Little is known about the interaction between climatically expressed hydrology and topographic evolution of dryland basins because the processes by which they are shaped occur so infrequently and typically on timescales longer than human lives. In semi-arid to arid drainage basins, the primary driver of changes at or near the Earth’s surface is convective rainstorms. These storms are short-lived and small-in-area relative to drainage basin size, yet they dominate runoff generation and groundwater recharge, and control both water supply and flood risk to marginal communities of people. They also govern the availability of water to vegetation and other ecology, as well as spatial patterns of sediment, nutrient, and contaminant transport and deposition on local to basin scales. How would dryland landscapes (vegetation, water storage, and landforms) evolve to a wetter/drier climate regime or one with increased/decreased storminess? This information gap creates great challenges for predicting expected hydrologic patterns and processes under a shifting climate within dryland drainage basins, thus limiting research advances in environments occupying 41% of the Earth’s surface and home to 1/3 of the world’s population.
We have been working to better understand the climate drivers in dryland environments and the Earth surface responses to heterogeneous runoff generation with a broader goal of characterizing the evolving water balance and landscape evolution under climate change. We have made contributions to the development of new modeling tools for simulating the spatial and temporal effects of individual rainstorms over the landscape and their influence on soil moisture, runoff, streamflow, groundwater recharge, and evapotranspiration. We have also compiled new topographic databases of the world’s drainage basins that enabled us to identify distinct and unprecedented climatic signatures within topography that segregate by regional aridity.
Projects on this research theme include:
Climatic controls on river topography. PhD Project of Shiuan-An (Andrew) Chen.
Detecting signatures of drought in vegetation of East Africa. PhD Project of Isaac Kipkemoi.
Drought Resilience In East African dryland Regions (DRIER). Funded by The Royal Society, Michaelides (PI), Wasonga (University of Nairobi, Kenya, Co-PI), Assen (Addis Ababa University, Ethiopia, Co-PI), Singer, Cuthbert, Mitchell, Rosolem, Tebboth, Few, 2019-2022
Relevant group publications:
Michaelides, K. & Martin, G.J. (2012) Sediment transport by runoff on debris-mantled dryland hillslopes. Journal of Geophysical Research-Earth Surface, doi:10.1029/2012JF002415, 117, F03014.
Michaelides, K. & Singer, M.B. (2014) Impact of coarse sediment supply from hillslopes to the channel in runoff-dominated, dryland fluvial systems. Journal of Geophysical Research–Earth Surface, doi:10.1002/2013JF002959, 119 (6) 1205 – 1221.
Singer, M.B. & Michaelides, K. (2014) How is topographic simplicity maintained in ephemeral, dryland channels? Geology, doi:10.1130/G36267.1.
Michaelides, K., *Hollings, R., Singer, M.B., Nichols, M., Nearing, M. (2018) Spatial and temporal analysis of hillslope-channel coupling and implications for the longitudinal profile in a dryland basin. Earth Surface Processes and Landforms doi:10.1002/esp.4340
Calvert, J., Balazs, M. and Michaelides, K. (2018) Unifying particle-based and continuum models of hillslope evolution with a probabilistic scaling technique. Journal of Geophysical Research–Earth Surface. doi:10.1029/2018JF004612.
*Chen S-A., Michaelides, K., Grieve, S.W.D. and Singer, M.B. (2019) Aridity is expressed in river topography globally. Nature 573–577, doi.org/10.1038/s41586-019-1558-8.