Rapid urbanization has altered the natural hydrological cycle of the Tub Ma catchment, inducing major floods after heavy rainfall events. For that reason, structural mitigation measures were built, including floodwalls along the channel and a pumping station at the outlet. However, no operational rules were available for operating the river outlet structures and inundation was still common. To prevent or reduce flooding by improving the operational management of the outlet pumping system, an early warning system was required. The objective of this research was to assess whether informed decision-making resulted in an operational pumping strategy that prevents or reduces fluvial flooding. First, the question was asked whether water level monitoring could result in a timely and reliable warning service for an early warning system. The second question was whether timely operation of the outlet pumping station prevented fluvial flooding. For the fulfillment of the data requirements in this thesis, a fieldwork trip was organized first. During a short period of dedicated data survey, water level time series and river geometries were obtained. Water levels from three gauging stations were statistically tested as precursors for fluvial flooding in Tub Ma. Consequently, a hydraulic model was built to assess the flood mitigation capabilities of the outlet pumping station. Lastly, synthetic flood design hydrographs were run through the model for different pumping station operation strategies, with and without notification from a flood early warning system. The results from this thesis demonstrated that monitoring water levels in the upstream tributaries of Tub Ma was a useful information source for an early warning system that forecasts flood waves. This water level based early warning enabled a maximum potential lead time of 13-15 hours for flood mitigation. Nevertheless, connecting flood early warning to the operation of the pumping station did not reduce or prevent flooding. The Tub Ma river had a flow regime of limited baseflow and rapidly rising discharge, and as a result, the discharge capacity of the pumping station ahead of flood waves was physically limited by water level and inflow. Therefore, improved operation of the pumping station was not the solution for preventing or reducing fluvial flooding. On the basis of the results from this research, structural measures were suggested for flood mitigation, like temporary storage, a bypass channel, and measures that slow down the run-off processes. Also, it was recommended to examine the value of a flood early warning system by using 13-15 hours of lead time within a broader scope of disaster risk reduction in Tub Ma.

Continuous functioning of sewer systems and water distribution networks is crucial for liveability, public health and economic prosperity in urban areas. Progressive deterioration of these underground water infrastructures leads to an increased probability of failure. Maintenance is needed to ensure a desired level of functioning. For municipalities and drinking water companies as asset owners, the trend is to develop risk-based asset management. A risk-based asset management strategy links the likelihood of failure with the consequences. Hence, knowledge is needed on the condition of the underground water infrastructure and the consequences in case of failure. Within this strategy, a risk assessment should be performed to prioritise the maintenance and renewal of underground water infrastructure. Based on their criticality, resources can be applied appropriately. The more critical a conduit segment, the more important it is to perform maintenance. To contribute to risk-based asset management, this study investigates the consequences of failure in sewer systems and water distribution networks. In this research, a methodology is developed for mapping consequences of underground water infrastructure failure to guide asset management. Including the consequences of underground water infrastructure failure in the risk determination may lead to a different prioritisation of maintenance activities. Three failure mechanisms are considered: structural sewer failure, hydraulic sewer failure and water distribution network failure. Structural sewer failure leads to partial or complete loss of the load-carrying capacity, whereas hydraulic sewer failure occurs when a system does not meet serviceability requirements for system performance. For water distribution networks, it is assumed that hydraulic failure (caused by overpressure) and structural failure occur simultaneously. Hence, no distinction is made between failure mechanisms in water distribution networks. Using a screening method, the consequences of underground water infrastructure failure are mapped. The consequences of failure are expressed as the affected area and the characteristics of the built environment. The affected area consists of the sinkhole area and the flood zone. The characteristics of the built environment are displayed by means of consequence categories. Within this study, five different consequence categories are taken into account, using hydraulic modelling and (open) classified data. The consequence categories are: 1) Damage to buildings 2) Traffic obstruction 3) Impact on human health 4) Costs of conduit reconstruction 5) Drinking water supply outage. A flat, typical Dutch study area in Tuindorp (Utrecht) is used to test the methodology. For these five consequence categories, findings are illustrated and compared with the results of the hydraulic network functioning according to the Graph Theory method (GTM). This GTM determines the effects of failure of individual conduits on the functioning of a system as a whole, based on a simplified network structure using links and nodes. Results of the analyses show a positive relation between the individual consequences in case of hydraulic sewer failure. For example, critical conduits in the category `damage to buildings', are critical for `impact on human health' as well. Besides, there is a positive relation between the consequence categories and the hydraulic network functioning. Conduits with large diameters are stated as critical for both methods, yet dead-end segments are only critical for hydraulic network functioning. Contradictory, individual consequences are uncorrelated for structural sewer failure and water distribution network failure. The consequences are independent and can not be linked. Besides, there is no relation between the hydraulic network functioning and the individual consequences of structural sewer failure and water distribution network failure.

