My research focuses on surface water flow generation and its interaction with the land surface at a variety of time and space scales. My work is both theoretical and applied and involves field, experimental, analytical and modelling components. The various strands of my research can be summarised as follows:
Hillslope hydrology and sediment transport: The action of running water is undoubtedly one of the most important drivers of landscape change globally which is directly coupled to climate. The importance of runoff driven erosional processes in landscape evolution has long been recognized, yet theoretical expressions relating sediment flux to hillslope and rainfall attributes are lacking. The relationship between hillslope attributes and sediment flux forms the basis of geomorphic transport laws used to model the topographic evolution of drainage basins, so gaining functional insights into the controls on hillslope sediment flux for different erosional mechanisms (and climatic characteristics) is important for constraining basin-scale sediment supply and for determining the limits of applicability of generalized transport equations. Hillslope sediment supply to valley floors remains poorly constrained because it is episodic and spatially variable within basins and is controlled by the interplay between hillslope characteristics and climatic forcing. In my most recent research I have been investigating the theoretical relationships between sediment flux and hillslope attributes in runoff-dominated systems using numerical modelling. I have been developing a numerical model based on first principles which couples rainfall-runoff generation to a sediment transport of mixed sediment sizes which I have used to investigate the theoretical relationship between rainfall, runoff, hillslope attributes and sediment flux to the slope base and the impact on river channel characteristics.
Dryland hydrology and geomorphology: I am interested in the way dryland basins respond to rainstorms in the short term and in the way they evolve morphologically in the long-term. Current theoretical frameworks are inadequate for understanding dryland basin response and evolution due to the infrequent but spatially variable rainstorms and the ephemeral channel flow. My research aims to understand the role of rainstorm characteristics on the balance between hillslope sediment supply and channel sediment evacuation in drylands. Hillslope sediment supply constrains river channel grain sizes and influences incision rates and river long profile development. I have been exploring the impact of longitudinal hillslope sediment supply (flux and grain size distribution) on fluvial response and bed material grain-size distributions. I use numerical modelling and field investigations to understand the role of hillslope runoff and sediment supply on channel sediment dynamics. Over the long term, the balance between hillslope sediment supply and channel sediment evacuation may be climatically determined and affects the evolution of the valley floor with implications for flood risk. My ultimate goal is to develop theory and numerical modelling capability to understand dryland basin evolution in response to climatic changes.
Fate and transport of dissolved and sediment-bound constituents: Erosion is a globally significant problem with implications for soil fertility and off-site pollut ion. My interests in hydrology and sediment transport processes, have led to a number of fruitful interdisciplinary collaborations with biogeochemists and soil scientists with whom I work on to investigate the fate and transport of organic matter, nutrients and pesticides by flow- and erosion-driven processes. This work has attracted funding from industry, particularly large regional water companies, who are facing increasing challenges in managing water resources and want to understand the residence times of pesticides/fertilizers in soils and the timescales for their transport to drinking-water reservoirs or groundwater through leaching, runoff and erosion processes. Runoff and erosion are the major vectors for nutrient/contaminant transport. I work in agricultural settings and dryland ecosystems and have been investigating the relative roles of runoff and erosion on nutrient transport. I setup and manage a large-scale experimental hillslope facility (TRACE) which I have been using to develop novel sediment tracing techniques and to test hypotheses on biogeochemical fate and transport under controlled conditions.
View complete publications list in the University of Bristol publications system
Dr Michaelides currently teaches 4 courses:
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