Spatial assessment of probable recharge areas – Investigating the hydrogeological controls of an active deep-seated gravitational slope deformation

Abstract. Continuous and slow-moving deep-seated landslides entail challenges for the effective planning of mitigation strategies aiming at the reduction of landslide movements. Given that the activity of most of these landslides is governed by pore pressure variations within the shear zone, profound knowledge about their hydrogeological control is required. In this context, the present study presents a new approach for the spatial assessment of probable recharge areas to better understand a slope's hydrogeological system. The highly automated geo-statistical approach allows deriving recharge probability maps of groundwater based on stable isotope monitoring and a digital elevation model (DEM). By monitoring stable isotopes in both, groundwater and precipitation, mean elevations of recharge areas can be determined and further constrained in space with the help of the DEM. The approach was applied to the Vögelsberg landslide, an active slab of a deep-seated gravitational slope deformation (DSGSD) in the Watten valley (Tyrol, Austria). Resulting recharge probability maps indicate that shallow groundwater emerging at springs on the landslide recharges between 1100–1500 m a.s.l.. In contrast, groundwater encountered in wells in up to 49 m below the landslide’s surface indicates a mean recharge elevation of up to 2200 m a.s.l. matching the highest parts of the catchment. Further inferred proxies, including flow path length, estimated recharge area sizes, and mean transit times of groundwater validated against field measurements of electrical conductivity, water temperature, and discharge resulted in a profound understanding of the hydrogeological driver of the landslide. It is shown that the new approach can provide valuable insights into the spatial pattern of probable recharge areas where mitigation measures aiming at reducing groundwater recharge could be most effective.

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Modeling Epidemic Spread among a Commuting Population Using Transport Schemes

Mathematics ◽

10.3390/math9161861 ◽

2021 ◽

Vol 9 (16) ◽

pp. 1861

Author(s):

Daniela Calvetti ◽

Alexander P. Hoover ◽

Johnie Rose ◽

Erkki Somersalo

Keyword(s):

Network Model ◽

Transport Theory ◽

Optimal Transport ◽

State Level ◽

Compartment Model ◽

Census Bureau ◽

Mitigation Strategies ◽

Mitigation Measures ◽

Metapopulation Model ◽

Infection Dynamics

Understanding the dynamics of the spread of COVID-19 between connected communities is fundamental in planning appropriate mitigation measures. To that end, we propose and analyze a novel metapopulation network model, particularly suitable for modeling commuter traffic patterns, that takes into account the connectivity between a heterogeneous set of communities, each with its own infection dynamics. In the novel metapopulation model that we propose here, transport schemes developed in optimal transport theory provide an efficient and easily implementable way of describing the temporary population redistribution due to traffic, such as the daily commuter traffic between work and residence. Locally, infection dynamics in individual communities are described in terms of a susceptible-exposed-infected-recovered (SEIR) compartment model, modified to account for the specific features of COVID-19, most notably its spread by asymptomatic and presymptomatic infected individuals. The mathematical foundation of our metapopulation network model is akin to a transport scheme between two population distributions, namely the residential distribution and the workplace distribution, whose interface can be inferred from commuter mobility data made available by the US Census Bureau. We use the proposed metapopulation model to test the dynamics of the spread of COVID-19 on two networks, a smaller one comprising 7 counties in the Greater Cleveland area in Ohio, and a larger one consisting of 74 counties in the Pittsburgh–Cleveland–Detroit corridor following the Lake Erie’s American coastline. The model simulations indicate that densely populated regions effectively act as amplifiers of the infection for the surrounding, less densely populated areas, in agreement with the pattern of infections observed in the course of the COVID-19 pandemic. Computed examples show that the model can be used also to test different mitigation strategies, including one based on state-level travel restrictions, another on county level triggered social distancing, as well as a combination of the two.

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Design of COVID-19 staged alert systems to ensure healthcare capacity with minimal closures

Nature Communications ◽

10.1038/s41467-021-23989-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Haoxiang Yang ◽

Özge Sürer ◽

Daniel Duque ◽

David P. Morton ◽

Bismark Singh ◽

...