The number of fatalities due to a potential flood event is traditionally determined utilizing 'mortality functions’. Data of recent large-scale flooding in the Netherlands are not available since the Netherlands was successful in flood prevention. Therefore, only data from the last coastal flood event in 1953 with 1795 direct fatalities are available. The mortality functions are empirical relationships to provide mortality as a function of three explicit flood characteristics, namely water depth, flow velocity, and water level rise rate. Many more factors are included implicitly since the functions were derived from 1953 data. These underlying factors are thus based on the circumstances of the coastal flooding in 1953 and might not be representative anymore for future flood events elsewhere in the Netherlands. The three flood characteristics in current flood risk assessments are determined by means of coarse flood simulations. Since modern software is becoming more advanced, more detailed flood simulations are becoming possible. Therefore, the applicability of the mortality functions needs to be studied if finer model resolutions are used. This report presents the case study of river area the Bommelerwaard in which the validity of the 1953-based functions, possibilities for alternative functions, and finer model resolutions in hydrodynamic models are tested and analyzed with regards to their impact on flood fatality risk. A hydrodynamic model is developed using the new software program D-Flow Flexible Mesh which is able to apply finer resolutions at locations that require more detail. The different model resolutions that are tested are 100m and 25m, and 5m for the area close to the breach. The flood simulations with these model resolutions resulted in similar outcomes for the number of estimated fatalities in this case study. Overall, the 100m model is preferred because it is sufficiently able to indicate the dangerous locations, provide the order of magnitude of the flood characteristics, while it demands short computation times and matches the level of detail of the data of 1953. However, it is recommended to model the area around the breach (‘breach zone’) with finer model resolutions because the resulting higher local peak velocities are relevant for potential building collapse. For the areas around obstacles and underpasses, it is also recommended to use finer resolutions or to make use of 1D objects or fixed weirs. This study concluded that finer model resolutions at dangerous locations have an impact on the individual risk value of the neighbourhood, and this can have consequences for the maximum individual risk value and thus the overall safety standard of a large dike ring. Furthermore, the case study illustrated that compartment dikes have a significant impact on the local mortality because of the high water level rise rates just upstream. It is recommended to look into possibilities to reduce this high local mortality rate and hence, individual risk, for example by optimizing the location and number of compartment dikes or exploring the effects of openings in the dikes. Moreover, this study identified the discussion points in the current Dutch loss of life approach by a literature study, knowledge of recent flood events abroad, and loss of life approaches internationally. Alternative mortality functions are proposed based on the literature and analyzed through sensitivity analyses in the case study. It is recommended to substantiate and take into account the factors water arrival time, improved building characteristics, and age in the loss of life approach. Preventive evacuation is already taken into account in this approach, but in addition, water arrival time can be included by means of fleeing. This study shows that water arrival time has a great effect on the number of fatalities because some areas have relatively large arrival times and this enables inhabitants to flee the area. Emergency response is thereby of crucial importance. Also in 1953 this factor proved to be relevant. The improved building characteristics compared to 1953 are shown to have a limited impact on the absolute number of fatalities in this case study but it reduced the maximum value of the individual risk and is thus of relevance, especially for dike ring areas with large water depths (>2.1m) and high rise rates (>0.5m/h). Moreover, this study underlines the vulnerability of the elderly during flood events. Since the age distribution has shifted since 1953 and significantly more elderly are present in society nowadays, it is relevant to take this explicitly into account. This case study shows that correcting for age can have a significant impact on the number of fatalities. The impact on the individual risk is limited, but this depends on the spatial distribution of the elderly and should be further analyzed. Finally, the individual risk is sensitive to the configuration of the neighbourhoods. It is therefore also recommended to look into more robust approaches to determine the individual risk.

