BEACH PLANFORM EQUILIBRIUM, APPLICATION AND METHODOLOGIES FOR CLIMATE CHANGE RESILIENCY CONSIDERATION

Climate change and sea level rise (SLR) present a challenge and added uncertainty for managing coastal areas. Many coastal cities and developed coastal areas are assessing future vulnerabilities to SLR and developing adaptation plans for improved resiliency. Equilibrium conditions for beach planform can be critical to the long-term stability of beaches and dunes fronting coastal cities. In many cases, resiliency and adaptation programs for beachfront areas are based on assumptions of evaluating scenarios of higher water elevations and hydrodynamic forcing under present time topographic and bathymetric conditions. These evaluation parameters suggest that the coastline and existing morphological features are near equilibrium condition and are expected to remain near similar equilibrium over the SLR scenarios under consideration. Such assumptions may be limited to open coast conditions where the beach and the developed coastal planform follows theoretical open coast conditions or constant equilibrium planform. This paper discusses factors influencing beach planform along the Florida Atlantic and Gulf of Mexico coastlines and proposes conceptual methodologies in various applications.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/gWsbmi6VIo0

Groundwater Isotopes in the Sonoyta River Watershed, USA-Mexico: Implications for Recharge Sources and Management of the Quitobaquito Springs

Groundwater resources in the southwestern United States are finite and riparian and wetland areas are vulnerable to aquifer overdraft and unregulated groundwater use. Environmental isotopes and water chemistry were used to distinguish water types, recharge mechanisms, and residence time along several reaches of the Sonoyta River and Quitobaquito Springs located near the U.S.-Mexico border. Areas located upgradient from the Sonoyta River, such as the Puerto Blanco Mountains and La Abra Plain, are supported by local recharge which corresponds to water from the largest 30% of rain events mainly occurring during winter. For Quitobaquito Springs, the δ18O and δ2H values are too low to be derived from local recharge. Stable isotope data and Cl/SO4 mass ratios indicate that the Sonoyta River supplied Quitobaquito Springs through flow along a suggested fault system. Based on these results, Quitobaquito Springs flow could be diminished by any activity resulting in increased groundwater extraction and lowering of water elevations in the Sonoyta River regional aquifer.

Modeling of reservoir flushing by means of existing hydrodynamic models

<p>Sediment flushing has been reported as one of the most efficient techniques for reservoir desiltation. This technique consists in opening the bottom outlets of a dam to induce an accelerated flow that mobilizes part of the sediments deposited in the reservoir. The efficacy of flushing depends much on conditions such as the hydraulic head in the reservoir, the discharge capacity of the outlets, the sediment characteristics, and the topography of the reservoir, among others. In this context, numerical models become an extraordinarily useful tool for reservoir operators, as the efficacy of flushing can be previously evaluated by means of numerical modeling. However, though there are several studies that have simulated flushing numerically, most of them are based on specific case studies whose conditions cannot be generalized. This study aims to analyze the capacity of three hydrodynamic models (HEC-RAS-1D, IBER-2D and FLOW-3D) to simulate flushing events. For that purpose, those conditions tested in laboratory for two experimental setups were implemented and simulated in these hydrodynamic models. The first experimental setup was based on a one-dimensional approach in which the width of the outlet coincided with the width of the reservoir. This experimental setup was carried out in a 12.5 m long and 0.30 m wide horizontal rectangular flume at Universidad Politécnica de Cartagena, Spain. Here, 10 pairs <em>h<sub>s</sub></em> – <em>h<sub>w</sub></em> were tested, where <em>h<sub>s</sub></em> and <em>h<sub>w</sub></em> stand for the initial sediment and water elevations, respectively. Sediments consisted of a uniform sand with <em>d<sub>50</sub></em> = 0.7 mm, bulk density <em>ρ<sub>b</sub></em> = 1650 kg/m<sup>3</sup>, and grain density <em>ρ<sub>s</sub></em> = 2650 kg/m<sup>3</sup>. In these experiments, the evolution of the water surface and bed surface, as well as the liquid and solid hydrographs, were characterized by means of videos recorded from a side of the flume. The second experimental setup consisted of 3 of the experiments documented in the PhD thesis by Lai (1994), which were conducted in a 50 m long, 2.4 m wide and 1.5 m high rectangular concrete flume at University of California at Berkeley. In this experimental setup, the reservoir was emptied through a 0.15 m wide and 0.25 m high sluice gate., which allows analyzing the influence of the width ratio between outlet and reservoir. Sediments consisted of walnut shell grit with <em>d<sub>50</sub></em> = 1.25 mm and <em>ρ<sub>s</sub></em> = 1390 kg/m<sup>3</sup>. In these experiments, liquid and solid hydrographs were characterized by means of discrete measurements of the water surface and sediment concentration at the outlet. To assess the capacity of the hydrodynamic models to simulate flushing, the hydrographs obtained from laboratory experiments are compared to those obtained numerically. Preliminary results show that the model FLOW-3D obtained the best approach to the results obtained in laboratory. The results obtained with HEC-RAS also show a good approach to the experimental results, but with comparatively high differences in magnitudes for the peaks of the liquid and solid hydrographs. The results obtained with IBER show the greatest differences with respect to the results obtained in laboratory.</p>

