Integrated Assessment Models (IAMs) helps the researchers and policymakers understand the long-term consequences of varying socioeconomic development and climate change scenarios. IAMs are widely used for accessing the costs and benefits of climate change impacts and mitigation strategies. These models integrate different sectors (global economy, energy, water, and agriculture) to answer policy insights at global and local scales. New methods and tools are needed to better integrate the Energy Water Land (EWL) sectors in IAMs for analyzing complex synergies and trade-offs relevant to climate impacts and water resources. This dissertation proposal presents methods for improved EWL representation using MESSAGEix IAM. Specifically, the existing IAM is planned to be modified by i) focusing on a spatially resolved representation of the water sector to retain essential hydrological information without compromising computational complexity, and ii) endogenous representation of water system impacts and adaptation responses.