Comparing Approaches for Reconstructing Groundwater Levels in the Mountainous Regions of Interior British Columbia, Canada, Using Tree Ring Widths

Observed groundwater level records are relatively short (<100 years), limiting long-term studies of groundwater variability that could provide valuable insight into climate change effects. This study uses tree ring data from the International Tree Ring Database (ITRDB) and groundwater level data from 22 provincial observation wells to evaluate different approaches for reconstructing groundwater levels from tree ring widths in the mountainous southern interior of British Columbia, Canada. The twenty-eight reconstruction models consider the selection of observation wells (e.g., regional average groundwater level vs. wells classified by recharge mechanism) and the search area for potential tree ring records (climate footprint vs. North American Ecoregions). Results show that if the climate footprint is used, reconstructions are statistically valid if the wells are grouped according to recharge mechanism, with streamflow-driven and high-elevation recharge-driven wells (both snowmelt-dominated) producing valid models. Of all the ecoregions considered, only the Coast Mountain Ecoregion models are statistically valid for both the regional average groundwater level and high-elevation recharge-driven systems. No model is statistically valid for low-elevation recharge-driven systems (rainfall-dominated). The longest models extend the groundwater level record to the year 1500, with the highest confidence in the later portions of the reconstructions going back to the year 1800.

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Tree growth across the Nepal Himalaya during the last four centuries

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133317714247 ◽

2017 ◽

Vol 41 (4) ◽

pp. 478-495 ◽

Cited By ~ 15

Author(s):

UK Thapa ◽

S St. George ◽

DK Kharal ◽

NP Gaire

Keyword(s):

Tree Ring ◽

Tree Growth ◽

Environmental Changes ◽

Ring Width ◽

High Elevation ◽

Forest Growth ◽

Tree Ring Width ◽

Early 19Th Century ◽

Tree Ring Data ◽

Instrumental Records

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.

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Analysis of Climate change from high elevation sites of North West Himalaya based on tree ring data

Himalayan Journal of Sciences ◽

10.3126/hjs.v5i7.1320 ◽

1970 ◽

Vol 5 (7) ◽

pp. 138

Author(s):

Santosh K Shah ◽

Amalava Bhattacharyya ◽

Vandana Chaudhary

Keyword(s):

Climate Change ◽

Tree Ring ◽

High Elevation ◽

Special Issue ◽

North West ◽

West Himalaya ◽

Tree Ring Data

DOI = 10.3126/hjs.v5i7.1320 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.138

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Modelling groundwater level fluctuation in an Indian coastal aquifer

Water SA ◽

10.17159/wsa/2020.v46.i4.9081 ◽

2020 ◽

Vol 46 (4 October) ◽

Cited By ~ 1

Author(s):

Safieh Javadinejad ◽

Rebwar Dara ◽

Forough Jafary

Keyword(s):

Groundwater Level ◽

Coastal Aquifer ◽

M5 Model Tree ◽

Groundwater Levels ◽

Proposed Model ◽

Soft Computing Techniques ◽

Input Variables ◽

Lag Times ◽

Observation Wells

Estimating groundwater level (GWL) fluctuations is a vital requirement in hydrology and hydraulic engineering, and is commonly addressed through artificial intelligence (AI) models. The purpose of this research was to estimate groundwater levels using new modelling methods. The implementation of two separate soft computing techniques, a multilayer perceptron neural network (MLPNN) and an M5 model tree (M5-MT), was examined. The models are used in the estimation of monthly GWLs observed in a shallow unconfined coastal aquifer. Data for the water level were collected from observation wells located near Ganjimatta, India, and used to estimate GWL fluctuation. To do this, two scenarios were provided to achieve optimal input variables for modelling the GWL at the present time. The input parameters applied for developing the proposed models were a monthly time-series of summed rainfall, the mean temperature (within its lag times that have an effect on groundwater), and historical GWL observations throughout the period 1996–2006. The efficiency of each proposed model for Ganjimatt was investigated in stages of trial and error. A performance evaluation showed that the M5-MT outperformed the MLPNN model in estimating the GWL in the aquifer case study. Based on the M5-MT approach, the development of this model gives acceptable results for the Indian coastal aquifers. It is recommended that water managers and decision makers apply these new methods to monitor groundwater conditions and inform future planning.

