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Predictive analytical model for chloride concentrations in the Port of Rotterdam : for analyzing the effect of human interventions in the Rhine-Meuse Delta

Linneman, R.H. (2019) Predictive analytical model for chloride concentrations in the Port of Rotterdam : for analyzing the effect of human interventions in the Rhine-Meuse Delta.

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Abstract:Fresh water from estuaries is widely used, from drinking water production to agricultural use. The water quality standards for these various applications are regulated. One of these standards concerns the chloride concentration. Alterations in estuaries, such as deepening, may affect the chloride concentration inside the estuary. The Rhine-Meuse delta is such an estuary in which the fresh water is widely used for e.g. shipping but also for drinking water production and cooling. Therefore, predicting chloride concentrations in estuaries is important. Based on previously obtained measurement data, an analytical model is developed which provides insight in the importance and influence of boundary conditions on chloride concentrations. Chloride concentrations within the estuary are affected by many processes, which can be summarized in three main factors; the inflow of salt water due to tides; the inflow of fresh water due to river discharge and the mixing processes between these inflows. Previous research indicated that deepening of the New Waterway and Botlek may lead to increased chloride concentrations in the Rhine-Meuse delta. In this research daily averaged values were used. Due to the dependence of the inflow of salt water on the tidal water movement, however, this analysis is best performed at the time scale of the in- and outflow of the tidal wave. The inflow of fresh water in the Rhine-Meuse delta originates from the Waal, Meuse and Lek rivers, of which the discharge volumes are measured upstream of the estuary. These discharges take a certain amount of time to reach the measurement locations for chloride concentrations in the estuary. Similarly, the inflow of salt water with the tidal wave, measured as the water level at the mouth of the estuary, takes time to propagate into the estuary and reach the chloride concentration measurement locations. These time lags are determined, with the use of a cross-correlation analysis between the observed boundary conditions and the chloride concentrations, at four different locations in the estuary. Resulting time lags vary from 110 minutes to 280 minutes regarding the tide and 750 minutes to 1900 minutes regarding the discharges of the Waal, Meuse and Lek. Variations in chloride concentrations at all four examined measurement locations are best explained with a non-linear analytical model, including parameters that describe the autocorrelation of the input parameters with a moving weighted average. Performance of the developed predictive analytical model of Lekhaven on the training dataset was determined at a R2 value of 0.87 and a RMSE value of 469.4 mg/L and on the validation dataset at a R2 value of 0.80 and a RMSE value of 579.1 mg/L. Similar results were found for the three other measurement locations. For the analysis of the effects of human interventions on chloride concentrations in the estuary of the Rhine-Meuse Delta, such as deepening of the New Waterway and Botlek, the developed analytical predictive models can be applied on post human-intervention gathered data. This analysis on measurement data can be used to validate results of theoretical models, and as indication on how relations between input parameters have changed due to human intervention in the Rhine-Meuse Delta. Furthermore, the developed prediction models can be used for predictions of chloride concentrations with the use of expected values for the discharge of the Rhine and the astronomical tide.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
Link to this item:http://purl.utwente.nl/essays/79687
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