The freshwater alga Spirogyra grevilleana was used in an experimental biofiltration system to reduce levels of Escherichia coli, nitrates, and phosphates. Water collected from a 2.32 ha lake in Atlanta, Georgia, USA was pumped at a constant rate ( m3 hr-1) through the algal filtration devices with low and high concentrations of S. grevilleana. Effluent water was tested over time for E. coli, nitrate, phosphate, dissolved oxygen, and pH levels. Both concentrations of S. grevilleana reduced E. coli by 100% and significantly reduced nitrate concentrations (30% ± 13%) and phosphate concentrations (23% ± 5%) while maintaining dissolved oxygen and pH at normal levels. Utilizing S. grevilleana in an algal filtration device could potentially provide a sustainable, flexible, and low-cost method of E. coli reduction in freshwater lakes worldwide. Initial results indicate that the use of S. grevilleana in conjunction with an algal filtration device is potentially capable of creating potable water.
Management of uncertainty in hydrologic modeling is related to our ability to (a) select appropriate values for model parameters and (b) assess the extent to which their variation affects a simulated response. We focus on the application of sensitivity and uncertainty analyses to assess the influence of main parameters associated with the widely used distributed watershed model TopModel in estimating surface runoff in the area of the Middle Magdalena Valley, Colombia. We ground our study on the GLUE methodology, as included in the MCAT Toolbox. This methodology is conducive to a Regional Sensitivity Analysis (RSA), rendering global information about the relative importance of given model parameters through an a-posteriori probability function. GLUE is viewed as a first step to undertake a comprehensive global sensitivity analysis based on the statistical moments characterizing the outputs of the simulations. We do so upon relying on (a) the Sobol’ indices, associated with a classical decomposition of variance and (b) recently developed indices quantifying the relative contribution of each uncertain model parameter to the (ensemble) mean, skewness and kurtosis of the model output. Our analyses are grounded on a collection of 150.000 model simulations, each spanning a 12-year temporal window. These are constructed by assuming those model parameters are random and associated with a uniform distribution within a support of width selected on the basis of literature studies and preliminary model calibration against available data. Results of the global sensitivity analysis enable identifying a reduced set of model parameter values, showing that the parameter driving the transmissivity recession curve (associated with an exponential decrease of saturated hydraulic conductivity with depth), the maximum root zone storage deficit, and the initial subsurface flow can be considered as the most sensitive ones. Observed and simulated high values of surface runoff due to the excess of infiltration suggest a high water storage capacity of the soil and dominance of subsurface runoff processes, consistent with the local characteristics of the soils in the region.
For designing of Ground Source Heating Systems (GSHS) Thermal Response Tests (TRT) are used for a long time. TRTs generally provide a profound basis for the final implementation of a GSHS. They obtain the effective thermal conductivity and thermal resistance of a borehole. Until today several TRT types have been introduced and defined as Geothermal Response Test (GRT), Enhanced GRT (EGRT), Constant Heat Flux TRT (chTRT), Constant temperature (ctTRT ) etc.. These models mainly focus on closed heat exchangers in shallow boreholes. However, recent developments in medium depth drilling technologies make deeper boreholes more economic. Furthermore, advanced methodologies for obtaining thermal conductivities in deep and open boreholes are progressing. In this study, we introduce a new simple thermal conductivity obtaining methodology that can be used for deep and open boreholes. Generally, TRTs are applied with the circulation of water inside pipes or immersing probes in water. In case of water circulation in deep boreholes, different heat flux values will be attributed to different layers. Moreover, by introducing a constant heat flux similar to conventional TRT into water-filled boreholes or water-filled pipes, convective movements of water will occur and thermal conductivities cannot be obtained. However, immersed probes as a heat source might prevent water convection cells inside a pipe or a borehole. In deep boreholes, the heat flux is depended on the thermal conductivity of each layer. Thus, deep boreholes require a discrete heat introduction into every single layer of different thermal conductivity in order to keep the temperature constant. The thermal conductivity of each layer can be approximated and integrated over the total length of a deep borehole. This effect is analytically and numerically investigated in this study.
