Analyzing the impact of thermal stress on vegetation health and agricultural drought – a case study from Gujarat, India

TLDR

In India, drought is mainly driven by poor monsoon rainfall, but heat waves during pre‑monsoon and monsoon seasons also impose thermal stress that degrades vegetation health. The study used multi‑sensor satellite vegetation indices, land‑use/land‑cover data, and GIS analysis of heat‑wave and temperature records from 1981‑2010 to assess vegetation health and agricultural drought in Gujarat. Time‑series analysis revealed that combined moisture‑ and thermal‑stress, reflected in the Vegetation Health Index, strongly correlates with temperature, crop yield, and the Temperature Condition Index, demonstrating that thermal stress drives drought severity and reduces agricultural productivity.

Abstract

Although poor precipitation due to delayed arrival and/or early retreat of the southwest monsoon is considered the chief architect of drought in India, heat waves may also play a crucial role in the intensification of droughts. In the Indian subcontinent, occurrence of heat waves during the pre-monsoon and high air-temperature in the subsequent monsoon season imparts thermal stress on vegetation causing degradation of vegetation health (VH). In the present study, various vegetation indices and land-use/land-cover data derived from multi-sensor satellite have been used to assess VH and agricultural drought in Gujarat during 1981–2010. This Geographical Information Systems-based study has also used heat wave and temperature data to analyze the adverse effects of high temperature on VH. The time series of Vegetation Condition Index and Temperature Condition Index (TCI) has shown that the combined influence of moisture-stress and thermal stress determines the occurrence and severity of drought, which is reflected in the Vegetation Health Index (VHI). A strong correlation among aboveground air-temperature, the TCI and the VHI indicates definite influence of thermal stress on VH. Further, a systematic variation and strong resemblance between temperature, crop yield, TCI and VHI has established the impact of thermal stress on agricultural productivity.