The purpose of this research is to provide a better understanding of the physical and social aspects of rip currents in ocean areas that will lead to better forecasts, better governmental policies in beach areas, and ultimately to save lives. A rip current is a nearshore circulation in which breaking waves run up onto the beach then retreat rapidly in deeper channels back toward the sea. Rip currents pose a significant threat to beachgoers and can pull even the strongest swimmers out to sea. The primary factors associated with rip current formation on unarmored beaches are variations in the local beach bathymetry, wind-generated longshore waves of varying height, and lower tidal stages. The rationale for this study is highlighted when rip current deaths are put in context with deaths from other weather related deaths. The average number of rip current deaths per year in the United States is 46 and in the year 2010 rip currents were responsible for 64 deaths which was higher than the deaths associated with lightning, tornadoes, hurricanes and the cold winter during the year. The methodology followed for this study includes a review of demographics from over 500 rip current drowning reports along the Atlantic Ocean, Pacific Ocean and Gulf of Mexico coasts of the United States from 1994-2012. This research indicates that tourists are often victims, and rescuers can become the victims. For each state or sub-state area where rip current drownings are prevalent, an analysis of social aspects, beach areas, and associated ocean and weather patterns was conducted using averaged wind and pressure fields over wave generation areas, buoy data, and tide data. It is important to understand the evolution of these drowning events and seek solutions to mitigate the problem.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-13T12:35:48Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Mestrado_Gabriel_Dannunzio_Gomes_Junior.pdf: 5445671 bytes, checksum: 0fbfa28afa66b0dd5cc8217c1d6c2418 (MD5) / Made available in DSpace on 2016-04-13T12:35:48Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Mestrado_Gabriel_Dannunzio_Gomes_Junior.pdf: 5445671 bytes, checksum: 0fbfa28afa66b0dd5cc8217c1d6c2418 (MD5) Previous issue date: 2015-08-26 / Existe uma crescente atenção voltada para o tema erosão costeira, devido principalmente à mudança climática de causas antrópicas, que está induzindo ao lento e gradual aumento do nível dos oceanos de forma irreversível a curto prazo, de acordo com a grande maioria dos cientistas do clima. Outro fator que influencia no aumento do risco de erosão costeira é a ocupação antrópica desordenada da área de pós-praia, que serve como proteção natural, bem como reserva de sedimentos para a área de praia, e que está constantemente sendo modificada pela ação das ondas e da corrente costeira. Este trabalho possui dois focos principais que estão interconectados. O primeiro trata do estudo de um caso de intervenção antrópica numa área de praia altamente suscetível à erosão costeira, numa zona urbana densamente povoada no litoral da zona metropolitana do Recife. Esta intervenção consiste na construção de um quebra-mar, com a intenção de proteger esta área de praia resultou na transferência da problemática da erosão costeira para a praia ao Norte. Numa segunda tentativa de resolver o problema, foi adotada uma terceira configuração que aparentemente teve um impacto positivo na prevenção da erosão costeira. Estudou-se os três cenários de configuração deste quebra-mar, utilizando-se de um pacote de software de simulação de ondas, correntes costeiras e transporte de sedimento, com o objetivo específico de se estudar, testar e encontrar soluções que possam eliminar a erosão costeira. O segundo foco deste trabalho trata-se de estudar o clima de ondas da região, através de medições feitas por um ondógrafo direcional durante um período de três anos. Para esta finalidade, desenvolveu-se uma metodologia de classificação das ondas a partir do espectro direcional, obtido através das medições, de forma a se distinguir com mais clareza as características de cada sistema de ondas que fazia parte deste espectro. Após esta etapa foi feita uma comparação entre o clima de ondas obtido através das medições, com o clima de ondas que faz parte da base de dados que acompanha o pacote de software utilizado na primeira etapa deste trabalho, de forma a validar o uso do software como uma ferramenta confiável no estudo do impacto da erosão. O resultado da comparação foi que o software possui uma base de dados confiável, mas que precisa de alguns ajustes para obter uma melhor descrição do clima de ondas da região. / There is increasing attention on the coastal erosion issue, mainly due to anthropogenic causes, first on the climate change, which led to the slow and gradual sea level rise, and also by the irregular occupation of the post-beach area, which serves as a natural protection and a sediment reserve to the beach area, which is constantly being modified by wave action and coastal currents. This work has two main focuses which are interconnected. The first is the study of a human intervention case in a beach area highly susceptible to coastal erosion in a densely populated urban area on the coast of the metropolitan area of Recife. This intervention , made by installing a breakwater with the intention to protect this beach area, but resulted in the transfer of the coastal erosion problem to the northern beach. In a second attempt to solve this problem, it was adopted a third configuration that apparently had a positive impact on the prevention of the coastal erosion. These three different breakwater configuration scenarios were studied, using a software package that simulates waves, coastal currents and sediment transport, with the specific objectives of studying, testing and finding solutions in order to eliminate the coastal erosion. The second focus of this work is to study the wave climate of the region, through the measurements of a directional wave buoy over a period of three years. For this purpose it was developed a practical wave partitioning method to be applied on the measured directional spectra, in order to more clearly distinguish the characteristics of each wave system that is part of the spectrum. After this step, a comparison was made between the wave climate obtained through the buoy measurements, and the wave climate obtained through the software package, used in the first stage of this work, in order to validate the use of this software as a reliable tool in the study of the coastal erosion impact. The result of this comparison is that the software has a reliable database, but it needs some tweaking to get a better description of the region wave climate.