Keyword(s):

Hospital Admissions ◽

Optimal Strategies ◽

Mitigation Strategies ◽

Mitigation Measures ◽

Public Confidence ◽

Proof Of Concept ◽

Alert System ◽

System Safety ◽

Reducing Costs ◽

Restrictive Measures

AbstractCommunity mitigation strategies to combat COVID-19, ranging from healthy hygiene to shelter-in-place orders, exact substantial socioeconomic costs. Judicious implementation and relaxation of restrictions amplify their public health benefits while reducing costs. We derive optimal strategies for toggling between mitigation stages using daily COVID-19 hospital admissions. With public compliance, the policy triggers ensure adequate intensive care unit capacity with high probability while minimizing the duration of strict mitigation measures. In comparison, we show that other sensible COVID-19 staging policies, including France’s ICU-based thresholds and a widely adopted indicator for reopening schools and businesses, require overly restrictive measures or trigger strict stages too late to avert catastrophic surges. As proof-of-concept, we describe the optimization and maintenance of the staged alert system that has guided COVID-19 policy in a large US city (Austin, Texas) since May 2020. As cities worldwide face future pandemic waves, our findings provide a robust strategy for tracking COVID-19 hospital admissions as an early indicator of hospital surges and enacting staged measures to ensure integrity of the health system, safety of the health workforce, and public confidence.

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Assessing Soil Loss by Water Erosion in a Typical Mediterranean Ecosystem of Northern Greece under Current and Future Rainfall Erosivity

Water ◽

10.3390/w13152002 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2002

Author(s):

Stefanos Stefanidis ◽

Vasileios Alexandridis ◽

Chrysoula Chatzichristaki ◽

Panagiotis Stefanidis

Keyword(s):

Open Source ◽

Soil Loss ◽

Renewable Resource ◽

Mitigation Strategies ◽

Mitigation Measures ◽

Mediterranean Ecosystem ◽

Rainfall Erosivity ◽

Negative Consequences ◽

Northern Greece ◽

Erosion Risk

Soil is a non-renewable resource essential for life existence. During the last decades it has been threatened by accelerating erosion with negative consequences for the environment and the economy. The aim of the current study was to assess soil loss changes in a typical Mediterranean ecosystem of Northern Greece, under climate change. To this end, freely available geospatial data was collected and processed using open-source software package. The widespread RUSLE empirical erosion model was applied to estimate soil loss. Current and future rainfall erosivity were derived from a national scale study considering average weather conditions and RCMs outputs for the medium Representative Concentration Pathway scenario (RCP4.5). Results showed that average rainfall erosivity (R-Factor) was 508.85 MJ mm ha h−1 y−1 while the K-factor ranged from 0.0008 to 0.05 t ha h ha−1 MJ−1 mm−1 and LS-factor reached 60.51. Respectively, C-factor ranged from 0.01 to 0.91 and P-factor ranged from 0.42 to 1. The estimated potential soil loss rates will remain stable for the near future period (2021–2050), while an increase of approximately 9% is expected by the end of the 21th century (2071–2100). The results suggest that appropriate erosion mitigation strategies should be applied to reduce erosion risk. Subsequently, appropriate mitigation measures per Land Use/Land Cover (LULC) categories are proposed. It is worth noting that the proposed methodology has a high degree of transferability as it is based on open-source data.

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An algorithm for delineating and extracting hillslopes and hillslope width functions from gridded elevation data

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-8865-2011 ◽

2011 ◽

Vol 8 (5) ◽

pp. 8865-8901

Author(s):

P. Noel ◽

A. N. Rousseau ◽

C. Paniconi

Keyword(s):

Three Dimensional ◽

Rainfall Runoff ◽

Dimensional Representation ◽

New Approach ◽

One Dimensional ◽

Digital Elevation ◽

Elevation Data ◽

Average Profile ◽

Elevation Model ◽

Digital Elevation Model Resolution

Abstract. Subdivision of catchment into appropriate hydrological units is essential to represent rainfall-runoff processes in hydrological modelling. The commonest units used for this purpose are hillslopes (e.g. Fan and Bras, 1998; Troch et al., 2003). Hillslope width functions can therefore be utilised as one-dimensional representation of three-dimensional landscapes by introducing profile curvatures and plan shapes. An algorithm was developed to delineate and extract hillslopes and hillslope width functions by introducing a new approach to calculate an average profile curvature and plan shape. This allows the algorithm to be independent of digital elevation model resolution and to associate hillslopes to nine elementary landscapes according to Dikau (1989). This algortihm was tested on two flat and steep catchments of the province of Quebec, Canada. Results showed great area coverage for hillslope width function over individual hillslopes and entire watershed.