In remote sensing, being able to ensure the accuracy of the satellite data being produced remains an issue; this is especially true for phenological variables such as the Fraction of Photosynthetically Active Radiation (FPAR). FPAR, which is considered an essential climate variable by the Global Terrestrial Observation System (GTOS), utilizes the 400–700 nm wavelength range to quantify the total amount of solar radiation available for photosynthetic use. It is a variable that is strongly influenced by the seasonal, diurnal, and optic properties of vegetation making it an accurate representation of vegetation health. Measurements of ground level FPAR can be completed using flux towers along with a limited number of wireless ground sensors, but due to the finite number and location of these towers, many research initiatives instead use the Moderate Resolution Imaging Spectroradiometer (MODIS) FPAR product, which converts Leaf Area Index (LAI) to a FPAR value using Beer’s Law. This is done despite there being little consensus on whether this is the best method to use for all ecosystems and vegetation types. One particular ecosystem that has had limited study to determine the accuracy of the MODIS derived FPAR products are the Tropical Dry Forests (TDFs) of Latin America. This ecosystem undergoes drastic seasonal changes from leaf off during the dry season to green-up during the wet seasons. This study aims to test the congruency between the MODIS derived FPAR values and ground-based FPAR values in relation to growing season length, growing season start and end dates, the peak and mean of FPAR values, and overall growth/phenological trends at the Santa Rosa National Park Environmental Monitoring Super Site (SR-EMSS) in Costa Rica and FPAR MODIS products. We derive our FPAR from a Wireless Sensor Network (WSN) consisting of more than 50 nodes measuring transmitted PAR, temperature, relative humidity, and soil moisture over custom time intervals ranging from 2-Hz to 15 min since 2013. Our fundamental goal is to demonstrate how accurate and reflective the MODIS derived FPAR product is of TDF phenology. This will be the first step taken in identifying potential problems with the MODIS derived FPAR products over TDFs in the Americas.
Increase in concentration in the atmosphere of greenhouse gases (GHG) is considered as one of the possible reasons of climatic changes. Recently all their possible anthropogenic sources including artiﬁcial reservoirs are considered. The actual task is the inventory of GHG emissions various sources for possible reduction and parameterization of emission from the underlying surface to deﬁne the conditions of interaction with the atmosphere in climate models. The work concerned questions of time-spatial changes of contents and emission of methane from a surface of polytypic reservoirs. On the basis of comparison of the ﬁeld observations on the Mozhaisk and Gorky reservoirs the distinctions of contents and speciﬁc ﬂuxes of methane for reservoirs with various water residence time and hydrological regime are shown. Comparison with literary data has shown that emission rate from reservoirs of a boreal zone with slow water exchange can be underestimated.
