Land surface hydrology represents the study of the exchanges of water and energy between the land and the atmosphere, and the movement of water within and over the land surface. These processes have immediate and significant impacts on the quality of life on earth. The focus of this HESS special issue is the cascading, through various hydrologic subsystems, of the heterogeneities (in space) and the variability (in time) that arise from the non-linear, dynamical interactions between the land surface and the atmosphere, how they manifest in hydrologic variability at a range of scales including extremes, and how they can be observed, modelled, predicted and utilised for decision-making at a wide range of time- and space scales. The broad range of topics to be covered in this special issue will include, but are not limited to, the following:

• the nature of the heterogeneity of the land surface and precipitation, with a focus on organization and self-similarity, and the interactive impact on the heterogeneity of soil moisture, runoff production, and evapotranspiration;
• parameterization of the effects of sub-grid heterogeneity of landscape properties and soil moisture on grid-scale water and energy fluxes in large catchment-to-global-scale hydrologic models;
• effects of human impacts on the nature of hydrologic variability, including the frequency and magnitude of floods and droughts, and associated coupled human-water system feedbacks;
• approaches to multi-scale measurements of hydrologic variability, including both ground-based measurements and remote sensing, and their synthesis;
• the nature of land surface-atmosphere interactions and feedbacks, including global teleconnections, and implications for local, regional, and global climate change impacts;
• controls, interactions, and changes of continental and global water and energy cycles;
• the nature of hydrological predictability as derived from land surface memory, land-atmosphere interactions and climate predictability, and how this varies with season and location;
• flood and drought predictability, real time forecasting, and associated risk assessments.

This special issue, consisting of both invited and contributed papers, will be published in recognition of the outstanding contributions of Professor Eric Wood to hydrologic science and practice, and to water resources engineering, as well as his lifetime of service to and leadership in the hydrologic science community. In a career spanning 4 decades, Professor Wood has made significant contributions to the fields of hydrology and water resources management, from his early development of ideas on hydrologic scaling behaviour to more recent work on bringing together ground and satellite observations with large-scale modelling to understand and predict changes in the hydrological cycle.