Coastal hydro-morphodynamics present significant uncertainties, one order of magnitude larger for sediment transport than for the driving hydrodynamics. Met-ocean factors (waves, currents, and levels essentially) are normally selected from a probability distribution, where only the central trend is considered, and then the analysis of hydro-morphodynamic processes is carried out within a deterministic framework. This analysis is often based on a non-updated topo-bathymetry, with implicit error intervals for many variables, which results in uncertainties that, unless presented from an ethical perspective, tend to hinder proactive decision making and thus result in growing coastal degradation. To address this challenge, the article starts with the uncertainty in water/sediment fluxes and resulting morphodynamic impacts under average and storm conditions, proving the need to include explicit error levels in the analysis and subsequent assessments. The article develops this approach for field and lab data, considering how they are extrapolated to estimate key variables in coastal sustainability and engineering decisions, illustrated in terms of the longshore sand transport. Such a key variable estimation presents large uncertainties and thus requires a stricter ethical approach for extreme events, which serves to illustrate the transmission of uncertainties. The article concludes with a short overview of the implications that these uncertainties may have for coastal risk assessments and proactive decision making, discussing how large error levels without a suitable ethical assessment may result in socio-economic mistrust, which will limit the necessary optimism to address future coastal sustainability.

沿海流体形态动力学存在显着的不确定性，沉积物运输比驱动流体动力学大一个数量级。气象海洋因素（基本上是波浪、洋流和水位）通常是从概率分布中选择的，其中只考虑中心趋势，然后在确定性框架内进行流体形态动力学过程的分析。这种分析通常基于未更新的地形水深测量，许多变量具有隐含的误差区间，这会导致不确定性，除非从道德角度提出，否则往往会阻碍主动决策，从而导致沿海退化加剧。为了应对这一挑战，文章从水/沉积物通量的不确定性以及平均和风暴条件下产生的形态动力学影响开始，证明需要在分析和后续评估中包括明确的误差水平。本文针对现场和实验室数据开发了这种方法，考虑了如何将它们外推以估计沿海可持续性和工程决策中的关键变量，以沿岸沙子运输为例。这种关键变量的估计存在很大的不确定性，因此需要对极端事件采取更严格的伦理方法，这有助于说明不确定性的传递。文章最后简要概述了这些不确定性可能对沿海风险评估和主动决策产生的影响，