bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of non‐Darcian flow observed during packer testing in fractured sedimentary rock
Authors: Quinn Patryk M. , Cherry John A. , Parker Beth L.
Published: August 2011

High‐precision straddle packer tests were conducted in boreholes in a fractured dolostone aquifer using constant rate injection (Q) step tests to identify the conditions of change from Darcian to non‐Darcian flow on the basis of Q versus the applied head above ambient (dH), where the ambient head represents static conditions. The linear portion, representing Darcian flow, passes through the origin, but after the onset of non‐Darcian flow, there is proportionally less Q per unit dH, and the transmissivity (T) calculated for the test interval using Darcy's law‐based models can be substantially underestimated. Onset of nonlinear flow depends on the test interval length and permeability, typically beginning at injection rates less than 0.5 L min−1 for a relatively transmissive (2 × 10−5 m2 s−1) 1.5 m test interval. In studies of nonlinear flow during pumping tests, the Forchheimer equation is commonly used to describe nonlinear flow near the well using a Q2 versus dH relationship. However, for packer tests in fractured rock, we propose the Darcy‐Missbach equation, which relates Qn to dH, as an alternative equation. While both equations accurately predict the observed dH within the range of flows used, the Darcy‐Missbach exponent (n) describes the degree of deviation from the linear regime; moreover, all calculated exponents were less than 2, implying that the flow is nonlinear but not quadratic in nature. This quantification of the linear to nonlinear flow relations provides for a more accurate identification of the Darcian range, resulting in better T estimates.
U.S. Department of Agriculture Agricultural Research Service Mahantango Creek Watershed, Pennsylvania, United States: Physiography and history
Authors: Bryant Ray B. , Veith Tamie L. , Feyereisen Gary W. , Buda Anthony R. , Church Clinton D. , Folmar Gordon J. , Schmidt John P. , Dell Curtis J. , Kleinman Peter J. A.
Published: August 2011

The 420 km2 Mahantango Creek Watershed, within the Northern Appalachian Ridges and Valleys Province, is a subwatershed of the Susquehanna River, which flows to the Chesapeake Bay. Research on agricultural management and hydrologic processes controlling nonpoint source nutrient loss is conducted within a 7.3 km2 subwatershed designated WE‐38. The physical watershed description and history of monitoring and research activities contained herein and the data discussed in three companion papers are intended to facilitate the use and interpretation of archived databases on the U.S. Department of Agriculture Agricultural Research Service's Sustaining the Earth's Watersheds—Agricultural Research Data System (STEWARDS) Web site. Sources for regional geospatial data not maintained on STEWARDS are also identified.
U.S. Department of Agriculture Agricultural Research Service Mahantango Creek Watershed, Pennsylvania, United States: Long‐term precipitation database
Authors: Buda Anthony R. , Veith Tamie L. , Folmar Gordon J. , Feyereisen Gary W. , Bryant Ray B. , Church Clinton D. , Schmidt John P. , Dell Curtis J. , Kleinman Peter J. A.
Published: August 2011

A long‐term precipitation database has been developed by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) Pasture Systems and Watershed Management Research Unit to support intensive hydrologic and water quality research within WE‐38, a 7.3 km2 experimental subwatershed of Mahantango Creek Watershed located in east central Pennsylvania and draining to the Susquehanna River. Daily precipitation data were collected at three sites, with record lengths of 40 years (1968–2007) at two sites and of 29 years (1979–2007) at a third site. Data are available on the USDA ARS's Sustaining the Earth's Watersheds—Agricultural Research Data System (STEWARDS) Web site.
U.S. Department of Agriculture Agricultural Research Service Mahantango Creek Watershed, Pennsylvania, United States: Long‐term stream discharge database
Authors: Buda Anthony R. , Feyereisen Gary W. , Veith Tamie L. , Folmar Gordon J. , Bryant Ray B. , Church Clinton D. , Schmidt John P. , Dell Curtis J. , Kleinman Peter J. A.
Published: August 2011

A long‐term streamflow discharge database has been developed by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) Pasture Systems and Watershed Management Research Unit to support intensive hydrologic and water quality research within WE‐38, a 7.3 km2 experimental subwatershed of Mahantango Creek Watershed located in east central Pennsylvania and draining to the Susquehanna River. Daily streamflow discharge data were collected at the outflow of WE‐38 from 1968 to 2007, producing a 40 year record of streamflow. Data are available on USDA ARS's Sustaining the Earth's Watersheds—Agricultural Research Data System (STEWARDS) Web site.
U.S. Department of Agriculture Agricultural Research Service Mahantango Creek Watershed, Pennsylvania, United States: Long‐term water quality database
Authors: Church Clinton D. , Veith Tamie L. , Folmar Gordon J. , Buda Anthony R. , Feyereisen Gary W. , Bryant Ray B. , Schmidt John P. , Dell Curtis J. , Kleinman Peter J. A.
Published: August 2011