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Self-optimizer data-mining method for aquifer level prediction

Water Science & Technology Water Supply ◽

10.2166/ws.2019.204 ◽

2019 ◽

Vol 20 (2) ◽

pp. 724-736

Author(s):

Omid Bozorg-Haddad ◽

Mohammad Delpasand ◽

Hugo A. Loáiciga

Keyword(s):

Groundwater Level ◽

Hybrid Algorithm ◽

Water Source ◽

Support Vector ◽

Mining Method ◽

Parameter Calibration ◽

Groundwater Levels ◽

Municipal Water Supply ◽

Predictive Skill ◽

Observation Wells

Abstract Groundwater management requires accurate methods for simulating and predicting groundwater processes. Data-based methods can be applied to serve this purpose. Support vector regression (SVR) is a novel and powerful data-based method for predicting time series. This study proposes the genetic algorithm (GA)–SVR hybrid algorithm that combines the GA for parameter calibration and the SVR method for the simulation and prediction of groundwater levels. The GA–SVR algorithm is applied to three observation wells in the Karaj plain aquifer, a strategic water source for municipal water supply in Iran. The GA–SVR's groundwater-level predictions were compared to those from genetic programming (GP). Results show that the randomized approach of GA–SVR prediction yields R2 values ranging between 0.88 and 0.995, and root mean square error (RMSE) values ranging between 0.13 and 0.258 m, which indicates better groundwater-level predictive skill of GA-SVR compared to GP, whose R2 and RMSE values range between 0.48–0.91 and 0.15–0.44 m, respectively.

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A Tree-Ring Based Late Summer Temperature Reconstruction (AD 1675–1980) for the Northeastern Mediterranean

Radiocarbon ◽

10.2458/azu_rc.56.18323 ◽

2014 ◽

Vol 56 (4) ◽

pp. S69-S78 ◽

Cited By ~ 13

Author(s):

Valerie Trouet

Keyword(s):

Tree Ring ◽

Late Summer ◽

Temperature Reconstruction ◽

High Elevation ◽

Global Scale ◽

Summer Temperature ◽

Latewood Density ◽

Reconstructed Temperature ◽

Tree Ring Data ◽

Summer Temperature Reconstruction

This article presents a late summer temperature reconstruction (AD 1675–1980) for the northeastern Mediterranean (NEMED) that is based on a compilation of maximum latewood density tree-ring data from 21 high-elevation sites. This study applied a novel approach by combining individual series from all sites into one NEMED master chronology. This approach retains only the series with a strong and temporally robust common signal and it improves reconstruction length. It further improved the regional character of the reconstruction by using as a target averaged gridded instrumental temperature data from a broad NEMED region (38–45°N, 15–25°E). Cold (e.g. 1740) and warm (e.g. 1945) extreme years and decades in the reconstruction correspond to regional instrumental and reconstructed temperature records. Some extreme periods (e.g. cold 1810s) reflect European-wide or global-scale climate conditions and can be explained by volcanic and solar forcing. Other extremes are strictly regional in scope. For example, 1976 was the coldest NEMED summer over the last 350 years, but was anomalously dry and hot in northwestern Europe and is a strong manifestation of the summer North Atlantic Oscillation (sNAO). The regional NEMED summer reconstruction thus contributes to an improved understanding of regional (e.g. sNAO) vs. global-scale (i.e. external) drivers of past climate variability.

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Influence of sampling and disturbance history on climatic sensitivity of temperature-limited conifers

The Holocene ◽

10.1177/0959683618782605 ◽

2018 ◽

Vol 28 (10) ◽

pp. 1574-1587 ◽

Cited By ~ 14

Author(s):

Miloš Rydval ◽

Daniel L Druckenbrod ◽

Miroslav Svoboda ◽

Volodymyr Trotsiuk ◽

Pavel Janda ◽

...

