Land Suitability Assessment For Stormwater Management, Mayiladuthurai District, Tamil Nadu

Land is a finite resource with competing and conflicting use. Unplanned and unscientific use of land can exacerbate climate change, and disasters like drought or floods. Judicious use of land resources is key in meeting the state’s social, economic, and environmental development goals. A comprehensive land suitability assessment can guide responsible and sustainable development practices and land-use policies.

Land and water are closely interlinked, as the availability and flow of freshwater depends on the land characteristics, such as its topography and composition, amongst other factors. Therefore, certain areas of lands naturally act as better sinks for capturing stormwater or surface run-off water from precipitation. Freshwater, on the other hand, is a critical resource, and the stress on freshwater resources is expected to increase with growing population, development, and climate change. According to India’s Composite Water Management Index (Niti Aayog, 2018), 600 million people in the country are suffering from an acute shortage of water.

The National Water Mission (NWM) is one of the eight programmes in the National Action Plan on Climate Change, reflecting the high political priority given to water security in India in the face of climate change. Some of the areas under the NWM include:

•                studies on management of surface water resources,

•                management and regulation of ground water resources,

•                and the conservation of wetlands

Thus, in line with the NWM, one of the climate actions to mitigate the depletion of freshwater resources is to implement stormwater management strategies, and to build water harvesting infrastructure. In this context this report aims to identify unused lands in Mayiladuthurai district and evaluate to what extent these unused lands can be utilized for storm water management, and thereby contribute to the district’s long–term water security.

Strategically located unused or fallow lands can not only improve water security but also aid in forestation and agriculture. Thus, with geospatial data unused lands within the district are identified and are assessed for their suitability for stormwater harvesting. They are further analysed in terms of their suitability for capturing water in the form of surface waterbodies and ground water. The results that are obtained could provide aid to the local authorities to plan and prioritize areas to secure water in the region.

The objective of this report is to analyse and assess the water harvesting potential of the identified unused lands in Mayiladuthurai district. Considering meeting 25% of the annual water extraction from the estimated population of the district, the water harvesting target is quantified as 156 MCM/year.

The district has a total geographical area of 1,186 km2 of which 118 km2 or 10% has been classified as unused or fallow lands. It experiences an estimated annual rainfall of 1,393 mm. The land suitability analysis revealed that 9,816 acres of unused land have a technical potential for stormwater harvesting. These lands are distributed over 2,179 plots. These lands indicate a potential to capture 84.28 million cubic metres (MCM) per year, which is 54% of the set target. The majority of the plots were found suitable for surface water harvesting.