scholarly journals Post-Closure Safety Analysis of Nuclear Waste Disposal in Deep Vertical Boreholes

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6356
Author(s):  
Stefan Finsterle ◽  
Richard A. Muller ◽  
John Grimsich ◽  
Ethan A. Bates ◽  
John Midgley
Keyword(s):  
Land Surface ◽  
Spent Nuclear Fuel ◽  
Hydrological Cycle ◽  
Decay Chain ◽  
Geothermal Gradient ◽  
Great Depth ◽  
Salinity Stratification ◽  
Integrated Simulation ◽  
Safety Features ◽  
The Impact

Isolation of spent nuclear fuel assemblies in deep vertical boreholes is analyzed. The main safety features of the borehole concept are related to the repository’s great depth, implying (a) long migration distances and correspondingly long travel times, allowing radionuclides to decay, (b) separation of the repository from the dynamic hydrological cycle near the land surface, (c) stable geological and hydrogeological conditions, and (d) a geochemically reducing environment. An integrated simulation model of the engineered and natural barrier systems has been developed to examine multiple scenarios of the release of radionuclides from the waste canisters, the transport through a fractured porous host rock, and the extraction of potentially contaminated drinking water from an aquifer. These generic simulations include thermal effects from both the natural geothermal gradient and the heat-generating waste, the influence of topography on regional groundwater flow, moderated by salinity stratification at depth, and the role of borehole sealing. The impact of these processes on the transport of select radionuclides is studied, which include long-lived, soluble, sorbing or highly mobile isotopes along with a decay chain of safety-relevant actinide metals. The generic analyses suggest that a deep vertical borehole repository has the potential to be a safe option for the disposal of certain waste streams, with the depth itself and the stable hydrogeological environment encountered in the emplacement zone providing inherent long-term isolation, which allows for reduced reliance on a complex engineered barrier system.

Land-surface feedbacks on temperature and precipitation in CMIP6-LS3MIP projections

2021 ◽  
Author(s):  
Franco Catalano ◽  
Andrea Alessandri ◽  
Wilhelm May ◽  
Thomas Reerink
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Land Surface ◽  
Hydrological Cycle ◽  
Climate Change Signal ◽  
Moisture Change ◽  
Climate Conditions ◽  
Temperature And Precipitation ◽  
Systematic Biases ◽  
The Impact

<p align="justify"><span>The Land Surface, Snow and Soil Moisture Model Intercomparison Project (LS3MIP) aims at diagnosing systematic biases in the land models of CMIP6 Earth System Models and assessing the role of land-atmosphere feedbacks on climate change. Two components of experiments have been designed: the first is devoted to the assessment of the systematic land biases in offline mode (LMIP) while the second component is dedicated to the analysis of the land feedbacks in coupled mode (LFMIP). Here we focus on the LFMIP experiments. In the LFMIP protocol (van den Hurk et al. 2016), which builds upon the GLACE-CMIP configuration, two sets of climate-sensitivity projections have been carried out in amip mode: in the first set (amip-lfmip-pdLC) the land feedbacks to climate change have been disabled by prescribing the soil-moisture states from a climatology derived from “present climate conditions” (1980-2014) while in the second set (amip-lfmip-rmLC) 30-year running mean of land-surface state from the corresponding ScenarioMIP experiment (O’Neill et al., 2016) is prescribed. The two sensitivity simulations span the period 1980-2100 with sea surface temperature and sea-ice conditions prescribed from the first member of historical and ScenarioMIP experiments. Two different scenarios are considered: SSP1-2.6 (f1) and SSP5-8.5 (f2).</span></p><p align="justify"><span>In this analysis, we focus on the differences between amip-lfmip-rmLC and amip-lfmip-pdLC at the end of the 21st Century (2071–2100) in order to isolate the impact of the soil moisture changes on surface climate change. The (2071-2100) minus (1985-2014) temperature change is positive everywhere over land and the climate change signal of precipitation displays a clear intensification of the hydrological cycle in the Northern Hemisphere. Warming and hydrological cycle intensification are larger in SSP5-8.5 scenario. Results show large differences in the feedbacks between wet, transition and semi-arid climates. In particular, over the regions with negative soil moisture change, the 2m-temperature increases significantly while the cooling signal is not significant over all the regions getting wetter. In agreement with Catalano et al. (2016), the larger effects on precipitation due to soil moisture forcing occur mostly over transition zones between dry and wet climates, where evaporation is highly sensitive to soil moisture. The sensitivity of both 2m-temperature and precipitation to soil moisture change is much stronger in the SSP5-8.5 scenario.</span></p>