This research assesses the impact of plastic waste accumulation on flood events with citizen observations in Kumasi, Ghana. In Kumasi, the fastest growing city in Ghana, flooding events have become more intense due to rapid urbanisation and land use intensification. Additionally, rapid population growth, urbanisation and lack of organised waste collection, brings along tonnes of solid (plastic) waste on the streets, riverbeds and -ways. Plastic waste creates blockages in drains and rivers, which causes flooding of open areas, streets and houses. To what degree plastic waste accumulation aggrevates flooding in Kumasi remains poorly understood. Therefore, this study investigates to what extent plastic accumulation impacts flood severity, in response to rainfall events in the city of Kumasi, Ghana. This is done by modelling different rainfall scenarios in a 1D-2D model developed with the software HEC-RAS. This model was forced with static and dynamic data available from open source databases and collected during fieldwork. Data collection took place during six consecutive weeks in May-June 2019 and consists of bathymetry and discharge measurements, a flood- and plastic waste survey performed together with citizens. The impact can be determined using different model scenarios varying in rainfall magnitude and in obstruction of riverways, serving as plastic accumulation. Flood severity was analysed in terms of extent, depth, velocity, local hydraulic impact and flow distribution. The model has been validated with two events, one during which velocity and stage was measured, which results in the same order of magnitude, modelled slightly lower than measured in the field. The second event was a historic rainfall event, which could be validated with community reported flood depths. From this validation it became clear the flood extent of the event was underestimated and depths close to the streams were overestimated. The results show that the selected rainfall events without blockage cover the studied area between 11-25% with water depths higher than 10 cm. The inundated areas are adjacent to the river streams and inundate flat and low lying areas. Comparing this to the scenarios where bridges where obstructed to 33% and 67% individually, the total inundated area remains more or less the same, varying between 0-3% in inundated area compared to the scenario without blockage. However, in terms of flood distribution, areas around the blocked bridge are impacted more, thus inundation areas shift within the observed study area. Comparing this to the rest of the area, upstream or downstream less flooded areas arise, making the change in total flood extent only change slightly. Furthermore, the two bridges that are obstructed have different impact on the flow in the study area, as the scenarios of obstructing the second bridge with 33% produce a numerical instability and therefore incorrect results. From the plastic waste survey it followed that plastic waste is very much abundant in the study area, thus the occurrence of plastic accumulation at the bottleneck locations seem inevitable. The results of this research have shown the main contribution to flooding is flow from upstream areas exceeding river capacity, while local blockages mainly aggravate flooding around the blocked locations.

The Haringvliet sluices is one of the Delta Works. The sluices were finished in 1970 and are thus 50 years old. This research is initiated because the expected lifetime of hydraulic structures is thought to decrease significantly due to climate change. This study aims to provide insight in the functions the Haringvliet sluices fulfill and to what extent climate change influences the functioning of the Haringvliet sluices. If the lifetime of the current structure is reached multiple other strategies are suggested. The lifetime of the sluices is determined, based on the effect of climate change on the functions the sluices fulfils. The climate scenarios used for the assessment of the sluices are the KNMI’14 climate scenarios (Gl and Wh). These are the most mild and most extreme scenarios. The amount of sea level rise and the change in annual river discharge distribution of these scenarios are used for the assessment of the sluices.   For the assessment of the Haringvliet sluices, multiple tools are used. Calculations are made with the programs SOBEK and Hydra-BS, available literature is used, information received from interviews with experts and hand calculations have been used as tools to assess the Haringvliet sluices.  Flood protection, fresh water availability and ecology are the functions for which the sluices have been assessed. Another failure mechanism for which the sluices have been assessed is structural failure. The lifetime for which the sluices fail constructively are conducted by a semi-structured interview. Not opening, not closing, overtopping and overflow are the failure mechanisms included in the assessment for flood protection. The effect of the failure mechanisms in combination with climate change may not lead to hydraulic loads which exceed the retaining height with 0.2 meter of at least two dike sections at the hinterland. With the Kierbesluit, the Haringvliet sluices are opened during high-tide. The requirement concerning fresh water availability is that the chloride concentration at Middelharnis-Spui may not exceed 300 mg/litre. The requirement for ecology is based on fish migration in combination with the Kierbesluit. Multiple fish species must be able to migrate from the North-Sea to the Haringvliet for at least 50\% of the time as indicated for each specie in the migration calender. The sluices may also not be closed for 50 consecutive days. This reduces migration via the Haringvliet.  