). Results obtained on study areas as follows: San Antonio West where the index ranges from a value of 0.50 and 0.45, reflecting increased human activity related to the extraction of mineral resources, fisheries. The area of San

Comportamiento hidrológico del Arroyo Claromecó, Argentina

Flowing across an important farming area, and located in the south-east of the Argentinian provice of Buenos Aires, the Claromeco Creek is a plain stream with a permanent water pattern. The behaviour of its waters was gauged over a period of five years by means of a current meter and a phreatic limnimeter. The average water level is about 0.87 m3/s and the maximum height is reached in October, which is the rainiest month of the year. Meanwhile, the lowest levels are seen in the winter months of June and July, when both the volume of the waters and the amount of sediment are small. The results of the study were recorded on a hydrograph which shows an upward curve lasting five days, a downward curve lasting 10 days and a levelling occurring around the 12th day after the beginning of the fieldwork. The irregular water levels along the year have to do mainly with the variability in the annual rainfall. The regime presented by the creek is typical of the plains and can be described as pluvial oceanic.