The chemical composition of natural water is derived from many different sources of solutes, including gases and aerosols from the atmosphere, weathering and erosion of rocks and soil, solution or precipitation reactions occurring below the land surface, and cultural effects resulting from human activities. Broad interrelationships among these processes and their effects can be discerned by application of principles of chemical thermodynamics. Some of the processes of solution or precipitation of minerals can be closely evaluated by means of principles of chemical equilibrium, including the law of mass action and the Nernst equation. Other processes are irreversible and require consideration of reaction mechanisms and rates. The chemical composition of the crustal rocks of the Earth and the composition of the ocean and the atmosphere are significant in evaluating sources of solutes in natural freshwater. The ways in which solutes are taken up or precipitated and the amounts present in solution are influenced by many environmental factors, especially climate, structure and position of rock strata, and biochemical effects associated with life cycles of plants and animals, both microscopic and macroscopic. Taken together and in application with the further influence of the general circulation of all water in the hydrologic cycle, the chemical principles and environmental factors form a basis for the developing science of natural-water chemistry. Fundamental data used in the determination of water quality are obtained by the chemical analysis of water samples in the laboratory or onsite sensing of chemical properties in the field. Sampling is complicated by changes in the composition of moving water and by the effects of particulate suspended material. Some constituents are unstable and require onsite determination or sample preservation. Most of the constituents determined are reported in gravimetric units, usually milligrams per liter or milliequivalents

Study and Interpretation of the Chemical Characteristics of Natural Water

A hydrological forecasting model is presented that attempts to combine the important distributed effects of channel network topology and dynamic contributing areas with the advantages of simple lumped parameter basin models. Quick response flow is predicted from a storage/contributing area relationship derived analytically from the topographic structure of a unit within a basin. Average soil water response is represented by a constant leakage infiltration store and an exponential subsurface water store. A simple non-linear routing procedure related to the link frequency distribution of the channel network completes the model and allows distinct basin sub-units, such as headwater and sideslope areas to be modelled separately. The model parameters are physically based in the sense that they may be determined directly by measurement and the model may be used at ungauged sites. Procedures for applying the model and tests with data from the Crimple Beck basin are described. Using only measured and estimated parameter values, without optimization, the model makes satisfactory predictions of basin response. The modular form of the model structure should allow application over a range of small and medium sized basins while retaining the possibility of including more complex model components when suitable data are available.

A physically based, variable contributing area model of basin hydrology

A hydrological forecasting model is presented that attempts to combine the important distributed effects of channel network topology and dynamic contributing areas with the advantages of simple lum...

A physically based, variable contributing area model of basin hydrology / Un modèle à base physique de zone d'appel variable de l'hydrologie du bassin versant

This paper reviews the importance of large continuous openings (macropores) on water flow in soils. The presence of macropores may lead to spatial concentrations of water flow through unsaturated soil that will not be described well by a Darcy approach to flow through porous media. This has important implications for the rapid movement of solutes and pollutants through soils. Difficulties in defining what constitutes a macropore and the limitations of current nomenclature are reviewed. The influence of macropores on infiltration and subsurface storm flow is discussed on the basis of both experimental evidence and theoretical studies. The limitations of models that treat macropores and matrix porosity as separate flow domains is stressed. Little-understood areas are discussed as promising lines for future research. In particular, there is a need for a coherent theory of flow through structured soils that would make the macropore domain concept redundant.

/pdf/macropores-and-water-flow-in-soils-3lig0kc4ob.pdf

Macropores and water flow in soils

https://core.ac.uk/download/pdf/374223.pdf

A manifesto for the equifinality thesis

Water Resource Research was born under the watchful eye of Walter Langbein, a modern-day Renaissance man whose interests spanned not only hydrology but all of the earth sciences, and not only the earth sciences but all of science. From its founding in1965 to the present day, the editors of WRR have always seen the journal as a medium of interdisciplinary interaction. On this 25th anniversary of WRR, I thought it might be worthwhile to look back on the interdisciplinary successes and failures of the past quarter decade, in our journal and in our science.

There is no question that research in water resources is an interdisciplinary endeavor. At my university we have a graduate program in interdisciplinary hydrology on the books, and on those occasions when we gather together, there are students and faculty there from as many as seven different departments: geography, geology, soil science, forestry, civil engineering, mining engineering, and bioresource engineering. In addition, our campus hosts the Westwater Research Institute where physical scientists can get involved in interdisciplinary research with social scientists from regional and community planning, resource management, resource economics, commerce, and law. I suspect that many campuses have a similar breadth of water resources interests. It is this breadth that WRR is designed to serve.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/WR026i009p01865

Water Resources Research and interdisciplinary hydrology

Reply [to “Comments on ‘Role of subsurface flow in generating surface runoff: 1, Base flow contributions to channel flow’ by R. Allan Freeze”]

Reply [to “Comments on ‘Role of subsurface flow in generating surface runoff: 2, Upstream source areas’ by R. Allan Freeze”]

Vignettes of a Life in Hydrogeology

This article lays out a framework for the evaluation of hydrogeological data worth at waste-management facilities that are potential point sources of groundwater contamination The framework is developed as a part of the engineering design process; it is based on the premise that hydrogeological data have worth only if the knowledge gained can aid in making decisions between alternative courses of action The methodology is applicable during the siting process, during facility design, and during assessment of remedial alternatives It involves the integration of: (1) risk-cost-benefit analysis, (2) a geostatistical description of the hydrogeological parameters, (3) Monte Carlo stochastic simulation, (4) sensitivity analysis, (5) variance reduction, (6) Bayesian updating, and (7) economic regret

R. Allan Freeze

Papers

Water Resources Research and interdisciplinary hydrology

Reply [to “Comments on ‘Role of subsurface flow in generating surface runoff: 1, Base flow contributions to channel flow’ by R. Allan Freeze”]

Reply [to “Comments on ‘Role of subsurface flow in generating surface runoff: 2, Upstream source areas’ by R. Allan Freeze”]

Vignettes of a Life in Hydrogeology

Advances in the Assessment of Data Worth for Engineering Decision Analysis in Groundwater Contamination Problems