| publications-2541 |
Peer reviewed articles |
2021 |
Jorrit P. Mesman, Julio A. A. Stelzer, Vasilis Dakos, Stéphane Goyette, Ian D. Jones, JérÎme Kasparian, Daniel F. McGinnis, Bas W. Ibelings |
The role of internal feedbacks in shifting deep lake mixing regimes under a warming climate |
Freshwater Biology |
10.1111/fwb.13704 |
Data Management & Analytics |
Natural Water Bodies |
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Abstract Climate warming is causing changes in the physics of deep lakes, such as longer summer stratification, increased water column stability, reduced ice cover, and a shallower depth of winter overturns. An ultimate consequence of warming would be a transition to a different mixing regime. Here we investigate the role of physical, chemical, and biological feedback mechanisms that unfold during a shift in mixing regime, and whether these feedbacks could prompt and stabilise the new regime. Although climate, interannual temperature variation, and lake morphometry are the main determinants of a mixing regime, when climate change causes shifts in mixing regime, internal feedback mechanisms may gain in importance and modify lake ecosystem functioning. We review the role of these feedbacks in three mixing regime shifts: from polymictic to seasonally stratified, from dimictic to monomictic, and from holomictic to oligomictic or meromictic. Polymictic lakes of intermediate depth (c. 3â10Â m mean depth) could experience seasonal stratification if a stratification event triggers phytoplankton blooms or dissolved organic matter release, reducing transparency and therefore further heating the surface layer. However, this feedback is only likely to have influence in small and clear lakes, it would be easily disturbed by weather conditions, and the resulting stratified state does not remain stable in the long term, as stratification is lost in winter. The iceâalbedo feedback might cause an accelerated shift from iceâcovered (dimictic) to iceâfree (monomictic) winters in sufficiently deep (mean depth 50Â m or more) lakes, where temperature memory is carried over from one winter to the next. Nevertheless, there is an ongoing debate into whether this process can persist during natural weather variations and overcome selfâstabilising mechanisms such as thermal insulation by snow. The majority of studies suggest that a gradual transition from dimictic to monomictic is more likely than an abrupt transition. A shift from a holomictic to a meromictic regime can occur if anoxia is triggered by incomplete mixing and an increase in deepâwater densityâthrough the accumulation of solutesâexceeds a density decrease by hypolimnetic warming. A shift to meromixis would strongly alter the biology of a lake and might be difficult to reverse. If solutes accumulate only minimally in the hypolimnion, an oligomictic regime is formed, in which years with complete and incomplete mixing alternate. Understanding the importance of feedback mechanisms and the role of biogeochemistry when lakes shift in mixing regime could lead to a better understanding of how climate change affects lake ecosystems. |
722518 |
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| publications-2542 |
Peer reviewed articles |
2020 |
JesĂșs Chazarra-Zapata, JosĂ© Miguel Molina-MartĂnez, Francisco-Javier PĂ©rez de la Cruz, Dolores Parras-Burgos, Antonio RuĂz Canales |
How to Reduce the Carbon Footprint of an Irrigation Community in the South-East of Spain by Use of Solar Energy |
Energies |
10.3390/en13112848 |
IoT & Sensors |
Water Distribution Networks |
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The climate change that plagues the world is causing extended periods of water shortage. This situation is forcing farmers in the region of Murcia in Spain to modernize their irrigation systems to optimize use of the scarce water they have and seek a circular water economy using the recovered water. Moreover, an associated problem is the need for energy that these facilities require in order to pressurize the required water. The use of photovoltaic generation contributes to the reduction of greenhouse gas (GHG) emissions. Food produced in this region tends to have guaranteed markets in Europe and, geographically, due to the high quality of phytosanitary controls and traceability during their marketing, their optimal cultivation, and selection and labelling is verified, specifying valuable information such as: collection date, origin, the use of organic fertilizers among others. To maintain market access, it is important to continue implementing other environmental improvements, i.e., reductions in either hydro or carbon footprints. Previous studies have failed to include the prospect of environmental use of isolated facilities to replace existing consumption, seeking the monetarization of the facility as well as prioritizing the reduction of GHG. Previous studies have failed to include the perspective of environmental use of isolated photovoltaic installations, based on existing consumption, thus, going beyond the monetarization of the facility, to prioritize the reduction of GHG applied in practice by environmentally sensitized farmers. This study was conducted in an existing facility with great technical complexity and three different sources of water supply, over 1500 plots and an altitude range in plots and reservoirs of more than 400 m. |
