Sebastián Solari

Peaks Over Threshold (POT): A methodology for automatic threshold estimation using goodness of fit p-value

Threshold estimation in the Peaks Over Threshold (POT) method and the impact of the estimation method on the calculation of high return period quantiles and their uncertainty (or confidence intervals) are issues that are still unresolved. In the past, methods based on goodness of fit tests and EDF-statistics have yielded satisfactory results, but their use has not yet been systematized. This paper proposes a methodology for automatic threshold estimation, based on the Anderson-Darling EDF-statistic and goodness of fit test. When combined with bootstrapping techniques, this methodology can be used to quantify both the uncertainty of threshold estimation and its impact on the uncertainty of high return period quantiles. This methodology was applied to several simulated series and to four precipitation/river flow data series. The results obtained confirmed its robustness. For the measured series, the estimated thresholds corresponded to those obtained by nonautomatic methods. Moreover, even though the uncertainty of the threshold estimation was high, this did not have a significant effect on the width of the confidence intervals of high return period quantiles.

Analysis of the recent evolution of the sand spit at the Solís Chico river mouth

ABSTRACT Solari, S., Chreties, Ch., López, G., Teixeira, L., 2014. Analysis of the recent evolution of the sand spit at the Solís Chico river mouth. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 616–620, ISSN 0749-0208. The Solís Chico river, located on the southern Uruguayan coast, flows into the Río de la Plata estuary. The seaside resorts La Floresta and Parque del Plata are located on the estuary. In recent years the river mouth has migrated westward, away from the river axis, forming a sand spit that hinders the recreational use of Parque del Plata beach. In turn, at La Floresta there is a beach nourishment project whose main objective is to mitigate the erosion of the beach and the adjoining cliffs. This work aims to identify the causes of the recent migration of the river mouth and to analyze the possibility of using the sand spit as a borrow area for the beach nourishment. The river sediment supply to the coast for the period 1900–2010 was estimated, along with the long-shore and cross-shore sediment transport produced by sea waves. Furthermore, the plan-view stability of the river was studied in order to determine if the long-term evolution of the river is affecting the migration of the mouth. It was found that the migration of the mouth is mainly due to an extraordinarily high river sediment supply in 2002, combined with an increase in the net westward potential long-shore transport rate since the late 90s, and that the meander dynamics of the river are not affecting the evolution of the mouth. Additionally, the most likely area of natural breaching of the sand spit was identified, recommending its use as a borrow area for nearby beach nourishment.

Coastal Erosion in Balneario Solís, Uruguay

ABSTRACT Alonso, R.; López, G.; Mosquera, R.; Solari, S., and Teixeira, L., 2014. Coastal erosion in Balneario Solís, Uruguay. Balneario Solís is a seaside resort located in Uruguay, on the northern coast of the outer Río de la Plata estuary. Its main beach has suffered an erosion process that has affected the cliffs, producing a retreat of approximately 35 m between 1980 and 2001. Nowadays, some buildings are at risk of collapse and tourism has been seriously affected. Aerial photo analysis shows a temporal coincidence between the beginning of the erosion process and a change in the growing direction of a sandspit located next to the beach. Assuming the later as a geomorphologic indicator of the net littoral transport, the erosion process was linked to littoral transport change. No human factors were clearly identified to explain this change. Therefore, two hypotheses were formulated and analyzed: climate variability and natural modifications of the bathymetry in the outer zone of the beach. Finally, beach nourishment is proposed in order to restore the beach and protect the cliffs, and some questions are formulated for guiding future works in the site.

Performance of a flap-type wave energy converter on the Uruguayan Atlantic coast

Marine energy is an untapped resource, which could make a significant contribution to the renewable and clean energy generation matrix. Amongst the marine sources, wave energy is the most promising one in a microtidal and template zone like the Uruguayan oceanic coast. In this article the performance of a flap-type wave energy converter was analyzed in the basis of an analytical model and spectra wave hindcast data at a specific location of the Uruguayan coast. The results of our study allowed us to estimate the amount of energy that may be harvest for this particular site and device.