A long‐term water quality database has been developed by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) Pasture Systems and Watershed Management Research Unit to support water quality research within WE‐38, a 7.3 km2 experimental subwatershed of Mahantango Creek Watershed located in east central Pennsylvania and draining to the Susquehanna River. Water quality data were collected at the outflow of WE‐38, with record lengths of 24 years (1983–2007) for nitrate‐N and ammonium‐N and 23 years (1984–2007) for orthophosphate‐P. Data are available on USDA ARS Sustaining the Earth's Watersheds—Agricultural Research Data System (STEWARDS) Web site.
Scale dependence of spatiotemporal intermittence of rain
Authors: Kundu Prasun K. , Siddani Ravi K.
Published: August 2011

It is a common experience that rainfall is intermittent in space and time. This is reflected by the fact that the statistics of area‐ and/or time‐averaged rain rate is described by a mixed distribution with a nonzero probability of having a sharp value zero. In this paper we have explored the dependence of the probability of zero rain on the averaging space and time scales in large multiyear data sets based on radar and rain gauge observations. A stretched exponential formula fits the observed scale dependence of the zero‐rain probability. The proposed formula makes it apparent that the space‐time support of the rain field is not quite a set of measure zero as is sometimes supposed. We also give an explanation of the observed behavior in terms of a simple probabilistic model based on the premise that rainfall process has an intrinsic memory.
Groundwater flow patterns adjacent to a long‐term stratified (meromictic) lake
Authors: Oz I. , Shalev E. , Gvirtzman H. , Yechieli Y. , Gavrieli I.
Published: August 2011

This paper examines, for the first time, the unique situation of a groundwater system adjacent to a long‐term stratified (meromictic) lake. Using conceptual and numerical models, the configuration of groundwater interfaces between the three different water bodies (regional groundwater and upper and lower lake waters) and the flow patterns were quantitatively evaluated assuming a homogenous aquifer. A complex flow system, controlled by density difference, is created near the lake, where three circulation cells are developed. These results are different from the classic circulation cell that is found adjacent to nonstratified water bodies (lakes or oceans). Sensitivity analyses reveal that the results are sensitive to changes in thickness and density of the upper water mass of the lake. The Dead Sea, under its possible future meromictic conditions, serves as an ideal example of such a system. Thus, the model's results can be used as a preliminary assessment for groundwater behavior adjacent to the lake, if and when stratification will develop.
Single‐site monthly streamflow simulation using entropy theory
Authors: Hao Z. , Singh V. P.
Published: August 2011

Using entropy theory, a new method for single‐site monthly streamflow simulation is developed, which is capable of preserving mean, standard deviation, skewness, and lag‐one correlation. The method entails deriving joint and conditional probability density functions using the entropy theory, determining the Lagrange multipliers using the information obtained from the historical record, and then simulating streamflow by sequential sampling from the conditional distribution. The advantage of the entropy‐based method is that it does not make any assumptions about the probability distribution of the streamflow data. It can also preserve the cross‐correlation between streamflow of the last month of the previous year and the first month of the current year and avoid the generation of negative values. The method can also be extended to incorporate higher‐order moments and more lag correlations if needed. The disadvantage is that the method will be cumbersome when more statistics need to be preserved and the bimodality that may exist in the empirical probability density function cannot yet be resolved. Application to the Colorado River basin shows that the entropy‐based method satisfactorily simulates monthly streamflow.
Entrainment of coarse grains in turbulent flows: An extreme value theory approach
Authors: Valyrakis Manousos , Diplas Panayiotis , Dancey Clint L.
Published: August 2011

The occurrence of sufficiently energetic flow events characterized by impulses of varying magnitude is treated as a point process. It is hypothesized that the rare but extreme magnitude impulses are responsible for the removal of coarse grains from the bed matrix. This conjecture is investigated utilizing distributions from extreme value theory and a series of incipient motion experiments. The application of extreme value distributions is demonstrated for both the entire sets of impulses and the maxima above a sufficiently high impulse quantile. In particular, the Frechet distribution is associated with a power law relationship between the frequency of occurrence and magnitude of impulses. It provides a good fit to the flow impulses, having comparable performance to other distributions. Next, a more accurate modeling of the tail of the distribution of impulses is pursued, consistent with the observation that the majority of impulses above a critical value are directly linked to grain entrainments. The peaks over threshold method is implemented to extract conditional impulses in excess of a sufficiently high impulse level. The generalized Pareto distribution is fitted to the excess impulses, and parameters are estimated for various impulse thresholds and methods of estimation for all the experimental runs. Finally, the episodic character of individual grain mobilization is viewed as a survival process, interlinked to the extremal character of occurrence of impulses. The interarrival time of particle entrainment events is successfully modeled by the Weibull and exponential distributions, which belong to the family of extreme value distributions.
A flow resistance model for assessing the impact of vegetation on flood routing mechanics
Authors: Katul Gabriel G. , Poggi Davide , Ridolfi Luca
Published: August 2011