The ‘global tree restoration potential’: a first estimation of the hydrological effects

2021 ◽  
Author(s):  
Anne J. Hoek van Dijke ◽  
Imme Benedict ◽  
Kaniska Mallick ◽  
Martin Herold ◽  
Miriam Machwitz ◽  
...  
Keyword(s):  
Water Availability ◽  
Land Surface ◽  
Hydrological Cycle ◽  
Local Maximum ◽  
Atmospheric Moisture ◽  
Moisture Recycling ◽  
Restoration Potential ◽  
Tracking Model ◽  
The Impact ◽  
Hydrological Effects

<p>Vegetation plays an important role in the exchange of water between the land surface and the atmosphere through evaporation and redistribution of water. Hence, changes in vegetation cover alter the terrestrial hydrological cycle. Large-scale forest restoration is an effective climate change mitigation strategy through carbon sequestration and is expected to impact the water availability. A better understanding of the impact of reforestation is needed, given the numerous different reforestation missions.</p><p>Our study aims to provide an estimation of the hydrological effects of 900 million hectares of reforestation, called the ‘<em>global tree restoration potential</em>’ (Bastin et al., 2019). We include the effects of forest planting on evaporation and moisture recycling, where evaporation effects local water availability, and moisture recycling effects both local and remote water availability. We used the conventional Budyko’s moisture index framework to calculate the effects of reforestation on evaporation, and afterwards we used the UTrack dataset to calculate the changes in precipitation. The UTrack dataset presents the monthly climatological mean atmospheric moisture flows from evaporation to precipitation and is created using the Lagrangian moisture tracking model UTrack (Tuinenburg et al., 2020).</p><p>The results show that reforesting the ‘<em>global tree restoration potential</em>’ would effect water availability for most of the Earth’s surface. The global mean increase in terrestrial evaporation is 8 mm yr<sup>-1</sup>. The increase in evaporation is highest around the equator (on average 20 mm yr<sup>-1</sup>), with local maximum changes of up to 200 mm yr<sup>-1</sup>. This is related to a relatively high restoration potential in low latitude areas, and a generally large evaporation response in high precipitation regions. Enhanced moisture recycling has the potential to partly compensate for this decreased water availability by increasing the downwind precipitation.</p><p> </p><p>Bastin, J.-F., Finegold, Y., Garcia, C., Mollicone, D., Rezende, M., Routh, D., Zohner, C.M., Crowther, T.W. The global tree restoration potential. Science, 365, 76-79, http://doi.org/10.1126/science.aax0848, 2019.</p><p>Tuinenburg, O. A., Theeuwen, J. J. E., and Staal, A.: High-resolution global atmospheric moisture connections from evaporation to precipitation, Earth Syst. Sci. Data, 12, 3177–3188, https://doi.org/10.5194/essd-12-3177-2020, 2020.</p>

scholarly journals "Blueprint" for the UP Modelling System for Large Scale Hydrology

1997 ◽  
Vol 1 (1) ◽  
pp. 55-69 ◽  
Author(s):  
J. Ewen
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Weather Forecasting ◽  
Hydrological Cycle ◽  
Sufficient Information ◽  
Forecasting Models ◽  
Wide Range ◽  
Physically Based ◽  
Up Elements ◽  
The Impact

