Current modeling practices for social-ecological systems (SES) are often qualitative and use causal loop diagrams (CLDs), as these models promote an evaluation of the systems loops and variable connectivity. Our literature review demonstrated that quality assurance of these models often lacks a consistent validation procedure. Therefore, a guide to improving the validation of qualitative models is presented. The presumed utility protocol is a multi-dimensional protocol with 26 criteria, organized into four dimensions, designed to assess specific parts of the modeling process and provide recommendations for improvement. This protocol was applied to three demonstration cases, located in the Arctic Northeast Atlantic Ocean, Macaronesia, and the Tuscan archipelago. The “Specific Model Tests” dimension, which focuses on the structure of the model, revealed positive evaluations of its structure, boundaries, and capacity to be scaled up. "Guidelines and Processes", which focuses on the meaning and representativeness of the process, showed positive results regarding purpose, usefulness, presentation, and meaningfulness. "Policy Insights and Spillovers", a dimension focused on the policy recommendations, revealed a high number of "not apply", indicating that several criteria are too advanced for the status of the models tested. The "Administrative, Review, and Overview" dimension, which focused on the managerial overview, showed the models needed improvement in the documentation and replicability, while time and cost constraints were positively evaluated. The presumed utility protocol has shown to be a useful tool providing quantitative and qualitative evaluations for an intermediate evaluation of the model-building process, helping to substantiate confidence, with recommendations for improvements and applications elsewhere.
In hydraulic model tests, it is common practice to relate the response of the tested structure to the incident wave parameters at the toe. Estimation of the incident wave parameters at the toe is thus an essential part of the analysis of hydraulic model testing. In many cases, the design conditions at the toe are given by waves that are highly nonlinear or even depth limited. Modelling such conditions requires reproducing the prototype foreshore slope in the model. The present paper provide guidelines on the accuracy of a nonlinear reflection separation algorithm when applied to nonlinear waves over sloping foreshores. A simple methodology has been established to estimate the expected errors on the incident wave parameters.
The present paper deals with overtopping prediction for berm breakwaters in line with the EurOtop methodology. The basis for the paper is the recent advances proposed for EurOtop for conventional breakwaters with respect to the influence of the wave steepness and the crest width. New model tests have been performed to investigate the applicability of these influence factors to berm breakwaters. To cover a white spot in existing data for berm breakwaters, the model tests included wave conditions with very low wave steepness. The results show that the recently developed influence factors for conventional breakwaters also improve predictions for berm breakwaters. Based on this, an additional influence factor for the dimensionless berm width is established. The berm width was in previous studies made dimensionless by the wave height, but the present study indicates that the wavelength is more appropriate.
The main objective of this research is to present an improved and more accurate formula to estimate the reflection coefficient (K R ) for rubble mound breakwaters. Physical model tests were performed for this purpose and existing data was also considered. The evaluation of existing prediction formulas for K R based on the Iribarren number (ξ) shows that the scatter in the experimental results increases with increasing ξ. This is caused by the wavelength having greater influence on the reflection than the wave height and thus the use of the wave steepness is inappropriate. The influence of potentially dimensionless parameters on the wave reflection from literature was analyzed. The major dimensionless parameters were found to be the relative water depth (h/L) and the structure front slope angle (α). Hence, a formula to estimate wave reflection for rubble mound breakwaters based on these two parameters is proposed.
The design of large diameter monopiles (8–10 m) at intermediate to deep waters is largely driven by the fatigue limit state and mainly due to wave loads. The scope of the present paper is to assess the mitigation of wave loads on a monopile by perforation of the shell. The perforation design consists of elliptical holes in the vicinity of the splash zone. Wave loads are estimated for both regular and irregular waves through physical model tests in a wave flume. The test matrix includes waves with Keulegan–Carpenter (KC) numbers in the range 0.25 to 10 and covers both fatigue and ultimate limit states. Load reductions in the order of 6%–20% are found for KC numbers above 1.5. Significantly higher load reductions are found for KC numbers less than 1.5 and thus the potential to reduce fatigue wave loads has been demonstrated.