# Hydrologic Discovery - Oral Presentations (Videos)

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This international symposium of May, 2012 presents a broad overview of the state-of-the-art in hydrologic discovery in honor of two legendary leaders of this process – Wilfried H. Brutsaert and Jean-Yves Parlange – upon the occasion of their retirements at Cornell University.

The oral presentation videos from this symposium are provided as Streaming Videos. Also, QuickTime files are provided that are playable on Apple Devices or on computers using a QuickTime player (free downloads for Macintosh and Windows computers). Both high definition (HD) and standard definition (SD) files are provided.

The high definition QuickTime videos may be played using a computer video player with H.264 codec, 1280x720 pixels, millions of colors, AAC audio at 44100Hz and 29.97 frames per second. The data rate is 5Mbps. File sizes are on the order of 600-900 MB. (Other formats may be added later.) Free QuickTime players for Macintosh and Window computers may be located using a Google search on QuickTime.

We have provided a companion set of standard definition videos (to reduce downloading from 15+ minutes for HD to 5+ minutes for SD versions. However, on a multitasking computer you may continue working during the downloading, but must wait until an entire file has been downloaded before playing it. In addition, the slides used in the presentation are included as PDF files for the benefit of the serious student and to provide clarity in the mathematical expressions in the SD versions.

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Item K1. Reflections by Colleagues(Internet-First University Press, 2012-05)Once downloaded, these high definition QuickTime videos may be played using a computer video player with H.264 codec, 1280x720 pixels, millions of colors, AAC audio at 44100Hz and 29.97 frames per second. The data rate is 5Mbps. File sizes are on the order of 600-900 MB. (Other formats may be added later.) Free QuickTime players for Macintosh and Window computers may be located using a Google search on QuickTime. The DVD was produced by J. Robert Cooke.Item J1. Tribute to Spouses(Internet-First University Press, 2012-05)Item I2. On the Brutsaert Baseflow Recessions and Their Geomorphic OriginsRinaldo, Andrea; Parlange, Marc; Mutzner, Raphael; Tomasic, Nevena; Ceola, Serena; Bertuzzo, Enrico; Rodriguez-Iturbe, Ignacio (Internet-First University Press, 2012-05)Moving from a classic study on the base flow characteristics of six basins in the Finger Lakes region [1], a set of Brutsaert recession curves (the lower envelope of available records of |dQ/dt| as a function of Q, where Q is at-a-station gauged flow rate) has been constructed from Swiss streamflow data relatively unaffected by snowmelt. The Lecture builds on the functional dependences found in [1] (chiefly through Boussinesq’ nonlinear solution of free-surface groundwater flow, yielding a specific relation to local drainage area and total stream length) and on the expedient avoidance of proper time references, to apply and generalize recent results aimed at the geomorphic origins of recession curves [2], that is, fully integrating sizable geometric and topologic complexity. In particular, such results propose a link between river network morphology and the parametrization in [1], in particular by assimilating the basic scaling exponent a (i.e. |dQ/dt|µQa) to that characterizing the empirical relation N(x) µ G(x)a (where x is the downstream distance from the channel heads, N(x) is the number of channel reaches exactly located at distance x from their heads, and G(x) is the total drainage network length at a distance greater or equal to x down to the gauging station where Q is recorded [2]). Application of the method, originally tested on DTMs and daily discharge observations in 67 US basins, suggests a definite linkage of active drainage and source functions with the basic features of the Brutsaert envelopes. The possible morphological predictability of base flow features is central to transport processes at catchment scales, not least for its implications on our understanding of the geomorphic structure of the hydrologic response [3] and of the stationarity of the ensuing travel time distributions leading to the so-called old water paradox [4]. These issues are briefly discussed in the Lecture. Here, through a broad survey of Swiss field data, we go on suggest that the method [2] provides excellent results only in catchments where drainage density (roughly defined as the ratio of total channel network length to its drainage area [L-1], defined at a station) can be regarded as spatially constant. When uneven drainage