Evaluation of Tea Plantation Dynamics and Health in Northeast India Using Cloud-Based Geospatial Analysis

Tea is an evergreen shrub whose leaves produce a beverage known as one of the world’s three principal drinks. Tea plantations are a special economic activity that promotes the affluence of many developing countries. In India, the Northeast region (NER) accounted for nearly half of India’s tea production. Identification of tea plantations based on traditional methods is expensive and tedious. In this study, we employed the Google Earth Engine (GEE) platform to map tea plantations based on a supervised classifier (i.e., Random Forest) and satellite images of 1990 (Landsat-5) and 2022 (Sentinel-2A). Furthermore, we assessed its health conditions based on the Leaf Area Index (LAI) derived from Sentinel-2A satellite images of 2022. The results showed that over the span of 1990-2022, the tea plantation area increased significantly in Assam, situated in NER. About 1029.5 km² (i.e., 75.9%) of tea plantations increased from four districts (Jorhat, Sibsagar, Dibrugarh, Tinsukia) of Assam. Among the above districts, the highest growth was observed in Dibrugarh (112%) and the least growth was seen in Sibsagar (45%). Classification accuracy was assessed using the F1 score, which varies from 0.80 to 0.90, as derived from precision and recall metrics. Health assessment was performed using LAI, which serves as a crucial indicator of leaf canopy density. The LAI of tea plantations ranges from two to four, indicating moderate to good health conditions. Higher LAI values were found in the tea plantations of Dibrugarh, whereas lower LAI values were seen in Sibsagar. It can be concluded that this study demonstrates the potential of remote sensing techniques to evaluate the dynamism of tea plantations and their health. It provides a reference basis for the fine mapping of tea plantations in NER. It can also assist policymakers in managing tea estates to improve tea health and tea production.