The specification of a flow resistance factor to account for vegetative effects in the Saint‐Venant equation (SVE) remains uncertain and is a subject of active research in flood routing mechanics. Here, an analytical model for the flow resistance factor is proposed for submerged vegetation, where the water depth is commensurate with the canopy height and the roughness Reynolds number is sufficiently large so as to ignore viscous effects. The analytical model predicts that the resistance factor varies with three canonical length scales: the adjustment length scale that depends on the foliage drag and leaf area density, the canopy height, and the water level. These length scales can reasonably be inferred from a range of remote sensing products making the proposed flow resistance model eminently suitable for operational flood routing. Despite the numerous simplifications, agreement between measured and modeled resistance factors and bulk velocities is reasonable across a range of experimental and field studies. The proposed model asymptotically recovers the flow resistance formulation when the water depth greatly exceeds the canopy height. This analytical treatment provides a unifying framework that links the resistance factor to a number of concepts and length scales already in use to describe canopy turbulence. The implications of the coupling between the resistance factor and the water depth on solutions to the SVE are explored via a case study, which shows a reasonable match between empirical design standard and theoretical predictions.
New education and outreach opportunities for scientists
Authors: Johnson Roberta
Published: August 2011

A scientist works late to finish up yet another proposal for research funding. Time is short—the proposal is due in only a week. The research description is well in hand, compelling and at the forefront of the field. But the scientist is less confident of what to propose for a “broader impacts” component that will actually be meaningful. What does it mean to have a broader impact? What can be proposed that will make a difference but will not divert too much time from conducting research, searching for funding, or writing papers? For many scientists, particularly those who rely on soft money for research funding, the above scenario is a familiar story. These days, research solicitations from funding agencies consistently require that in addition to proposing innovative and cutting‐edge research, scientists must also include elements in their proposals that provide meaningful broader impacts to their research programs—in essence, they must show how their research will benefit society and spread knowledge.
New AGU Climate Communication Prize: Call for nominations
Authors: McPhaden Michael J.
Published: August 2011

AGU is pleased to announce the newly launched AGU Climate Communication Prize. This new Union prize, generously funded by Nature's Own, a purveyor of fossils, minerals, and handcrafted jewelry in Boulder, Colo., will honor an AGU member‐scientist for the communication of climate science. The prize highlights the importance of promoting scientific literacy, clarity of message, and efforts to foster respect and understanding of science‐based values as they relate to the implications of climate change. The prize will be awarded annually and will be presented at AGU's Fall Meeting. It will carry a cash award of $25,000.
AGU signs memorandum of agreement with Soil Science Society of America
Authors: McEntee Chris
Published: August 2011

I am pleased to announce that AGU has taken another step in our effort to build strategic alliances with partner groups by signing a memorandum of agreement with the Soil Science Society of America (SSSA). This agreement is based on the common interests of our members and will allow us to strengthen our respective organizations by

Exchanging information on key programs and initiatives.

Expanding membership of both our organizations through possible joint programs.>

Exchanging information and possible joint activities concerning educational opportunities, student programs, and professional services.

Exchanging information and possible co‐organization of scientific conferences.
Model gives a 3‐month warning of Amazonian forest fires
Authors: Schultz Colin
Published: August 2011

The widespread drought suffered by the Amazon rain forest in the summer of 2005 was heralded at the time as the drought of the century. Because of the dehydrated conditions, supplemented by slash and burn agricultural practices, the drought led to widespread forest fires throughout the western Amazon, a portion of the rain forest usually too lush to support spreading wildfires. Only 5 years later, the 2005 season was outdone by even more widespread drought, with fires decimating more than 3000 square kilometers of western Amazonian rain forest. Blame for the wildfires has been consistently laid on deforestation and agricultural practices, but a convincing climatological explanation exists as well. (Geophysical Research Letters, doi:10.1029/2011GL047392, 2011)
Ocean floor faulting explains differences in Central American lavas
Authors: Schultz Colin
Published: August 2011

The steady eastward progression of the Cocos tectonic plate, which lies off the west coast of Central America, forces it under the Caribbean and North American plates, driving seismic and volcanic activity. Along the Central American coast, the chemical content of the lava produced by such volcanism varies significantly, an unusual finding given that the raw material for the magma—the Cocos plate—feeds the entire region. For instance, magma in central Nicaragua has a much higher ratio of barium to lanthanum than the magma in Costa Rica, with the concentrations of these and other trace elements serving as an indicator that distinct processes were involved in generating the different magma. To identify structural properties that vary along the Cocos plate that may explain these differences, Van Avendonk et al. conducted a 396‐kilometer sweep of the plate's eastern boundary, collecting measurements of seismic velocity, i.e., how fast seismic waves are able to travel through the various rock layers. Previous research describes a complicated history of the Cocos plate. The northern half, which lies off Nicaragua, was the product of deep‐ocean spreading at the East Pacific Rise (EPR). The Cocos‐Nazca (CN) spreading region, along with intraplate volcanism near the Galápagos Islands, generated the southern portion of the plate. The authors found that seismic velocities within the northern portion of the plate are anomalously low. The authors suggest that as the Cocos plate is forced down, forming the Middle America Trench, the rock stretches and breaks. This high degree of faulting within the crust would allow seawater to penetrate into the mantle and form hydrated rocks called serpentinites. As the northern portion of the Cocos plate is subducted, these high serpentinite concentrations are carried deeper into the mantle, releasing their trapped water and significantly affecting the chemical composition of the magma. (Geochemistry, Geophysics, Geosystems, doi:10.1029/2011GC003592, 2011)
Reconstructing the thermal structure of the upper ocean: Insights from planktic foraminifera shell chemistry and alkenones in modern sediments of the tropical eastern Indian Ocean
Authors: Mohtadi Mahyar , Oppo Delia W. , Lückge Andreas , DePol‐Holz Ricardo , Steinke Stephan , Groeneveld Jeroen , Hemme Nils , Hebbeln Dierk
Published: August 2011

