Time series modelling of drought in a semi-arid region of south Gujarat, India

Abstract

Gujarat is situated within a climatic spectrum ranging from arid to semi-arid, characterised by periodic and recurrent drought phenomena coupled with an enduring and consistent challenge of water scarcity. Drought events in the Gujarat region place substantial stress on its water resource infrastructure, thereby impacting not only the hydrological aspects but also exerting notable repercussions on the intricate interplay between agriculture, economics, and the broader societal domain. Despite the implementation of numerous legislations and protocols aimed at mitigating the impact of drought and ameliorating the aftermath, the state of Gujarat experiences a recurring pattern of drought, resurfacing approximately every three years and inflicting substantial disruption upon the lives of its residents. This research focuses on analysing the current drought scenarios using the standard precipitation index (SPI) and meteorological drought modelling using autoregressive integrated moving average with exogenous variable (ARIMAX) for identifying future drought conditions, which is a statistical modelling approach. Analysis of reference locations was carried out to identify the best model and the same model used for drought modelling and forecasting in the remaining locations. A meteorological drought risk map and drought frequency map were prepared using forecasting results. Model validation was done by computing RMSE and R² of multiple locations in the entire region.

Research highlights

• The study focuses on the recurring drought challenges faced by Gujarat due to its arid to semi-arid climate, leading to persistent water scarcity issues

• The research explores the intricate effects of droughts across hydrology, agriculture, economics, and society, highlighting their far-reaching consequences

• Despite mitigation efforts, a consistent drought pattern emerges approximately every three years, posing ongoing challenges to water resource management and societal stability

• The research employs a two-pronged strategy – utilising the standardized precipitation index (SPI) for assessing current drought conditions and leveraging the ARIMAX model for future predictions

• The ARIMAX model is carefully chosen and fine-tuned using reference locations to ensure accurate predictions across diverse geographical areas

• A significant outcome of the research is the development of drought risk maps, providing spatial insights into vulnerability levels and enabling targeted mitigation strategies

• The research rigorously validates the accuracy of its predictions using metrics such as root mean squared error (RMSE) and coefficient of determination (R²), enhancing the credibility of the findings

• The study reveals nuanced patterns, indicating that the west coast experiences frequent droughts, while inland areas face less frequent but longer-lasting events

• Understanding regional differences guides the formulation of customised approaches to address varying degrees of drought impact

• Through its comprehensive analysis, predictive capabilities, and spatial insights, the research equips stakeholders with actionable strategies to effectively manage and mitigate the recurring challenges posed by drought events