Tech Tools To Help Save Water Bodies Of Tamil Nadu

Chennai: The Tamil Nadu government has developed two systems using satellite imagery, Geographic Information Systems (GIS) and Artificial Intelligence (AI) to identify and monitor water body encroachments.

The two systems were developed by the Institute for Water Studies, Hydrology and Quality Control, coming under the water resources ministry. The Remote Sensing Centre functioning under the control of this institute is analysing the details on geology, geomorphology, lineament through satellite-based data and providing details of estimation and planning of water resources to water users’ departments.

Encroachment of water bodies and polluting them by letting out sewage, besides dumping garbage, is very high. Though Tamil Nadu remains a water-starved state, it occupies the first place in water body encroachments in the country as per the first water bodies census released by the Union water resources ministry two years ago.

As per the census, of the 38,496 water bodies encroached in the country, 8,366 are in Tamil Nadu, which is nearly 22 per cent of the total encroachments in the country.

The state has 1,06,957 water bodies, including ponds, tanks, lakes and reservoirs. While 1.6 per cent of the water bodies in the country are encroached, in Tamil Nadu 7.8 per cent of the water bodies are encroached which is five times higher than the national count.

There are 2,805 ponds, 3,565 tanks, 1,458 lakes, five reservoirs, 69 dams (including check-dams) in the state. Out of all these 8,366 water bodies, the encroachment area can be assessed in 4,933 water bodies.

Among the water bodies whose encroachment area can be assessed, 2,596 are assessed to have less than 25 per cent area under encroachment, 1,328 have encroachment area ranging between 25 and 75 per cent and 1,009 have more than 75 per cent encroachment area, the report said.

Since most of the suburban areas come under the panchayats, permission to construct buildings are given by the panchayats without any consideration for protecting water bodies. In most of the places, the sluices of lakes are closed and big apartments have come up in what used to be the canals carrying surplus water from the lakes during floods.

The encroachments lead to flooding during the northeast monsoon season since the catchment areas are obstructed by buildings and the water inundates the residential areas instead of filling up the lakes. Since the lakes are not filled in the rainy season, the suburbs face scarcity of water during summer.

The institute has developed two web portals through consultancy services which were launched on July 3 last year. The two systems, Tamil Nadu Water Resources Information and Management System (TN-WRIMS) and Tamil Nadu Satellite-Based Water Bodies Information, Monitoring and Protection System (TN-Swip) monitor the water bodies and send alerts if construction activities are noticed on them.

The TN-WRIMS is integrated with the Indian Space Research Organisation (ISRO) to get live and historic remote sensing data. It combines a web geographical and a mobile application designed to monitor water resources and automatically flag structural or physical encroachments. The live tracking features are rolled out across high-risk areas, including Chennai and its surrounding districts of Chengalpet, Kanchipuram and Tiruvallur.

The lakes in Selaiyur, Rajakilpakkam, Irumbuliyur, Tambaram, Kadatheri, Madambakkam, Medavakkam and Sholinganallur in the southern suburbs of Chennai will be watched closely by the system for encroachments. On the northern side of the city, the areas including Thirumullaivoyal, Surapattu, Pudhur, near the Puzhal lake, and Vinayagapuram, Lakshmipuram, Kolathur, MGR Nagar and Cycle Shop areas near the Retteri, besides the Korattur and Kolathur lakes will come under scrutiny for encroachments.

Apart from the Chennai suburbs, the lakes and small water bodies in Kanchipuram, Chengalpet and Tiruvallur have been slowly coming under human occupation. All the lakes in the four districts, Chennai, Chengalpet, Kanchipuraman and Tiruvallur - will be monitored through TN-Swip.

The system using new information technologies like AI and satellite data will be used to ensure conservation and restoration of water bodies through real-time monitoring of water bodies with regard to water availability and its quality. A sum of Rs. 3.55 crore has been sanctioned for implementation of the satellite-based water bodies information.

According to the water resources department officials, it is a system that works with a web-based geoportal and mobile app. This module consists of two main modules: real-time monitoring of water bodies and encroachment detection. This system has been developed on an experimental basis to monitor the water bodies in Tiruvallur, Kanchipuram, Chengalpet and Chennai districts.

Besides the water resources department, the system will also provide useful data to the departments of rural development and panchayat raj, revenue and disaster management, agriculture, municipal administration and water supply besides the Tamil Nadu Pollution Control Board for prevention of encroachment and restoration of water bodies.

The water bodies real-time monitoring module is used to calculate the catchment area using optical and microwave satellite data for water stock assessment. Using the latest satellite imagery, a system has been developed to assess the intensity of water level change in lakes over the years. This module provides real-time information of water bodies, intensity of water level change, such as increase, decrease or no change in the amount of water in the water body.

The encroachment module detects capacity loss of water bodies due to changes in area, using revenue records and actual area of water bodies, using satellite data and AI. It sends alerts to the department officials about changes in water bodies for field-based verification and helps in eviction of encroachments.

Besides the quantity of water, the quality could also be monitored through a sensor to know if sewage has been let out into the water body or solid waste has been dumped. The solid waste dump identification module identifies the dumping of solid waste in water bodies with the help of high-resolution satellite imagery.