Shell chemistry of planktic foraminifera and the alkenone unsaturation index in 69 surface sediment samples in the tropical eastern Indian Ocean off West and South Indonesia were studied. Results were compared to modern hydrographic data in order to assess how modern environmental conditions are preserved in sedimentary record, and to determine the best possible proxies to reconstruct seasonality, thermal gradient and upper water column characteristics in this part of the world ocean. Our results imply that alkenone‐derived temperatures record annual mean temperatures in the study area. However, this finding might be an artifact due to the temperature limitation of this proxy above 28°C. Combined study of shell stable oxygen isotope and Mg/Ca ratio of planktic foraminifera suggests that Globigerinoides ruber sensu stricto (s.s.), G. ruber sensu lato (s.l.), and G. sacculifer calcify within the mixed‐layer between 20 m and 50 m, whereas Globigerina bulloides records mixed‐layer conditions at ∼50 m depth during boreal summer. Mean calcifications of Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, and Globorotalia tumida occur at the top of the thermocline during boreal summer, at ∼75 m, 75–100 m, and 100 m, respectively. Shell Mg/Ca ratios of all species show a significant correlation with temperature at their apparent calcification depths and validate the application of previously published temperature calibrations, except for G. tumida that requires a regional Mg/Ca‐temperature calibration (Mg/Ca = 0.41 exp (0.068*T)). We show that the difference in Mg/Ca‐temperatures of the mixed‐layer species and the thermocline species, particularly between G. ruber s.s. (or s.l.) and P. obliquiloculata, can be applied to track changes in the upper water column stratification. Our results provide critical tools for reconstructing past changes in the hydrography of the study area and their relation to monsoon, El Niño‐Southern Oscillation, and the Indian Ocean Dipole Mode.
A two‐parameter stochastic process for Dansgaard‐Oeschger events
Authors: Braun H. , Ditlevsen P. , Kurths J. , Mudelsee M.
Published: August 2011

Various climatic processes are thought to evolve as rapid, shift‐like events, which points at the presence of nonlinear dynamics. Time series analysis of nonlinear processes, however, is not trivial, for example, because of the difficulty in coming up with a realistic random process as a viable null hypothesis. In this methodology paper we construct a basic two‐parameter process of shift‐like excursions in an excitable system with a threshold. We demonstrate that this stochastic process, in comparison with a specific one‐parameter process, can better reproduce main features of the waiting time histogram of abrupt glacial climate events, the Dansgaard‐Oeschger events, as seen in two paleoclimatic proxy records, the North Greenland Ice core Project (NGRIP) ice core and the Sofular stalagmite δ18O records. We use the two‐parameter process to test some arguments that were proposed in the ongoing discussion of a possible solar role in triggering Dansgaard‐Oeschger events. Using our approach, we suggest for future studies to generate time series of random events which can serve as a more plausible null hypothesis for Monte Carlo based statistical tests on the regularity of shift‐like processes such as Dansgaard‐Oeschger events.
Review of crop growth and soil moisture monitoring from a ground‐based instrument implementing the Interference Pattern GNSS‐R Technique
Authors: Rodriguez‐Alvarez N. , Bosch‐Lluis X. , Camps A. , Aguasca A. , Vall‐llossera M. , Valencia E. , Ramos‐Perez I. , Park H.
Published: August 2011

Reflectometry using Global Navigation Satellite Systems signals (GNSSR) has been the focus of many studies during the past few years for a number of applications over different scenarios as land, ocean or snow and ice surfaces. In the past decade, its potential has increased yearly, with improved receivers and signal processors, from generic GNSS receivers whose signals were recorded in magnetic tapes to instruments that measure full Delay Doppler Maps (the power distribution of the reflected GNSS signal over the 2‐D space of delay offsets and Doppler shifts) in real time. At present, these techniques are considered to be promising tools to retrieve geophysical parameters such as soil moisture, vegetation height, topography, altimetry, sea state and ice and snow thickness, among others. This paper focuses on the land geophysical retrievals (topography, vegetation height and soil moisture) performed from a ground‐based instrument using the Interference Pattern Technique (IPT). This technique consists of the measurement of the power fluctuations of the interference signal resulting from the simultaneous reception of the direct and the reflected GNSS signals. The latest experiment performed using this technique over a maize field is shown in this paper. After a review of the previous results, this paper presents the latest experiment performed using this technique over a maize field. This new study provides a deeper analysis on the soil moisture retrieval by observing three irrigation‐drying cycles and comparing them to different depths soil moisture probes. Furthermore, the height of the maize, almost 300 cm, has allowed testing the capabilities of the technique over dense and packed vegetation layers, with high vegetation water content.
Three months of local sea level derived from reflected GNSS signals
Authors: Löfgren J. S. , Haas R. , Scherneck H.‐G. , Bos M. S.
Published: August 2011

