He is an engineering hydrologist interested in problems involving hydrological uncertainty. Much of his research has focussed on the impact of climate change and variability on hydrological practice, along with applications related to remote sensing, formulating stochastic approaches, developing hydrological models, and the two big hydrology bread-and-butter problems - design flood estimation + water resources management.
Ashish has served as the President of the International Commission of Hydrologic Sciences (IAHS) Commission on Statistical Hydrology (STAHY) since 2016.
Ashish has served on the Australian Research Council's College of Experts twice.
Ashish served on the Technical Committee overseeing the development of the Australian Rainfall and Runoff Design Flood Estimation guidelines (ARR2016).