Spatial and temporal flux data coverage have improved significantly in recent years, due to standardization, automation and management of data collection, and better handling of the generated data. With more stations and networks, larger data streams from each station, and smaller operating budgets, modern tools are required to effectively and efficiently handle the entire process. These tools should produce standardized verifiable datasets, and provide a way to cross-share the standardized data with external collaborators to leverage available funding, and promote data analyses and publications. In 2015, new open-path and enclosed flux measurement systems1 were developed, based on established gas analyzer models2,3, with the goal of improving stability in the presence of contamination over older models4, refining temperature control and compensation5,6, providing more accurate gas concentration measurements1, and synchronizing analyzer and anemometer data streams in a very careful manner7. In late 2017, the new open-path system was further refined to simplify hardware configuration, to significantly reduce power consumption and cost, and to prevent or considerably minimize flow distortion8 in the anemometer to increase data coverage. Additionally, all new systems incorporate complete automated on-site flux calculations using EddyPro® Software9 run by a weatherized remotely-accessible microcomputer to provide standardized traceable data sets for fluxes and supporting variables. This presentation will describe details and results from the latest field tests of the new flux systems, in comparison to older models and control reference instruments. References: 1 Burba G., W. Miller, I. Begashaw, G. Fratini, F. Griessbaum, J. Kathilankal, L. Xu, D. Franz, E. Joseph, E. Larmanou, S. Miller, D. Papale, S. Sabbatini, T. Sachs, R. Sakai, D. McDermitt, 2017. Comparison of CO2 Concentrations, Co-spectra and Flux Measurements between Latest Standardized Automated CO2/H2O Flux Systems and Older Gas Analysers. 10th ICDC Conference, Switzerland: 21-25/08 2 Metzger, S., G. Burba, S. Burns, P. Blanken, J. Li, H. Luo, R. Zulueta, 2016. Optimization of an enclosed gas analyzer sampling system for measuring eddy covariance fluxes of H2O and CO2. AMT, 9: 1341-1359 3 Burba, G., 2013. Eddy Covariance Method for Scientific, Industrial, Agricultural and Regulatory Applications. LI-COR Biosciences: 331 pp. 4 Fratini, G., McDermitt, D.K. and Papale, D., 2014. Eddy-covariance flux errors due to biases in gas concentration measurements: origins, quantification and correction. Biogeosciences, 11(4), pp.1037-1051. 5 McDermitt, D., J. Welles, and R. Eckles, 1993. Effects of temperature, pressure, and water vapor on gas phase infrared absorption by CO2. LI-COR, Inc. Lincoln, NE. 6 Welles, J. and D. McDermitt, 2005. Measuring carbon dioxide in the atmosphere. In: Hatfield J. and J. Baker (Eds.) Micrometeorology in Agricultural Systems. ASA-CSSA-SSSA, Madison, W
The physical mechanisms that govern preferential flow dynamics in unsaturated fractured rock formations are complex and not well understood. Fracture intersections are critical relay points along preferential flow paths and control the partitioning behavior, leading to temporal delay and intermittent flow. In this work, a three-dimensional Pairwise-Force Smoothed Particle Hydrodynamics (PF-SPH) model is being applied in order to simulate gravity- driven droplet flow at synthetic fracture intersections. SPH, as a mesh-less Lagrangian method, is particularly suitable for modeling deformable interfaces, such as three-phase contact dynamics of droplets. The static and dynamic contact angle can be recognized as the most important parameter of gravity-driven free-surface flow. In SPH, surface tension and adhesion naturally emerges from the implemented pairwise fluid-fluid (s_f f ) and solid- fluid (s_sf ) interaction force. The model was calibrated to a contact angle of 65 ◦ , which corresponds to the wetting properties of water on Poly(methyl methacrylate). The accuracy of the SPH simulations were validated against an analytical solution of Poiseuille flow between two parallel plates and against laboratory experiments. Using the SPH model, the complex flow mode transitions from droplet to rivulet flow of an experimental study were repro- duced. Additionally, laboratory dimensionless scaling experiments of water droplets were successfully replicated in SPH. Finally, SPH simulations were used to investigate the partitioning dynamics of single droplets into syn- thetic horizontal fractures with various apertures (∆d_f = 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 mm) and offsets (∆d_of f = 1.5, 1.0, 0.5, 0, 1.0, 2.0, 3.0 mm). The perfect conditions of ideally smooth surfaces and the SPH inherent advantage of particle tracking allow the recognition of small scale partitioning mechanisms and its importance for bulk flow behavior. The aim of this study is to derive an analytical correlation and interpretation of partitioning dynamics, droplet height and aperture
In the semi-arid extratropical Andes Cordillera, the seasonal snowpack acts as a natural water reservoir, releasing spring snowmelt runoff that accounts for more than 60 % of the total annual streamflow and sustains multiple productive uses, population needs, and unique ecosystems. Official seasonal streamflow forecasts (Sept-Mar runoff volumes) are currently generated by the General Water Directorate of Chile (DGA), based solely on regression-based methods that incorporate in-situ meteorological variables observed during winter as predictors. This work aims to assess the potential of the ensemble streamflow prediction (ESP) methodology for improved seasonal forecasts in high mountain basins in Central Chile, incorporating simple post-processing methods. To this end, we apply the GR4J rainfall-runoff model, as implemented in the airGR package, combined with the snow accumulation and ablation model CemaNeige in a set of case study basins. Preliminary results show that ESP forecast errors are smaller than those produced by the General Water Directorate of Chile (DGA). Ongoing efforts are aimed to identify potential differences and shortcomings in these techniques – using different verification measures – in terms of their capability to harness climatic and hydrologic sources of predictability.
