Projects

Introduction

For operational control and crisis management, fast salt intrusion prediction models are essential to prevent damage to industry, agriculture, drinking water supply and ecology. Given the present limitations of computational speed, water managers have to rely on data analytical tools and 1D models, which simplify channel complexity. In this project, existing and new field data is collected and analysed to yield databased prediction tools, and theoretical building blocks are being developed for an improved 1D model enabling a better representation of channel network complexity. The obtained knowledge will allow rapid evaluation of alternative measures designed to counteract salt intrusion.

Project description

Given the present limitations of computational power, water managers are often forced to rely on fast 1D models for operational control and crisis management. These models are oversimplifications of the multidirectional heterogeneity of salt intrusion in branching channel networks, which limits their predictive capacity. In this project, tools are developed to deal with this. New time-series analysis tools are being build, and parametrisations are developed for different scales of estuary networks, to be used as improved dispersion formulations in 1D models. Nowadays, nature-based solutions for flood protection, and potentially salt intrusion mitigation, are widely applied. We will highlight the effects that natural banks can have on salt dispersion mechanisms, relative to fixed channel embankments. The results are integrated in the Decision Support System of Project Delta in the SaltiSolutions research programme.

Work packages and research questions

The projects is split in two workpackages (WPs). In WP4.1, the project addresses the range of scales from a specific site where a salinity sensor is operational, to an individual branch. Nonstationary time-series analysis tools are being extended to predict future salinity values, and the influence of 3D flow processes on 1D dispersion is being captured in simple parameterizations of dispersion. WP4.2 addresses the scale of an entire channel network, focussing on wind influences and channel junction processes in particular.

Project deliverables

• Field data sets collected during hydrographic surveys over tidal cycles during spring tide and neap tide, to be used for model calibration and validation (WP4.1 and WP4.2).
• A new harmonic regression model that is capable of accurately predicting salt concentration at a site. This new model relies on existing data series for calibration and will be able to accurately provide short-term salinity predictions from forecasted storms surge levels and upstream river discharge (WP4.1).
• Dispersion theory for an advanced 1D model based on:
  • Nodal point relations that parameterize three-dimensional dispersion processes at channel junctions, derived from an idealised three-dimensional model (WP 4.2).
  • Semi-analytical formulations for 1D dispersion, that parameterize the effect of lateral salt exchange processes resulting from complex geometry (WP4.1).
• Initial assessments of alternative measures to counter salt intrusion by geometrical adjustments of branches and nodes in the Rhine Meuse Delta channel network (WP4.2).