The equilibrium profile concept is a useful tool for the knowledge and management of the coastline. This concept is based on several assumptions that rarely are satisfied in nature. One of these considers that the geologic setting has no influence in the profile morphology. The Victoria beach is a good example that questions this hypothesis. Muñoz-Pérez (1996) and Muñoz-Pérez et al. (1999) proposed an analytical expression of equilibrium beach profile for reefprotected beaches. In this work, data measured at Victoria beach are used to confirm the goodness of this model. The results obtained show that the occurrence of a horizontal rocky platform in subtidal zone modifies the beach slope and the seasonal evolution of the profile.

During a full tidal cycle, the beach profile is exposed to continuously changing hydrodynamical conditions. Consequently, the profile evolves constantly to adapt to these changes. The equilibrium condition on tidal beaches is defined in terms of the relative occurrence of swash, surf zone and shoaling processes. We have assumed that the tidal beach profile is in equilibrium when the net sediment transport along a tidal cycle is zero. In this model the contribution of swash is considered negligible. A simple and easy-to-apply equilibrium profile formulation is proposed. This model is based on the assumption that surf zone processes dominate the profile morphology wherever wave breaking occurs during the tidal cycle. The obtained equilibrium profile is valid from the high tide level to the breaker point at low tide level. The tidal influence on the profile morphology is the lengthening of the surf profile. The higher the tidal range, the longer the surf profile. The model was tested against field and laboratory data, showing reasonable predictions of measured beach profiles.

Abstract. This paper explores a new approach to lumped hydrological modelling based on general laws of growth, in particular using the classic logistic equation proposed by Verhulst. By identifying homologies between the growth of a generic system and the evolution of the flow at the outlet of a river basin, and adopting some complementary hypotheses, a compact model with 3 parameters, extensible to 4 or 5, is obtained. The model assumes that a hydrological system, under persistent conditions of precipitation, potential evapotranspiration and land uses, tends to reach an equilibrium discharge that can be expressed as a function of a dynamic aridity index, including a free parameter reflecting the basin properties. The rate at which the system approaches such equilibrium discharge, which is constantly changing and generally not attainable, is another parameter of the model; finally, a time lag is introduced to reflect a characteristic delay between the input (precipitation) and output (discharge) in the system behaviour. To test the suitability of the proposed model, 5 previously studied river basins in the UK, with different characteristics, have been analysed at a daily scale, and the results compared with those of the model IHACRES (Identification of unit Hydrographs and Component flows from Rainfall, Evaporation and Streamflow data). It is found that the logistic equilibrium model with 3 parameters properly reproduces the hydrological behaviour of such basins, improving the IHACRES in four of them; moreover, the model parameters are relatively stable over different periods of calibration and evaluation. Adding more parameters to the basic structure, the fits only improve slightly in some of the analysed series, but potentially increasing equifinality effects. The results obtained indicate that growth equations, with possible variations, can be useful and parsimonious tools for hydrological modelling, at least in certain types of watersheds.

Traditionally, the shoreline hindcast under the influence of changing marine conditions has been considered by means of existing robust shoreline evolution models, such as one-line, multi-line, combined or 3D models. All of them require long data series, many calibration parameters and are computationally intensive. This study presents a new shoreline evolution model considering the integration of cross-shore, planform and rotation equilibrium-based models, applicable over time-scales spanning days, months or several years. The new model successfully reaches the general erosion-accretion trend at a qualitative and quantitative level. As the main conclusion, this is a simple equilibrium-based shoreline evolution model that requires few calibration parameters and is computationally efficient and versatile.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/zkQ7AoAWmEE

No abstract