Natural coastal foredune systems often contain blowouts, through which beach sand is blown into the more landward dunes. Along many developed coasts, blowouts have long been considered a safety hazard, endangering the strength of the foredune as the primary sea defense. Natural blowouts have thus been actively vegetated to promote sand accumulation in the foredune. Recent studies have, however, illustrated that the cessation of sand input in the landward dunes has contributed to a reduction in biodiversity. Nowadays, the safety of coastal foredunes can be assessed with sufficient accuracy allowing for the reintroduction of blowouts. As there is little knowledge on how to optimize blowout layout, the present approach is largely ‘learning by doing’. As a result, many different layouts, varying in blowout width, plan view and orientation, have been adopted in various dune restoration projects. The aim of this study is to model the airflow through an existing man-made blowout and to validate the model results using field observations. We expect that a better understanding of airflow patterns will help in optimizing the design of future blowouts as part of dune restoration projects. The open source Computational Fluid Dynamics (CFD) package OpenFOAM was used to model wind flow through a man-made trough blowout in Dutch National Park Zuid-Kennemerland. The length of the blowout extends roughly 100 m through the foredune; its width narrows from 100 m at the seaward entrance to 20 m at its narrowest part after which it widens again. The deepest part is around 7 m above mean sea level (MSL) while the crest of the surrounding foredune is at 21 m above MSL. The blowout orientation is nearly parallel to the dominant SW wind direction and oblique with respect to the approximately N-S coast line. The field data comprises long-term (many months) observations of wind speed and direction at four locations on the blowout basin and depositional lobe. The model is able to reproduce the observed topographical steering of the wind towards the blowout normal under oblique wind approach as well as the wind-speed acceleration toward the narrowest part of the blowout. Consistent with the observations, the degree of steering and acceleration depend strongly on the wind approach angle, not on the wind speed. As a next step we envision the modeling of different blowout topographies to determine the blowout shape that potentially maximizes the sand transport toward the landward dunes.
Due to heavy urbanisation, approaches in greener cities are required. This is addressed by a number of initiatives, including seeing the city as an ecosystem, and the dialogue between economy and ecology. Sustainable and resilient cites mean connection between the city and the landscape, bringing the landscape into the city, for example through nature based solutions such as green walls or through more open spaces which are green, such as urban parks. In this context the landscape quality of the city can be judged. The renewable energy in the city can relate to solar energy of the passive house which can be a house of heavy geomaterials. In this contribution the authors present their approach to sustainable and resilient cities, including the first author’s approach to renewable energy and landscape quality. The first author would like to thank the Inclusiveness Target Countries grant scheme for supporting participation in the conference to represent the COST Action TU1401 (http://www.cost-rely.eu/).
