Hydrology Days

Permanent URI for this collection

https://hdl.handle.net/10217/199983

Each year the American Geophysical Union "Hydrology Days" meeting brings together water scientists, researchers, and students to discuss the current state of the science and latest water-related research findings. Digital copies of the meetings from 2000-2018 may be found here. Digital copies of the meetings from 2019- are published in issues of the Colorado Water Center newsletter.

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Open Access
Twentieth annual AGU hydrology days: conference program and abstracts
(Colorado State University. Libraries, 2000) American Geophysical Union, author; Colorado State University, author; Colorado State University, publisher
To access abstracts, please see: http://hydrologydays.colostate.edu/program.htm.
Open Access
Hydrology days 2001: conference program
(Colorado State University. Libraries, 2001) American Geophysical Union, author; Colorado State University, author; Colorado State University, publisher
The 21st annual AGU hydrology days was held in the Cherokee Park Room, Lory Student Center, Colorado State University on April 2-5, 2001. To access abstracts, please see: http://hydrologydays.colostate.edu/schedule_01.htm.
Open Access
Conference program: AGU hydrology days 2002
(Colorado State University. Libraries, 2002) American Geophysical Union, author; Colorado State University, author; Colorado State University, publisher
Twenty-second annual AGU hydrology days was held in the Cherokee Park Room, Lory Student Center, Colorado State University on April 1-4, 2002. To access abstracts, please see: http://hydrologydays.colostate.edu/schedule_02.htm.
Open Access
Cellular automata models of particle interactions in sediment entrainment
(Colorado State University. Libraries, 2003) Brown, Nancy E., author; Ramírez, Jorge A., author; Whol, Ellen E., author; Colorado State University, publisher
The geometry of a river bed surface is determined by the arrangement and size of the particles that form the bed. In gravel-to-boulder bed rivers, the surface geometry around any individual particle may be complex and highly variable, and tends to include multi-particle structures. These textural and structural characteristics influence whether an individual particle is entrained. The effect on entrainment is generally described as particle hiding and protrusion, which together define the degree to which an individual particle is sheltered by surrounding particles. Two variants of a cellular automata (CA) model are used here to investigate the effect of controls on sediment entrainment resulting from particle sheltering. One model variant uses the degree of sheltering as a threshold constraint; the other variant uses the degree of sheltering as an extremal condition. There is a striking contrast in the spatial pattern of particle sizes that result with these different entrainment rules. The extremal rule results in a patchy distribution of particles sizes, in which groups of adjacent cells tend to have the same particle size. The effect of the extremal rule is roughly analogous to considering a sequence of flow events that progressively increase the overall stability of particles on the channel bed, so that over time successively higher flows are required to mobilize particles. In contrast, the threshold rule results in a channel bed that tends to coarsen with time.
Open Access
Evolutionary neural network modeling for describing rainfall-runoff process
(Colorado State University. Libraries, 2003) Nazemi, Alireza, author; Poorkhadem N., Hossein, author; Akbarzadeh, T., author; Mohammad, R., author; Hosseini, Seyed Mahmood, author; Colorado State University, publisher
Since the last decade, several studies have shown the ability of Artificial Neural Networks (ANNs) in modeling of rainfall-runoff process. From methodological viewpoint, ANN belongs to more general paradigm, i.e., soft computing or computational intelligence, in which independent methodologies, mostly Fuzzy Logic (FL), ANN, and Genetic Algorithms (GAs), are combined together in order to provide an intelligent behavior in computational frameworks. Consequently, in the context of rainfall-runoff modeling, this question rises whether hybridization of ANNs with other soft computing-related methodologies improves the overall performance of modeling or not. In this study, based on the idea of structure and/or parameter identification of ANNs with GAs, the evolutionary neural networks modeling paradigm is examined for describing the rainfall-runoff process. One of the benchmark data set of current literature, i.e., Leaf River basin (near Collins, Mississippi) data set, is used for simulation. The results show that on the one hand, the overall accuracy is improved; but one the other hand, in evolutionary neural modeling, the computational time is increased significantly. Hence the modeler may be faced with a trade-off problem between accuracy and computational difficulties which may have different importance in a particular rainfall-runoff problem.
Open Access
Conference program: AGU hydrology days 2003
(Colorado State University. Libraries, 2003) Ramírez, Jorge A., editor; American Geophysical Union, author; Colorado State University, author; Colorado State University, publisher
23rd annual AGU hydrology days was held on March 31-April 2, 2003 at Colorado State University. To access abstracts, please see: http://hydrologydays.colostate.edu/schedule_03.htm.
