The tropics are characterized by greater energy inputs, higher rainfall variability compared to temperate and boreal environments and higher rates of environmental change. This results in extreme spatial and temporal uncertainties, including unpredictable patterns in soil moisture replenishment and groundwater recharge. Most tropical regions are hot spots for climate change and play important role in regional and global water, carbon and nutrient cycles. These ecosystems are susceptible to perturbations that include, but are not limited to, frequent and severe droughts and periods of extreme intense rainfall events. This environmental variability together with local hydro(geo)logical, geomorphological, and ecosystem factors are directly influencing the water quality and quantity, generating the increase in soil salinity as well as overgrazing and a general over-exploitation by humans, especially in years where resource availabilities are low.
Although modelling and novel observational techniques have been applied to develop cutting-edge research, their application remains cost prohibitive in the tropics. A robust data collection in the tropics is not feasible due mostly to economic and political shortcomings and, therefore, hydro(geo)logical and soil-plant-atmosphere processes across different scales in the tropics remain still poorly understood.

We invite field experimentalists and modellers who work in both wet and dry tropics to present their research on:
• Innovative observational techniques using sensors, hydrochemical and stable isotope tracers, plot and monitoring networks, citizen science, radars, and unmanned aerial vehicles;
• Modelling studies that use novel theories and data developed and applied to tropical catchments and ecosystems for a better understanding of the water fluxes from the plot to regional scales.