scholarly journals The Use of the Inverse Problem of Spectral Analysis to Forecast Time Series

2019 ◽  
Vol 6 (1) ◽  
pp. 74-78
Author(s):  
A.I. Sedov ◽  
Keyword(s):  
Inverse Problem ◽  
Time Series ◽  
Spectral Analysis ◽  
Forecast Time

scholarly journals Assessing Stream-Aquifer Connectivity in a Coastal California Watershed

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 416
Author(s):  
Bwalya Malama ◽  
Devin Pritchard-Peterson ◽  
John J. Jasbinsek ◽  
Christopher Surfleet
Keyword(s):  
Time Series ◽  
Spectral Analysis ◽  
Water Level ◽  
Time Series Data ◽  
Series Data ◽  
Low Permeability ◽  
Pumping Tests ◽  
Stream Flows ◽  
The Impact

We report the results of field and laboratory investigations of stream-aquifer interactions in a watershed along the California coast to assess the impact of groundwater pumping for irrigation on stream flows. The methods used include subsurface sediment sampling using direct-push drilling, laboratory permeability and particle size analyses of sediment, piezometer installation and instrumentation, stream discharge and stage monitoring, pumping tests for aquifer characterization, resistivity surveys, and long-term passive monitoring of stream stage and groundwater levels. Spectral analysis of long-term water level data was used to assess correlation between stream and groundwater level time series data. The investigations revealed the presence of a thin low permeability silt-clay aquitard unit between the main aquifer and the stream. This suggested a three layer conceptual model of the subsurface comprising unconfined and confined aquifers separated by an aquitard layer. This was broadly confirmed by resistivity surveys and pumping tests, the latter of which indicated the occurrence of leakage across the aquitard. The aquitard was determined to be 2–3 orders of magnitude less permeable than the aquifer, which is indicative of weak stream-aquifer connectivity and was confirmed by spectral analysis of stream-aquifer water level time series. The results illustrate the importance of site-specific investigations and suggest that even in systems where the stream is not in direct hydraulic contact with the producing aquifer, long-term stream depletion can occur due to leakage across low permeability units. This has implications for management of stream flows, groundwater abstraction, and water resources management during prolonged periods of drought.

scholarly journals Quantile spectral analysis for locally stationary time series

2017 ◽  
Vol 79 (5) ◽  
pp. 1619-1643 ◽  
Author(s):  
Stefan Birr ◽  
Stanislav Volgushev ◽  
Tobias Kley ◽  
Holger Dette ◽  
Marc Hallin
Keyword(s):  
Time Series ◽  
Spectral Analysis ◽  
Stationary Time Series ◽  
Stationary Time ◽  
Locally Stationary Time Series

Spectral analysis for GNSS coordinate time series using chirp Fourier transform

2017 ◽  
Vol 65 (6) ◽  
pp. 1111-1118
Author(s):  
Shengtao Feng ◽  
Wanju Bo ◽  
Qingzun Ma ◽  
Zifan Wang
Keyword(s):  
Time Series ◽  
Spectral Analysis ◽  
Fourier Transform ◽  
Coordinate Time ◽  
Coordinate Time Series

Spectral Analysis of Economic Time Series

1966 ◽  
Vol 48 (4) ◽  
pp. 1040
Author(s):  
R. L. Ehrich ◽  
C. W. J. Granger
Keyword(s):  
Time Series ◽  
Spectral Analysis ◽  
Economic Time Series ◽  
Economic Time
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