In a warmer world, the hydrological cycle will change in intensity and in its geographic behaviour. This, in turn, will change patterns of river flood and the risk associated with them. The Last Interglacial (LIG; 125,000 years ago) is the most recent instance of climate warmer than today - especially in the high northern latitudes-, sea level was higher, ice sheets were smaller and monsoons were stronger. We use daily output from multi-century LIG simulations of an ensemble of paleoclimate models, and study how global precipitation patterns and extremes deviate from the preindustrial climate. We validate these results by comparing them with the first compilation, to our knowledge, of global LIG precipitation patterns. Successively, we use the daily temperature and precipitation from the paleoclimate models to drive two global hydrological models (PCR-GLOBWB and CWATM), and simulate river discharges at 5-30’ resolution. With this, we force a hydrodynamic model, CaMa-Flood, and produce floods maps for different return periods. At the end of this model cascade, we look into what would happen if a climate similar to the LIG were to materialize in the coming decades: we combine the flood maps with maps of exposure through vulnerability relationships, and to calculate the risk that floods may pose to future people and assets.
The Chiapanecan Volcanic Arc it is located in the central portion of Chiapas in southern Mexico. This volcanic arc it is merge in a geological complex zone where the interaction of the North American, Caribbean and Cocos plates, near the Motagua-Polochic fault system takes place. The central part of the Chiapanecan Volcanic Arc it is conformed by at least 10 volcanic structures. In this study we focus on five volcanic domes known as La Iglesia, La Mispía, La Lanza, Venustiano Carranza and Santotón. It is described that the volcanic activity in the Chiapanecan Volcanic Arc was effusive accompanied by explosive and phreatomagmatic events. The main lithology varies from andesitic to dacitic rocks with porphyric texture. Both lithologies are mainly composed of euhedral amphibole, pyroxene subhedral plagioclase, as well as subhedral biotite as accessory mineral. It is possible to recognize mafic microgranular enclaves with ovoidal shapes within the andesitic rocks. This work aims to understand the petrological composition, the magmatic activity and its relationship with the subduction of the Cocos plate under the North American plate.
Blowouts are characteristic features of many natural coastal foredunes. These dynamic bowl- or trough-shaped depressions act as conduits for aeolian transport of beach sand into the more landward dunes. Along many inhabited coasts foredunes and their blowouts have been planted with vegetation to retain the sand in the foredune, facilitate blowout closure and hence function as sea defense. The resulting vegetated and uniform foredune has, subsequently, contributed to a widespread reduction in the biodiversity of the backdunes. Present-day dune management therefore increasingly involves artificially creating blowouts to maintain and improve backdune biodiversity. The design criteria are high, aiming to postpone or prevent blowout closure as long as possible. Such dune restoration projects often follow a learning-by-doing approach, as information on the underlying aeolian processes, including airflow patterns that steer blowout development, is scarce. Here, we focus on airflow patterns measured in a man-made trough blowout in Dutch National Park Zuid-Kennemerland excavated in winter 2012. The blowout is approximately 100 m long and up to 11 m deep, and has a trapezoidal plan view that narrows from 100 to 20 m in the landward direction. It is approximately aligned with the dominant southwesterly wind direction and hence obliquely with the roughly N-S coastline. Four ultrasonic 3D anemometers, sampling at 10 Hz, were installed in winter/spring 2017 from the mouth of the blowout, across its basin, on to the depositional lobe and have been operational since. The wind recordings at a nearby weather station operated by the Royal Netherlands Meteorological Institute serve as the offshore reference. Wind speed-up through the blowout varied with offshore wind approach angle, and was generally strongest (140%) when the wind was aligned with the blowout axis up to approximately 30° to the south of this axis. Intriguingly, winds approaching with the same angle from the north did not accelerate. We suspect that this asymmetry in speed-up is invoked by the asymmetric blowout shape, with a substantially steeper northern than southern sidewall. Wind deceleration on the lobe was also a function of offshore wind approach angle, with the largest deceleration (40%) for winds approaching from the north of the blowout axis. Winds with approach angles up to 70° were all steered into the blowout, to become approximately aligned with the blowout axis at the landward blowout end. On the lobe, however, the wind closely followed the offshore wind direction. Future work will focus on modelling air flow patterns with computational fluid dynamics, and exploring the relationship between the airflow patterns, blowout morphology and sand transport pathways using additional field observations.