Green Water on A Fixed Structure Due to Incident Bores: Guidelines and Database for Model Validations Regarding Flow Evolution

This paper presents a two-dimensional experimental study of the interaction of wet dam-break bores with a fixed structure, regarding the evolution of the incident flows and the resultant green water events on the deck. The study employs image-based techniques to analyse flow propagation from videos taken by high-speed cameras, considering five different shipping water cases. The features of small air-cavities formed in some green water events of the plunging-dam-break type were analysed. Then, the spatial and temporal distribution of water elevations of the incident bores and green water were investigated, providing a database to be used for model validations. Some guidelines for the selection of the freeboard exceedance, which is of relevance for green water simulations, were provided. Finally, the relationship between the incident bore and water-on-deck kinematics was discussed. The proposed study can be used as a reference for performing simplified and systematic analyses of green water in a different two-dimensional setup, giving high-resolution data that visually capture the flow patterns and allow model validations to be performed.

Capturing Two Consecutive Green Water Events by Convolution

Capturing the propagation of green water events on in ships and other marine structures is of importance when studying the hydrodynamic effects on their motion and the structure’s behavior. Analytical models used to predict green water elevations, such as dam-break models, have been considered to represent time series of water elevations of single green water events. This paper presents the use of a convolution approach to represent the time series of water elevations of two consecutive green water events on deck of a fixed structure. The procedure is described considering green water events, generated with regular waves, on a barge-type fixed structure. Its application is compared with results available elsewhere in the literature. With the assumptions related with the selection of input parameters of the convolution model, and considering only the first green water event, the results show that this methodology allows two consecutive green water events to be captured acceptably. It is hoped that this methodology will be useful in further time-domain applications which study the dynamic behavior of structures subjected to green water.

EFFECTS OF STORM SURGE ON WATER LEVELS OF THE LAGOON SYSTEM OF JACAREPAGUÁ – RIO DE JANEIRO, BRAZIL

The Lagoon System of Jacarepaguá is the most vulnerable coastal area of Brazil due to its high population density and important economic activities. Severe meteorological conditions due to climate changes are more likely to affect the lagoon system in the future, increasing the exposure of the area and the probability of flooding of the low-lying surrounding areas. To determine the vulnerability of the area to diverse agents, this work addressed the impact of different combinations of sea level rise, heavy rainfall and storm surges. The study cases considered two different bathymetry conditions, the actual silting bathymetry, and the resulting bathymetry after a planned dredging project. Tidal prism, the maximum water elevations and the time of occurrence were analyzed. The main results showed that storm surge has the most impact on the maximum water elevations, overcoming the impact of an increase in the sea level, river flow and changes in bathymetry. The results of time lags comparing the time of occurrence of maximum elevation recorded at the open sea and the time of occurrence of maximum elevation on the north margin, the most populated area, of the lagoon system showed a time lag of 13-17h. The benefits of the planned dredging project would be mostly to allow a better water renovation in the lagoons, due to a higher tidal prism.

