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| Titel |
Analysis of groundwater drought building on the standardised precipitation index approach |
| VerfasserIn |
J. P. Bloomfield, B. P. Marchant |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 12 ; Nr. 17, no. 12 (2013-12-04), S.4769-4787 |
| Datensatznummer |
250086012
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| Publikation (Nr.) |
 copernicus.org/hess-17-4769-2013.pdf |
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| Zusammenfassung |
| A new index for standardising groundwater level time series and
characterising groundwater droughts, the Standardised Groundwater level
Index (SGI), is described. The SGI builds on the Standardised Precipitation
Index (SPI) to account for differences in the form and characteristics of
groundwater level and precipitation time series. The SGI is estimated using
a non-parametric normal scores transform of groundwater level data for each
calendar month. These monthly estimates are then merged to form a continuous
index. The SGI has been calculated for 14 relatively long, up to 103 yr,
groundwater level hydrographs from a variety of aquifers and compared with
SPI for the same sites. The relationship between SGI and SPI is site
specific and the SPI accumulation period which leads to the strongest
correlation between SGI and SPI, qmax, varies between sites. However,
there is a consistent positive linear correlation between a measure of the
range of significant autocorrelation in the SGI series, mmax, and
qmax across all sites. Given this correlation between SGI mmax and
SPI qmax, and given that periods of low values of SGI can be shown to
coincide with previously independently documented droughts, SGI is taken to
be a robust and meaningful index of groundwater drought. The maximum length
of groundwater droughts defined by SGI is an increasing function of
mmax, meaning that relatively long groundwater droughts are generally
more prevalent at sites where SGI has a relatively long autocorrelation
range. Based on correlations between mmax, average unsaturated zone
thickness and aquifer hydraulic diffusivity, the source of autocorrelation
in SGI is inferred to be dependent on dominant aquifer flow and storage
characteristics. For fractured aquifers, such as the Cretaceous Chalk,
autocorrelation in SGI is inferred to be primarily related to
autocorrelation in the recharge time series, while in granular aquifers,
such as the Permo–Triassic sandstones, autocorrelation in SGI is inferred to
be primarily a function of intrinsic saturated flow and storage properties
of aquifer. These results highlight the need to take into account the
hydrogeological context of groundwater monitoring sites when designing and
interpreting data from groundwater drought monitoring networks. |
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