734560 |
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| publications-2543 |
Peer reviewed articles |
2020 |
JesĂșs Chazarra-Zapata, Dolores Parras-Burgos, Carlos Arteaga, Antonio Ruiz-Canales, JosĂ© Miguel Molina-MartĂnez |
Adaptation of a Traditional Irrigation System of Micro-Plots to Smart Agri Development: A Case Study in Murcia (Spain) |
Agronomy |
10.3390/agronomy10091365 |
Data Management & Analytics |
River Basins |
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Currently, water users associations (WUAs) in semi-arid areas of southeastern Spain (Murcia region) send a multitude of data supplied by sensors in the field to the cloud. The constant technological revolution offers opportunities for small farms not to be abandoned, thanks to the Internet of Things (IoT). This technology allows them to continue to manage remotely using smartphones/tablets/laptops. This new system contributes to the mitigation of climate change from several aspects: reduction of water footprint and energy consumption (in the pumps that pressurize the grid, such as in the optimization of the proposed solution, by using batteries that communicate in low radiation of electric and magnetic alternating fields (LoRad), General Packet Radio Service (GPRS), or narrowband IoT (NB-IoT), or clean energy). The analysis of these data and the incorporation of new IoT technologies facilitate the maintenance of green roofs and ensure the continuity of these farms. The direct benefit obtained is remarkable CO2 removal that prevents desertification by the abandonment of arable land. This communication shows the implementation of a Smart Agri system in areas with micro-plots (surface less than 0.5 ha) with low-cost technology based on long-range (LoRa) systems, easily maintainable by personnel with basic knowledge of automation, which transforms into a very interesting solution for regions with development roads. In addition, complex orography and difficult access are added in both physical and technological environments. The main technical limitations found in such plots are poor coverage for mobile phones and unworkable and expensive implementation by wiring or WiFi/radio systems. Currently, thanks to the Smart Agri system implemented in this WUA in Murcia, farmers can manage and control the irrigation systems in their plots from home. Then, they cannot lose their crops and respect the isolation conditions imposed by the Spanish government as a result of the alarm caused by COVID-19. |
734560 |
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| publications-2544 |
Peer reviewed articles |
2020 |
JesĂșs Chazarra-Zapata, Dolores Parras-Burgos, Francisco-Javier PĂ©rez-de-la-Cruz, Antonio RuĂz-Canales, JosĂ© Miguel Molina-MartĂnez |
Reducing the Carbon Footprint of the Water-Energy Binomial through Governance and ICT. A Case Study |
Water |
10.3390/w12113187 |
Data Management & Analytics |
Water Distribution Networks |
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This paper reveals reductions of up to 485 t CO2 eq (CO2 equivalent) of greenhouse gas (GHG) emissions of energy origin associated with the water-energy binomial which can be achieved after modernizing and automating a Water User Association (WUA) of over 1780 users with microplots in a total area of 775 ha in southeastern Spain. This case study aims to show how the latest advances in information and communication technologies (ICTs) for precision agriculture are being applied efficiently with the implementation of a Smart Agri system, capable of making improvements through the use of renewable energies (64.49% of the total CO2e- avoided), automation in irrigation water management, by applying adequate governance, use of ICTs (731,014 m3 per water footprint reduction with 20.41% of total CO2 eq of associated electrical origin), hydraulic improvements (283,995 m3 per water footprint reduction, 13.77% of the total CO2 eq of associated electrical origin) and reduction of evaporation in reservoirs (26,022 m3 of water by water footprint reduction with 1.33% of the total CO2 eq electrical origin avoided) that act as batteries to accumulate the daily solar energy and enable watering at night, when irrigation is most efficient. It is important to consider the valuable contribution of these artificial green lungs, not only in terms of food for the European Union, but also as a CO2 eq sink that supports the planetâs GHGs. As shown in this study, this is made possible by the joint governance led by the Water Users Association (WUA) and co-led by different management organizations with the support of ICT. |