Surge Height and Current Estimation Along K-G Basin

Numerical investigation on storm surge characteristics would benefit the planners and designers of coastal structures and offshore platforms along the Krishna-Godavari (K-G) basin. The adjoining coastline has a wide range of geomorphological features and varying geometries due to the sediment deposition from the two major rivers, Krishna and Godavari. Two severe cyclonic storms (SCS) Laila (2010) and Helen (2013) that approached the basin from two different directions and made landfalls closer to each other were analyzed for determining the storm surge heights and currents along the K-G river basin. The maximum water elevations and maximum currents during the storm event and evolution of storm surge heights at different locations were studied. It could be concluded from the study that when a SCS event approaches K-G basin, in addition to the tide and wave effect, a maximum storm surge height and current of 1 m and 1.2 m/s can be expected along the coast, respectively. Similarly, the surge and current in the offshore regions were found to be 0.3 m and 0.8 m/s, respectively. These values may be considered while deriving design parameters for the offshore installations. The critical regions in the basin were identified where high surge heights and currents are expected.

Resolving Hydrometeorological Data Discontinuities along an International Border

Monitoring, understanding, and forecasting the hydrologic cycle of large freshwater basins often requires a broad suite of data and models. Many of these datasets and models, however, are susceptible to variations in monitoring infrastructure and data dissemination protocols when watershed, political, and jurisdictional boundaries do not align. Reconciling hydrometeorological monitoring gaps and inconsistencies across the international Laurentian Great Lakes–St. Lawrence River basin is particularly challenging because of its size and because the basin’s dominant hydrologic feature is the vast surface waters of the Great Lakes.For tens of millions of Canadian and U.S. residents that live within the Great Lakes basin, seamless binational datasets are needed to better understand and predict coastal water-level fluctuations and other conditions that could potentially threaten human and environmental health. Binational products addressing this need have historically been developed and maintained by the Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data (Coordinating Committee). The Coordinating Committee recently held its one-hundredth semiannual meeting and reflected on a range of historical accomplishments while setting goals for future work. This article provides a synthesis of those achievements and goals. Particularly significant legacy and recently developed datasets of the Coordinating Committee include historical Great Lakes surface water elevations, basin-scale tributary inflow to the Great Lakes, and basin-scale estimates of both over-lake and over-land precipitation. Moving forward, members of the Coordinating Committee will work toward customizing state-of-the-art hydrologic and meteorological forecasting systems across the entire Great Lakes basin and toward promoting their products and protocols as templates for successful binational coordination across other large binational freshwater basins.

Pressure Oscillations in Piva Hydro Power Plant Draft Tube: Case Studies

In this paper performed the analysis and comparison the measured values of pressure oscillations in the draft tube of Francis units obtained in tests from 1976 and 2009. HPP “Piva” has been operating since 1976. In July 1976, September 1976 and in October 1976, performed tests on Francis units HPP “Piva”, at different levels of head water elevations, reason for which measurements are repeated complexity of the observed problems, the excessive pressures oscillations in the unit’s draft tube. Also during 2009 performed measurements the pressure oscillations on the rim of the draft tube and at turbine head cover Francis units HPP “Piva”, as a supervising engineer I worked on these measurements. During 1976, team from Litostroj-Ljubljana performed the measurements and recording of pressures oscillations in the middle of draft tube (in direction of the unit’s axis), at 0.25 Ds distance from the draft tube’s rim, and at the mere rim of the draft tube. The most unfavourable results were obtained, on the measuring point at 0.25 Ds from the rim the draft tube. In order improve the performances of Francis turbines installed in the HPP “Piva” units, it is very important thoroughly investigate and eliminate the causes of increased pressure oscillations in the draft tube HPP “Piva” units.