To effectively mitigate environmental changes and to manage coastal environments, a good under- standing of nearshore bathymetry and its evolution is required. The coastal zone is expected to be vulnerable in the foreseeable future due to the combined effects of increased coastal impacts and a growing coastal population. The use of spaceborne remote sensing methods has been developed in recent decades to estimate nearshore bathymetry. Compared to traditional methods, spaceborne remote sensing techniques offer a relatively large spatial coverage as well as frequent temporal mon- itoring. The Sentinel-2 mission (EC/ESA) is potentially able to provide regular bathymetry estima- tions, mainly due to its significant revisit time and freely accessible data.

This research focuses on the development of a spatio-temporal cross-correlation model in order to construct a one-minute wave-representing video. The video is used to show the potential for wave- derived bathymetry estimation, exploiting a DMD-based DIA to invert depth. The model is ap- plied to two distinct datasets: a synthetic FUNWAVE dataset and Sentinel-2 imagery. The Sentinel-2 imagery covers research sites in Saint-Louis, Senegal and Capbreton, France. An application frame- work related to the model is furthermore developed by analysing a set of synthetic sinusoidal waves.

Three model requirements are created based on the research objectives. The model should show wave propagation for at least one minute and, moreover, the waves in the video should accurately represent the wave field. Both requirements are demanded by the use of a DMD-based DIA. Lastly, the resulting video should enable an accurate bathymetry estimation. Based on the requirements, the developed spatio-temporal cross-correlation model includes four model parts: pre-processing, image resolution augmentation, wave characteristics estimation and video construction.

The research has led to a range of insights. A discrepancy between the quality of constructed videos and related bathymetry estimations is observed. The videos as constructed by the model generally show a good representation of average wave propagation for a sufficiently long duration, while the bathymetry estimations are less accurate. The low quality of bathymetry estimations is explained by three main error sources: celerity estimation errors, the applied filtering methods and the way in which the video is constructed. These three error sources together lead to videos that lack pixel-wise detail and therefore decrease the bathymetry estimation quality. The developed application frame- work shows that estimating wave characteristics from Sentinel-2 imagery by means of the model is at the edge of possibilities. In temporal sense, relatively large celerity estimation errors are expected for wave periods lower than 5 s and higher than 7 s. The model is less sensitive for spatial parame- ters: as long as wavelengths are larger than circa 150 m the celerity estimation error is acceptable.

All together, the developed model and related video constructions offer added value, although not for the purpose of a bathymetry estimation by means of a DMD-based DIA. The constructed videos represent wave propagation in an average sense and can therefore be exploited for wave-related purposes, e.g. obtaining wave spectra, estimating dominant wave direction and estimating wave climates. In general, the video offers a way to enlarge the temporal range of Sentinel-2 imagery. It is furthermore concluded that the model is probably more suitable for use in combination with other types of imagery, including satellite imagery with larger burst duration and increased spatial resolution as well as standard video imagery. ... Read more

It has been determined that the plastic waste load in the Petanu river (Bali, Indonesia) can be as high as 2015.5 kg/day in the beginning of the rainy season. To restore the ecosystem and protect human livelihood this load should be reduced drastically. The enormous pollution rate is largely due to the massive amounts of mismanaged (plastic) waste at household level. This is the part of the waste that is either burned or dumped by the households, rather than collected or brought to a recycling facility. Extensive mismanagement of waste is an indication of an inadequate functioning waste management system. In Bali, and this watershed specifically, the existing system is decentralised and its waste management strategies rely heavily upon public participation. As a result, in some areas households have limited options regarding waste handling due to a lack of a collection system and other waste services. At the same time, households need to pay for those services. In order to improve the current waste management, it is therefore important to understand the trade-off made by the households between the environmental impact of plastic waste and cost of the waste management system.

In this report, this trade-off is studied by creating a real-world, coupled economic-environmentalmodel, of the Petanu’s watershed in the Gianyar regency. The model consists of two parts: 1) a production possibility frontier (PPF) and 2) a utility curve. The PPF is an arc curve that visualises the relation between the plastic waste load originating from households and the average impact on the monthly purchasing power of a household. The purchasing power is impacted since users of the waste management system need to pay for the services. The utility curve, on its turn, visualises a households trade-off between plastic waste load and impact on monthly purchasing power. Coupling these curves gives insights in how well the current waste management system satisfies the preference of the households regarding cost versus pollution rate. If the current waste management matches perfectly with these preferences, the point of tangency of both curves would be the location on the curve representing the current plasticwaste load and impact on the purchasing power. If the point of tangency has a lower plastic waste load and hence higher impact on purchasing power, households are willing to invest more in their waste management to improve the environmental quality of the Petanu river.

To gain insight in the trade-offs people make regarding four disposal methods (Self-Service, Pick-Up, Burn and Dump), cost and time, a stated choice experiment was set up. This is done by means of a questionnaire in which respondents were asked to make choices between hypothetical choice situations. The choice sets consist of different combinations of the disposal methods with varying attribute levels for cost and time. The survey has been conducted under 300 respondents from six different villages, located in the watershed of the Petanu river. With the help of data analysing program Biogeme, an open source Python package, the stated choice data has been transformed into the utility curve. Besides a general utility curve for the whole population living in the watershed of the Petanu river, also utility curves have been established for certain segments of the population, based on age, educational level and currently used disposal method. Hence, the questionnaire contained also questions about socio-demographic characteristics, the currently used disposal method and the corresponding cost. The latter two are not only used for the segmented utility curve but also for the creation of the PPF. The PPF is built-up by defining five different scenarios, i.e. the current situation, three scenarios with an improved waste management system and a scenario without a waste management system. The scenarios with an improved system have an increasedwaste collection rate or additional locationswhere recyclables can be handed in, in exchange for money. For all scenarios, the corresponding average cost per household and the plastic waste load in the Petanu river have been calculated. The quadratic best fit to these data points gives the PPF.

By combining the PPF with the general utility curve it was found that an average household in the watershed of the Petanu is willing to pay more for the waste management system than they are currently doing in order to decrease the plastic waste load in the Petanu river. It was even found that households want to achieve very low plastic waste load values and are willing to invest 47,400 IDR per month to reduce their contribution to plastic waste load by 100 grams per day. An exact equilibrium point is however not found as the PPF entails to many uncertainties at very low plastic waste load values. Nevertheless, the model gives a good indication and it is therefore recommended to increase the current collection rate of household waste. Furthermore, it is recommended to invest in TPS3R facilities in which waste is sorted and send to recycling facilities. Moreover, the combination of the PPF with the segmented utility curves gave some very interesting
insides. First of all, the younger generation (· 31 years old) has a higher willingness to pay for the reduction of plastic waste load, than the older generation. This is likely the result of the awareness programs on waste management at schools. Hence, it is recommended to expand this educational program. Secondly, educational level is positively correlated with willingness to pay. Remarkably, income level and gender did not have a significant relation with willingness to pay. Lastly, time is a significant determinant for the choice of disposal method, which corresponds to a certain plastic waste load. Therefore, it is recommended that waste management at household level should be as time-efficient as possible. This means the collection should be as much as possible be done at the doorstep of the houses and recycling bins should be located close-by.

All in all, it has been demonstrated that the households in the watershed of the Petanu river are very willing to pay for the waste management services, however, current waste management options are too limited. It is now the task of the governmental institutions and community leaders to enable collection of waste for every household in every village. ... Read more