Hydrology Days
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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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Browsing Hydrology Days by Author "Angulo-Jaramillo, Rafael, author"
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Item 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, publisherAccurate 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.Item 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, publisherAnalytical 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.