Extracting coherent regional information from local measurements with Karhunen‐Loève transform: Case study of an alluvial aquifer (Rhine valley, France and Germany)

Longuevergne, Laurent; Florsch, Nicolás; Elsass, Philippe

doi:10.1029/2006wr005000

Cited by 39 publications

(25 citation statements)

References 23 publications

(25 reference statements)

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“…A possible start to disentangle the different influences could be using methods such as the Karhunen-Loéve transform, as for example used by Longuevergne et al (2007) in the Rhine valley aquifer.…”

Section: Future Workmentioning

confidence: 99%

Characterizing the spatiotemporal variability of groundwater levels of alluvial aquifers in different settings using drought indices

Haas

Birk

2017

Hydrol. Earth Syst. Sci.

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Abstract. To improve the understanding of how aquifers in different alluvial settings respond to extreme events in a changing environment, we analyze standardized time series of groundwater levels (Standardized Groundwater level Index -SGI), precipitation (Standardized Precipitation Index -SPI), and river stages of three subregions within the catchment of the river Mur (Austria). Using correlation matrices, differences and similarities between the subregions, ranging from the Alpine upstream part of the catchment to its shallow foreland basin, are identified and visualized.Generally, river stages exhibit the highest correlations with groundwater levels, frequently affecting not only the wells closest to the river, but also more distant parts of the alluvial aquifer. As a result, human impacts on the river are transferred to the aquifer, thus affecting the behavior of groundwater levels. Hence, to avoid misinterpretation of groundwater levels in this type of setting, it is important to account for the river and human impacts on it.While the river is a controlling factor in all of the subregions, an influence of precipitation is evident too. Except for deep wells found in an upstream Alpine basin, groundwater levels show the highest correlation with a precipitation accumulation period of 6 months (SPI6). The correlation in the foreland is generally higher than that in the Alpine subregions, thus corresponding to a trend from deeper wells in the Alpine parts of the catchment towards more shallow wells in the foreland.Extreme events are found to affect the aquifer in different ways. As shown with the well-known European 2003 drought and the local 2009 floods, correlations are reduced under flood conditions, but increased under drought. Thus, precipitation, groundwater levels and river stages tend to exhibit uniform behavior under drought conditions, whereas they may show irregular behavior during floods. Similarly, correlations are found to be weaker in years with little snow as compared with those with much snow. This is in agreement with typical aquifer response times over 1 month, suggesting that short events such as floods will not affect much of the aquifer, whereas a long-term event such as a drought or snow-rich winter will.Splitting the time series into periods of 12 years reveals a tendency towards higher correlations in the most recent time period from 1999 to 2010. This time period also shows the highest number of events with SPI values below −2. The SGI values behave in a similar way only in the foreland aquifer, whereas the investigated Alpine aquifers exhibit a contrasting behavior with the highest number of low SGI events in the time before 1986. This is a result of overlying trends and suggests that the groundwater levels within these subregions are more strongly influenced by direct human impacts, e.g., on the river, than by changes in precipitation. Thus, direct human impacts must not be ignored when assessing climate change impacts on alluvial aquifers situated in populated valleys.

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Section: Future Workmentioning

confidence: 99%

Characterizing the spatiotemporal variability of groundwater levels of alluvial aquifers in different settings using drought indices

Haas

Birk

2017

Hydrol. Earth Syst. Sci.

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“…It can also provide a framework for further modelling of groundwater-stream water interactions , help to identify the hydrological active functional properties on the landscape scale (Lischeid et al, 2010), regionalize the different hydrological contributions to the aquifer dynamics (Longuevergne et al, 2007), or be used as explorative data analysis tool to develop hypothesis such as the spatial patterns of areas of relative low and high effective hydraulic conductivity of floodplain sediment as done in the present study.…”

Section: Discussionmentioning

confidence: 99%

A novel method to evaluate the effect of a stream restoration on the spatial pattern of hydraulic connection of stream and groundwater