Open Access
Parameter estimation technique for a water balance model and application to measured data
(Colorado State University. Libraries, 2003) Toninelli, V., author; Salvucci, D. G., author; Mancini, M., author; Colorado State University, publisher
A new method has been developed to estimate the parameters of a water balance model's components (actual evapotranspiration, drainage plus runoff) as functions of the soil moisture and of the estimated parameters. The technique requires limited information, that is measured precipitation and soil moisture plus potential evapotranspiration; in particular, the method needs only an index of the soil moisture content, becoming easy to be applied to remotely sensed measures of soil moisture. The method's skills are evaluated using long series of synthetic data, both at point and hillslope scales, and series of data measured for shorter periods.
Open Access
Habitat improvement techniques for aquatic fishery: application experiences at Ta-Chia River in Taiwan
(Colorado State University. Libraries, 2003) Lin, Bing-Shyan, author; Yeh, Chao-Hsien, author; Lien, Hui-Pang, author; Tuan, Ching-Hao, author; Colorado State University, publisher
With characteristics of river continuum, stream ecosystems have diverse components and environments from upstream channel to estuarine area. Therefore, the habitat requirements and composition of conservative object should be well understood before applying any improvement measure. In this paper, the causes of stream habitat changes were first illustrated with the categories and principles of habitat restoration methods. The structural restoration techniques of fish habitat improvement, including dam partial-removal, utilized by the authors for two research projects during last dozen years were then presented. Through the introductions on the project background, planning guidelines, structure design, and ecological evaluation, this paper tried to provide some effective examples of ecological engineering that ecological experts were invited for cooperation and advising.
Open Access
Proceedings of the twenty-third annual AGU hydrology days: table of contents
(Colorado State University. Libraries, 2003) Ramírez, Jorge A., editor; American Geophysical Union, author; Colorado State University, author; Colorado State University, publisher
Table of contents for the proceedings of the 23rd annual AGU Hydrology Days; includes dedication page to José Salas.
Open Access
Aggregation scenarios to model water fluxes in watersheds with spatial changes in soil texture
(Colorado State University. Libraries, 2003) Soria, Jose M., author; Leij, Feike J., author; Angulo-Jaramillo, Rafael, author; Fuentes, Carlos, author; Haverkamp, Randel, author; Parlange, J.-Yves, author; Colorado State University, publisher
Accurate knowledge of water fluxes in the vadose zone of watersheds is important for applications such as water resources management and climate forecasting. Most, if not all, largescale studies follow a pragmatic approach where simplifying assumptions have to be made regarding problem formulation and estimation of hydraulic properties. This study investigates simplifications in both regards to predict infiltration and evaporation fluxes near or at the surface for a generic, rectangular watershed consisting of sand and silt loam columns. The two-dimensional flow problem (reference scenario) as well as simplifying 1-D problems are solved with the finite-element method (FEM) for 1, 10, 100, and 1000 m widths of the flow domain and different proportions of the sand and silt loam soils. The hydraulic functions are estimated from soil texture. In the simplifying scenarios, the flow domain is either represented as an equivalent soil using a weighted particle-size distribution as previously applied in physico-empirical predictions of hydraulic properties (a priori aggregation) or as two parallel stream tubes with area-weighted contributions to the total flux (a posteriori aggregation). Substantial differences were found between the fluxes based on the "equivalent" and reference scenarios even though our approach was based on a most favorable situation where only a limited number of texturedependent hydraulic parameters were different. The "stream tube" scenario typically provided a good description of the flux according to the reference scenario except for infiltration in case of domains less than 10 m wide. No pronounced textural differences are likely to occur over such small distances and the stream tube model appears to be a viable method to describe near-surface fluxes in catchments with a spatially variable soil texture.
Open Access
Preliminary analysis of sediment transport capacity in the Colorado Plateau
(Colorado State University. Libraries, 2003) Milhous, Robert T., author; Colorado State University, publisher
Previous investigators (Hereford et al, 2002) have postulated there have been three climate regimes in the Colorado Plateau during the 20th Century: 1905-1941, 1942-1977, and 1978-1998. Changes in the ability of four rivers in the Colorado Plateau (USA) to transport sediment were investigated using the time series of an index (STCI) of the ability of the river to transport sediment. The four rivers are the Rio Puerco near Bernardo, NM; Paria River at Lees Ferry, AZ; Sevier River at Hatch, UT; and the Little Colorado at Woodruff, AZ. The index is calibrated to measured sediment concentrations. The Sediment Transport Capacity Index (STCI) time series graphs suggest there was a change in the climate about 1941 and there is a high probability a change in the climate also occurred in 1923. The situation for the postulated change in 1977 is not clear. There does appear to be changes between the dry 1942-1977 period and the wet 1978-1998 period but these are not the same in each of the four rivers. The STCI time series for the Sevier River had the expected pattern because the STCI increased nearly to the pre-1942 values from lower 1942-1977 values. The average STCI for the Little Colorado River increased but not nearly as much as suggested by the change in precipitation. The STCI for the Paria River essentially did not change. The real difference between expected change based on the change in precipitation, and the changes in the other three rivers, is the change in the time series of STCI for the Rio Puerco. The STCI of the Rio Puerco decreased significantly between the 1942-1997 period and the 1978-1998 period.
