Supplement of Missing Data in Groundwater-Level Variations of Peak Type Using Geostatistical Methods

Chung, Sang Yong; Senapathi, Venkatramanan; Elzain, Hussam Eldin; Selvam, S.; Prasanna, Mohan Viswanathan

doi:10.1016/b978-0-12-815413-7.00004-3

Cited by 25 publications

(9 citation statements)

References 12 publications

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“…As lacunar morphometries were different near the surfaces of the bone as compared to the mid-cortex, we next investigated the spatial variation of volume, stretch, and oblateness within individual samples. Borrowing from geostatistics, we generated a continuous spatial model of lacunar morphometries over a sample of the bone by implementing kriging (39) . The kriging estimator is the best linear and unbiased estimator for a Gaussian process with a known covariance structure between observations.…”

Section: Resultsmentioning

confidence: 99%

Reduced local mechanical stimuli in spaceflight diminishes osteocyte lacunar morphometry and spatial heterogeneity in mouse cortical bone

Coulombe

Mullen

Wiens

et al. 2022

Preprint

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Three-dimensional (3D) imaging of osteocyte lacunae has recently substantiated the connection between lacunar shape and size, and osteocyte age, viability, and mechanotransduction. Yet it remains unclear why individual osteocytes reshape their lacunae and how networks of osteocytes change in response to local alterations in mechanical loads. We evaluated the effects of local mechanical stimuli on osteocyte lacunar morphometrics in tibial cortical bone from young female mice flown on the Space Shuttle for ~13 days. We optimized scan parameters, using a laboratory-based submicrometer-resolution X-Ray Microscope, to achieve large ~ 0.3 mm3 fields of view with sufficient resolution (≥ 0.3 μm) to visualize and measure thousands of lacunae per scan. Our novel approach avoids large measurement errors that are inherent in 2D and enables a facile 3D solution as compared to the lower resolution from benchtop micro-computed tomography (CT) systems or the cost and inaccessibility of synchrotron-based CT. Osteocyte lacunae were altered following microgravity exposure in a region-specific manner: more elongated (+7.0% Stretch) in predominately tensile-loaded bone as compared to those in compressively-loaded regions. In compressively-loaded bone, lacunae formed in microgravity were significantly larger (+6.9% Volume) than in the same region formed on Earth. We also evaluated lacunar heterogeneity (i.e., spatial autocorrelation of lacunar morphometric parameters) via kriging models. These statistical models demonstrated that heterogeneity varied with underlying spatial contributors, i.e. the local mechanical and biological environment. Yet in the absence of gravitational loading, osteocyte lacunae in newly formed bone were larger and were collectively more homogenous than in bone formed on Earth. Overall, this study shows that osteocyte reshape their lacunae in response to changes, or absence, in local mechanical stimuli and different biological environments. Additionally, spatial relationships among osteocytes are complex and necessitate evaluation in carefully selected regions of interest and of large cell populations.

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Section: Resultsmentioning

confidence: 99%

Reduced local mechanical stimuli in spaceflight diminishes osteocyte lacunar morphometry and spatial heterogeneity in mouse cortical bone

Coulombe

Mullen

Wiens

et al. 2022

Preprint

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“…Kriging is the best linear optimum unbiased interpolation method of estimating unknown values of spatial and temporal variables with a minimum mean interpolation error (Chung et al 2019). Generally, several types of kriging methods are available: ordinary, simple, universal, Poisson probability, and more (Böhner & Bechtel 2017).…”

Section: Methodsmentioning

confidence: 99%

“…The selection of the method depends on the characteristics of the available data. For instance, universal kriging is appropriate for nonstationary data, and cokriging suits better for a group of correlated data (Chung et al 2019).…”

Section: Methodsmentioning

confidence: 99%

“…Following the model fitting, the differences between estimated and observed values were summarized using the cross-validation statistics described by Ahmed and De Marsily (1987). The crossvalidation statistics include the estimates of root-mean-square error (RMSE) and average standard error (SE) (Chung et al 2019;Taye et al 2018). A smaller RMSE and SE indicate a closer observed and predicted groundwater depths by the empirical semivariogram models.…”

