Integrated urban water management modeling under future water demand and climate scenarios for the city of Bangalore, India

Climate change and population growth have a significant impact on urban water supplies. This is due to the fact that meeting urban water demand with the available water resources is quite challenging due to ever-growing water demand, variable supply as a result of climate uncertainties, and water pollution. In many urban areas around the world, the concept of integrated urban water management (IUWM) has become quite prominent in recent decades to tackle the challenges of urban water supply and management. The main principle of IUWM is to incorporate non-conventional water supply sources, such as stormwater, rooftop rainwater, and recycled wastewater, to augment the water supply and provide fit-for-purpose water. IUWM, if implemented successfully, has the potential to mitigate multiple challenges outlined above including enhanced water security during droughts, reduced waste streams, reduced floods, and enhanced groundwater recharge as well as reduced water pollution.

In this research, an IUWM principles incorporated water balance model (i.e., developed using eWater Source Version 5.4.0.11797) was used to identify the most suitable supply options from multiple water sources to satisfy the water demands under future demand and climate scenarios for the city of Bangalore, India. Five different water supply configurations were generated based on available water sources and within the policy framework to meet water demand. The effect of climate change has been incorporated into the IUWM model configurations through the runoff responses from future precipitation and temperature changes. Future climate change scenarios for four IPCC emission scenarios i.e., ssp126, ssp246, ssp323, and ssp586 have been incorporated from thirteen Coupled Model Intercomparison Project-6 (CMIP6) models (i.e., 0.25° spatial resolution available at the study location). Three water demand scenarios i.e., low (150 liters per capita per day), average (175 liters per capita per day), and high (200 liters per capita per day) for the projected population were considered as per the Indian Standards. The selected configurations were evaluated for water supply reliability (i.e., time and volumetric reliability) in the study area. Further, as multiple future scenarios resulted in multiple water supply reliability solutions under five IUWM model configurations, the robust solution was identified using robustness metrics.