Quantification of Salt Intrusion caused by Navigation Locks and their Operation for Policy Analysis, Water Management or Salt Dispersion Modelling

Abstract

Sea locks can be a source of saltwater intrusion into inland surface waters, coastal reservoirs or canals, protected by coastal dams. Typical analytical models for calculating the amount of salt intrusion are either calibrated on existing locks or make conservative assumptions about the operation (for instance, assuming full exchange of the lock chamber contents upon opening the gate). This paper presents a model which can quantify the salt intrusion based on building blocks describing the volume exchanges in the different lock phases. Validation using field measurements showed a model underestimation of 7-10%. This model can be readily applied to future unknown situations, such as increased vessel traffic, rising sea levels and/or changes in lock operation. In addition, the application of mitigation measures, such as bubble screens, can be included. The relative effect of these inputs is illustrated here using generic examples. It is shown that lock operation has a significant effect on the salt intrusion through the lock. The model can be used stand-alone or in combination with salt dispersion modelling to determine the requirements for lock operation, in the evaluation of mitigating measures, or in the design of new locks within the context of water management of the inland water system.