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A short note on the natural and anthropogenic variations in the water storage changes at Visakhapatnam, Andhra Pradesh, India

Mathews Gathala Vinod, Rajesh Rekapalli, Begum Shaik Kareemunnisa

Acta Geophysica

2022

Vol. 70, no 4

1847--1854

We analyze the periodic and stochastic/random dynamics in the water storage changes at Visakhapatnam, Andhra Pradesh, India. We used time-variable gravity data in terms of Equivalent Water Thickness (EWT) measured from Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellite missions for the period 2002 to 2021 along with average rainfall data to assess the natural and anthropogenic impacts on water storage changes. We employ Wavelet Spectrum and Singular Spectrum Analysis (SSA) methods to analyze the non-stationary variation of spectral power and principal components. The water storage in the study area shows a significant positive trend with a peak correlation of 0.52 with the rainfall data at a lag of 3 months. The first, second, third, fourth, and fifth principal components depicting the monotonic trend and oscillations together contribute 69.48% to the total water storage changes. The wavelet spectrum of the SSA reconstructed signal from the first four principal components revealed non-stationary annual and 1.3 to 8 years periodicities associated with natural solar and El-Nino Southern Oscillations (ENSO) respectively. The phase plot of the residual signal of ~ 30% variance suggests the random dynamics. Thus the study suggests: (i) an increasing groundwater trend in the study area, (ii) nearly 70% of the water storage changes are linked with natural solar and ENSO variations, and (iii) 30% of water storage changes are with random dynamics possibly linked with anthropogenic activities and catastrophic climatic episodes of shorter duration at Visakhapatnam, Andhra Pradesh, India.

The use of the wavelet-analysis for the research of the unsteady processes in the pipeline network of a pumping complex

Zagirnyak Mykhaylo, Manko Roman, Kravets Oleksii, Korenkova Tetyana

Przegląd Elektrotechniczny

2019

R. 95, nr 5

35--38

The authors propose the use of the wavelet-analysis to research the wave processes in the unsteady modes of the pumping complex operation. We demonstrate that the use of the wavelet analysis enables the determination of both the fact of the presence of the emergency mode and the time of the beginning of the unsteady process. We determined that the frequency-time dependences of wavelet coefficients are to underlie the quantitative assessment of the unsteady modes in the pipeline network. We obtained the frequency ranges and the boundaries of the waveletcoefficients variation for each of the analyzed unsteady processes.

Autorzy proponują wykorzystanie analizy falkowej do badania procesów falowych w niestabilnych trybach pracy zespołu pompowego. Pokazujemy, że wykorzystanie analizy falkowej umożliwia określenie zarówno faktu wystąpienia trybu awaryjnego, jak i momentu początku stanu niestabilnego. Ustaliliśmy, że zależności częstotliwościowo-czasowe współczynników falkowych mają leżeć u podstaw ilościowej oceny trybów niestabilnych w sieci wodociągowej. Uzyskaliśmy zakresy częstotliwości i granice zmienności współczynników falek dla każdego z analizowanych procesów nieustalonych.