Section: Methodsmentioning

confidence: 99%

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Analysis of groundwater table variability and trend using ordinary kriging: the case study of Sylhet, Bangladesh

et al. 2021

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Many developing countries experience widespread groundwater declination. Sustainable management actions include generation of an accurate groundwater distribution based on an extensive groundwater monitoring network which is often cost prohibiting in the context of a developing country such as Bangladesh. Further, such knowledge is lacking for the Sylhet region where groundwater was documented to be under tremendous pressure. Specifically, the gap in the current literature exists regarding groundwater trends and its areal extent for this region. This paper bridges the gap in research by focusing on trends and spatial and temporal variation of groundwater level changes for this area. This study addresses this problem by creating groundwater level predictions at the ungauged areas using geostatistical methods applied to a detailed set of data. In this study, the spatial variability of annual-average depth to the water table at 46 observation wells in the Sylhet division in Bangladesh is analyzed for 2000, 2005, 2010, and 2015. The geostatistical analysis applies the ordinary kriging method with cross-validation to create the water table maps for the study area. The results indicate a substantial increase in groundwater depths during the studied period from 2000 to 2015 in some locations in the study area. Importantly, this work identifies the vulnerable zones in the area due to the groundwater lowering trend. The study adds to the groundwater management research in developing countries and focuses on the spatial and temporal groundwater variation. The findings from the modeling exercise contribute to identification of the vulnerable areas and therefore help policymakers in making informed decisions to manage groundwater resources in this sensitive region sustainably.

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“…Kriging is the most commonly used interpolator for estimating water quality (Bouteraa et al, 2019). It is a local estimation technique of the best linear unbiased estimator for the unknown spatial and temporal variables (Chung et al, 2019). The general formula for Kriging is expressed as Equation 4: ∑ (4) where Z K is the estimated value at prediction location, Z i is the measured value at the ith location, λ i is a weight for Z i , and N is the number of measured values.…”

Section: Mapping Saltwater Intrusionmentioning

confidence: 99%

Performance evaluation of Auto-Regressive Integrated Moving Average models for forecasting saltwater intrusion into Mekong river estuaries of Vietnam

Thanh

Liem

Thanh

et al. 2021

Vietnam J. Earth Sci.

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The Mekong Delta is the most severely affected area by saltwater intrusion in Vietnam. Recent studies have focused on predicting this disaster with weekly and decade lead times without many seasonal forecasts, which is important for planning crop selection, crop structure, and sowing time. This study aims to forecast the spatial distribution of saltwater intrusion into the Mekong river estuaries of Vietnam during the dry season of 2021 by integrating Auto-Regressive Integrated Moving Average with Geographic Information System. ARIMA models were trained with a single input of water salinity measurements from 2012 to 2020. Compared to the weekly salinity observations in 2021, these models predicted very well in the My Tho and Ham Luong rivers but unsatisfactory performance in the Co Chien river. The deepest saltwater intrusion will occur between March 19th and April 16th of 2021, when the 4‰ saline front will move the farthest distance of 41,41 and 44 kilometers inland from the sea through My Tho, Ham Luong Co Chien rivers, respectively. The entire river system will be exposed to moderate risk of saltwater intrusion. Freshwater zones decreased significantly to 0.73% of the whole area of Ben Tre province. These findings could provide a valuable scientific foundation for the appropriate management of coastal aquifers to control or reduce saltwater intrusion.

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Supplement of Missing Data in Groundwater-Level Variations of Peak Type Using Geostatistical Methods

Cited by 25 publications

References 12 publications

Reduced local mechanical stimuli in spaceflight diminishes osteocyte lacunar morphometry and spatial heterogeneity in mouse cortical bone

Reduced local mechanical stimuli in spaceflight diminishes osteocyte lacunar morphometry and spatial heterogeneity in mouse cortical bone

Analysis of groundwater table variability and trend using ordinary kriging: the case study of Sylhet, Bangladesh

Performance evaluation of Auto-Regressive Integrated Moving Average models for forecasting saltwater intrusion into Mekong river estuaries of Vietnam

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