Assessment of Eco-Environment Quality of Darjeeling and Kalimpong Districts, West Bengal, India using Remote Sensing based Ecological Index

Ecological Environmental Quality (EEQ) is an important measure of evaluating the comprehensive characteristics of ecosystem elements, structure, and function that can reflect the strengths and weaknesses of the regional ecological environment. In the present study, an attempt has been made to assess the Eco-Environment Quality (EEQ) and its spatio-temporal changes in Darjeeling and Kalimpong districts using Remote Sensing based Ecological Index (RSEI) during the years 1999 and 2022. It is assessed by synthesizing four ecological indicators viz. Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up and Bare Soil Index (NDBSI), Land Surface Moisture (LSM), and Land Surface Temperature (LST) representing greenness, dryness, wetness, and heat. Further, Principal Component Analysis (PCA) is performed within the PressureState-Response (PSR) Framework, where NDBSI is put under the “Pressure” category, NDVI under “State” and “LSM” & “LST” under the “Response” category. The results indicate that mean RSEI values have increased from 0.49 in 1999 to 0.58 in 2022, showing an overall improvement of 15% in ecological environment quality during the study period. The spatial distribution of ecological indicators shows that the northern part of the study area (part of Darjeeling Himalaya) has relatively higher values in case of NDVI and LSM which indicates better ecological quality; while the southern region which is the plain area shows relatively higher values in case of NDBSI and LST, indicating poor ecological quality of the region.