By receiving Global Navigation Satellite System (GNSS) signals that are reflected off the sea surface, together with directly received GNSS signals (using standard geodetic‐type receivers), it is possible to monitor the sea level using regular single difference geodetic processing. We show results from our analysis of three months of data from the GNSS‐based tide gauge at the Onsala Space Observatory (OSO) on the west coast of Sweden. The GNSS‐derived time series of local sea level is compared with independent data from two stilling well gauges at Ringhals and Gothenburg about 18 km south and 33 km north of OSO, respectively. A high degree of agreement is found in the time domain, with correlation coefficients of up to 0.96. The root‐mean‐square differences between the GNSS‐derived sea level and the stilling well gauge observations are 5.9 cm and 5.5 cm, which is lower than for the stilling well gauges together (6.1 cm). A frequency domain comparison reveals high coherence of the data sets up to 6 cycles per day, which corresponds well to the propagation of gravity waves in the shallow waters at the Kattegat coast. Amplitudes and phases of some major tides were determined by a tidal harmonic analysis and compared to model predictions. From the GNSS‐based tide gauge results we find significant ocean tidal signals at fortnightly, diurnal, semi‐diurnal, and quarter‐diurnal periods. As an example, the amplitudes of the semi‐diurnal M2 and the diurnal O1 tide are determined with 1σ uncertainties of 11 mm and 12 mm, respectively. The comparison to model calculations shows that global ocean tide models have limited accuracy in the Kattegat area.
Estimating ionospheric delay using kriging: 2. Impact on satellite‐based augmentation system availability
Authors: Sparks Lawrence , Blanch Juan , Pandya Nitin
Published: August 2011

An augmentation of the Global Positioning System, the Wide Area Augmentation System (WAAS) broadcasts, at each node of an ionospheric grid, an estimate of the vertical ionospheric delay and an integrity bound on the vertical delay error. To date, these quantities have been determined from a planar fit of slant delay measurements, projected to vertical using an obliquity factor specified by the standard thin shell model of the ionosphere. In a future WAAS upgrade (WAAS Follow‐On Release 3), however, they will be calculated using an established, geo‐statistical estimation technique known as kriging that generally provides higher estimate accuracy than planar fit estimation. This paper analyzes the impact of kriging on system availability. In a preliminary assessment, kriging is found to produce improvements in availability of up to 15%.
Improved forecasts of solar wind parameters using the Kalman filter
Authors: Innocenti M. E. , Lapenta G. , Vršnak B. , Crespon F. , Skandrani C. , Temmer M. , Veronig A. , Bettarini L. , Markidis S. , Skender M.
Published: August 2011

Data assimilation through Kalman filtering is a powerful statistical tool that allows researchers to combine modeling and observations and thus to increase the degree of knowledge of a given system. The application of this technique to an empirical solar wind forecasting model which enables the forecasting of solar wind parameters from coronal hole observations is here described and discussed. The forecasts for the solar wind proton velocity and temperature and for the magnetic field magnitude with and without data assimilation are validated against Advanced Composition Explorer observations, and it is shown that Kalman filtering can improve the quality of the forecasts and extend the period of applicability of the baseline model. In a subset of cases, some degree of robustness toward solar transient activity not accounted for in the original model is also provided.
Effects of long‐term irrigation with treated wastewater on the hydraulic properties of a clayey soil
Authors: Assouline S. , Narkis K.
Published: August 2011

The increasing demand for freshwater (FW) for domestic use turns treated wastewater (WW) into an attractive source of water for irrigated agriculture. The main goal of this study was to evaluate the impact of 15 yrs of irrigation with WW on hydraulic properties and flow processes in a clayey soil, compared to FW use. It also quantitatively addressed the distribution with depth along the soil profile of that impact on soil hydraulic properties. Standard methods used in soil physics at the laboratory scale, and numerical solutions of the flow equations on the basis of HYDRUS, were applied to define fundamental soil hydraulic properties of disturbed soil samples from 0–20, 20–40, and 40–60 cm layers in the root zone. Results showed that saturated hydraulic conductivity, sorptivity, and infiltration rates are consistently lower in the WW irrigated soil samples at all depths. Water retention and hydraulic conductivity functions were affected by the use of WW, leading to a smaller, simulated‐wetted volume below a dripper for the WW‐irrigated soil case. These results illustrate the combined and complex effect of WW use on soil‐exchangeable sodium percentage, and suggest changes in contact angle and pore size distribution. They also suggest that WW application will affect differently different zones in the soil profile, depending on irrigation management parameters and plant uptake characteristics.
Recovery efficiency of aquifer storage and recovery (ASR) with mass transfer limitation
Authors: Lu Chunhui , Du Pengfei , Chen Yiming , Luo Jian
Published: August 2011