Keyword(s):

Tree Ring ◽

Ring Width ◽

Low Frequency ◽

High Elevation ◽

Climate Signal ◽

High Frequency Response ◽

Climatic Trends ◽

Tree Ring Data ◽

Temperature Signal ◽

Romanian Carpathians

Accurately capturing medium- to low-frequency trends in tree-ring data is vital to assessing climatic response and developing robust reconstructions of past climate. Non-climatic disturbance can affect growth trends in tree-ring-width (RW) series and bias climate information obtained from such records. It is important to develop suitable strategies to ensure the development of chronologies that minimize these medium- to low-frequency biases. By performing high density sampling (760 trees) over a ~40-ha natural high-elevation Norway spruce ( Picea abies) stand in the Romanian Carpathians, this study assessed the suitability of several sampling strategies for developing chronologies with an optimal climate signal for dendroclimatic purposes. There was a roughly equal probability for chronologies (40 samples each) to express a reasonable ( r = 0.3–0.5) to non-existent climate signal. While showing a strong high-frequency response, older/larger trees expressed the weakest overall temperature signal. Although random sampling yielded the most consistent climate signal in all sub-chronologies, the outcome was still sub-optimal. Alternative strategies to optimize the climate signal, including very high replication and principal components analysis, were also unable to minimize this disturbance bias and produce chronologies adequately representing climatic trends, indicating that larger scale disturbances can produce synchronous pervasive disturbance trends that affect a large part of a sampled population. The Curve Intervention Detection (CID) method, used to identify and reduce the influence of disturbance trends in the RW chronologies, considerably improved climate signal representation (from r = 0.28 before correction to r = 0.41 after correction for the full 760 sample chronology over 1909–2009) and represents a potentially important new approach for assessing disturbance impacts on RW chronologies. Blue intensity (BI) also shows promise as a climatically more sensitive variable which, unlike RW, does not appear significantly affected by disturbance. We recommend that studies utilizing RW chronologies to investigate medium- to long-term climatic trends also assess disturbance impact on those series.

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A Tree-Ring Based Late Summer Temperature Reconstruction (AD 1675–1980) for the Northeastern Mediterranean

Radiocarbon ◽

10.1017/s0033822200050372 ◽

2014 ◽

Vol 56 (04) ◽

pp. S69-S78 ◽

Cited By ~ 1

Author(s):

Valerie Trouet

Keyword(s):

Tree Ring ◽

Late Summer ◽

Temperature Reconstruction ◽

High Elevation ◽

Global Scale ◽

Summer Temperature ◽

Latewood Density ◽

Reconstructed Temperature ◽

Tree Ring Data ◽

Summer Temperature Reconstruction

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Tree ring growth and stable isotopes as potential indicators of historical seabird activities on forested islands in coastal British Columbia

The Canadian Field-Naturalist ◽

10.22621/cfn.v127i2.1445 ◽

2013 ◽

Vol 127 (2) ◽

pp. 146 ◽

Cited By ~ 2

Author(s):

T. E. Reimchen ◽

S. McGehee ◽

B. W. Glickman

Keyword(s):

