A joint study conducted by the Space Applications Centre (SAC-ISRO) and the Kerala University of Fisheries and Ocean Studies (KUFOS) has found an abrupt decline (42 per cent) of the mangrove ecosystem in Ernakulam due to large-scale infrastructure development projects with a major decrease seen in Puthuvypeen near Kochi.
“Researchers utilised satellite images (Landsat 5 & 8, NASA) to detect the rapid changes over the last two decades,” said K Riji John, Vice Chancellor of KUFOS. “Drastic deprivation of mangroves in the area was identified based on a non-linear model and the researchers were able to note the changes from mangrove area to water and built-up areas.”
Reflectance properties of mangrove vegetation, water, and urban zones over the visible and near-infrared electromagnetic spectrum were analysed to distinguish between mangroves and non-mangrove areas, and identify the non-linear changes over mangrove forests.
Impact of human activities
Over the last few decades, anthropogenic activities have triggered the rate of change in the function of mangrove ecosystems in coastal urban areas of Ernakulum. However, monitoring the activities is challenging because of the inaccessible and harsh nature of the mangrove ecosystems, said John.
The area around Puthuvypeen had a large mangrove cover two decades ago. But, it drastically declined due to several port-related infrastructure projects, dumping of waste, disturbing the natural course of seawater, etc. During constructions and other landfilling activities, the salt water supply to the mangroves was cut off, causing its depletion.
A sign of hope
However, an area near container road in Mulavukad showed a positive trend in mangrove replenishment, which is encouraging for bringing the region back to its pre-damaged state.
This is the first time satellite images over a decade were utilised to identify the degradation of mangroves.
This methodology is scalable for large-scale mangrove change analyses, said Girish Gopinath, Associate Professor, Remote Sensing and Geographical Information System, KUFOS, and Anand Sahadevan, a scientist at SAC-ISRO.