734560 |
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| publications-2545 |
Peer reviewed articles |
2021 |
R. Ian Acworth, Gabriel C. Rau, Mark O. Cuthbert, Keith Leggett, Martin S. Andersen |
Runoff and focused groundwater-recharge response to flooding rains in the arid zone of Australia |
Hydrogeology Journal |
10.1007/s10040-020-02284-x |
Simulation & Modeling |
River Basins |
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AbstractA groundwater recharge investigation in the arid zone of Australia is presented. The investigation used a wide range of hydrogeological techniques including geological mapping, surface and borehole geophysics, groundwater hydraulics, streambed temperature and pressure monitoring, and hydrogeochemical and environmental tracer sampling, and it was complemented by analysis of rainfall intensity from 18 tipping-bucked rain gauges, climate data and stream runoff measurements. Run-off and recharge from a 200-mm rainfall event in January 2015, the largest daily rainfall in the local 50-year record, were investigated in detail. While this major storm provided substantial run-off as a potential source for focused, indirect recharge, it only produced enough actual recharge to the shallow aquifer to temporarily halt a long-term groundwater recession. A series of smaller rainfall-runoff events in 2016 produced a similar recharge response. The results suggest that the total magnitude of a flood event is not the main control on indirect groundwater recharge at this location. A deeper aquifer shows no hydraulic response to surface-water flow events and is isolated from the shallow system, consistent with its Pleistocene groundwater age. This supports a growing body of evidence indicating that attributing or predicting generalised changes in recharge to changes in climate in dryland environments should not be attempted without first unravelling the dynamic processes governing groundwater recharge in the locality of interest. The results should prompt more detailed and long-term field investigation in other arid zone locations to further understand the episodic and nonlinear nature of recharge in such environments. |
835852 |
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| publications-2546 |
Peer reviewed articles |
2021 |
Daniel Schweizer, Vincent Ried, Gabriel C. Rau, Jonathan E. Tuck, Petre Stoica |
Comparing Methods and Defining Practical Requirements for Extracting Harmonic Tidal Components from Groundwater Level Measurements |
Mathematical Geosciences |
10.1007/s11004-020-09915-9 |
Simulation & Modeling |
Natural Water Bodies |
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AbstractThe groundwater pressure response to the ubiquitous Earth and atmospheric tides provides a largely untapped opportunity to passively characterize and quantify subsurface hydro-geomechanical properties. However, this requires reliable extraction of closely spaced harmonic components with relatively subtle amplitudes but well-known tidal periods from noisy measurements. The minimum requirements for the suitability of existing groundwater records for analysis are unknown. This work systematically tests and compares the ability of two common signal processing methods, the discrete Fourier transform (DFT) and harmonic least squares (HALS), to extract harmonic component properties. First, realistic conditions are simulated by analyzing a large number of synthetic data sets with variable sampling frequencies, record durations, sensor resolutions, noise levels and data gaps. Second, a model of two real-world data sets with different characteristics is validated. The results reveal that HALS outperforms the DFT in all aspects, including the ability to handle data gaps. While there is a clear trade-off between sampling frequency and record duration, sampling rates should not be less than six samples per day and records should not be shorter than 20 days when simultaneously extracting tidal constituents. The accuracy of detection is degraded by increasing noise levels and decreasing sensor resolution. However, a resolution of the same magnitude as the expected component amplitude is sufficient in the absence of excessive noise. The results provide a practical framework to determine the suitability of existing groundwater level records and can optimize future groundwater monitoring strategies to improve passive characterization using tidal signatures. |
835852 |
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| publications-2547 |
Peer reviewed articles |
2020 |
Manuel A. Gossler, Peter Bayer, Gabriel C. Rau, Florian Einsiedl, Kai Zosseder |
On the Limitations and Implications of Modeling Heat Transport in Porous Aquifers by Assuming Local Thermal Equilibrium |
Water Resources Research |
10.1029/2020wr027772 |
Simulation & Modeling |
Natural Water Bodies |
