Relative humidity gradients as a key constraint on terrestrial water and energy fluxes Hydrology and Earth System Sciences DOI 10.5194/hess-25-5175-2021 12 November 2021 Here, we present a novel physically based evaporation model to demonstrate that vertical relative humidity (RH) gradients from the land surface to the atmosphere tend to evolve towards zero due to land–atmosphere equilibration processes. Collapsing RH gradients on daily to yearly timescales indicate an emergent land–atmosphere equilibrium, making it possible to determine evapotranspiration using only meteorological information, independent of land surface conditions and vegetation controls. Read more
From hydraulic root architecture models to macroscopic representations of root hydraulics in soil water flow and land surface models Hydrology and Earth System Sciences DOI 10.5194/hess-25-4835-2021 20 October 2021 Root water uptake is an important process in the terrestrial water cycle. How this process depends on soil water content, root distributions, and root properties is a soil–root hydraulic problem. We compare different approaches to implementing root hydraulics in macroscopic soil water flow and land surface models. Read more
Rainbow color map distorts and misleads research in hydrology – guidance for better visualizations and science communication Hydrology and Earth System Sciences DOI 10.5194/hess-25-4549-2021 4 October 2021 We found with a scientific paper survey (~ 1000 papers) that 45 % of the papers used rainbow color maps or red–green visualizations. Those rainbow visualizations, although attracting the media’s attention, will not be accessible for up to 10 % of people due to color vision deficiency. The rainbow color map distorts and misleads scientific communication. The study gives guidance on how to avoid, improve and trust color and how the flaws of the rainbow color map should be communicated in science. Read more
Nonstationary weather and water extremes: a review of methods for their detection, attribution, and management Hydrology and Earth System Sciences DOI 10.5194/hess-25-3897-2021 20 August 2021 Weather and water extremes have devastating effects each year. One of the principal challenges for society is understanding how extremes are likely to evolve under the influence of changes in climate, land cover, and other human impacts. This paper provides a review of the methods and challenges associated with the detection, attribution, management, and projection of nonstationary weather and water extremes. Read more
Summary and synthesis of Changing Cold Regions Network (CCRN) research in the interior of western Canada – Part 2: Future change in cryosphere, vegetation, and hydrology Hydrology and Earth System Sciences DOI 10.5194/hess-25-1849-2021 19 May 2021 This article examines future changes in land cover and hydrological cycling across the interior of western Canada under climate conditions projected for the 21st century. Key insights into the mechanisms and interactions of Earth system and hydrological process responses are presented, and this understanding is used together with model application to provide a synthesis of future change. This has allowed more scientifically informed projections than have hitherto been available. Read more
Do small and large floods have the same drivers of change? A regional attribution analysis in Europe Hydrology and Earth System Sciences DOI 10.5194/hess-25-1347-2021 26 April 2021 Recent studies have shown evidence of increasing and decreasing trends for average floods and flood quantiles across Europe. Studies attributing observed changes in flood peaks to their drivers have mostly focused on the average flood behaviour, without distinguishing small and large floods. This paper proposes a new framework for attributing flood changes to potential drivers, as a function of return period (T), in a regional context. Read more
Vapor plumes in a tropical wet forest: spotting the invisible evaporation Hydrology and Earth System Sciences DOI 10.5194/hess-25-619-2021 3 March 2021 Forest evaporation exports a vast amount of water vapor from land ecosystems into the atmosphere. This work describes the formation process of vapor plumes in a tropical wet forest as evidence of evaporation processes happening during rain events. Read more
Intercomparison of freshwater fluxes over ocean and investigations into water budget closure Hydrology and Earth System Sciences DOI 10.5194/hess-25-121-2021 27 January 2021 The net exchange of water between the surface and atmosphere is mainly determined by the freshwater flux: the difference between evaporation ( E ) and precipitation ( P ), or E−P . Although there is consensus among modelers that with a warming climate E−P will increase, evidence from satellite data is still not conclusive, mainly due to sensor calibration issues. We here investigate the degree of correspondence among six recent satellite-based climate data records and ERA5 reanalysis E−P data. Read more
New flood frequency estimates for the largest river in Norway based on the combination of short and long time series Hydrology and Earth System Sciences DOI 10.5194/hess-24-5595-2020 24 December 2020 We combine systematic, historical, and paleo information to obtain flood information from the last 10 300 years for the Glomma River in Norway. We identify periods with increased flood activity (4000–2000 years ago and the recent 1000 years) that correspond broadly to periods with low summer temperatures and glacier growth. The design floods in Glomma were more than 20 % higher during the 18th century than today. We suggest that trends in flood variability are linked to snow in late spring. Read more
The pulse of a montane ecosystem: coupling between daily cycles in solar flux, snowmelt, transpiration, groundwater, and streamflow at Sagehen Creek and Independence Creek, Sierra Nevada, USA Hydrology and Earth System Sciences DOI 10.5194/hess-24-5095-2020 7 December 2020 Streams and groundwaters often show daily cycles in response to snowmelt and evapotranspiration. These typically have a roughly 6 h time lag, which is often interpreted as a travel-time lag. Here we show that it is instead primarily a phase lag that arises because aquifers integrate their inputs over time. We further show how these cycles shift seasonally, mirroring the springtime retreat of snow cover to higher elevations and the seasonal advance and retreat of photosynthetic activity. Read more