Monsoon variation and vegetative drought patterns in the Luni Basin in the rain-shadow zone

Drought has a significant impact on agricultural, ecological and socio-economic spheres. Poor and delayed monsoon, high temperature and insufficient water resources lead to recurrent drought in the Luni River basin located in the rain-shadow zone of western India. In the present study, monsoon variation was studied in relation to spatio-temporal patterns of vegetative drought in the Luni Basin. The Vegetation Condition Index, the Temperature Condition Index and the Vegetation Health Index derived through multi-channel data of NOAA AVHRR satellite were used for drought monitoring, and seasonal variation in rainfall and vegetation response were analysed, compared and correlated. The study finds inconsistent and erratic rainfall patterns in the Luni Basin. The monsoon variation was found to control vegetation health during the monsoon season but sometimes in the non-monsoon period too, and vegetative drought intensity and duration vary widely depending upon moisture and thermal stresses. Inertia in vegetation health is reflected in the inter-seasonal persistence of vegetative drought conditions. The study finds that a good monsoon helps in maintaining vegetation health during following seasons. On the contrary, vegetation health is found to be more sensitive to moisture and thermal stresses in the immediate season after a drought.