From engineering hydrology to Earth system science: milestones in the transformation of hydrologic science Hydrology and Earth System Sciences DOI 10.5194/hess-22-1665-2018 7 March 2018 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. Read more
Using hydraulic head, chloride and electrical conductivity data to distinguish between mountain-front and mountain-block recharge to basin aquifers Hydrology and Earth System Sciences DOI 10.5194/hess-22-1629-2018 2 March 2018 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. Read more
Imaging groundwater infiltration dynamics in the karst vadose zone with long-term ERT monitoring Hydrology and Earth System Sciences DOI 10.5194/hess-22-1563-2018 1 March 2018 Understanding water infiltration in karst regions is crucial as the aquifers they host provide drinkable water for a quarter of the world’s population. We present a non-invasive tool to image hydrological processes in karst systems. At our field site, the injection of electrical current in the ground, repeated daily over a 3-year period, allowed imaging changes in the groundwater content. We show that specific geological layers control seasonal to rainfall-triggered water infiltration dynamics. Read more
Citizen observations contributing to flood modelling: opportunities and challenges Hydrology and Earth System Sciences DOI 10.5194/hess-22-1473-2018 28 February 2018 Citizens can contribute to science by providing data, analysing them and as such contributing to decision-making processes. For example, citizens have collected water levels from gauges, which are important when simulating/forecasting floods, where data are usually scarce. This study reviewed such contributions and concluded that integration of citizen data may not be easy due to their spatio-temporal characteristics but that citizen data still proved valuable and can be used in flood modelling. Read more
Minimum forest cover required for sustainable water flow regulation of a watershed: a case study in Jambi Province, Indonesia Hydrology and Earth System Sciences DOI 10.5194/hess-22-581-2018 24 January 2018 This study is the first to describe the quantitative association between forest and plantation areas and the flow indicators (surface runoff and baseflow) in a watershed; this understanding is required by spatial planners if they are to balance the ecology and socioeconomic functions of a landscape with the rapid expansion of plantation crops. In addition, our study provides data regarding how SWAT input parameters related to tropical plantations such as oil palm and rubber should be adjusted. Read more
Can riparian vegetation shade mitigate the expected rise in stream temperatures due to climate change during heat waves in a human-impacted pre-alpine river? Hydrology and Earth System Sciences DOI 10.5194/hess-22-437-2018 18 January 2018 In eastern Austria, where air temperature rise is double that recorded globally, stream temperatures of a human-impacted river were simulated during heat waves, as calculated by regional climate models until 2100. An increase of up to 3 °C was predicted – thus exceeding thresholds of resident cold-adapted species. Vegetation management scenarios showed that adding vegetation can reduce both absolute temperatures and its rate of increase but is not able to fully mitigate the expected rise. Read more
The potamochemical symphony: new progress in the high-frequency acquisition of stream chemical data Hydrology and Earth System Sciences DOI 10.5194/hess-21-6153-2017 7 December 2017 We present a new prototypelab in the fieldnamed River Lab (RL) designed for water quality monitoring to perform a complete analysis at sub-hourly frequency of major dissolved species in river water. The article is an analytical paper to present the proof of concept, its performances and improvements. Our tests reveal a significant improvement of reproducibility compared to conventional analysis in the laboratory. First results are promising for understanding the critical zone. Read more
The CAMELS data set: catchment attributes and meteorology for large-sample studies Hydrology and Earth System Sciences DOI 10.5194/hess-21-5293-2017 20 October 2017 We introduce a data set describing the landscape of 671 catchments in the contiguous USA: we synthesized various data sources to characterize the topography, climate, streamflow, land cover, soil, and geology of each catchment. This extends the daily time series of meteorological forcing and discharge provided by an earlier study. The diversity of these catchments will help to improve our understanding and modeling of how the interplay between catchment attributes shapes hydrological processes. Read more
Improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity Hydrology and Earth System Sciences DOI 10.5194/hess-21-5009-2017 6 October 2017 A field-scale average of near-surface water content can be sensed by cosmic-ray neutron detectors. To interpret, calibrate, and validate the integral signal, it is important to account for its sensitivity to heterogeneous patterns like dry or wet spots. We show how point samples contribute to the neutron signal based on their depth and distance from the detector. This approach robustly improves the sensor performance and data consistency, and even reveals otherwise hidden hydrological features. Read more
Complex relationship between seasonal streamflow forecast skill and value in reservoir operations Hydrology and Earth System Sciences DOI 10.5194/hess-21-4841-2017 28 September 2017 This study investigates the relationship between skill and value of ensemble seasonal streamflow forecasts. Using data from a modern forecasting system, we show that skilled forecasts are more likely to provide benefits for reservoirs operated to maintain a target water level rather than reservoirs operated to satisfy a target demand. We identify the primary causes for this behaviour and provide specific recommendations for assessing the value of forecasts for reservoirs with supply objectives. Read more