Application of Granger-causality to study the climate change impacts on depletion patterns of inland water bodies

Abstract

When it comes to projecting the potential effects of climate change on hydro-climatic variables using time-series models, the conventional approach has been to examine correlations with exogenous variables. Establishing correlations among endogenous and exogenous variables, however, cannot guarantee that there is a cause-effect relationship among the variables. This study, therefore, used Granger-causality for a more accurate alternative to the exogenous variables needed to expand time-series models. To demonstrate this, Maharlou Lake, Iran was selected for a case study not only because this inland water body has been exhibiting unprecedented depletion patterns recently, but also because studies are projecting that a changing local climate could add pressure to the region’s water resources. Both restricted and extended models reveal that shrinkage observed in the lake’s time-series data is expected to continue in the near future. This depletion, however, is projected to be more pronounced in August, September, and October, and milder in February, March, and April. Furthermore, the results from the extended model hint at a more severe pattern of shrinkage rooted in the adverse impacts of projected climate change.