The lifetime for which the function of flood protection is reached, is based on literature, spreadsheet calculations and the use of the models SOBEK-RE and Hydra-BS. With SOBEK-RE water level calculations are carried out in which the failure mechanisms of not opening and not closing are added. The results have been stored in a database which is used as input for Hydra-BS. Hydra-BS probabilistically calculates water levels through the south western delta. The effect of the failure mechanism of overtopping is calculated by calculating overtopping volumes with formulas found in prior research (Van der Meer, 2008). The overtopping volumes can be significant but due to the large storage area at the Haringvliet, the effect is relatively small. Also, the coincidence between a storm at the North Sea and large discharges at the Rhine is relatively low.  The assessments of the functions fresh water availability and fish migration are based on the aggregation of multiple researches in combination with the effect of a changing climate, for which the KNMI’14 climate scenarios are used. Concluded is that the function for fish migration cannot be fulfilled in the most extreme scenario around 2050.  First strategy proposed to extend the lifetime is to change the Kierbesluit. Sluices may be opened by lower discharges during high tide. However, this decreases the lifetime for fresh water availability. The lifetime with another Kierbesluit can be enlarged by circa 30 years. With this measure the functions of fresh water availability and fish migration still reach the lifetime first around the year 2080. Life time extending measures can be thought of and can be of both economic and social points of view. Closing the sluices more frequently (social point) reduces the fish migration. Relocating the fresh water intake locations more upstream or by building a fish passage from the North-Sea to the Haringvliet is a measure which is coming from an economical viewing point.   When taking into account the extending measure concerning ecology, the lifetime of the sluices become as follows. In case of an extreme scenario the functional lifetime can be met until at least 2050 and the structural lifetime is reached around 2100. In case of an average climate scenario, all the functions fail in a relatively short time span of 20 years, around the year 2130. With the Gl climate scenario used in this thesis the sluices fail first structurally, which is around the year 2170.   In case of an average or mild climate scenario, the sluices need to be removed or covered because they fail structurally. To replace or cover the current Haringvliet sluices when the lifetime is reached, multiple functional strategies have been developed.  For the development of the new functional strategies it is assumed that the requirements do not change compared to the current requirements. The functional strategies are based on three possible designs for the Haringvliet: a permanent closure of the Haringvliet in which pumps are installed, a similar sluice complex or creating an open estuary again. These three strategies are used in combination with other structures. Eventually two verified designs are evaluated. It turned out that closing of the Haringvliet can fulfil all the requirements. A larger sluice complex including a fish passage turned out to be the best functional design. With the rough assumptions used in the evaluation, the variant in which larger sluices combined with a fish passage is suggested comes out as the best strategy. Other strategies could turn out to be more suitable for the requirements, criteria and boundary conditions valid at that moment. Therefore adaptive coastal and river management is recommended.  What must be noted is that backward salt intrusion, intrusion via the Nieuwe Waterweg and Spui to the Haringvliet can cause problems concerning the quality (salt concentration) of drinking water. Closing the Nieuwe Waterweg is a solution concerning the requirements composed for the Haringvliet. However, the effect on the Port of Rotterdam and the costs involved for this closure are not estimated and are therefore not included in the functional designs.  In this thesis multiple methods are used to calculate the effect of a failure mechanism of the Haringvliet sluices on the hydraulic load. Suggested is to come up with a model in which the failure mechanisms not opening, not closing and overtopping are included. Further, with the data from Rijkswaterstaat on the chloride concentrations in the Haringvliet a salt intrusion model can be made to improve the Kierbesluit.

