A pro-active regional control system framework for the polder “De Eendragt” in the Netherlands.

Abstract

Due to climate change the Netherlands will have longer periods of droughts, and more extreme precipitation events during both summer and winter. It’s in society interest to secure crop yield, ensure healthy water quality, prevent damage in urban areas and make the management cost-effective. “Smart” water management could contribute to uniform, transparent and efficient management decisions. Water board Hollandse Delta (WSHD) has set up a project called “New Control of the Water System, technical automation (NBWS-TA)” in which WSHD aims to set-up regional control systems (RCS’s), which will be implemented into a SCADA-system (Supervisory Control and Data Acquisition). SCADA displays all assets connected to a PLC (Programmable Logic Controller). A RCS forms a set of rules that determines how multiple assets should be controlled during a certain situation. WSHD has the prospective to incorporate this into a Decision Support System (DSS) in which external data input is integrated. This thesis aims to develop RCS’s for the Eendragt polder by answering the following research question; How can the control of assets in the polder “De Eendragt” be integrated to have a water system that is adaptive to changing meteorological conditions? Firstly, the water management philosophy at WSHD has been explained. Secondly, the best practices of Smart water management have been evaluated. Thirdly, the management scenarios during regular circumstances, prolonged drought and periods of intense rainfall have been described and the corresponding management strategies have been explained. Fourthly, the effectiveness of the rainfall management strategy has been evaluated. Lastly, possible corresponding algorithms have been proposed. WSHD must mitigate climate extremes and ensure clean and enough water in the polder. Waterverordening “Zuid Holland” describes the maximal allowed increase in water level during an intense rainfall event. During regular circumstances, no intense rainfall events or prolonged droughts or exceptional events occur. During a prolonged drought, the water level drops further than the maximal allowed drop in water level. A rainfall event is considered intense if the maximal drainage capacity of 17 mm/day is exceeded. Currently, each scenario has a corresponding management strategy. Before implementing a DSS, there must be a clear aim, it is a supportive system, reflecting reality. Local characteristics, initial state, type of rainfall event affects the impact of a rainfall event. In a DSS the uncertainty of a rainfall event can be diminished by postponing the decision, performing high frequent calculations, obtaining meteorological advice, high-quality data input, and data validation. The robustness of the water system affects the goals, which influences the input parameters. More data points offer an extra backup. Indirect values help to determine signal values. During regular circumstances and a prolonged drought multiple (conflicting) interests should be incorporated and prioritized by WSHD. The heterogeneityof the Eendragt polder and seasonal variability makes it undesirable to design a management strategy based on land-use type. Therefore, only the “Equal filling degree” strategy and “Risk informed management” strategy focusing on mitigating an intense rainfall event have been elaborated further. Whereas the Equal filling degree strategy incorporates an equal filling degree in all sub-polders, the Risk informed management strategy classifies the sub-polders into vulnerability levels. The management strategy Equal filling degree resulted in a more even water distribution and less inundation. This strategy is most effective if all weirs are automated and can reach a 100% filling degree. The results of the Risk informed management strategy were largely in alignment with the previous strategy. This could be caused by a too high rainfall intensity, or the chosen filling degrees could have an effect. The given algorithms can be specified and argued later according to the wishes of WSHD. In a DSS these algorithms could be expanded further by also utilizing external data input. It can therefore be concluded that Smart water management offers great potential in the support for transparent, well-reasoned decisions. WSHD is still in the orienting phase. A clear prioritization of management goals and interests is needed, this could be achieved by conducting additional interviews or brainstorming sessions. Future research is needed to evaluate the potential of the Risk informed management strategy. This could be done by elaborating the vulnerability levels and chosen filling degrees in further detail. Although the SOBEK simulations consisted of several constrains, it provided valuable insights in the change in water levels when applying multiple management strategies.