Aquifer storage and recovery (ASR) is an effective strategy for water resources management and has been widely used in many contaminated and saline aquifers. However, its recovery efficiency (RE) may be significantly affected by mass transfer limitations. A numerical model is developed to simulate ASR performance by combining the convergent and divergent dispersion models with a first‐order mass transfer model. By analyzing the concentration history at the pumping well, we obtain simple and effective relationships for investigating ASR efficiency under various mass transfer parameters, including capacity ratio and mass transfer timescale, and operational parameters, including injection durations and well‐pumping rates. On the basis of such relationships, one can conveniently determine whether a site with mass transfer limitations is appropriate or not for ASR and how many ASR cycles are required for achieving a positive RE. Results indicate that the immobile domain may function as a contaminant source or sink or both during the recovery phase and RE usually improves with well‐flow rate, the decrease of capacity ratio, and the ASR cycles. However, RE is a nonmonotonic function of the mass transfer timescale and the injection duration. A critical timescale is given for quantifying this nonmonotonic behavior. When the injection period is greater than such a critical value, increasing injection period results in a higher RE. Contrarily, when the injection period is less than the critical value, increasing the injection period may even yield a lower RE.
Development and application of a simple hydrogeomorphic model for headwater catchments
Authors: Sidle Roy C. , Kim Keewook , Tsuboyama Yoshio , Hosoda Ikuhiro
Published: August 2011

We developed a catchment model based on a hydrogeomorphic concept that simulates discharge from channel‐riparian complexes, zero‐order basins (ZOB, basins ZB and FA), and hillslopes. Multitank models simulate ZOB and hillslope hydrological response, while kinematic wave models predict saturation overland runoff from riparian zones and route inputs from ZOB and riparian corridors through the channel. The model was parameterized and tested in the Hitachi Ohta Experiment Watershed, Japan. Tank models were parameterized for a 6 month period from May to October 1992, and these models were then tested for the same 6 month period in 1993. In ZB, with relatively shallower soils, total outflow for the 6 month period in 1993 was underpredicted by 25%. Better predictions were obtained for outflow from FA (deeper soils; −17%) and the entire catchment (−5%). Total runoff from the channel and riparian area depends on the ratio of this area to the total catchment area because this corridor is assumed to be saturated at all times. Stormflow response from ZOB was limited during relatively dry conditions and increased substantially during wetter conditions, especially in ZB, which has shallower soils (1.4 m of average); such effects were diminished in FA (deeper soils) and hillslopes. Outflow from ZB had the highest proportion of rapid flow, while slower flow dominates outflow from FA and hillslopes; these different responses appear to be mainly associated with soil depth and topography. Groundwater recharge, estimated by leakage from the lowermost tank in the models, was as high as 61 mm week−1 from ZB, with lesser recharge from other geomorphic components (18–21 mm week−1). These spatially explicit simulations provide a simpler approach to the greater data demands of distributed hydrologic models without compromising process function.
Statistical analysis of the impact of radar rainfall uncertainties on water resources modeling
Authors: He Xin , Refsgaard Jens Christian , Sonnenborg Torben O. , Vejen Flemming , Jensen Karsten H.
Published: August 2011

Uncertainty analysis in hydrological modeling has become an essential step in the scientific interpretation of model results and a useful tool to support decision making. Among many uncertainty sources in the modeling practice, uncertainties in precipitation estimation play an important role since it is the main driving force for other hydrological processes. The present study demonstrates a statistical method for generating radar rainfall realizations that account for the uncertainties in radar‐based quantitative precipitation estimation (QPE). The random sampling technique used to generate stochastic uncertainty fields is based on sequential Gaussian simulation. The hydrological impact of the uncertainties in radar QPE is analyzed by propagating the rainfall ensemble through a distributed and integrated water resources model. The study shows that the uncertainty of the simulated stream discharge depends on the intensity of the rainfall input signal. The coefficient of variation is calculated for simulated stream discharge and groundwater recharge at subcatchments with various sizes. The results reveal strong scale dependency showing higher variations of hydrological uncertainties at smaller catchments, especially for catchment areas smaller than 50 km2. The uncertainties from precipitation input are generally amplified in the hydrological model. This effect is less obvious for groundwater recharge but rather substantial for stream discharge, where the coefficient of variation increases by a factor of three.
Kohonen self‐organizing map estimator for the reference crop evapotranspiration
Authors: Adeloye Adebayo J. , Rustum Rabee , Kariyama Ibrahim D.
Published: August 2011

