Physical Hydrology Research Articles

Three‐dimensional architecture and hydrostratigraphy of cross‐cutting buried valleys using airborne electromagnetics, glaciated Central Lowlands, Nebraska, USA

AbstractBuried valleys are characteristic features of glaciated landscapes, and their deposits host important aquifers worldwide. Understanding the stratigraphic architecture of these deposits is essential for protecting groundwater and interpreting sedimentary processes in subglacial and ice‐marginal environments. The relationships between depositional architecture, topography and hydrostratigraphy in dissected, pre‐Illinoian till sheets is poorly understood. Boreholes alone are inadequate to characterize the complex geology of buried valleys, but airborne electromagnetic surveys have proven useful for this purpose. A key question is whether the sedimentary architecture of buried valleys can be interpreted from airborne electromagnetic profiles. This study employs airborne electromagnetic resistivity profiles to interpret the three‐dimensional sedimentary architecture of cross‐cutting buried valleys in a ca 400 km2 area along the western margin of Laurentide glaciation in North America. A progenitor bedrock valley is succeeded by at least five generations of tunnel valleys that become progressively younger northward. Tunnel‐valley infills are highly variable, reflecting under‐filled and over‐filled conditions. Under‐filled tunnel valleys are expressed on the modern landscape and contain fine sediments that act as hydraulic barriers. Over‐filled tunnel valleys are not recognized in the modern landscape, but where they are present they form hydraulic windows between deep aquifer units and the land surface. The interpretation of tunnel‐valley genesis herein provides evidence of the relationships between depositional processes and glacial landforms in a dissected, pre‐Illinoian till sheet, and contributes to the understanding of the complex physical hydrology of glacial aquifers in general.

Overcoming Urban Water Insecurity with Infrastructure and Institutions

Urban growth and development depends on both the local hydrologic conditions and how water resources are procured and managed. The objective of this study was to assess the water security of large urban areas based on their physical hydrology, existing water supply infrastructure, and water management institutions. This study examined 108 large cities (>750,000 people) in the United States (n = 50) and Africa (n = 58), encompassing a broad range of hydrologic and socio-economic conditions, including degrees of institutional complexity. Urban water availability was estimated as the volume of water available from local, natural water sources, as well as water captured via infrastructure such as reservoirs, wellfields, or water transfers. Urban institutional complexity was assessed based on ability to provide, regulate and maintain urban water supplies. Over half of the cities in this study rely on captured water to meet urban demands and maintain high levels of institutional complexity in doing so. Cities able to adequately supply water from local natural sources (37 %) maintain significantly lower institutional complexity than cities using water captured from non-local sources. Cities categorized as water insecure (7 %) had minimal access to either local or captured water resources and operated using the simplest water institutions. Results suggest that low local availability drives the urban response for capturing additional water supplies, and is both the cause and product of more complex institutional frameworks. Efforts to address urban water insecurity should focus more attention on meeting not only the physical but managerial needs of a city.

Tidal River Dynamics

Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology.

陸水物理研究会2015年大会の報告

陸水物理研究会2015年大会の報告

Evaluating the relationship between topography and groundwater using outputs from a continental‐scale integrated hydrology model

AbstractWe study the influence of topography on groundwater fluxes and water table depths across the contiguous United States (CONUS). Groundwater tables are often conceptualized as subdued replicas of topography. While it is well known that groundwater configuration is also controlled by geology and climate, nonlinear interactions between these drivers within large real‐world systems are not well understood and are difficult to characterize given sparse groundwater observations. We address this limitation using the fully integrated physical hydrology model ParFlow to directly simulate groundwater fluxes and water table depths within a complex heterogeneous domain that incorporates all three primary groundwater drivers. Analysis is based on a first of its kind, continental‐scale, high‐resolution (1 km), groundwater‐surface water simulation spanning more than 6.3 million km2. Results show that groundwater fluxes are most strongly driven by topographic gradients (as opposed to gradients in pressure head) in humid regions with small topographic gradients or low conductivity. These regions are generally consistent with the topographically controlled groundwater regions identified in previous studies. However, we also show that areas where topographic slopes drive groundwater flux do not generally have strong correlations between water table depth and elevation. Nonlinear relationships between topography and water table depth are consistent with groundwater flow systems that are dominated by local convergence and could also be influenced by local variability in geology and climate. One of the strengths of the numerical modeling approach is its ability to evaluate continental‐scale groundwater behavior at a high resolution not possible with other techniques.

