The undertaken thesis work conducts a research study based on the study area — Laakhaven, The Hague, to develop an implementation example of the Adaptation Pathway approach, in order to support long-term adaptive stormwater management planning on urban adaptation measures to mitigate pluvial flooding under the climatic and socio-economic uncertainties.

The methodology is presented in the stepwise procedure to develop adaptation pathways. The core part of this method is expressed as the risk-based approach, which considers the flood risk from the aspects of the probability and the consequence. Different climate and socio-economic scenarios are developed to represent the uncertain environment for policymaking resulting from long-term changes. An urban water balance model is applied to produce the novel empirical performance indicator for the effectiveness of adaptation measures as the critical input to this assessment. Sell-by dates of adaptation actions
are computed based on the assumption that, once a policy action reaches the perspective-based socially acceptable risk, it is said to encounter an adaptation tipping point thus requiring additional interventions. With the computed sell-by dates, the adaptation pathways maps are assembled under certain rules that exclude illogical sequences. Robust adaptation pathways that can succeed over various future scenarios are outlined from the pool of pathways. The developed adaptation pathways map provides the policymakers with a range of possible options. The results indicate the significance of investing in the modular rainwater harvesting devices on private space since it is effective and flexible action
that supports the development of dynamic robust strategies for the long-term adaptive stormwater management planning. The implementation methodology of this case study is theoretically viable and its potential to make a more comprehensive study has been proven. Therefore, it is recommended to take the undertaken study as a starting point and further improve it to find the ultimate answer through sub-selecting preferred pathways.

This thesis describes the approaches applied to attempt to solve the numerical problems of the regional atmospheric model incorporated in the coupled modelling of regional water balance and anthropogenic land cover change in Amazon basin. For computational efficiency, the previous atmospheric model is evaluated at monthly scale. In order to cope with the numerical instability, nearest neighbouring averaging interpolation is iteratively performed to smooth the solutions as a transitional approach. Therefore a subsequent study is conducted to investigate the origin of the numerical instability and whether there are feasible measures to fix the numerical problem of the modelling. Chapter 1 serves as an introduction, which briefly introduces the background and research question — Whether there is any possible remedy that can solve the numerical instability of the monthly-timestep regional water balance model and obtain convergent solutions? Chapter 2 contains 7 sections, each of which gives statement of the specific problem, the experimental method applied, the corresponding results and related discussions. It has been concluded from the series of experiments that — a. adding diffusion terms makes no sense; b. applying smaller fractions of wind helps alleviate instability but the applied monthly timestep length seems to make the model paradoxic and inherently not convergent; c. instability is not really relevant with the iterative method; d. after correcting a dormant error in previous research, the results gets no better; e. the model may be so oversimplified that cannot reflect the reality; f . wind and monstrous timestep length are the keys to the problem, especially the latter is more problematic. Chapter 3 summarizes the discussions and conclusions from chapter 2 and proposes several recommendations for future research such as trade-offs between model complexity and efficiency, a heuristic way of making wind endogenous and reconsideration of the model architecture.