densities are observed, chiefly in our test cases for high mountainous areas where drainage density varies significantly owing to complex cryosphere dynamics and geologic or pedologic constraints, the method’s assumptions do not hold. In the Lecture a detailed reexamination of the premises of the approaches [1,2] is proposed. A revision is then proposed, which includes geomorphic corrections based on a proper description of the drainage density seen as a random space function [5]. Such corrections properly vanish should drainage density become spatially constant. Overall, it is recognized a definite geomorphic origin for Brutsaert recessions, with notable implications. REFERENCES [1] W. Brutsaert & J.L. Nieber, Regionalized drought flow hydrograph from a mature glaciated plateau, Water Resources Research, 13(3), 637-643, 1977 [2] B. Basudev & M. Marani, Geomorphological origin of recession curves, Geophysical Research Letters, 37, L24403, 2010 [3] I. Rodriguez-Iturbe and J.B. Valdes, The geomorphologic structure of the hydrologic response, Water Resources Research, 15(6), 1409-1420, 1979 [4] G. Botter, E. Bertuzzo, A. Rinaldo, Transport in the hydrologic response: Travel time distributions, soil moisture dynamics, and the old water paradox, Water Resources Research, 46, W03514, 2010 [5] G. Tucker, F. Catani and R.L. Bras, Statistical analysis of drainage density from digital terrain data, Geomorphology, 36, 187-202, 2001Item I1. Green’s Function and Watershed ModellingYeh, Gour-Tsyh (Internet-First University Press, 2012-05)Watershed modelling deals with multiple processes occurring in multiple media. The processes include flow and thermal, salinity, sediment, and biogeochemical transport. The multiple media cover stream/river/canal/open channel networks, lakes/reservoirs, land surfaces, and subsurface media. Analytical and numerical models are commonly employed for simulations to understand sciences or to assess environmental consequences. Why analytical models offer the advantage of clearly and easily explaining the physics involved, the numerical models give practical applications of assessing the impact and interaction among processes and media. This presentation will discuss the issues and difficulties associated with the employment of Green functions to yield analytical models and troubles associated with the use of numeric to generate computational models. Various means of overcoming these difficulties and troubles will be outlined and addressed.Item H2. Hot Thermodynamics for Frozen SoilsGroenevelt, Pieter H. (Internet-First University Press, 2012-05)Q. What is the driving force that lifts buildings, pipelines and roads into the air when the soil underneath freezes? A. Ask Clapeyron……A unifying theory is proposed, bringing together the CRRELL School of Duwayne Anderson and the CORNELL School of Bob Miller, leading to the definition of a Heave Index for the sensitivity of soils to exhibit frost heave. While traveling through the Northern parts of Idaho and Montana with my colleagues, Wilco van Loon (left) and Ed Perfect (right), we were warned about the hazards of freezing soilItem H1. Groenevelt AutobiographyGroenevelt, Pieter H. (Internet-First University Press, 2012-05)Pieter H. Groenevelt, using time reallocated due to absence of a speaker, provided a broad view of his life experience and expressed his heartfelt gratitude for the generosity beyond belief he received after World War II.Item G2. Snippets from Infiltration: Where Approximate Becomes ExactBroadbridge, Philip (Internet-First University Press, 2012-05)The Darcy-Buckingham macroscopic approach to soil-water modelling, leading to a nonlinear Richards’ diffusion-convection equation, has been very useful for many decades. Some sharp results of the 1970s by W. Brutsaert and J.-Y. Parlange have been an influence on many, including myself. Since the 1980s, several groups have used an integrable one-dimensional version of Richards’ equation, with realistic nonlinear transport coefficients, to predict experimentally verifiable quantities. Neat expressions have been derived for time to incipient ponding, for the dependence of sorptivity on pond depth and for the second and higher infiltration coefficients. These exact results are at odds with those of the traditional Green-Ampt model. In the limit of delta-function diffusivity, the water content profile approaches a step function, so the water content is everywhere close to either the boundary value or the initial value. As explained by Barry et al (1995), far from there being a unique “Green-Ampt limit”, practical predictions in the limit of a delta function diffusivity depend subtly on the relationship between diffusivity and conductivity at intermediate