Chennai is embarking on an ambitious project to construct its sixth reservoir on the currently unused salt pans of Nemmeli. Situated between Thiruporur and Mamallapuram, this proposed reservoir by the Water Resources Department (WRD) promises to be a substantial addition to the city’s water infrastructure, dwarfing the fifth reservoir at Kannankottai Thervaikandigai in Tiruvallur district by covering an expansive area of over 4,000 acres.Upon completion, the Nemmeli reservoir is projected to augment Chennai’s water storage capacity by approximately 2.3 thousand million cubic feet (tmcft) annually. This would position it as the fourth largest among the city’s existing reservoirs, trailing behind Chembarambakkam, Red Hills, and Poondi, each capable of storing over 3 tmcft of water.
The reservoir’s catchment area is estimated to be slightly over 400 square kilometres, with officials anticipating that nearly three-quarters of its water supply will be replenished by rainfall, underscoring the project’s reliance on natural hydrological cycles.
The groundwork for this crucial infrastructure project is already underway, with the WRD engineers having submitted a preliminary feasibility report. A detailed project report is now in progress, marking the next critical phase in bringing this vision to fruition. The urgency of this project is underscored by the stark reality of Chennai’s current water demand.
The city, including the areas under the Chennai Metropolitan Area, requires around 1,700 million litres of water per day. However, existing sources, including desalination plants, can only supply approximately 1,000 million litres, leaving a significant deficit that necessitates innovative and large-scale solutions.Looking ahead, the long-term master plan formulated by the Chennai Metropolitan Water Supply and Sewerage Board paints an even more challenging picture. By 2050, the city’s total water demand is projected to soar to nearly 39 tmcft, while the current availability hovers just over 11 tmcft. This looming gap of nearly 28 tmcft highlights the critical need for proactive and strategic water management interventions to ensure the sustainability and resilience of Chennai’s water supply in the face of rapid urbanisation and potential climate variability.
In response to this pressing challenge, the WRD has formulated a comprehensive ‘Water Security Plan’. This multifaceted strategy integrates supply-side solutions, sophisticated demand forecasting, and essential governance reforms. A central pillar of this plan is the preservation of existing water sources, recognising their intrinsic value, alongside the identification and development of new locations suitable for additional water storage. The Nemmeli reservoir project is a key component of this supply-side strategy, aiming to harness the potential of previously underutilised land for the greater public good.
The selection of unused salt pans at Nemmeli presents an intriguing case of repurposing land for essential infrastructure. While salt pans might be considered economically less productive, their topography and proximity to water sources could make them suitable for reservoir development. However, careful environmental impact assessments will be crucial to ensure that the project does not adversely affect the local ecosystem, including any remaining salt marsh habitats or coastal biodiversity.
Balancing the need for water security with ecological preservation will be a critical tightrope walk for the project planners.The reliance on rainfall for a significant portion of the Nemmeli reservoir’s water supply also brings the vagaries of climate change into sharp focus. Chennai has experienced both severe droughts and devastating floods in recent years, underscoring the increasing unpredictability of rainfall patterns. Therefore, the design and management of the reservoir will need to incorporate strategies to mitigate the risks associated with climate variability, such as efficient water conservation measures and robust drought contingency plans.Furthermore, ensuring equitable access to this additional water supply will be paramount. The benefits of the new reservoir must reach all segments of Chennai’s population, particularly those in vulnerable communities who often bear the brunt of water scarcity.
This necessitates inclusive planning and distribution mechanisms that prioritise equity and social justice.The Chennai model of tapping unconventional land resources like salt pans for water infrastructure could offer valuable lessons for other urban centres in India facing similar water stress. As cities grapple with increasing populations and the impacts of climate change, innovative and sustainable solutions for water management are becoming ever more critical. The Nemmeli reservoir project, while still in its early stages, represents a significant step towards enhancing Chennai’s water security and building a more resilient and sustainable urban future. The success of this venture will hinge on meticulous planning, environmental stewardship, and a commitment to equitable distribution, setting a potential benchmark for urban water management in the years to come.