Abstract. There are at least two needs to be met by the current research efforts on large scale hydrological modelling. The first is for practical conceptual land-surface hydrology schemes for use with existing operational climate and weather forecasting models, to replace the overly simple schemes often used in such models. The second is for models of large scale hydrology which are properly sensitive to changes in physical properties and inputs measured (or predicted) over a wide range of scales, from the point-scale upwards, yet are simple enough in structure to be coupled to climate and weather forecasting models. Such models of large scale hydrology are needed for studying the environmental impact of pollution and changes in climate and land-use, especially the impact On water resources. The UP system (name derived from Upsealed Physically-based) is an attempt to satisfy the second need. It uses a physically-based approach and has a simple structure, yet incorporates sufficient information on sub-grid behaviour to make it a useful tool for the study of environmental impacts over a wide range of scales. The system uses a new approach to large scale modelling, giving physically-based predictions of hourly flows, storages, saturated areas, etc., for regions covering hundreds of thousands of square kilometres. The basic component of the system is the UP element. This has seven water storage compartments (one each for the snowpack, vegetation canopy, surface water, root zone, unsaturated percolation, interflow and groundwater) and allows all the main processes of the terrestrial phase of the hydrological cycle to be represented. A region is modelled as a collection of UP elements, linked by a river routing scheme. Each compartment represents a fixed zone within the area covered by the UP element, and each is related to a physical process such as groundwater flow. Most of the parameterizations for the compartments are in the form of look-up tables, linking the outputs from the compartments to state variables such as the current storage in the compartment. These parameterizations are, in the main, derived from results from physically-based, distributed models applied to the zones (e.g. a groundwater compartment is parameterized using a groundwater model). For large regions modelled using many UP elements, the UP parameters are regionalized using a classification scheme, thus reducing the overall effort spent in parameterization. The development of the UP system is a long-term project involving research into physically-based parameterization of large scale hydrology models, including the effects of sub-grid spatial variations. The first stage involved developing a "blueprint" for the UP element, based on experience with physically-based, distributed river basin modelling and reviews of existing techniques and modelling approaches for large scale and linked atmosphere-hydrology modelling. This paper describes the UP element and the concepts and ideas behind the development of the UP system and, briefly, describes some of the research and development work currently in progress on UP and its parameterization.

scholarly journals An Initial Intercomparison of Atmospheric and Oceanic Climatology for the ICE-5G and ICE-4G Models of LGM Paleotopography

2006 ◽  
Vol 19 (1) ◽  
pp. 3-14 ◽  
Author(s):  
F. Justino ◽  
A. Timmermann ◽  
U. Merkel ◽  
W. R. Peltier
Keyword(s):  
North America ◽  
Last Glacial Maximum ◽  
Land Surface ◽  
Hydrological Cycle ◽  
Ice Sheet ◽  
Glacial Maximum ◽  
Positive Temperature ◽  
Last Glacial ◽  
The Impact ◽  
Ice Sheet Topography

Abstract This paper investigates the impact of the new ICE-5G paleotopography dataset for Last Glacial Maximum (LGM) conditions on a coupled model simulation of the thermal and dynamical state of the glacial atmosphere and on both land surface and sea surface conditions. The study is based upon coupled climate simulations performed with the ocean–atmosphere–sea ice model of intermediate-complexity Climate de Bilt-coupled large-scale ice–ocean (ECBilt-Clio) model. Four simulations focusing on the Last Glacial Maximum [21 000 calendar years before present (BP)] have been analyzed: a first simulation (LGM-4G) that employed the original ICE-4G ice sheet topography and albedo, and a second simulation (LGM-5G) that employed the newly constructed ice sheet topography, denoted ICE-5G, and its respective albedo. Intercomparison of the results obtained in these experiments demonstrates that the LGM-5G simulation delivers significantly enhanced cooling over Canada compared to the LGM-4G simulation whereas positive temperature anomalies are simulated over southern North America and the northern Atlantic. Moreover, introduction of the ICE-5G topography is shown to lead to a deceleration of the subtropical westerlies and to the development of an intensified ridge over North America, which has a profound effect upon the hydrological cycle. Additionally, two flat ice sheet experiments were carried out to investigate the impact of the ice sheet albedo on global climate. By comparing these experiments with the full LGM simulations, it becomes evident that the climate anomalies between LGM-5G and LGM-4G are mainly driven by changes of the earth’s topography.

scholarly journals Quantifying Recycled Moisture in Precipitation in Qilian Mountains

2021 ◽  
Vol 13 (23) ◽  
pp. 12943
Author(s):  
Zhuanxia Zhang ◽  
Guofeng Zhu ◽  
Hanxiong Pan ◽  
Zhigang Sun ◽  
Liyuan Sang ◽  
...  
Keyword(s):  
Land Surface ◽  
Hydrological Cycle ◽  
Qilian Mountains ◽  
Water Runoff ◽  
Qilian Mountain ◽  
Hydrothermal Conditions ◽  
Mountain Areas ◽  
Circulating Water ◽  
The Qilian Mountains ◽  
The Impact