Open Access
Analysis of short-time single-ring infiltration under falling-head conditions with gravitational effects
(Colorado State University. Libraries, 2003) Angulo-Jaramillo, Rafael, author; Elrick, David, author; Parlange, J.-Yves, author; Gérard-Marchant, Pierre, author; Haverkamp, Randel, author; Colorado State University, publisher
Analytical solutions of the flow equation for infiltration offer an interesting tool for the hydrodynamic characterization of non-saturated soils by optimization of the hydraulic conductivity, Kfs, and the capillary sorptivity, So. However, the experimental conditions have to satisfy the governing assumptions. For falling head infiltration tests the initial water height, Ho, is a third unknown parameter that has to be optimized. For the short0time, the classic solution expresses the depth of water infiltrated as a function of time as a term that depends only on the sorptivity. This, however, neglects gravitational effects. We improved the falling head infiltration problem, after a period of constant head infiltration, for the case of rigid materials without any assumptions for a particular hydraulic conductivity relationship and taking into account gravity effects. A comparison of two solutions, i.e., the equation of one and two terms, was made using the results of falling head infiltration tests. Neglecting the effects of gravity in the infiltration equation leads to an overestimation of the hydrodynamic parameters, Ho and So, and a concomitant underestimation of Kfs compared to our improved solution developed here. Consequently, the depth of ponded water predicted by the one term infiltration equation is higher than that calculated by the improved two term solution. Unfortunately, the actual depth of water infiltrated into the soil cannot be independently verified. To accomplish this, it is recommended that future studies include a measure of the change in stored soil water content at the test site, or a continuous measure of the variation in soil water content by a non-destructive method.
Open Access
Modeling the continental-scale dynamics of the coupled land-surface and atmospheric water balances with a stochastic differential equation
(Colorado State University. Libraries, 2003) Kochendorfer, John P., author; Ramírez, Jorge A., author; Colorado State University, publisher
Using a stochastic differential equation (SDE) approach, we examine the dynamics of the continental-scale water balance in the central United States. White-noise and colored-noise versions of the model are developed based on analysis of atmospheric data from the National Center for Environmental Prediction (NCEP) re-analysis project and long-term records of precipitation and soil moisture. Improved correspondence to observations is achieved by inclusion of terms in the SDE representing both hydrodynamic and thermodynamic soil-moisture feedbacks. We show that temporally correlated (i.e., colored) atmospheric moisture flux removes the bimodality of the soil moisture probability distribution and that our colored-noise formulation successfully captures the water balance dynamics in the study region despite the absence of multiple soil moisture states. Specifically, the improved model reproduces both the autocorrelation structure and the inter-annual variability in the observations.
Open Access
2002 municipal response to drought in the Colorado Front Range
(Colorado State University. Libraries, 2003) Kenney, Douglas, author; Klein, Roberta, author; Morrison, Adam, author; Colorado State University, publisher
As part of its ongoing efforts to analyze the vulnerability of water resources in Colorado's South Platte River Basin to the impacts of climate variability and regional growth, the Western Water Assessment examined the drought response of nine cities along the Front Range during the summer of 2002. Our hypothesis was that outdoor watering restrictions imposed in response to drought result in less water being consumed than would normally be expected, given climatic conditions and population growth. The study compared water use during summer of 2002 during restrictions to use in 2000 and 2001 when such restrictions were not in place. An additional goal was to compare cities to each other, identifying potential trends between different strategies and different levels of success. Results for each city are tabulated using a standardized methodology, allowing cross-city comparisons. The goal is to help municipal water managers assess and refine drought coping strategies.
Open Access
Limiting source dimensions of three-dimensional analytical point source model for solute transport
(Colorado State University. Libraries, 2003) Ahsanuzzaman, A. Noman M., author; Kolar, Randall, author; Zaman, Musharraf, author; Colorado State University, publisher
This article presents a criterion for limiting source dimensions of the instantaneous point source model. The source dimensions are required for applying superposition of the point sources in space to represent the non-point sources. The criterion generates less than one percent error when compared to the existing finite source model. A comparison between the existing point and the finite source models is conducted. It is found that the finite source model does not give acceptable output at all times, if series distribution is used to compute the error function. The front and tail of the concentration breakthrough curve from the finite source model shows uncharacteristic output depending on the source dimension and the distance of the observation point. On the contrary, the point source model generates smooth breakthrough curves at all time.