Reference crop evapotranspiration (ETo) estimation is of importance in irrigation water management for the calculation of crop water requirements and its scheduling, in rainfall‐runoff modeling and in numerous other water resources studies. Due to its importance, several direct and indirect methods have been employed to determine the reference crop evapotranspiration but success has been limited because the direct measurement methods lack in precision and accuracy due to scale issues and other problems, while some of the more accurate indirect methods, e.g., the Penman‐Monteith benchmark model, are time‐consuming and require weather input data that are not routinely monitored. This paper has used the Kohonen self‐organizing map (KSOM), unsupervised artificial neural networks, to predict the ETo. based on observed daily weather data at two climatically diverse basins: a small experimental catchment in temperate Edinburgh, UK and a semiarid lake basin in Udaipur, India. This was achieved by using the powerful clustering capability of the KSOM to analyze the multidimensional data array comprising the estimated ETo (based on the Food and Agricultural Organization (FAO) Penman‐Monteith model) and different subsets of climatic variables known to affect it. The findings indicate that the KSOM‐based ETo estimates even with fewer input variables were in good agreement with those obtained using the conventional FAO Penman‐Monteith formulation employing the full complement of weather data at the two locations. More crucially, the KSOM‐based estimates were also found to be significantly superior to those estimated using currently recommended empirical ETo methods for data scarce situations such as those in developing countries.
A new model for predicting relative nonwetting phase permeability from soil water retention curves
Authors: Kuang Xingxing , Jiao Jiu Jimmy
Published: August 2011

Relative permeability of the nonwetting phase in a multiphase flow in porous media is a function of phase saturation. Specific expressions of this function are commonly determined by combining soil water retention curves with relative nonwetting phase permeability models. Experimental evidence suggests that the relative permeability of the nonwetting phase can be significantly overestimated by the existing relative permeability models. A new model for the prediction of relative nonwetting phase permeability from soil water retention curves is proposed in this paper. A closed form expression can be obtained in combination with soil water retention curves. The model is mathematically simple and can easily and efficiently be implemented in numerical models of multiphase flow processes in porous media. The predicting capability of the proposed model is contrasted with well‐supported models by comparing the measured and predicted relative air permeability data for 11 soils, representing a wide range of soil textures, from sand to silty clay loam. In most of the cases the proposed model improves the agreement between the predicted relative air permeability and the measured data.
A Hypothesis about the Biological Basis of Expert Intuition
Authors: Chassy Philippe , Gobet Fernand
Published: August 2011

It is well established that intuition plays an important role in experts’ decision making and thinking generally. However, the theories that have been developed at the cognitive level have limits in their explanatory power and lack detailed explanation of the underlying biological mechanisms. In this paper, we bridge this gap by proposing that Hebb's (1949) concept of cell assembly is the biological realization of Simon's (1974) concept of chunking. This view provides mechanisms at the biological level that are consistent with both biological and psychological findings. To further address the limits of previous theories, we introduce emotions as a component of intuition by showing how they modulate the perception-memory interaction. The idea that intuition lies at the crossroads between perception, knowledge, and emotional modulation sheds new light on the phenomena of expertise and intuition.
Near Infrared Microspectroscopy, Fluorescence Microspectroscopy, Infrared Chemical Imaging and High-Resolution Nuclear Magnetic Resonance Analysis of Soybean Seeds, Embryos and Single Cells
Authors: Baianu I. , Korban Schyler , You Tiefeng
Published: August 2011

Chemical analysis of soybean seeds, somatic embryos and single cells were carried out by Fourier Transform Infrared (FT-IR), Fourier Transform Near Infrared (FT-NIR) Microspectroscopy, Fluorescence and High-Resolution NMR (HR-NMR). The first FT-NIR chemical images of biological systems approaching 1 micron (1μ) resolution are presented here. Chemical images obtained by FT-NIR and FT-IR Microspectroscopy are presented for oil in soybean seeds and somatic embryos under physiological conditions. FT-NIR spectra of oil and proteins were obtained for volumes as small as 2μ3. Related, HR-NMR analyses of oil contents in somatic embryos are also presented here with nanoliter precision. Such 400 MHz 1H NMR analyses allowed the selection of mutagenized embryos with higher oil content (e.g. ~20%) compared to non-mutagenized control embryos. Moreover, developmental changes in single soybean seeds and/or somatic embryos may be monitored by FT-NIR with a precision approaching the picogram level. Indeed, detailed chemical analyses of oils and phytochemicals are now becoming possible by FT-NIR Chemical Imaging/ Microspectroscopy of single cells. The cost, speed and analytical requirements of plant breeding and genetic selection programs are fully satisfied by FT-NIR spectroscopy and Microspectroscopy for soybeans and soybean embryos. FT-NIR Microspectroscopy and Chemical Imaging are also shown to be potentially important in functional Genomics and Proteomics research through the rapid and accurate detection of high-content microarrays (HCMA). Multi-photon (MP), pulsed femtosecond laser NIR Fluorescence Excitation techniques were shown to be capable of Single Molecule Detection (SMD). Therefore, such powerful techniques allow for the most sensitive and reliable quantitative analyses to be carried out both in vitro and in vivo. Thus, MP NIR excitation for Fluorescence Correlation Spectroscopy (FCS) allows not only single molecule detection, but also molecular dynamics and high resolution, submicron imaging of femtoliter volumes inside living cells and tissues. These novel, ultra-sensitive and rapid NIR/FCS analyses have numerous applications in important research areas, such as: agricultural biotechnology, food safety, pharmacology, medical research and clinical diagnosis of viral diseases and cancers.
Characterization And Rejuvenation Of Local Ecorace Sukinda In Odhisa State
Authors: Sahay Alok , Satpathy Subrat , Sharan Shashikant
Published: August 2011