Elements of physical hydrology

Elements of physical hydrology

The Effect of Modeling and Visualization Resources on Student Understanding of Physical Hydrology

ABSTRACTWe investigated the effect of modeling and visualization resources on upper-division, undergraduate and graduate students' performance on an open-ended assessment of their understanding of physical hydrology. The students were enrolled in one of five sections of a physical hydrology course. In two of the sections, students completed homework problems and projects using only Excel (Microsoft, Redmond, WA) or MATLAB (MathWorks, Natick, MA) as modeling resources, and in the other three sections, some of the homework exercises were replaced with modeling and visualization activities using the interactive modeling software COMSOL Multiphysics (COMSOL, Burlington, MA). Other aspects of the course (instructor, syllabus coverage, lectures, and textbook) remained the same throughout the study. We performed a repeated-measures analysis of variance, which showed that gains from pretest to posttest were statistically significant overall and were independent of the section in which students were enrolled for all but one component on the assessment. In that case, students who did not have access to the COMSOL modules marginally outperformed the others, but not to the required level of statistical significance. These results were complemented by a qualitative investigation of students' interaction with the modeling software. We interviewed a subset of students and assigned codes to themes that arose when we analyzed the resulting transcripts. This process allowed us to develop a theory of how students were interacting with the modeling and visualization resources. A significant theme was the issue of “scaffolding,” or supports, with both positive and negative consequences for students, depending on their personal preferences and previous experience.

Elements of Physical Hydrology, 2nd Edition

There will always be need for a book that in a succinct and undiluted way presents the fundamentals of hydrology to new generations of future scientists. However, it is difficult to write such a book because the breadth of the discipline includes a diverse array of specialties, e.g., geoscientists, meteorologists, engineers, and water resources specialists. The first edition of Elements of Physical Hydrology (EPH for brevity) was published in 1998, a time when considerable efforts were made to produce modern textbooks on hydrology. Among them were the 4th edition of Principles of Hydrology (Ward and Robinson 2000), the 2nd edition of Physical Hydrology (Dingman 2002), and Hydrology: An Introduction (Brutsaert 2005). The first edition of EPH was different in several ways. The authors distilled the science of hydrology to about 300 pages by showing principles, retaining only important aspects of the discipline, and providing a healthy combination of problems and training exercises. I have used it as a classroom text since then. In the hydrologic community, the book was lauded as a publishing model for hydrological education (Duffy 2000). The 2nd edition has largely left the original framework intact (Hornberger et al. 2014). The authors avoided the temptation to squeeze in much additional information, as often happens with new editions, and the volume of the text has increased only modestly. In fact, only two chapters are completely new, and existing material was thoroughly refreshed. Additional illustrations preserve the original efficient style. The hallmark of this book is again a combination of clarity, brevity, and focus. The revised Chapter 1 introduces the water cycle and water budget at different spatial and temporal scales. Chapter 2 covers basics of evaporation and precipitation using the energy balance concept, mass transfer equation, Bowen ratio, and the Penman method. Chapter 3 skillfully introduces elements of fluid dynamics as bases for hydrology with a minimum of derivations; it appeals to a broad audience. Chapter 4 covers classic open channel hydraulics, with

Dynamic hydrologic and biogeochemical processes drive microbially enhanced iron and sulfur cycling within the intertidal mixing zone of a beach aquifer