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A New Approach to the Quality Control of Slope and Aspect Classes Derived from Digital Elevation Models

Remote Sensing ◽

10.3390/rs13112069 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2069

Author(s):

M. V. Alba-Fernández ◽

F. J. Ariza-López ◽

M. D. Jiménez-Gamero

Keyword(s):

Quality Control ◽

Hypothesis Test ◽

Simulated Data ◽

Slope Aspect ◽

New Approach ◽

Reference Set ◽

Digital Elevation ◽

Using Data ◽

Elevation Model ◽

Degree Of Similarity

The usefulness of the parameters (e.g., slope, aspect) derived from a Digital Elevation Model (DEM) is limited by its accuracy. In this paper, a thematic-like quality control (class-based) of aspect and slope classes is proposed. A product can be compared against a reference dataset, which provides the quality requirements to be achieved, by comparing the product proportions of each class with those of the reference set. If a distance between the product proportions and the reference proportions is smaller than a small enough positive tolerance, which is fixed by the user, it will be considered that the degree of similarity between the product and the reference set is acceptable, and hence that its quality meets the requirements. A formal statistical procedure, based on a hypothesis test, is developed and its performance is analyzed using simulated data. It uses the Hellinger distance between the proportions. The application to the slope and aspect is illustrated using data derived from a 2×2 m DEM (reference) and 5×5 m DEM in Allo (province of Navarra, Spain).

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Emerging mitigation measures and strategies are needed for riverine ecology to ensure sustainable hydropeaking production in Norway

10.5194/egusphere-egu21-16429 ◽

2021 ◽

Author(s):

Jo Halvard Halleraker ◽

Mahmoud S. R. Kenawi ◽

Jan Henning L’Abée - Lund ◽

Anders G. Finstad ◽

Knut Alfredsen

Keyword(s):

Biological Indicators ◽

Ecological Impacts ◽

Mitigation Strategies ◽

Mitigation Measures ◽

National Database ◽

Political Agenda ◽

Regulated Rivers ◽

Hydropower Production ◽

Multiple Pressures ◽

Environmental Requirements

Riverine biodiversity is threatened with severe degradation from multiple pressures worldwide. One of the key pressures in European rivers are hydromorphological alterations. Rehabilitation of river habitats is accordingly high on the political agenda at the start of UN decade of ecological restoration (2021-2030).Water storage for hydropower production (HP) has severe impacts on aquatic ecology in Norway, with more than 3000 water bodies designated as heavily modified due to hydropower. Norway is the largest hydropower producer in Europe with a huge amount of high head storage schemes. Ca 86 TWh of this is&#160;storage hydropower, which constitutes more than 50% of the total in Europe. This makes Norway a potentially significant supplier of hydropeaking services. Flexible hydropower operations are crucial for EUs Green Deal in balancing electricity from renewable intermittent power generation such as wind and solar.&#160;Many Norwegian HP licenses were issued before modern environmental requirements evolved. Few are re-licensed with emerging strategies to mitigate hydropeaking. Still, there seems to be a common understanding of relevant mitigation strategies emerging between many large hydropower producers. For example, flow ramping from hydropower tailrace water with direct outlet into fjords or other lake reservoirs may be less environmentally harmful than outlet into riverine habitat.In this study, we have assessed the Norwegian hydropower portfolio of more than 1600 HP facilities constructing a national database focusing on the knowledge base for assessing potential downstream hydropower ecological impacts. The ecological severity of such flow ramping and the restoration/mitigation potential, may depend on;&#160;About 51 % of the HPs (ca 80TWh) have tailrace into shorter rivers (<1 km) or directly into fjords or lake/reservoirs. Many of the largest HPs are in this category (e.g 50 HP> 500 MW). Close to 800 HP might have downstream impacts on rivers (> 0.5 km; about 49 % of all HP, in total of ca 56 TWh). Probably > 3 000 km of regulated rivers in Norway therefor might need more ecosystem-based mode of HP operation.&#160;Flow ramping analysis: &#160;Ecosystem-based HP operational rules are established in a selection of sustainably managed Norwegian rivers, still with significant baseload production (0.35-0.76 - TWh annual prod). However, eco-friendly mode of operation seems to be rare as our analysis indicate that flow ramping with potential ecological degradation seems widespread in many rivers. Surprisingly, even in many with operational ramping restriction as required mitigation.Our database may be further improved and updated (with e.g. more flow ramping data and biological indicators) and serve as a basis for a national hydropeaking strategy, and hence make more of the Norwegian hydropower portfolio in line with the EUs sustainability taxonomy.

