We report the first ever regional-scale implementation of the Surface Temperature Initiated Closure (STIC1.2) model for mapping evapotranspiration (ET) using MODIS land surface and gridded climate datasets to overcome the existing uncertainties in aerodynamic temperature and conductance estimation in global ET models. Validation and intercomparison with SEBS and MOD16 products across an aridity gradient in the US manifested better ET mapping potential of STIC1.2 in different climates and biomes.

This study used a portable 56-sensor, 3-D temperature array with three heat pulse sources to measure the flow direction and magnitude below the water–sediment interface. Breakthrough curves from each of the sensors were analyzed using a heat transport equation. The use of short-duration heat pulses provided a rapid, accurate assessment technique for determining dynamic and multi-directional flow patterns in the hyporheic zone and is a basis for improved understanding of biogeochemical processes.

Streams are important sources of carbon (C) to the atmosphere, but it is unclear whether they only outgas C from terrestrial sources or mineralize terrestrial dissolved organic matter (DOM). Our unique synoptic study showed that DOM quantity and quality differed between the stream and riparian groundwater, and that DOM export decreased by up to half along a 4km reach. Thus, stream DOM is not a reflection of terrestrial DOM, and headwater streams could be key for assessing global C fluxes.

The paper presents major milestones in the transformation of hydrologic science over the last 50 years from engineering hydrology to Earth system science. This transformation has involved a transition from a focus on time (empirical) to space (Newtonian mechanics), and to time (Darwinian co-evolution). Hydrology is now well positioned to again return to a focus on space or space-time and a move towards regional process hydrology.

This article tackles the problem of finding the origin of groundwater in basin aquifers adjacent to mountains. In particular, we aim to determine whether the recharge occurs predominantly through stream infiltration along the mountain front or through subsurface flow from the mountain. To this end, we discuss the use of routinely measured variables: hydraulic head, chloride and electrical conductivity. A case study from Australia demonstrates the approach.