Preprints
Filtering by Subject: Hydrology
A machine learning approach for prioritizing groundwater testing for per-and polyfluoroalkyl substances (PFAS)
Published: 2020-10-20
Subjects: Environmental Engineering, Environmental Health and Protection, Environmental Monitoring, Geochemistry, Hydrology, Risk Analysis, Water Resource Management
Regulatory agencies are beginning to recognize and regulate per-and polyfluoroalkyl substances (PFAS) as concerning environmental contaminants. In groundwater management, testing and mitigation strategies are desirable, but can be time and cost-intensive processes. As a result, only a fraction of all groundwater wells has been tested for PFAS levels, resulting in potentially extended drinking [...]
Uncertainties in Projected Rainfall over Brazil: The Role of Climate Model, Bias Correction and Emission Scenario
Published: 2020-09-02
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
The aim of this study is to answer four main questions: How well the Eta regional climate model simulates past precipitation over Brazil? What is the impact of bias correction on the reduction of model’s biases? What is the contribution of climate models, bias correction and emission scenarios to the total uncertainty of projected precipitation? And finally, what is the projected change in [...]
Quantification of non-linear multiphase flow in porous media
Published: 2020-08-21
Subjects: Earth Sciences, Engineering, Hydrology, Life Sciences, Medicine and Health Sciences, Mineral Physics, Physical Sciences and Mathematics
We measure the pressure difference during two-phase flow across a sandstone sample for a range of injection rates and fractional flows of water, the wetting phase, during an imbibition experiment. We quantify the onset of a transition from a linear relationship between flow rate and pressure gradient to a non-linear power-law dependence. We show that the transition from linear (Darcy) to [...]
Bedload transport in rivers: size matters but so does shape!
Published: 2020-08-17
Subjects: Earth Sciences, Geomorphology, Hydrology, Physical Sciences and Mathematics, Sedimentology
Bedload transport modelling in rivers, which defines the threshold for pebble movement, takes into account the size and density of pebbles, but does not formally consider particle shape. The lack of analyses evaluating the influences of shape and density on particle mobility presents a major deficiency. To address this issue and to compare the relative roles of the density and shape of particles, [...]
Variability of headwater stream network extents controlled by flow regime and network hydraulic scaling
Published: 2020-08-15
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Stream networks expand and contract through time, impacting chemical export, aquatic ecosystem habitat, and water quality. Although recent advances improve prediction of the extent of the wetted channel network (L) based on discharge at the catchment outlet (Q), controls on the temporal variability of L remain poorly understood and unquantified. Here we develop a quantitative, conceptual [...]
Hydrogeologic and Geochemical Distinctions in Salar Freshwater Brine Systems
Published: 2020-08-06
Subjects: Earth Sciences, Geochemistry, Hydrology, Physical Sciences and Mathematics
The Salar de Atacama contains one of the world’s most important lithium resources and hosts unique and fragile desert ecosystems. Water use issues of the hyper-arid region have placed it at the center of global attention. This investigation is the first robust assessment of a salar system to incorporate geology, hydrogeology, and geochemistry of the aquifer system in the inflow, transition zone [...]
Serious Gaming for Water Resources Planning and Hazard Mitigation
Published: 2020-08-04
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Education, Environmental Engineering, Environmental Sciences, Hydrology, Physical Sciences and Mathematics, Sustainability, Water Resource Management
Hydrological hazards lead to a broad range of socio-economic and environmental risks. The development of a resilient community and risk reduction heavily rely on the adoption of holistic watershed master planning whereby the adaptation options consider the risk associated with individual or multiple hydrological hazards occurring simultaneously at a specific location. Such planning approaches [...]
