In this thesis the equilibrium cross-sectional areas of a tidal inlet are investigated. The most common used methods to study cross-sectional stability are the Escoffier method (Escoffier, 1940) and the Modified Escoffier method (Van de Kreeke, 2004). The Escoffier methods are mainly empirical and lack physical justification. Therefore, in this thesis a process-based model, as proposed by Hinwood et al. (2012), is used to show that in the long-term the inlet cross-sectional area approaches a stable equilibrium or closes. Additionally, the influence of higher harmonics on the equilibrium cross-sectional areas is studied. The stable equilibrium cross-sectional area of the Frisian inlet in the Dutch Wadden Sea is computed and the results are compared to earlier findings.

Coastal erosion in Myanmar causes the coastline to retreat, which increases the flood risk for those who live near the coast. Lack of data about the coastline retreat makes it difficult to design proper flood protection measurements (UNFCC 2007). Since Myanmar is a relative poor country traditional measuring techniques, such as laser mapping, are not applicable. Therefore, the rate of erosion was measured with the help of citizen science. A new method was tested, in which measurements were performed with the help from the camera in a smartphone. Pictures were taken from a point of reference on the beach. With the help of triangular symmetry the distance from the participant to the reference was determined. With the help of CTD divers and Xtides, the effect of the tides was included in the measurements as well. This resulted in beach width measurements over time. A decreasing trend in beach measurements indicated erosion of the beach, as expected. The method has proven to be useful for measuring erosion for less developed countries, such as Myanmar. When the method is compared to the existing project Sandwatch (Cambers,2009), the advantage is that it easier to participate, since no additional tools are needed and the measurements can be performed at any time.