Studies about the hydrological cycle based on basin or regional scales often ignore the uniqueness of recycling moisture in mountain areas, and little effort has been made to understand the impact of the local recycled moisture on precipitation in mountain areas. We collected and analyzed a series of samples (stable isotope of precipitation, soil water, plant water, runoff, and groundwater) in the Qilian Mountains, northwest of China. Based on the isotopic mixing model, the characteristics of recycled moisture in the Qilian Mountains were evaluated. The results showed that lateral advection moisture is the primary source of precipitation (83.5~98.38%). The contribution rate of recycled moisture to precipitation was higher in the spring, summer, and autumn (2.05~16.5%), and lower in the winter (1.62~3.32%). The contribution of recycled moisture to precipitation in the high-elevation areas (>2400 m) was higher than that in the foothills area (2100~2400 m). The contribution of vegetation transpiration (fTr) to precipitation in the east of Qilian Mountain was higher than that of the land surface evaporation (fEv). These proved that in the eastern part of Qilian Mountain, the arge-scale water cycle has a greater impact on precipitation in the area. The influence of local circulating water on precipitation dominated in the summer half of the year. Understanding the contribution of local circulating water to precipitation in the eastern part of Qilian Mountain will help us to understand the local hydrothermal conditions better and provide a basis for rationally arranging local agricultural production activities.

scholarly journals Impact of Urban Growth on Surface Climate: A Case Study in Oran, Algeria

2009 ◽  
Vol 48 (2) ◽  
pp. 217-231 ◽  
Author(s):  
Lahouari Bounoua ◽  
Abdelmounaine Safia ◽  
Jeffrey Masek ◽  
Christa Peters-Lidard ◽  
Marc L. Imhoff
Keyword(s):  
Land Use ◽  
Land Surface ◽  
Urban Areas ◽  
Hydrological Cycle ◽  
Total Carbon ◽  
Semiarid Region ◽  
Surface Model ◽  
Carbon Uptake ◽  
Mean Temperature ◽  
The Impact

Abstract The authors develop a land use map discriminating urban surfaces from other cover types over a semiarid region in North Africa and use it in a land surface model to assess the impact of urbanized land on surface energy, water, and carbon balances. Unlike in temperate climates where urbanization creates a marked heat island effect, this effect is not strongly marked in semiarid regions. During summer, the urban class results in an additional warming of 1.45°C during daytime and 0.81°C at night relative to that simulated for needleleaf trees under similar climate conditions. Seasonal temperatures show that urban areas are warmer than their surrounding areas during summer and slightly cooler in winter. The hydrological cycle is practically “shut down” during summer and is characterized by relatively large amounts of runoff in winter. The authors estimate the annual amount of carbon uptake to be 1.94 million metric tons with only 11.9% assimilated during the rainy season. However, if urbanization expands to reach 50% of the total area excluding forests, the annual total carbon uptake will decline by 35% and the July mean temperature would increase only 0.10°C relative to the current situation. In contrast, if urbanization expands to 50% of the total land excluding forests and croplands but all short vegetation is replaced by native broadleaf deciduous trees, the annual carbon uptake would increase by 39% and the July mean temperature would decrease by 0.9°C relative to the current configuration. These results provide guidelines for urban planners and land use managers and indicate possibilities for mitigating the urban heat.

scholarly journals Land Use/Land Cover Changes and Its Response to Hydrological Characteristics in the Upper Reaches of Minjiang River

2018 ◽  
Vol 379 ◽  
pp. 243-248
Author(s):  
Kai Ma ◽  
Xiaorong Huang ◽  
Biying Guo ◽  
Yanqiu Wang ◽  
Linyun Gao
Keyword(s):  
Land Use ◽  
Land Surface ◽  
Water Resource Management ◽  
Hydrological Cycle ◽  
Hydrological Process ◽  
Statistical Regression ◽  
Mean Flow ◽  
Hydrological Characteristics ◽  
Minjiang River ◽  
The Impact

Abstract. Land use changes alter the hydrological characteristics of the land surface, and have significant impacts on hydrological cycle and water balance, the analysis of complex effects on natural systems has become one of the main concerns. In this study, we generated the land use conversion matrixes using ArcGIS and selected several landscape indexes (contagion index, CONTAG, Shannon's diversity index, SHDI, etc.) to evaluate the impact of land use/cover changes on hydrological process in the upper reaches of Minjiang River. We also used a statistical regression model which was established based on hydrology and precipitation data during the period of 1959–2008 to simulate the impacts of different land use conditions on rainfall and runoff in different periods. Our results showed that the simulated annual mean flow from 1985 to 1995 and 1995 to 2008 are 9.19 and 1.04 m3 s−1 lower than the measured values, respectively, which implied that the ecological protection measures should be strengthened in the study area. Our study could provide a scientific basis for water resource management and proper land use planning of upper reaches of Minjiang River.