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Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities

10.26434/chemrxiv.13724026 ◽

2021 ◽

Author(s):

Leigh Crilley ◽

Yashar Iranpour ◽

Cora J. Young

Keyword(s):

Atmospheric Chemistry ◽

Field Measurements ◽

Air Pollutant ◽

Mitigation Strategies ◽

Ozone Production ◽

Linear Relationships ◽

Regional Sources ◽

Volatile Organic ◽

Emission Changes ◽

Indian Cities

To accurately quantify impact of short-term interventions (such as COVID-19 lockdown) on air pollutant levels, meteorology and atmospheric chemistry need to be considered in addition to emission changes. We demonstrate that regional sources have a significant influence on PM2.5 levels in Delhi and Hyderabad due to the small reduction calculated post-lockdown after weather-normalization, indicating that future PM2.5 mitigation strategies should focus on national-scale, as well as local sources. Furthermore, we demonstrate with field measurements that ozone production in Delhi is likely volatile organic compound (VOC)-limited, in agreement with previous modelling predictions, indicating that ozone mitigation should focus on dominant VOC sources. This work highlights the complexity in developing mitigation strategies for air pollution due to its non-linear relationships with emissions, chemistry and meteorology.

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Mitigation of Debris Flows—Research and Practice in Hong Kong

Environmental and Engineering Geoscience ◽

10.2113/eeg-d-20-00009 ◽

2021 ◽

Vol 27 (2) ◽

pp. 231-243

Author(s):

Ken K. S. Ho ◽

Raymond C. H. Koo ◽

Julian S. H. Kwan

Keyword(s):

Hong Kong ◽

Debris Flow ◽

Debris Flows ◽

Geotechnical Engineering ◽

Mitigation Strategies ◽

Mitigation Measures ◽

Landslide Risk ◽

Engineering Practice ◽

Design Methodologies ◽

Technical Framework

ABSTRACT Dense urban development on a hilly terrain coupled with intense seasonal rainfall and heterogeneous weathering profiles give rise to acute debris-flow problems in Hong Kong. The Geotechnical Engineering Office (GEO) of the Hong Kong SAR Government has launched a holistic research and development (R&D) programme and collaborated with various tertiary institutes and professional bodies to support the development of a comprehensive technical framework for managing landslide risk and designing debris-flow mitigation measures. The scope of the technical development work includes compilation of landslide inventories, field studies of debris flows, development and calibration of tools for landslide run-out modelling, back analysis of notable debris flows, physical and numerical modelling of the interaction between debris flows and mitigation measures, formulation of a technical framework for evaluating debris-flow hazards, and development of pragmatic mitigation strategies and design methodologies for debris-flow countermeasures. The work has advanced the technical understanding of debris-flow hazards and transformed the natural terrain landslide risk management practice in Hong Kong. New analytical tools and improved design methodologies are being applied in routine geotechnical engineering practice.

