A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Urban Water Engineering and Management Jointly offered by Asian Institute of Technology, Thailand and UNESCO - IHE, Delft, the Netherlands

Thesis (M. Sc.) - Asian Institute of Technology - UNESCO-IHE, 2019

After two severe floods in 1993 and 1995 in Meuse and Rhine Rivers -The Netherlands, water management authorities emphasized on the need for new flood management schemes based on dealing with the dynamics of riverine systems by providing Room for the Rivers. Moreover, those strategies represent opportunities for ecological rehabilitation of flood- prone areas and riparian wetlands, and the provision of simultaneous co-benefits that aims to improve the water management, enhance climate resilience and offer social cohesion and human-well-being. The research is conducted based on the Dutch expertise, which gradually has been built up areas as Flood control and Water Management into an export industry and a true laboratory for innovation. The recent flood incident in 20 11 -Thailand, has resulted in a large number of studies carried out in the Chao Phraya River Basin, to investigate potential options for flood risk reduction using traditional structural and non-structural measures that aim to decrease tangible damages. Thus, making room for the rivers was originally advocated by referring to a reduction of flood defenses probability failures and lowering of flood water levels that are translated into fewer consequences. Therefore, this research aims to demonstrate the influence of larger riverine system surface areas in the relationship between discharge and lower flood levels after combine Nature-based Solution as flood mitigation alternatives using a I-dimensional model. Based on the hydraulic effectiveness of individual and combine mitigation measures, will be evaluated those alternatives that have the potential to increase the conveyance capacity of the riverine system expressed in terms of water level reduction and its feasible implementation through a Cost-benefit analysis. Similarly, throughout a qualitative assessment will accounted those potential co-benefits obtained from the implementation of flood mitigation schemes that enhance the landscape aesthetics, preserve the cultural and natural heritage and provide multiple ecosystem services achieving by the interaction between natural processes and dynamic stability in both riverbed and floodplains.