Intertidal aquifers host a reactive zone comprised of Fe mineral-coated sands where fresh and saline groundwaters mix. This zone may significantly influence the export of C, N, P, Fe, and other metals in submarine groundwater discharge (SGD). Toward determining the roles of microbes in Fe and S mineralization, and the interplay of microbiology with geochemistry and physical hydrology, we conducted a biogeochemical study of pore waters at Cape Shores, Delaware. Here, fresh groundwater provides Fe(II), which precipitates as FeIIIOOH predominantly through microbial Fe(II) oxidation. Candidate division OP3 was the dominant microbial group associated with Fe(II)- and Fe(III)-rich regions of the aquifer, suggesting that this uncharacterized phylum may be involved in Fe(II) oxidation. Saline water brings O2, sulfate, and organic C into the intertidal mixing zone. Microbial reduction of sulfate produces sulfide that is transported to the Fe-mineralized zone leading to the transformation of FeOOH to Fe(II) sulfides. Microbial populations are structured by the availability of chemical species supplied along groundwater flow paths. Seasonal changes in the relative supply of fresh and saline groundwater affect solute fluxes, and therefore, microbial controls on the location and composition of the Fe-mineralized zone. Ultimately, the composition, extent, and dynamics of the Fe-mineralized zone will affect the sequestration, affinity, and residence time of solutes bound for export to coastal oceans through SGD.

Using field data to inform and evaluate a new model of catchment hydrologic connectivity

[1] We present a new hydrologic model based on the frequency distribution of hillslope landscape elements along the stream network as a basis for simulating landscape-scale hydrologic connectivity and catchment runoff. Hydrologic connectivity describes shallow water table continuity between upland and stream elements of the catchment and is important for the movement of water and solutes to streams. This concept has gained traction in physical hydrology but has received less attention in rainfall-runoff modeling. Our model is based on the empirical studies of Jencso et al. (2009, 2010), who found a strong correlation between the duration of shallow groundwater connectivity across hillslope, riparian, and stream zones and upslope accumulated area. We explored the relationship between catchment form and function by testing the extent to which streamflow generation could be predicted by a model based on the topographic form (distribution of landscape elements) of the catchment. We applied the model to the Stringer Creek catchment of the Tenderfoot Creek Experimental Forest, located in Montana, USA. Detailed field observations collected by Jencso et al. (2009) were used to inform the underpinnings of the model and to corroborate internal consistency of the model simulations. The model demonstrated good agreement between the observed and predicted streamflow and connectivity duration curves. The ability of this model to simulate internal dynamics without conditioning the parameters on these data suggests that it has the potential to be more confidently extrapolated to other shallow, topographically driven catchments than hydrologic models that fail to consistently reproduce internal variables.

Implementation of a linear optimization water allocation algorithm into a fully integrated physical hydrology model

Connections between groundwater and surface water are well-established and remain the focus of significant ongoing research. Within the water management community, stream-aquifer interactions are widely acknowledged and often subject to regulation. Yet, the tools most commonly used by water managers often have limited physical hydrology and a resulting inability to represent feedbacks between elements of the physical system. This paper presents the development of a water allocation module (WAM) for an integrated hydrologic model, ParFlow. The module presented here is designed to maximize the satisfaction of demand subject to a system of priorities, preferences and constraints. Because ParFlow solves the groundwater and surface water systems simultaneously, the coupled management model can explicitly incorporate groundwater surface water interactions into management decisions. Proof of concept for the new module is demonstrated for a hypothetical water management scenario, utilizing moisture dependent irrigation, in a real world basin, the Little Washita.

Residence time control on hot moments of net nitrate production and uptake in the hyporheic zone

AbstractThe retention capacity for biologically available nitrogen within streams can be influenced by dynamic hyporheic zone exchange, a process that may act as either a net source or net sink of dissolved nitrogen. Over 5 weeks, nine vertical profiles of streambed chemistry (NO3− and NH4+) were collected above two beaver dams along with continuous high‐resolution vertical hyporheic flux data. The results indicate a non‐linear relation of net NO3− production followed by net uptake in the hyporheic zone as a function of residence time. This Lagrangian‐based relation is consistent through time and across varied morphology (bars, pools, glides) above the dams, even though biogeochemical and environmental factors varied. The empirical continuum between net NO3− production and uptake and residence time is useful for identifying two crucial residence time thresholds: the transition to anaerobic respiration, which corresponds to the time of peak net nitrate production, and the net sink threshold, which is defined by a net uptake in NO3− relative to streamwater. Short‐term hyporheic residence time variability at specific locations creates hot moments of net production and uptake, enhancing NO3− production as residence times approach the anaerobic threshold, and changing zones of net NO3− production to uptake as residence times increase past the net sink threshold. The anaerobic and net sink thresholds for beaver‐influenced streambed morphology occur at much shorter residence times (1.3 h and 2.3 h, respectively) compared to other documented hyporheic systems, and the net sink threshold compares favorably to the lower boundary of the anaerobic threshold determined for this system with the new oxygen Damkohler number. The consistency of the residence time threshold values of NO3− cycling in this study, despite environmental variability and disparate morphology, indicates that NO3− hot moment dynamics are primarily driven by changes in physical hydrology and associated residence times. Copyright © 2013 John Wiley & Sons, Ltd.

