Speculations on the application of foliar 13C discrimination to reveal groundwater dependency of vegetation and provide estimates of root depth and rates of groundwater use Hydrology and Earth System Sciences DOI 10.5194/hess-22-4875-2018 18 September 2018 Groundwater is a significant water resource for humans and for groundwater-dependent vegetation. Several challenges to managing both groundwater resources and dependent vegetation include defining the location of dependent vegetation, the rate of groundwater use, and the depth of roots accessing groundwater. In this study we demonstrate a novel application of measurements of stable isotopes of carbon that can be used to identify the location, the rooting depth, and the rate of groundwater use. Read more
Estimating time-dependent vegetation biases in the SMAP soil moisture product Hydrology and Earth System Sciences DOI 10.5194/hess-22-4473-2018 22 August 2018 Satellite soil moisture products can provide critical information on incipient droughts and the interplay between vegetation and water availability. However, time-variant systematic errors in the soil moisture products may impede their usefulness. Using a novel statistical approach, we detect such errors (associated with changing vegetation) in the SMAP soil moisture product. The vegetation-associated biases impede drought detection and the quantification of vegetation–water interactions. Read more
On the dynamic nature of hydrological similarity Hydrology and Earth System Sciences DOI 10.5194/hess-22-3663-2018 10 July 2018 In this study we explore the role of spatially distributed information on hydrological modeling. For that, we develop and test an approach which draws upon information theory and thermodynamic reasoning. We show that the proposed set of methods provide a powerful framework for understanding and diagnosing how and when process organization and functional similarity of hydrological systems emerge in time and, hence, when which landscape characteristic is important in a model application. Read more
Inter-laboratory comparison of cryogenic water extraction systems for stable isotope analysis of soil water Hydrology and Earth System Sciences DOI 10.5194/hess-22-3619-2018 6 July 2018 To extract water from soils for isotopic analysis, cryogenic water extraction is the most widely used removal technique. This work presents results from a worldwide laboratory intercomparison test of cryogenic extraction systems. Our results showed large differences in retrieved isotopic signatures among participating laboratories linked to interactions between soil type and properties, system setup, extraction efficiency, extraction system leaks, and each lab’s internal accuracy. Read more
HESS Opinions: Science in today’s media landscape – challenges and lessons from hydrologists and journalists Hydrology and Earth System Sciences DOI 10.5194/hess-22-3589-2018 4 July 2018 Media play a key role in the communication between scientists and the general public. However, the interaction between scientists and journalists is not always straightforward. In this opinion paper, we present insights from hydrologists and journalists into the benefits, aftermath and potential pitfalls of science–media interaction. We aim to encourage scientists to participate in the diverse and evolving media landscape, and we call on the scientific community to support scientists who do so. Read more
Effects of climatic seasonality on the isotopic composition of evaporating soil waters Hydrology and Earth System Sciences DOI 10.5194/hess-22-2881-2018 15 May 2018 Evaporation causes the isotopic composition of soil water to become different from that of the original precipitation source. If multiple samples originating from the same source are available, they can be used to reconstruct the original source composition. However, soil water is influenced by seasonal variability in both precipitation sources and evaporation patterns. We show that this variability, if not accounted for, can lead to biased estimates of the precipitation source water. Read more
A new method, with application, for analysis of the impacts on flood risk of widely distributed enhanced hillslope storage Hydrology and Earth System Sciences DOI 10.5194/hess-22-2589-2018 27 April 2018 Flooding is a significant hazard and extreme events in recent years have focused attention on effective means of reducing its risk. An approach known as natural flood management (NFM) seeks to increase flood resilience by a range of measures that work with natural processes. The paper develops a modelling approach to assess one type NFM of intervention – distributed additional hillslope storage features – and demonstrates that more strategic placement is required than has hitherto been applied. Read more
Regional evapotranspiration from an image-based implementation of the Surface Temperature Initiated Closure (STIC1.2) model and its validation across an aridity gradient in the conterminous US Hydrology and Earth System Sciences DOI 10.5194/hess-22-2311-2018 18 April 2018 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. Read more
Active heat pulse sensing of 3-D-flow fields in streambeds Hydrology and Earth System Sciences DOI 10.5194/hess-22-1917-2018 20 March 2018 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. Read more
Decoupling of dissolved organic matter patterns between stream and riparian groundwater in a headwater forested catchment Hydrology and Earth System Sciences DOI 10.5194/hess-22-1897-2018 19 March 2018 Streams are important sources of carbon to the atmosphere, though knowing whether they merely outgas terrestrially derived carbon dioxide or mineralize terrestrial inputs of dissolved organic matter (DOM) is still a big challenge in ecology. Our study highlights that stream DOM is not merely a reflection of riparian groundwater entering the stream and that headwater streams have the capacity to internally produce, transform, and consume DOM. Read more