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In March 2015 unusual ocean and atmospheric conditions produced many years' worth of rainfall in a ~48 h period over northern Chile's Atacama Desert, one of Earth's driest regions, resulting in catastrophic flooding. Here we describe the hydrologic and geomorphic drivers of and responses to the 2015 Atacama floods. In the Salado River, we estimated a flood peak discharge of approximately 1000 m3/s, which caused widespread damage and high sediment loads that were primarily derived from valley‐fill erosion; hillslopes remained surprisingly intact despite their lack of vegetation. In the coastal city of Chañaral, flooding of the Salado River produced maximum water depths over 4.5 m, meters thick mud deposition in buildings and along city streets, and coastal erosion. The Atacama flooding has broad implications in the context of hazard reduction, erosion of contaminated legacy mine tailings, and the Atacama's status as a terrestrial analog for Mars.

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Cities are hotspots of commodity consumption, with implications for both local and systemic water resources. Water flows "virtually" into and out of cities through the extensive cross-boundary exchange of goods and services. Both virtual and real water flows are affected by water supply investments and urban planning decisions, which influence residential, commercial, and industrial development. This form of water "teleconnection" is being increasingly recognized as an important aspect of water decision-making. The role of trade and virtual water flows as an alternative to expanding a city's "real" water supply is rarely acknowledged, with an emphasis placed instead on monotonic expansion of engineering potable water supplies. We perform a literature review of water footprint studies to evaluate OPEN ACCESSSustainability 2015, 7 8462 the potential and importance of taking virtual flows into account in urban planning and policy. We compare and contrast current methods to assess virtual water flows. We also identify and discuss priorities for future research in urban water footprint analysis.

Abstract:Dry saline soils are common in the arid and hyper-arid basins located in the Chilean Altiplano, where evaporation from shallow groundwater is typically the major component of the water balance. Thus, a good understanding of evaporation processes is necessary for improving water resource planning and management in these regions. In this study, we conducted laboratory experiments with a natural saline soil column to estimate evaporation rates and assess the liquid and water vapor fluxes under different water table levels. Water content, electrical conductivity and temperature at different depths were utilized to assess the liquid and water vapor fluxes in the soil column. We observed movement of water that dissolves salts from the soil and transports them to areas in the column where they accumulate. Isothermal liquid flux was predominant, while thermal and isothermal liquid and thermal water vapor fluxes were negligible, except for deep water table levels where isothermal and thermal water vapor fluxes had similar magnitude but opposite directions. Differences observed in total fluxes for all water table levels were due to different upward and downward fluxes, which depend on changes in water content and temperature within the soil profile. Both the vapor flux magnitude and direction were found to be very sensitive to the choice of empirical parameters used in flux quantification, such as tortuosity and the enhancement factor for local temperature gradients in the air phase within the column.

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