Open Access
Progress in stochastic analysis, modeling, and simulation: SAMS-2003
(Colorado State University. Libraries, 2003) Sveinsson, O. G. B., author; Salas, J. D., author; Lane, W. L., author; Frevert, D. K., author; Colorado State University, publisher
SAMS is a software for stochastic analysis, modeling, and simulation of hydrologic time series such as streamflows. It has been written in MS Visual C++ and Fortran. The package consists of many menu option windows that focus on three primary application modules - Statistical Analysis of Data, Fitting of a Stochastic Model (including parameter estimation and testing), and Generating Synthetic Series. SAMS has the capability of analyzing single site and multisite annual and seasonal data such as monthly and weekly streamflows based on a number of single site and multisite models, and aggregation and disaggregation modeling schemes. Results can be presented in graphical and tabular forms and, if desired, saved to an output file. The purpose of the paper is to summarize and update on the current capabilities of SAMS. Some illustrations are made to demonstrate the improved technical capabilities of the program using flow data of the Colorado River system.
Open Access
Criteria for risk evaluation in groundwater management projects: a comparative study
(Colorado State University. Libraries, 2003) Miracapillo, Cinzia, author; Colorado State University, publisher
Environmental protection criteria in the decision making process on the choice of a drainage system at a construction site in the city of Basel are presented here. A comparative quantitative evaluation between two drainage systems was possible focusing on the definition of equivalence criteria for aquifer protection and on the design of measures that guarantee the same safety level with respect to the above-mentioned criteria. The criteria discussed in this article are based on the hydraulic characteristics of the groundwater system, as they result from two-dimensional groundwater simulations in the area of the project.
Open Access
On the probabilistic characterization of drought events
(Colorado State University. Libraries, 2003) Cancelliere, A., author; Bonaccorso, B., author; Rossi, G., author; Salas, J. D., author; Colorado State University, publisher
Drought characterization is an important step in water resources systems planning and management. The assessment of extreme drought events may help decision makers to set effective drought mitigation tools. Drought events can be objectively identified by three main characteristics, namely: drought duration, accumulated deficit and drought intensity. In this paper the joint cumulative distribution functions (cdf's) of accumulated deficit and duration and of intensity and duration are derived as functions of the stochastic characteristics of the underlying variable, which is assumed to be either normal, lognormal, or gamma distributed. The derived cdf's are then applied to determine the return period of critical droughts by considering jointly two drought characteristics, e.g. droughts with accumulated deficit and duration greater than or equal to some fixed values. The methodology has been tested and applied using numerical simulations and records of annual precipitation series. The results of such applications show a good correspondence between the observed and the analytical results.
Open Access
The application of quantitative assessment of land use changes impact on water conservation for reservoir watershed
(Colorado State University. Libraries, 2003) Chou, Tien-Yin, author; Xie, Zheng Dao, author; Chen, Mei-Hsin, author; Colorado State University, publisher
The recent increased pressure on slope land development in Taiwan has changed the land use pattern in many reservoir watershed areas and affected the hydrologic cycle. There were many local researches examined this related issue, but none of that can fully describe the relationship between water conservation capacity and land use patterns in watershed area. This study is to integrate and analyze the impact to water conservation from deforestation or other land use pattern changes. In this study, an integrated methodology combining Geographic Information Systems (GIS), Remote Sensing (RS), Global Positioning System (GPS), and hydrologic simulation program (HSPF) is utilized to define the factor-consequence relationship of this issue from digital database, satellite images, land use pattern identification, and hydrology model, in respectively. The first part of this research was to determine those factors influenced the hydrological processes, which includes water balance parameters extraction for various input data in hydrological model. Secondly, an environmentally sound database was built using GIS, RS and GPS technologies. Then HSPF hydrologic model was used to estimate the quantity of water conservation capacity. The last part was to link the database with water conservation model and estimate the changes due to land use development. This research also use ArcView Avenue Script and C++ to establish an user interface, that provides users to input data and output the results. It can get the volume change of water conservation capacity caused by land use change real time. It provides watershed manager the reference in reservoirs watershed area conservation and development policy.
Open Access
Improving MODFLOW's RIVER package for unsaturated stream/aquifer flow
(Colorado State University. Libraries, 2003) Fox, Garey, author; Colorado State University, publisher
Saturated flow is typically assumed for seepage from a stream underlain by an alluvial aquifer. However, if the water table in an unconfined aquifer falls a sufficient distance below the streambed, the head losses in this less conductive layer will cause the region beneath the streambed to become unsaturated. Unsaturated flow transforms streams from constant head boundaries to constant flux boundaries, impacting not only the quantity of stream recharge but also biogeochemical transformations. The objective of this paper is to analyze the impact of unsaturated flow on stream/aquifer exchange. The modeling capabilities of one of the most commonly used groundwater flow models, MODFLOW, in simulating unsaturated stream/aquifer exchange is improved. The effects of unsaturated flow on MODFLOW predictions of aquifer drawdown and stream leakage are illustrated for hypothetical stream/aquifer systems.