Climate change causes temperatures to rise worldwide. Up until now it is unclear what effect this has on the global water cycle. In this study the output of two GFDL model experiments were thoroughly investigated and used in the moisture tracking model WAM-2layers, accounting for model runs in a past case in the end-20th century and future case in the end-21st century, based on RCP8.5. This is done in order to acquire knowledge on what will happen to the global as well as regional water cycle in the future and to find out what processes provide climate change to have an effect on the water cycle. Changes in precipitation and evaporation rates are spatially highly dissimilar, therefore regional differences can be distinguished. Past studies have suggested that a DDWW paradigm - where dry regions dry out further and wet regions get wetter - will take place with climate change. Even though in some regions this might happen, results show that on land this is not necessarily the case - at least, if precipitation rate is the benchmark for a region to get drier or wetter. Processed GFDL data concludes that dry region Western Sahara gets wetter while dry region Middle East gets drier and wet region Indonesia gets wetter while wet region Amazonia gets drier. The DDWW paradigm covers another aspect as well, that there will be a larger spatial variability for variables characterising a region to be wet or dry. However, while everywhere on the globe the temperatures will rise according to the GFDL data, the spread of the yearly mean temperatures over the globe will actually decrease, meaning that mean yearly temperature in the coldest place will lie closer to the mean yearly temperature in the warmest place. This is also the case for mean yearly precipitation and evaporation rates. The mean yearly precipitation and evaporation rate in the driest place will lie closer to the mean yearly precipitation and evaporation rate in the wettest place in the future case. Continents show divergent effects in water cycle due to climate change. The continents with relatively larger sources of terrestrial moisture - North America, Europe and Asia - have an increased water cycle with higher precipitation and evaporation rates in the future. The increases in precipitation rates on these continents will originate from terrestrial evaporation and a higher percentage of evaporation will return as precipitation on land. South America shows a distinct effect, different than all other continents. This continent shows a decreased water cycle with lower precipitation and evaporation rates in the future. Of this precipitation a lower percentage comes from land and the evaporated moisture will return less on land. Africa and Oceania show another pattern. Both these continents will experience more precipitation in the future case, but this moisture will come from oceanic evaporation. Two case study areas are examined in more depth by looking at seasonality effects. A case study in the Amazon forest shows a distinct dry season in the future case, the effect of possible land use change in the Amazon forest. Less evaporation that is an effect of deforestation of the rain forest gives less moisture for clouds to form and precipitate. Moisture evaporates from the oceans on the East of Amazon region but moves over the region before it can precipitate. A case study in Western Africa shows a magnified rain season. The analyses show that during the wet season in the future case there in an increased amount of moisture coming from the oceans West and South of Western Africa and meanwhile there was still moisture coming in from the tropical rain forest East of the area.

Hydrological modifications to the natural flow regime through the regulation of a river threaten the integrity of river ecosystems. In Myanmar, the exponentially growing hydropower sector poses a threat to the ecohydrology of some of the last large free-flowing rivers in the world. This study investigates to what extent the natural flow regime of the Myitnge in Myanmar has been hydrologically altered by the Yeywa dam, which is currently the largest hydropower dam in Myanmar. The study furthermore examines which ecological processes have been or could potentially be most affected by these hydrological modifications. This is done by modelling the natural flow regime of the dammed Myitnge river in Myanmar using the distributed hydrological rainfall-runoff Wflow\_sbm model, which consists of a set of python programs to perform hydrological simulations. The suitability of this model as a tool for environmental flow management in Myanmar is simultaneously investigated. The model uses PCRaster, which in turn makes use of a dynamic modelling language within a GIS framework. It was forced using static and dynamic data which is mostly globally available from different satellites, and derivatives of this, and calibrated and validated on data collected during field visits in 2018 as well as some secondary data sources. The field data collection focused on river bathymetry and soil properties such as infiltration capacity. Furthermore, scenarios were developed and simulated that varied in dam operational capacity (29\% and 80\%), reservoir management (for flood mitigation), and irrigation demand. Using modelled discharge results, multiple environmental flow assessments were carried out, comparing pre- and post-dam scenarios. The results demonstrated that different elements of the flow regime can be altered slightly depending on the Yeywa operational scenario. For the irrigation scenario, the high water uptake to meet the crop demand alters the magnitudes and duration to the largest extent of all the scenarios. According to the results, the dam alone does not alter most of the components of the natural flow regime (and hence presumably the associated ecological factors) to a very large extent, regardless of the capacity it is operated at. This is because the attainable operational capacity is limited by inflow: raising the capacity at which the dam is operated can only be done for a limited amount of time due to the extreme seasonality. For the current operation and in the simulated scenarios, habitat availability for different species of plants and animals, as well as the river's ability to structure the channel morphology are the elements most at risk due to the Yeywa dam. This is mostly because the occurrence of large floods has significantly reduced or completely disappeared from the flow regime, as also demonstrated by a habitat inundation analysis for the Myitnge. There is potential for the optimisation of the operation of the Yeywa reservoir, but it remains limited to the availability of inflows, which in turn is dependent on the natural seasonality and the size of the reservoir. Therefore, one of the main recommendations is to avoid keeping the outflow below the natural inflow in the dry season, and to run the turbines at maximum capacity during the monsoon period. This is advised in order to protect the downstream channel area from dewatering in the dry season, and to maximize the electricity generation during the wet season, while simultaneously keeping the released discharge very close to the natural flow regime.