An experiment of outdoor rearing was conducted with the available Sukinda (TV) stock of BSM&TC, Sundargarh (SG), CTSSS, Lakha (CTS) and CTR&TI, Ranchi. The objective of this activity is to utilize economic wild life, conserving the associated environment for sustainable rural and tribal development (Raffi and Ramanujam, 2001; Gill and Lal, 2002; Mahapatra, 2009).The crop performance of SG showed highest cocoon yield i.e., 83 cocoons / dfl in 1st crop followed by 80 cocoons / dfl in 3rd crop and 42 cocoons / dfl during 2nd crop. Yellow coloured cocoons dominated (94-96%) the population in all the three crops. The cocoon weight, Shell weight and Silk Ratio were (9.72g, 1.07g&11 %) in 1st crop,(9.77g,1.05g & 10.75%) in 2nd crop and (11.11g,1.79g & 16.11%) in commercial third crop season. The ERR were 41.64 %, 50.00 % and 74.51% in 1st, 2nd and 3rd crop respectively. This approach for semi-domesticated and commercially exploited Sukinda ecoraces can further enhances their potential because of better inherent performance levels under in situ (Suryanarayana and Srivastava, 2005) over the current basic and commercial stocks maintained ex situ.
The serine/threonine kinase ULK1 is a target of multiple phosphorylation events
Authors: Bach Markus , Larance Mark , James David E. , Ramm Georg
Published: August 2011

Autophagy is a cellular degradation process that is up-regulated upon starvation. Nutrition-dependent regulation of mTOR (mammalian target of rapamycin) is a major determinant of autophagy. RTK (receptor tyrosine kinase) signalling and AMPK (AMP-activated protein kinase) converge upon mTOR to suppress or activate autophagy. Nutrition-dependent regulation of autophagy is mediated via mTOR phosphorylation of the serine/threonine kinase ULK1 (unc51-like kinase 1). In the present study, we also describe ULK1 as an mTOR-independent convergence point for AMPK and RTK signalling. We initially identified ULK1 as a 14-3-3-binding protein and this interaction was enhanced by treatment with AMPK agonists. AMPK interacted with ULK1 and phosphorylated ULK1 at Ser555in vitro. Mutation of this residue to alanine abrogated 14-3-3 binding to ULK1, and in vivo phosphorylation of ULK1 was blocked by a dominant-negative AMPK mutant. We next identified a high-stringency Akt site in ULK1 at Ser774 and showed that phosphorylation at this site was increased by insulin. Finally, we found that the kinase-activation loop of ULK1 contains a consensus phosphorylation site at Thr180 that is required for ULK1 autophosphorylation activity. Collectively, our results suggest that ULK1 may act as a major node for regulation by multiple kinases including AMPK and Akt that play both stimulatory and inhibitory roles in regulating autophagy.
Will we exceed 50% efficiency in photovoltaics?
Authors: Luque Antonio
Published: August 2011

Solar energy is the most abundant and reliable source of energy we have to provide for the multi-terawatt challenge we are facing. Although huge, this resource is relatively dispersed. High conversion efficiency is probably necessary for cost effectiveness. Solar cell efficiencies above 40% have been achieved with multijunction (MJ) solar cells. These achievements are here described. Possible paths for improvement are hinted at including third generation photovoltaics concepts. It is concluded that it is very likely that the target of 50% will eventually be achieved. This high efficiency requires operating under concentrated sunlight, partly because concentration helps increase the efficiency but mainly because the cost of the sophisticated cells needed can only be paid by extracting as much electric power form each cell as possible. The optical challenges associated with the concentrator optics and the tools for overcoming them, in particular non-imaging optics, are briefly discussed and the results and trends are described. It is probable that optical efficiency over 90% will be possible in the future. This would lead to a module efficiency of 45%. The manufacturing of a concentrator has to be addressed at three levels of integration: module, array, and photovoltaic (PV) subfield. The PV plant as a whole is very similar than a flat module PV plant with two-axes tracking. At the module level, the development of tools for easy manufacturing and quality control is an important topic. Furthermore, they can accommodate in different position cells with different spectral sensitivities so complementing the effort in manufacturing MJ cells. At the array level, a proper definition of the nameplate watts, since the diffuse light is not used, is under discussion. The cost of installation of arrays in the field can be very much reduced by self aligning tracking control strategies. At the subfield level, aspects such as the self shadowing of arrays causes the CPV subfields to be sparsely packed leading to a ground efficiency, in the range of 10%, that in some cases will be below that of fixed modules of much lower cell efficiency. All this taken into account, High Concentration PV (HCPV) has the opportunity to become the cheapest of the PV technologies and beat the prevalent electricity generation technologies. Of course the way will be paved with challenges, and success is not guaranteed.