För övervakning av svenska vatten krävs noggranna mätningar av oceanografiska parametrar såsom våghöjd, vågriktning, ytvattentemperatur och ytströmmar. Mätdata för parametrarna samlas in av Sveriges Meteorologiska och Hydrologiska Institut (SMHI) och används till prognoser, sjöfart samt forskning. I denna studie undersöktes möjligheten att ersätta eller komplettera vågbojarna av modellen Directional Waverider MkIII som SMHI använder idag, med ny kommersiellt tillgänglig fjärranalysteknik. Projektet begränsades till att studera två högfrekvens-radartekniker och en X-bandradar. Studien är platsspecifik och utreder kvalitetsmässiga, ekonomiska och miljömässiga för- och nackdelar med de utvalda radarteknikerna i relation till vågbojarna. En litteraturstudie och modellering av data över parametrar som påverkar radarteknikernas räckvidd och datatillgänglighet genomfördes. Ur modelleringen drogs slutsatsen att det är möjligt att erhålla likvärdig datatillgänglighet med vågradar som med vågboj. Vidare modellering ledde till slutsatsen att radarteknikerna begränsas till ungefär hälften av sin optimala räckvidd i Östersjön på grund av den låga salthalten, och därför är Sveriges västkust bättre lämpad för placering av radarteknik. Undersökning av isbildning i havsvatten, som kan begränsa radarteknikernas räckvidd, ledde till slutsatsen att Sveriges västkust också är att föredra utifrån detta perspektiv. Med anledning av radarteknikers möjlighet att utföra mätningar över större områden, finner studien att det finns goda grunder för att motivera en ersättning eller komplettering av vågbojarna med modern radarteknik. Vidare talar radarteknikernas goda anpassningsförmåga, lägre inverkan på miljön och enklare underhållskrav jämfört med vågbojarna till dess fördel. Att övergå till radarteknik medför däremot högre installations- och driftkostnader i jämförelse med vågbojar.

The recent trend in generating energy from the waves has led to several advancements in the methods and the various research is conducted across the world, to study the behaviour of point absorbers on the waves. The point absorbers such as wave buoys are designed to move according to the waves and the generator that is mechanically coupled with the buoys, generate electricity. But these buoys can also be used for measuring important parameters like the force acting on it due to the incident waves and their movement can be tracked to study the effects on the buoy due to the incident waves.  This project, as an extension of a previous work titled ‘Design and Development of a Measurement System to Track the Motion of a Point Absorber’ by Juliana Lüer, focuses on modifying and replacing the controller data acquisition and the communication system. The main aim is to increase the stability of the system and increasing the size of data storage and range of the data transmission. This is done in 3 steps that are as follows: - The Arduino based controller is replaced with an advanced Raspberry Pi based computer called RevPi Compact. - The Secure Digital (SD) card storage is replaced with a solid-state (Universal Serial Bus) USB memory stick with a large capacity. - The Radio Frequency (RF) based data transmission is replaced with a 4G (fourth generation) internet modem. The 60 W solar panels are retained from the previous project. But the Lead-Acid battery is replaced with two Lithium Polymer (Li-Po) batteries of 768 Wh capacity each. This increases the stability of the power source and enables the buoy to stay active for a longer time even when there is no useful solar irradiance for many days. There are two force transducers (strain gauge) to measure the line force and the angular force acting on the buoy. The Ellipse2-D Inertial Measurement Unit (IMU) from SBG systems is retained from the previous experiment. This sensor can track the Altitude and Heading Reference (AHRS) data along with the Global Positioning System (GPS) data with high levels of accuracy.  All the data collected are can be tracked instantaneously due to the 4G internet communication protocol and this is enabled by TelenorTM connection and HuaweiTM 4G modem. A copy of these data is also stored in a SanDisk USB memory of 500 GB capacity. The tests are carried out under the laboratory conditions and the outputs are as expected. The whole setup is to be installed in a metallic buoy and to be tested in the Lysekil test site in the future.