Shanghai is a city located in a coastal region and to understand the flood risks it is exposed to, it is of most importance to first understand the processes that control the water levels for the different flood scenarios. Historically, the Huangpu River has reached its highest levels during landfalling typhoon events, which create a combined scenario that involves high sea water levels due to storm surge, and high river water levels consequent not only of the storm surge at the river mouth, but also of the runoff generated by precipitation in the upstream regions. This research project will focus on the later, assessing the impact of torrential rainfall during tropical storms on the water levels along the Huangpu River in Shanghai city. By studying the hydrological regime of the area of interest, three main watershed regions are identified for the Huangpu river basin; the Taihu lake basin situated upstream regulates the yearly discharge on the downstream areas of the river and is controlled by means of a flood gate which remains closed once a certain flood risk is identified, an agricultural area covered in its majority by an interconnected lake system, and the river basin which encompasses the remaining contributing regions to the system. A hydrological model is built for the Huangpu river basin following the rational method, identifying from satellite databases the dominant land cover classes of the region, the hydrological soil group based on the different soil contents, and the average slope around the area based on a digital elevation model. Using the precipitation data from typhoon Fitow, the hydrological model was used to estimate the corresponding discharge time-series from the storm to be used as input on a hydrodynamic model of the Huangpu river. The hydrodynamic model of the river was built using D-Flow Flexible Mesh, it was used to assess different scenarios of the river system configuration, allowing to understand not only the overall contribution of rainfall-runoff to the river discharge but also the effect of each of the catchments on the river system. The performance of this model, as well as of the hydrological model was observed by comparing the predicted values with the site measurements at two hydrological stations, one midstream at Huangpu Park which highlighted the strong influence of the tide on the water levels for the river sections closer to the sea, and one upstream at Mishidu where the influence of the rainfall runoff to the water levels could be observed. The hydrological model was then validated using the precipitation data from typhoon Haikui, taking the corresponding discharge time-series for it to the DFM river model and comparing the estimated water levels to the actual measurements. Finally the river profile with the maximum water levels along it as predicted by the DFM model was compared to the scenario modelled with no rainfall-runoff discharge and the measured embankment height to understand the contribution to flood risk of the torrential rainfall during tropical storms on the water levels along the Huangpu River.

The Philippines is a country located in the typhoon belt of the Pacific. Its location makes it typhoon prone and on average around 20 typhoons enter the country every year (Asian Disaster Reduction Center, 2008). This natural phenomenon can have disastrous effects and therefore, good preparedness is of special importance. Traditionally weather forecasts have been used in order to predict the physical characteristics of typhoons to organise early actions that can dampen their damage. However, regardless the good meteorological forecasts, typhoons kept having large effects in coastal areas, due to the gap of knowledge between a hazard and its impact. For this reason, nowadays disaster managers are increasingly more interested in the knowing the repercussion of natural hazards, which can help to prepare and mitigate their consequences (Tozier de la Poterie et al., 2018).
Although forecasts that predict the impact of hazards, the so-called impact-based forecasts, are rising, there are not many of these systems operationalised yet. To make these forecasts more functional it is essential to understand what their users’ needs are. Because disaster managers work under stressful conditions, it is crucial to have the right information in order to take effective actions. This research has developed an impact-based forecasting prototype for Manila Bay, Philippines, considering the information needs of disaster managers. In order to do so, an iterative process has been followed in the creation of the system, in which disaster managers provided their inputs and feedbacks on the prototype. The impacts on the assets of relevance for the disaster managers have been forecasted with the use of Delft-FEWS and Delft-FIAT. Furthermore, this forecasting system has been novel in predicting the impact of typhoons considering not only the hazard and exposure but also implementing the vulnerabilities of the affected area. The findings of this study suggest that an impact-based forecasting system for Manila Bay should provide information on the affected population, livelihoods, hospitals, roads and schools. Those assets have been pointed out as most important for disaster managers at local scale. The output of the forecasting system should provide actionable results that allow disaster managers to make quick and relevant decisions. Furthermore, the data displayed in the system should be simple, clear and with colour codes that allow for a fast interpretation of the results and provide maps with information of the impacts on all the assets per municipality or province. Besides, it has been observed that vulnerability plays an important role when prioritising the action areas of disaster managers. The aim of this research was to develop an impact-based forecasting system that considers the information and display needs of disaster managers, while integrating the vulnerabilities of the affected area. Therefore, the objective of this thesis was not to develop an accurate mathematical model that provides the exact impact. Instead, it is a guide of what a disaster managers-based forecast should provide. Hence, in order to make this forecasting system operational, validation of the prototype and consideration of other hazards, such as wind speeds, are recommended.