Visualizing the daily evolution and extent of snow drought
Published: 2020-07-22
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Natural Resources Management and Policy, Physical Sciences and Mathematics
Snow droughts are commonly defined as below average snowpack at a point in time, typically 1 April in the western United States. This definition is valuable for interpreting the state of the snowpack for resource management but obscures the temporal evolution of snow drought. Borrowing from dynamical systems theory, we applied phase diagrams to visually examine the evolution of snowpack [...]
Navigating groundwater model uncertainty analysis
Published: 2020-07-20
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
The design of a groundwater model is based on the model objective, the management or research question that the model seeks to address. Designing the uncertainty analysis of a groundwater models likewise needs to consider the objective of the uncertainty analysis; how the uncertainty in model predictions will be used. In this paper a framework is presented to consider the various dimensions of [...]
Tracking and measuring of clay shrinking and swelling using spaceborne remote sensing
Published: 2020-07-13
Subjects: Earth Sciences, Geophysics and Seismology, Hydrology, Physical Sciences and Mathematics
New capabilities for measuring and monitoring are needed to improve the shrink/swell hazard. A new French experimental site at Chaingy (Centre-Val de Loire) has been instrumented using extensometers at the surface and soil moisture sensors in the clay layer. Here we show by direct comparison between remote and in situ data for a period longer than three years that the vertical ground [...]
Impact of Hydrostratigraphic Continuity in Heterogeneity on Brine-to-Freshwater Interface Dynamics; Implications from a 2-D Parametric Study in an Arid and Endorheic Basin
Published: 2020-07-10
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Despite the prevalence of density-driven flow systems in brine-rich aquifers of arid climates and coastal aquifers, the impact of realistic geologic conditions remains poorly constrained regarding interface geometry in arid regions and time-sensitive density-dependent dynamics in brine-bearing aquifers in general. Salar de Atacama provides an analog for exploring interface dynamics in arid [...]
Post-Processing a Conceptual Rainfall-Runoff Model with an LSTM
Published: 2020-07-10
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Physical Sciences and Mathematics
Machine learning is becoming an increasingly important part of streamflow forecasting, but as these models to date lack a physical basis, there is a potential that they may produce values that are not realistic. We tested a simple post-processing strategy that uses the outputs from a calibrated conceptual model (the Sacramento Soil Moisture Accounting Model with Snow-17; SAC-SMA) as inputs into a [...]
GANSim: Conditional Facies Simulation Using an Improved Progressive Growing of Generative Adversarial Networks (GANs)
Published: 2020-07-06
Subjects: Artificial Intelligence and Robotics, Computer Sciences, Earth Sciences, Geology, Hydrology, Mathematics, Physical Sciences and Mathematics, Sedimentology, Statistical Models, Statistics and Probability
Conditional facies modeling combines geological spatial patterns with different types of observed data, to build earth models for predictions of subsurface resources. Recently, researchers have used generative adversarial networks (GANs) for conditional facies modeling, where an unconditional GAN is first trained to learn the geological patterns using the original GANs loss function, then [...]
Exposure and vulnerability estimation for modelling flood losses to commercial assets in Europe
Published: 2020-07-06
Subjects: Earth Sciences, Hydrology, Multivariate Analysis, Physical Sciences and Mathematics, Statistics and Probability
Commercial assets comprise buildings, machinery and equipment, which are susceptible to floods. Existing damage models and exposure estimation methods for this sector have limited transferability between flood events. In this study we introduce two methodologies aiming at broader applicability: (1) disaggregation of economic statistics to obtain detailed building-level estimates of replacement [...]
Post-processing the National Water Model with Long Short- Term Memory Networks for Streamflow Predictions and Model Diagnostics
Published: 2020-07-02
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
We build three Long Short-Term Memory (LSTM) daily streamflow prediction models (deep learning networks) for 531 basins across the contiguous United States (CONUS), and compare their performance: (1) a LSTM post-processor trained on the U.S. National Water Model (NWM) outputs (LSTM_PP) as a target variable, (2) a LSTM post-processor trained on the NWM outputs and using atmospheric forcings [...]