Preprints
Filtering by Subject: Hydrology
Methane, Monsoons, and Modulation of Millennial-scale Climate
Published: 2019-11-20
Subjects: Climate, Earth Sciences, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Other Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Speleology
Earths orbital geometry exerts a profound influence on climate by regulating changes in incoming solar radiation. Superimposed on orbitally-paced climate change, Pleistocene records reveal substantial millennial-scale variability characterized by trends, tipping points, and rapid swings. However, the extent to which orbital forcing modulates the amplitude and timing of these millennial variations [...]
Stable and Radioisotope Systematics Reveal Fossil Water as Fundamental Characteristic of Arid Orogenic-Scale Groundwater Systems
Published: 2019-11-14
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
In arid and semi-arid regions, persistent hydrological imbalances illuminate the considerable gaps in our spatiotemporal understanding of fundamental catchment-scale governing mechanisms. The Salar de Atacama basin is the most extreme example of groundwater-dominated continental basins and therefore is an ideal place to probe these unresolved questions. Geochemical and hydrophysical observations [...]
Coherent streamflow variability in Monsoon Asia over the past eight centuries---links to oceanic drivers
Published: 2019-11-14
Subjects: Climate, Earth Sciences, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The Monsoon Asia region is home to ten of the world’s biggest rivers, supporting the lives of 1.7 billion people who rely on streamflow for water, energy, and food. Yet, a synoptic understanding of multi-centennial streamflow variability for this region is lacking. Here we produce the first large scale streamflow reconstruction over Monsoon Asia (63 stations in 16 countries), using a novel [...]
Pore network model predictions of Darcy-scale multiphase flow heterogeneity validated by experiments
Published: 2019-11-08
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Small-scale heterogeneities in multiphase flow properties fundamentally control the flow of fluids from very small to very large scales in geologic systems. Inability to characterize these heterogeneities often limits numerical model descriptions and predictions of multiphase flow across scales. In this study, we evaluate the ability of pore network models (PNM) to characterize multiphase flow [...]
Observing Rivers with Varying Spatial Scales
Published: 2019-10-31
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
The NASA/CNES Surface Water and Ocean Topography (SWOT) mission will estimate global river discharge using remote sensing. Synoptic remote sensing data extends in situ point measurements, but, at any given point, is generally less accurate. We address two questions: 1)What are the scales at which river dynamics can be observed, given spatial sampling and measurement noise characteristics? 2) Is [...]
Verifying pore network models of imbibition in rocks using time-resolved synchrotron imaging
Published: 2019-10-25
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Oil, Gas, and Energy, Physical Sciences and Mathematics
At the pore scale, slow invasion of a wetting fluid in porous materials is often modelled with quasi-static approximations which only consider capillary forces in the form of simple pore filling rules. The appropriateness of this approximation, often applied in pore network models, is contested in literature, reflecting the difficulty of predicting imbibition relative permeability with these [...]
The sensitivity of estimates of multiphase fluid and solid properties of porous rocks to image processing
Published: 2019-10-10
Subjects: Chemical Engineering, Civil and Environmental Engineering, Earth Sciences, Engineering, Hydrology, Petroleum Engineering, Physical Sciences and Mathematics, Transport Phenomena
X-ray microcomputed tomography X-ray microCT) is a rapidly advancing technology that has been successfully employed to study flow phenomena in porous media. It offers an alternative approach to core scale experiments for the estimation of traditional petrophysical properties such as porosity and single-phase flow permeability. It can also be used to investigate properties that control multiphase [...]
Controls of River Dynamics on Residence Time and Biogeochemical Reactions of Hydrological Exchange Flows in A Regulated River Reach
Published: 2019-10-06
Subjects: Biogeochemistry, Earth Sciences, Hydrology, Physical Sciences and Mathematics
Residence Time Distributions (RTDs) exerts an important control on biogeochemical translations in watershed systems. RTDs tend to follow time-invariant exponential, lognormal, or heavy-tailed RTDs that have power-law behaviors for long tails in headwater or low-order streams. However, there is increasing recognition that RTDs can be more complicated and time-variable in response to dynamic [...]
The water planetary boundary: interrogation and revision
Published: 2019-10-03
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Physical Sciences and Mathematics
The planetary boundaries framework has proven useful for many global sustainability contexts, but is challenging to apply to freshwater, which is spatially heterogeneous, part of complex socio-ecological systems and often dominated by local dynamics. To date, the planetary boundary for water has been simplistically defined by as the global rate of blue water consumption, functioning as a proxy [...]
Integrating the water planetary boundary with water management from local to global scales
Published: 2019-10-03
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Physical Sciences and Mathematics, Sustainability, Water Resource Management
The planetary boundaries framework defines the ‘safe operating space for humanity’ represented by nine global processes which can destabilize the Earth System if perturbed. The water planetary boundary attempts to provide a global limit to anthropogenic water cycle modifications, but it has been challenging to translate and apply it to the regional and local scales at which water problems and [...]
Research trends in the use of remote sensing for inland water quality science: Moving towards multidisciplinary applications
Published: 2019-10-03
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Remote sensing approaches to measuring inland water quality date back nearly 50 years to the beginning of the satellite era. Over this time span, hundreds of peer reviewed publications have demonstrated promising remote sensing models to estimate biological, chemical, and physical properties of inland waterbodies. Until recently, most of these publications focused largely on algorithm [...]
Representative elementary volumes, hysteresis and heterogeneity in multiphase flow from the pore to continuum scale
Published: 2019-09-22
Subjects: Earth Sciences, Engineering, Hydrology, Physical Sciences and Mathematics
Representative elementary volumes (REVs) and heterogeneity are key concepts in continuum multiphase flow, yet their manifestation from the pore-scale and associated impacts with the flow regime are not well understood. We use a multi-scale experimental and modelling approach to elucidate the role of REVs, hysteresis and heterogeneity in multiphase flow in two distinct water-wetting Bentheimer [...]
Global groundwater sustainability, resources and systems in the Anthropocene
Published: 2019-09-19
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Groundwater is a crucial resource for current and future generations but is not being sustainably used in many parts of the world. The objective of this review is to provide a clear portrait of global-scale groundwater sustainability, systems and resources in the Anthropocene, in order to inspire a pivot towards more sustainable pathways. We examine groundwater from three different but related [...]
The near-tip region of a hydraulic fracture with pressure-dependent leak-off and leak-in
Published: 2019-09-04
Subjects: Earth Sciences, Engineering, Environmental Sciences, Hydrology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Volcanology
This paper is concerned with an analysis of the near tip region of a propagating fluid-driven fracture in a saturated permeable rock. The study attempts to accurately resolve the coupling between the physical processes - rock breakage, fluid pressure drop in the viscous fluid flow in the fracture, and fluid exchange between fracture and the rock - that exert influence on the hydraulic fracture [...]
Towards Improved Predictions in Ungauged Basins: Exploiting the Power of Machine Learning
Published: 2019-08-27
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Long Short-Term Memory (LSTM) networks offer unprecedented accuracy for prediction in ungauged basins. We trained and tested an LSTM on the CAMELS basins (approximately 30 years of daily rainfall/runoff data from 531 catchments in the US of sizes ranging from 4 km² to 2,000 km²) using k-fold validation, so that predictions were made in basins that supplied no training data. This effectively [...]