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, Unfunded.

Drought Resilience In East African dryland Regions (DRIER). Funded by The Royal Society, K. Michaelides, M. Singer (co-PI), M. Cuthbert, D. Mitchell, R. Rosolem, 2019-2022

Publications on this research theme include:

Singer, M.B., Grieve, S.W.D., *Chen, S-A, Michaelides, K. (2024); Climatic controls on the length and shape of the world’s drainage basins, Geophysical Research Letters, 51, e2024GL111220, doi:10.1029/2024GL111220. pdf.

*Koppa, A., *Keune, J., Schumacher, D., Michaelides, K., Singer, M.B., Seneviratne, S., Miralles, D.G. (2024); Global dryland self-expansion enabled by land–atmosphere feedbacks, Science, 385(6712):967-972, doi:10.1126/science.adn6833. pdf.

Gebrechorkos, S., Peng, J., Dyer, E., Miralles, D.G., Vicente-Serrano, S.M., Funk, C., Beck, H., Asfaw, D., Singer, M.B., Dadson, S. (2023); Global High-Resolution Drought Indices for 1981-2022, Earth System Science Data, 15(12): 5449–5466, doi:10.5194/essd-15-5449-2023, pdf.

Michaelides, K., *Chen, S-A., Grieve, S.W.D., Singer, M.B. (2022); Reply to: Climate versus tectonics as controls on river profiles, Nature, 612(7941), E15-E17, doi:10.1038/s41586-022-05419-0. pdf

*Chen, S-A., Michaelides, K., Richards, D., Singer, M.B. (2022); Exploring exogenous controls on short- versus long-term erosion rates globally, Earth Surface Dynamics, doi:10.5194/esurf-10-1055-2022. pdf

*Quichimbo, E.A., Singer, M.B., Michaelides, K., Hobley, D., Rosolem, R., Cuthbert, M.O. (2021). DRYP 1.0: A parsimonious hydrological model of DRYland Partitioning of the water balance, Geoscientific Model Development, doi:10.5194/gmd-2021-137. pdf

*Kipkemoi, I., Michaelides, K., Singer, M.B., Rosolem, R. (In Preparation); Climatic expression of rainfall on soil moisture dynamics in drylands

Singer, M.B., Grieve, S.W.D., *Chen, S-A, Michaelides, K. (In Revision); Climatic controls on the length and shape of the world’s drainage basins

*Adloff, M., Singer, M.B., MacLeod, D.A., Michaelides, K., *Mehrnegar, N., Hansford, E., Funk, C., Mitchell, D. (In Review); Sustained water storage in East African drylands dominated by seasonal rainfall extremes

Singer, M.B., *Asfaw, D.T., Rosolem, R., Cuthbert, M.O., *Quichimbo, A., Miralles, D.G., MacLeod, D., Michaelides, K. (2021); Hourly potential evapotranspiration at 0.1˚ grid resolution for the global land surface from 1981-present, Scientific Data, 8(224) doi:10.1038/s41597-021-01003-9. pdf

*Quichimbo, A., Singer, M.B., Cuthbert, M.O. (2020); Characterizing groundwater-surface water interactions in idealized ephemeral stream systems, Hydrological Processes, 34: 3792-3806, doi: 10.1002/hyp.13847. pdf

*Chen, S-A., Michaelides, K., Grieve, S.W.D., Singer, M.B. (2019); Aridity is expressed in river topography profiles globally, Nature, 573:573–577, doi: 10.1038/s41586-019-1558-8. pdf

Singer, M.B., Michaelides, K., Hobley, D.E.J. (2018); STORM 1.0: A simple, flexible, and parsimonious stochastic rainfall generator for simulating climate and climate change, Geoscientific Model Development, 11:3713-3726, doi: 10.5194/gmd-11-3713-2018. pdf

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, 43:1608–1621, doi: 10.1002/esp.4340. pdf

Jaeger, K., Sutfin, N.A., Tooth, S., Michaelides, K., Singer, M.B. (2017); Geomorphology and sediment regimes of intermittent rivers and ephemeral streams; in Datry, T., Bonada, N., Boulton, A. (eds.), Intermittent Rivers and Ephemeral Streams, pp.21-49, Academic Press, Burlington, doi: 10.1016/B978-0-12-803835-2.00002-4. pdf

Singer, M.B., Michaelides, K. (2014); How is topographic simplicity maintained in ephemeral, dryland channels?, Geology, 42(12):1091-1094, doi: 10.1130/G36267.1. pdf