Assessing student understanding of physical hydrology

Abstract. Our objective is to devise a mechanism to characterize and assess upper division and graduate student thinking in hydrology. We accomplish this through development and testing of an assessment tool for a physical hydrology class. The instrument was piloted in two sections of a physical hydrology course. Students were asked to respond to two questions that probed understanding and one question that assessed their ability to apply their knowledge, both prior to and after the course. Student and expert responses to the questions were classified into broad categories to develop a rubric to score responses. Using the rubric, three researchers independently blind-coded the full set of pre- and post-artifacts, resulting in 89% inter-rater agreement on the pre-tests and 83% agreement on the post-tests. The majority of responses made by students at the beginning of the class were characterized as showing only recognition of hydrology concepts from a non-physical perspective; post surveys indicated that the majority had moved to a basic understanding of physical processes, with some students achieving expert understanding. Our study has limitations, including the small number of participants who were all from one institution and the fact that the rubric was still under development. Nevertheless, the high inter-rater agreement from a group of experts indicates that the process we undertook is potentially useful for assessment of learning and understanding physical hydrology.

Looking to the Future of Hydrologic Engineering

Looking to the Future of Hydrologic Engineering

A Phosphorus Index transport factor based on variable source area hydrology for New York State

The Phosphorus (P) Index concept is used in many states to help develop nutrient management plans for livestock agriculture to protect water quality. Although many P indices conceptually incorporate variable source area (VSA) runoff processes, they generally assume proximity to a water course is an adequate proxy of runoff risk. Here we propose a VSA-based transport factor that uses the topographic index concept to indicate runoff risk. We compared both transport factors based on the current New York State P Index and our VSA-based P Index to field measures of runoff probability across an abandoned agricultural site in upstate New York. We also compared transport factors and P indices using the current and VSA-based approaches on a farm in the Catskill Mountains of New York to evaluate differences at whole-field and farm scales. Field runoff-risk measurements were better correlated with VSA-based transport factor (<i>r</i>² = 0.63, α = 0.05) than with the current dissolved-P transport factor (<i>r</i>² = 0.40, α = 0.05). Although these point-scale differences in transport factor values translated into field-scale differences in transport factor, the net differences at the farm scale and in P Index were not very large. On a field-by-field basis, 12 out of 21 fields had different transport factor categories with the VSA method. However, the total land area classified as high risk changed very little between the two methods. There was more land classified as moderate risk using the VSA-based approach than using the current methods, due to some low risk areas being classified as higher risk and some high-risk areas being classified as lower risk. The VSA approach allows managers and producers to more easily manage farm units (e.g., fields) at finer resolutions both spatially and temporally, which will increase the options for managing nutrients on fields. These types of more rigorous links between management tools and physical hydrology provide valuable, more scientifically defensible information for improving our ability to control nonpoint source pollution.

Application of Water Evaluation and Planning (WEAP): A Model to Assess Future Water Demands in the Niger River (In Niger Republic)

Water resources management in Niger River basin is an issue of very high significance because of great socio-cultural, ecological and economic values. The basin comprises biospheres reserves, parks with a variety of wildlife, a significant livestock activity, a very fertile land for agriculture and a growing industry. In the territory of Niger, the Niger River Basin covers mostly all regions of Tillabery (including the city of Niamey), Dosso, Tahoua and some of the regions of Maradi and Agadez. This area is composed of an active part, including the river valley and its major tributaries and some inactive area.Water Evaluation And Planning (WEAP) provides a seamless integration of both the physical hydrology of the region and water management infrastructure that governs the allocation of available water resources to meet the different water needs. It is a priority driven software, employs priority based optimization algorithm as an alternative to hierarchal rule based logic that uses a concept of Equity Group to allocate water in time of inefficient supply. There is need for optimization of Niger River resources future need of its population.