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AbstractHeat transport in natural porous media, such as aquifers or streambeds, is generally modeled assuming local thermal equilibrium (LTE) between the fluid and solid phases. Yet, the mathematical and hydrogeological conditions and implications of this simplification have not been fully established for natural porous media. To quantify the occurrence and effects of local thermal disequilibrium during heat transport, we systematically compared thermal breakthrough curves from a LTE with those calculated using a local thermal nonequilibrium (LTNE) model, explicitly allowing for different temperatures in the fluid and solid phases. For the LTNE model, we developed a new correlation for the heat transfer coefficient representative of the conditions in natural porous aquifers using six published experimental results. By conducting an extensive parameter study (>50,000 simulations), we show that LTNE effects do not occur for grain sizes smaller than 7 mm or for groundwater flow velocities that are slower than 1.6 m dayâ1. The limits of LTE are likely exceeded in gravel aquifers or in the vicinity of pumped bores. For such aquifers, the use of a LTE model can lead to an underestimation of the effective thermal dispersion by a factor of up to 30 or higher, while the advective thermal velocity remains unaffected for most conditions. Based on a regression analysis of the simulation results, we provide a criterion which can be used to determine if LTNE effects are expected for particular conditions. |
835852 |
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| publications-2548 |
Peer reviewed articles |
2021 |
Hares Khan, Alo Laas, Rafael Marcé, Margot Sepp, Biel Obrador |
Eutrophication and Geochemistry Drive Pelagic Calcite Precipitation in Lakes |
Water |
10.3390/w13050597 |
Data Management & Analytics |
Natural Water Bodies |
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Pelagic calcification shapes the carbon budget of lakes and the sensitivity of dissolved inorganic carbon (DIC) responses to lake metabolism. This process, being tightly linked to primary production, needs to be understood within the context of summer eutrophication which is increasing due to human stressors and global change. Most lake carbon budget models do not account for calcification because the conditions necessary for its occurrence are not well constrained. This study aims at identifying ratios between calcification and primary production and the drivers that control these ratios in freshwater. Using in situ incubations in several European freshwater lakes, we identify a strong relationship between calcite saturation and the ratio between calcification and net ecosystem production (NEP) (p-value < 0.001, R2 = 0.95). NEP-induced calcification is a short-term process that is potentiated by the increase in calcite saturation occurring at longer time scales, usually reaching the highest levels in summer. The resulting summer calcification event has effects on the DIC equilibria, causing deviations from the metabolic 1:1 stoichiometry between DIC and dissolved oxygen (DO). The strong dependency of the ratio between NEP and calcification on calcite saturation can be used to develop a suitable parameterization to account for calcification in lake carbon budgets. |
722518 |
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| publications-2549 |
Peer reviewed articles |
2020 |
Gabriel C. Rau, Mark O. Cuthbert, R. Ian Acworth, Philipp Blum |
Technical note: Disentangling the groundwater response to Earth and atmospheric tides to improve subsurface characterisation |
Hydrology and Earth System Sciences |
10.5194/hess-24-6033-2020 |
Data Management & Analytics |
Groundwater |
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Abstract. The groundwater response to Earth tides and atmospheric pressure changes can be used to understand subsurface processes and estimate hydraulic and hydro-mechanical properties. We develop a generalised frequency domain approach to disentangle the impacts of Earth and atmospheric tides on groundwater level responses. By considering the complex harmonic properties of the signal, we improve upon a previous method for quantifying barometric efficiency (BE), while simultaneously assessing system confinement and estimating hydraulic conductivity and specific storage. We demonstrate and validate this novel approach using an example barometric and groundwater pressure record with strong Earth tide influences. Our method enables improved and rapid assessment of subsurface processes and properties using standard pressure measurements. |
835852 |
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| publications-2550 |
Peer reviewed articles |
2020 |
Julian Bruns, Florian Micklich, Johannes Kutterer, Andreas Abecker, Philipp Zehnder |
Spatial Operators for Complex Event Processing |
GI_Forum |
10.1553/giscience2020_02_s107 |
Simulation & Modeling |
River Basins |
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No abstract available |
820985 |
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