The Role of El Niño in Modulating the Effects of Deforestation in the Maritime Continent

2021 ◽  
Author(s):  
Tinghui lee ◽  
Minhui lo
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Land Use Changes ◽  
Critical Role ◽  
Atmospheric Environment ◽  
Maritime Continent ◽  
Deforestation Rate ◽  
Surface Warming ◽  
The Impact

<p>The deforestation rate in the Maritime Continent (MC) has been accelerating during the past several decades. Understanding the changes in local hydro-climatological cycles as deforestation takes place is essential because the MC is suffering from frequent and extreme droughts and fires, which often occur during the dry season and are more severe during El Niños. Therefore, this study explores how deforestation affects the hydrological cycle and precipitation in the MC during El Niños, focusing on the boreal autumn season and using the coupled atmosphere-land model simulations. It is found that the precipitation over the MC increases in the deforestation experiments, and the precipitation responses can be magnified during El Niño events. A strong subsidence anomaly associated with El Niño does not prevent enhanced convection associated with local deforestation. Instead, the subsidence reduces the cloud cover in the MC region during El Niño, which increases the incoming solar radiation and increases surface temperatures. Under a warmer environment induced by El Niño, the nonlinear biogeophysical feedbacks associated with deforestation also play a critical role in more substantial land surface warming. A warmer land surface induces a more unstable atmospheric environment associated with a tendency toward enhanced local convection and lateral moisture convergence. This study highlights how the different mean climate states may modulate the impact of local land-use changes on hydroclimatological cycles in the Maritime Continent, and sheds light on the state of our knowledge of interactions between the local land surface and remote large-scale atmospheric circulations.</p>

scholarly journals Assimilation of satellite data to optimize large scale hydrological model parameters: a case study for the SWOT mission

2014 ◽  
Vol 11 (4) ◽  
pp. 4477-4530
Author(s):  
V. Pedinotti ◽  
A. Boone ◽  
S. Ricci ◽  
S. Biancamaria ◽  
N. Mognard
Keyword(s):  
Land Surface ◽  
Water Surface ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Relative Bias ◽  
Water Levels ◽  
Model Parameters ◽  
Hydrological Data ◽  
The Impact

Abstract. During the last few decades, satellite measurements have been widely used to study the continental water cycle, especially in regions where in situ measurements are not readily available. The future Surface Water and Ocean Topography (SWOT) satellite mission will deliver maps of water surface elevation (WSE) with an unprecedented resolution and provide observation of rivers wider than 100 m and water surface areas greater than approximately 250 m × 250 m over continental surfaces between 78° S and 78° N. This study aims to investigate the potential of SWOT data for parameter optimization for large scale river routing models which are typically employed in Land Surface Models (LSM) for global scale applications. The method consists in applying a data assimilation approach, the Extended Kalman Filter (EKF) algorithm, to correct the Manning roughness coefficients of the ISBA-TRIP Continental Hydrologic System. Indeed, parameters such as the Manning coefficient, used within such models to describe water basin characteristics, are generally derived from geomorphological relationships, which might have locally significant errors. The current study focuses on the Niger basin, a trans-boundary river, which is the main source of fresh water for all the riparian countries. In addition, geopolitical issues in this region can restrict the exchange of hydrological data, so that SWOT should help improve this situation by making hydrological data freely available. In a previous study, the model was first evaluated against in-situ and satellite derived data sets within the framework of the international African Monsoon Multi-disciplinary Analysis (AMMA) project. Since the SWOT observations are not available yet and also to assess the proposed assimilation method, the study is carried out under the framework of an Observing System Simulation Experiment (OSSE). It is assumed that modeling errors are only due to uncertainties in the Manning coefficient. The true Manning coefficients are then supposed to be known and are used to generate synthetic SWOT observations over the period 2002–2003. The impact of the assimilation system on the Niger basin hydrological cycle is then quantified. The optimization of the Manning coefficient using the EKF algorithm over an 18 month period leads to a significant improvement of the river water levels. The relative bias of the water level is globally improved (a 30% reduction). The relative bias of the Manning coefficient is also reduced (40% reduction) and it converges towards an optimal value despite potential problems related to equifinality. Discharge is also improved by the assimilation, but to a lesser extent than for the water levels (7%). Moreover, the method allows a better prediction of the occurrence and intensity of flood events in the inner delta and shows skill in simulating the maxima and minima of water storage anomalies in several continental reservoirs, especially the groundwater and the aquifer reservoirs. Results obtained in this preliminary study demonstrate SWOT potential for global hydrologic modeling, especially to improve model parameters.

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