Lehr

Pöschke

Lewandowski

et al. 2015

Journal of Hydrology

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Keywords:Groundwater-stream water interactions Principal component analysis Signal propagation Hydraulic connectivity Clogging Riparian zone s u m m a r y Stream restoration aims at an enhancement of ecological habitats, an increase of water retention within a landscape and sometimes even at an improvement of biogeochemical functions of lotic ecosystems. For the latter, good exchange between groundwater and stream water is often considered to be of major importance. In this study hydraulic connectivity between river and aquifer was investigated for a four years period, covering the restoration of an old oxbow after the second year. The oxbow became reconnected to the stream and the clogging layer in the oxbow was excavated. We expected increasing hydraulic connectivity between oxbow and aquifer after restoration of the stream, and decreasing hydraulic connectivity for the former shortcut due to increased clogging. To test that hypothesis, the spatial and temporal characteristics of the coupled groundwater-stream water system before and after the restoration were analysed by principal component analyses of time series of groundwater heads and stream water levels. The first component depicted between 53% and 70% of the total variance in the dataset for the different years. It captured the propagation of the pressure signal induced by stream water level fluctuations throughout the adjacent aquifer. Thus it could be used as a measure of hydraulic connectivity between stream and aquifer. During the first year, the impact of stream water level fluctuations decreased with distance from the regulated river (shortcut), whereas the hydraulic connection of the oxbow to the adjacent aquifer was very low. After restoration of the stream we observed a slight but not significant increase of hydraulic connectivity in the oxbow in the second year after restoration, but no change for the former shortcut. There is some evidence that the pattern of hydraulic connectivity at the study site is by far more determined by the natural heterogeneity of hydraulic conductivities of the floodplain sediments and the initial construction of the shortcut rather than by the clogging layer in the oxbow.

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“…Basically, the goal of EOF analysis is to transform an original set of variables into a substantially smaller set of uncorrelated variables, which can reflect most of the information of the original dataset. It also has the ability to isolate various processes mixed in observation data [28]. The EOF has recently become a popular tool in various science areas such as meteorology, geology, and geography [29].…”

Section: Water Resource Spatial-temporal Series Analysismentioning

confidence: 99%

Remote Sensing Based Analysis of Recent Variations in Water Resources and Vegetation of a Semi-Arid Region

Ning

Ishidaira

Udmale

et al. 2015

Water

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This study is designed to demonstrate use of free remote sensing data to analyze response of water resources and grassland vegetation to a climate change induced prolonged drought in a sparsely gauged semi-arid region. Water resource changes over Hulun Lake region derived from monthly Gravity Recovery and Climate Experiment (GRACE) and Tropical Rainfall Measuring Mission (TRMM) products were analyzed. The Empirical Orthogonal Functions (EOF) analysis results from both GRACE and TRMM showed decreasing trends in water storage changes and precipitation over 2002 to 2007 and increasing trends after 2007 to 2012. Water storage and precipitation changes on the spatial and temporal scale showed a very consistent pattern. Further analysis proved that water storage changes were mainly caused by precipitation and temperature changes in this region. It is found that a large proportion of grassland vegetation recovered to its normal state after above average rainfall in the following years (2008)(2009)(2010)(2011)(2012) and only a small proportion of grassland vegetation (16.5% of the study area) is degraded and failed to recover. These degraded grassland vegetation areas are categorized as ecologically vulnerable to climate change and protective strategies should be designed to prevent its further degradation. OPEN ACCESSWater 2015, 7 6040

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Extracting coherent regional information from local measurements with Karhunen‐Loève transform: Case study of an alluvial aquifer (Rhine valley, France and Germany)

Cited by 39 publications

References 23 publications

Characterizing the spatiotemporal variability of groundwater levels of alluvial aquifers in different settings using drought indices

Characterizing the spatiotemporal variability of groundwater levels of alluvial aquifers in different settings using drought indices

A novel method to evaluate the effect of a stream restoration on the spatial pattern of hydraulic connection of stream and groundwater

Remote Sensing Based Analysis of Recent Variations in Water Resources and Vegetation of a Semi-Arid Region

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