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Effects of Ultraviolet-B Radiation on Woundfin Embryos and Larvae with Application to Conservation Propagation

Journal of Fish and Wildlife Management ◽

10.3996/042013-jfwm-030 ◽

2014 ◽

Vol 5 (1) ◽

pp. 87-98 ◽

Cited By ~ 2

Author(s):

Luke M. Holmquist ◽

Andrew M. Ray ◽

Betsy A. Bancroft ◽

Nick Pinkham ◽

Molly A. H. Webb

Keyword(s):

Larval Mortality ◽

Ultraviolet B ◽

Mitigation Strategies ◽

Mitigation Measures ◽

Parental Effects ◽

Endangered Fish ◽

Ultraviolet B Radiation ◽

Shade Cloth ◽

Low Levels ◽

Age At Exposure

Abstract Endangered woundfin Plagopterus argentissimus embryos and larvae were exposed to artificial ultraviolet-B (UV-B) radiation to directly examine the effects on mortality. The experiment was part of a project assisting the Virgin River Resource Management and Recovery Program's efforts to increase hatchery production of this endangered fish. The UV-B radiation used in this experiment was administered in treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25% of the ambient irradiance levels documented in outdoor tanks and living streams at Bubbling Ponds State Fish Hatchery, in Arizona. Embryos and larvae were exposed for 14.5 h followed by 9.5 h of darkness, in correspondence with the daylight hours at Bubbling Ponds. No embryos survived UV-B treatments; mortality among control (UV-B–free) treatments varied (5–100%) among females, indicating that there may be important parental effects that influence embryo mortality. Larval mortality was also 100% for individuals exposed to any of the three UV-B treatments. In contrast to embryo trials, larval mortality in UV-B–free treatments approached 20% for 2-d-old larvae. These experiments provide evidence that woundfin embryos and larvae are sensitive to even low levels of UV-B when exposed for 14.5 h. Susceptibility of larvae to UV-B also appears to be a function of age at exposure, with older larvae exhibiting significantly lower levels of mortality during the initial days of exposure. Experiments with UV-B mitigation strategies indicated that shade cloth, Aquashade®, and elevated dissolved organic carbon can aid in the attenuation of UV-B, and these strategies may assist hatchery managers in implementing UV-B mitigation measures during periods when woundfin are most susceptible.

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Local spatial structure of forest biomass and its consequences for remote sensing of carbon stocks

Biogeosciences ◽

10.5194/bg-11-6827-2014 ◽

2014 ◽

Vol 11 (23) ◽

pp. 6827-6840 ◽

Cited By ~ 51

Author(s):

M. Réjou-Méchain ◽

H. C. Muller-Landau ◽

M. Detto ◽

S. C. Thomas ◽

T. Le Toan ◽

...

Keyword(s):

Remote Sensing ◽

Spatial Variability ◽

Spatial Scales ◽

Forest Biomass ◽

Remote Sensing Data ◽

Field Measurements ◽

Forest Degradation ◽

Forest Carbon ◽

Mitigation Strategies ◽

Large Plot

Abstract. Advances in forest carbon mapping have the potential to greatly reduce uncertainties in the global carbon budget and to facilitate effective emissions mitigation strategies such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation). Though broad-scale mapping is based primarily on remote sensing data, the accuracy of resulting forest carbon stock estimates depends critically on the quality of field measurements and calibration procedures. The mismatch in spatial scales between field inventory plots and larger pixels of current and planned remote sensing products for forest biomass mapping is of particular concern, as it has the potential to introduce errors, especially if forest biomass shows strong local spatial variation. Here, we used 30 large (8–50 ha) globally distributed permanent forest plots to quantify the spatial variability in aboveground biomass density (AGBD in Mg ha–1) at spatial scales ranging from 5 to 250 m (0.025–6.25 ha), and to evaluate the implications of this variability for calibrating remote sensing products using simulated remote sensing footprints. We found that local spatial variability in AGBD is large for standard plot sizes, averaging 46.3% for replicate 0.1 ha subplots within a single large plot, and 16.6% for 1 ha subplots. AGBD showed weak spatial autocorrelation at distances of 20–400 m, with autocorrelation higher in sites with higher topographic variability and statistically significant in half of the sites. We further show that when field calibration plots are smaller than the remote sensing pixels, the high local spatial variability in AGBD leads to a substantial "dilution" bias in calibration parameters, a bias that cannot be removed with standard statistical methods. Our results suggest that topography should be explicitly accounted for in future sampling strategies and that much care must be taken in designing calibration schemes if remote sensing of forest carbon is to achieve its promise.

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