British Columbia ◽

Tree Ring ◽

Tree Rings ◽

Growth Period ◽

Nitrogen Isotope ◽

Picea Sitchensis ◽

Isotopic Signatures ◽

Tree Ring Data ◽

Year 2000 ◽

Seabird Guano

We examined yearly rings from increment cores of conifers on two seabird nesting islands (one in the Lucy Islands and one in the Rankine Islands, British Columbia), to determine whether trees contained signatures of historical activity of seabirds. Ten conifers (primarily Sitka Spruce, Picea sitchensis), ranging from 56 cm to 127 cm diameter (average 90 cm) and ranging from 70 to 232 years in age (average 132 years of age), were cored across a 200-m gradient in densities of seabird burrows. At the site in the lucy Islands, annual growth was highest (8–14 mm) in the trees with the highest seabird burrow densities and highest in the earliest rings (~1930), which were followed by a fluctuating reduction down to ~2 mm/year in the year 2000, but with a secondary elevated growth period in the 1970s. Adjacent control trees without seabird burrows had a growth rate of ~2 mm/year throughout the same period. At the site in the Rankine Islands, growth rates were also variable and exhibited a 10–15 year non-synchronous periodicity, with the highest growths in the location with high seabird burrow density. Nitrogen isotope signatures (δ15N), which are greatly elevated in seabird guano, ranged from minus 3.9% to 17.4% among tree rings (n = 245 rings) and were positively correlated to percentage nitrogen in rings, average ring growth, and burrow densities. Using these methods, we infer from our tree ring data that seabird activity declined on the lucy Islands over a 70-year period and that the combination of growth, nitrogen isotopic signatures, and percentage nitrogen in tree rings as well a more detailed sampling grid of target and adjacent control trees will provide seabird biologists with additional tools for evaluating spatial and historical trends in seabird activity on forested islands.

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Regional and ecological patterns in interior Douglas-fir climate–growth relationships in British Columbia, Canada

Canadian Journal of Forest Research ◽

10.1139/x09-197 ◽

2010 ◽

Vol 40 (2) ◽

pp. 308-321 ◽

Cited By ~ 18

Author(s):

Hardy P. Griesbauer ◽

D. Scott Green

Keyword(s):

Climate Change ◽

British Columbia ◽

High Elevation ◽

Climatic Conditions ◽

Douglas Fir ◽

Growth Patterns ◽

Growth Responses ◽

Study Region ◽

Tree Ring Data ◽

Dry Climates

How climate change will affect tree growth across species’ geographic and climatic ranges remains a critical knowledge gap. Tree-ring data were analyzed from 33 interior Douglas-fir ( Pseudotsuga menziesii var. glauca (Beissn.) Franco) stands spanning wide geographic and climatic conditions in the interior of British Columbia to gain insights into how within-species growth responses to climate can vary based on local environmental conditions over a broad climatic and geographic range, including populations growing at the species’ range and climatic margins. Populations growing in relatively warm and dry climates had growth patterns correlated mostly with annual precipitation, whereas populations growing in high-elevation wet and cold climates had growth patterns correlated with snowfall, winter and annual temperatures, and ocean–atmosphere climate systems. Populations growing at climatic extremes (e.g., coldest, driest, warmest) in each study region had the strongest responses to climate. Projected climate change may negatively influence Douglas-fir productivity across most of its range, and populations growing near the species’ climatic limits may provide early and strong indications of future responses.

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Observations on Holocene subfossil tree remains from high-elevation sites in the Italian Alps

The Holocene ◽

10.1177/0959683618798149 ◽

2018 ◽

Vol 28 (12) ◽

pp. 2017-2027 ◽

Cited By ~ 2

Author(s):

Mauro Bernabei ◽

Jarno Bontadi ◽

Kurt Nicolussi

Keyword(s):

Tree Ring ◽

Radiocarbon Dating ◽

Climatic Variability ◽

Eastern Alps ◽

High Elevation ◽

Anthropogenic Factors ◽

Italian Alps ◽

Sample Distribution ◽

Groundwater Levels ◽

Growth Decline

Subfossil tree remains from 38 high-elevation sites in the eastern Alps, which were mostly located in the province of Trentino, Italy, were dendrochronologically analysed. A total of 909 samples were collected, 497 of which were dated to calendar years through dendrochronology and separated into six groups. A further tree-ring series of 20 samples were cross-dated into two groups and their ages established by means of radiocarbon dating. The new Trentino Chronology that was established on the basis of these samples covers more than 80% of the last ca. 11,500 years. The uneven distribution of wood samples through time is most likely caused by different factors, for example, climatic and anthropogenic factors. According to our observations, the trees fell at the sites where they were found. The tree-ring series show that trees often died after a period of pronounced growth decline, for example, as a consequence of variations in groundwater levels. A comparison of the Holocene sample distribution of the new Trentino Chronology with contemporaneous records of other European tree-ring chronologies suggests that, at least partly, the greater scale of climatic variability influenced the depositional frequency. The new data contribute to our understanding of past climatic variability and environmental dynamics.

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