values of water content. In fact, the traditional Green-Ampt predictions, with a constant potential at the wet front, may be recovered from a linear, rather than step-function behaviour of conductivity vs water content. A number of practical predictions of the integrable model agree exactly with those of the approximate analytic method originated earlier by Parlange, involving approximations within an integrand after expressing the water conservation equation in integral form. The exactly solvable model refutes the traditional Green-Ampt model and validates the quasi-analytic integral formulation.Item G1. Infiltration into SoilsAssouline, Shmuel (Internet-First University Press, 2012-05)Item F3. Regional Evaporation Using Atmospheric Boundary Layer Profiles (a.k.a Brutsaert’s Balloons)Kustas, William P. (Internet-First University Press, 2012-05)Land surface temperature (LST) from thermal remote sensing is a surface boundary condition that is strongly linked to the partitioning of the available energy between latent (evapotranspiration) and sensible heat flux. Numerous modeling approaches have been developed ranging in level of complexity from semi-empirical to numerically-based soil-vegetation-atmosphere schemes. Many of the approaches require an accurate LST because the heat fluxes are related to the surface-air temperature differences. There is also difficulty estimating appropriate exchange coefficients for heterogeneous landscapes having a mixture of soil and vegetation temperatures influencing the LST observation and associated aerodynamic temperature. For regional applications this also means requiring an accurate air temperature distribution over the area of interest. These requirements have rendered many of the modeling approaches unusable for routine applications over complex land surfaces. However a two-source energy balance (TSEB) modeling scheme using time differencing in LST observations coupled to an atmospheric boundary layer growth model has been developed to adequately address the major impediments to the application of LST in large scale evapotranspiration determination. The modeling system, Atmospheric Land EXchange Inverse (ALEXI), using geostationary LST observations and the disaggregation methodology (DisALEXI) together with data fusion techniques will be described. This modeling system is currently providing regional and continental scale evapotranspiration estimates in the U.S. and plans are to develop a global product.Item F2. Evaporation from Lake Kasumigaura: Bulk Coefficients and Spatial Distribution of Latent Heat FluxMichiaki, Sugita; Zhongwang, Wei; Aiko, Miyano; Hiroya, Ikura (Internet-First University Press, 2012-05)Study of lake evaporation includes various aspects of Dr Brutsaert’s interests such as the exchange processes on water surface, the development of internal boundary layer, estimation of evaporation rate, among others. In the present study, issues on air-water interaction were first revisited. Secondly, horizontal distribution of latent heat fluxes over the lake surface was estimated to study its variability. For these purposes, 10 Hz water vapor, temperature, and wind velocity data have been obtained at the Koshin Observatory located near the center of Lake Kasumigaura, the second largest lake in Japan (220 km2 with mean depth of 4 m) since June of 2007. The corresponding fluxes were determined by applying the eddy correlation method to estimate the bulk coefficients. Agreement and disagreement with previous studies on the bulk transfer coefficients were identified. Also, the influence of lake current, wave, gustiness was investigated. Based on the derived functional form for the bulk coefficient, horizontal distribution of latent heat flux was estimated by first deriving a 100-m grid map of air temperature, wind speed and humidity over the lake area from interpolation of the observed data at meteorological stations in and around Lake Kasumigaura. The bulk method was then applied to each grid to derive latent heat flux every six hours over a year, by assuming the same surface temperature as that at the Koshin Observatory. This was acceptable as the satellite infrared images indicated the presence of quasi-uniform surface water temperature, presumably to reflect well-mixed water body of the shallow lake. The results indicate larger fluxes at the lake center with smaller values near lake shores, mainly to reflect wind speed differences. In comparison, humidity and air temperature is of lessor importance to cause latent heat variability. The mean evaporation over the entire lake surface was found to be 976 (±56) mm/y, while that at the Koshin observatory was 878 mm/y.

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