Introduction to physical hydrology

1: INTRODUCTION 2: ATMOSPHERIC WATER 3: GROUNDWATER 4: SOIL WATER 5: SURFACE WATER C CONCEPTUAL TOOLKIT M MATHEMATICS TOOLBOXES A ANSWERS TO THE EXERCISES

A National Assessment of Water Availability and Use

This article discusses the benefits and challenges of a national assessment of water availability and use. A national water assessment represents a unique opportunity to: develop consistent methods and indicators for assessing water availability and use; compile information on water resources comprehensively for the entire nation; address emerging issues for water resources; and, develop a framework for long‐range planning and a source of current information through regular, periodic updates. The article points out that a national assessment of water resources will depend on the coordination of many federal agencies working in collaboration with Native American tribes, state and local governments, public utilities, private water users, and others with an interest in the services provided by rivers, streams, lakes, aquifers, and estuaries. The article also discusses how, in the twenty‐first century, ecological needs and the integration of many different in‐stream and out‐of‐stream uses represent new issues in assessing water availability. Addressing these issues will require information not only on the basic physical hydrology of groundwater and surface water and current water use, but also on an understanding of how stream flow and groundwater function in ecosystems and how people benefit from functioning ecosystems. Moreover, this information is needed across entire river basins as water use becomes more intensive, widespread, and its effects are no longer just a local concern. The article offers an insert on the U.S. Department of the Interior's WaterSMART (Sustain and Manage America's Resources for Tomorrow) Program.

Recent hydrologic change in a Colorado alpine basin: an indicator of permafrost thaw?

AbstractHydrologic and hydrochemical studies have been conducted in Green Lakes Valley, Colorado Front Range, USA, above 3550 m since 1982. They show a classic seasonal hydrograph dominated by snowmelt and an earlier date for the start of spring flow and for peak flow over the period of record. This is consistent with patterns found at lower elevations in Colorado and throughout western North America. They also show an increasing trend in flows in September and October of 2.6 ±0.7 mm a−1 which is not found elsewhere and cannot be accounted for by increased autumn precipitation and the melting of surface ice. Because this late-season increase is not found at the highest elevations or in basins in which there is no evidence of permafrost, it seems best explained by the thawing of alpine permafrost at intermediate elevations. This is corroborated by an increase in the concentration of base cations and silica, and particularly in Ca2+ and SO4–, in the stream discharge starting in 2000. As with the physical hydrology, the geochemical signals have not been detected at the higher elevations in the basin, though they have previously been associated with streamflow from a small rock glacier in the valley. The combined evidence suggests the degradation of ice-rich permafrost on the north-facing slopes of the valley below 3700 m, where it has been detected at 3 m depth by geophysical surveys.

The Physical and Chemical Hydrology of a Niger Deltan tidal creek, Nigeria

The physical and chemical conditions of the Buguma Creek, Niger Delta, Nigeria were investigated between November, 2004 and October, 2006. Five stations, made up of two (4 and 5) from the main channel and three (1,2 and 3) from the associated interconnecting creeks were sampled. From the salinity record of 0-21%0, the creek ranges from limnetic/oligohaline to polyhaline condition. Of the twenty-five physical and chemical parameters determined, only water temperature, transparency, water level and total suspended solids were significantly different (P< 0.05) among the stations. The a posteriori DMR test showed that stations 1 and 2 which were still fairly well covered by mangrove had water temperature significantly lower (P< 0.05) than those of stations 3 to 5. Stations 2 and 4 had higher transparency than station 1. Station 4 had significantly higher water levels than stations 1 and 2 which were significantly different, while station 1 had significantly higher water level than stations 3 and 5 which were not significantly different. Stations 2 to 5 which were not significantly different from each other had significantly different total suspended solids than station 1. Most of the parameters were observed to exhibit temporal variations, due to high influx of run-off in the wet months, high incursion of seawater, and evaporation during the dry months. The generally low biochemical oxygen demand (0 – 4.50 mg/l), chemical oxygen demand (2.05 – 46.8 mg/l), and extremely low total hydrocarbon content (THC) (0.01 mg/l) indicate that the water was not polluted.