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1

Integrated preprocessing techniques with linear stochastic approaches in groundwater level forecasting

Azari Arash, Zeynoddin Mohammad, Ebtehaj Isa, Sattar Ahmed M. A., Gharabaghi Bahram, Bonakdari Hossein

Acta Geophysica

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2021

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Vol. 69, no. 4

1395--1411

EN

Accurate modeling of groundwater level (GWL) is a critical and challenging issue in water resources management. The GWL fuctuations rely on many nonlinear hydrological variables and uncertain factors. Therefore, it is important to use an approach that can reduce the parameters involved in the modeling process and minimize the associated errors. This study presents a novel approach for time series structural analysis, multi-step preprocessing, and GWL modeling. In this study, we identifed the time series deterministic and stochastic terms by employing a one-, two-, and three-step preprocessing techniques (a combination of trend analysis, standardization, spectral analysis, diferencing, and normalization techniques). The application of this approach is tested on the GWL dataset of the Kermanshah plains located in the northwest region of Iran, using monthly observations of 60 piezometric stations from September 1991 to August 2017. By removing the dominant nonstationary factors of the GWL data, a linear model with one autoregressive and one seasonal moving average parameter, detrending, and consecutive non-seasonal and seasonal diferencing were created. The quantitative assessment of this model indicates the high performance in GWL forecasting with the coefcient of determination (R2 ) 0.94, scatter index (SI) 0.0004, mean absolute percentage error (MAPE) 0.0003, root mean squared relative error (RMSRE) 0.0004, and corrected Akaike’s information criterion (AICc) 151. Moreover, the uncertainty and accuracy of the proposed linear-based method are compared with two conventional nonlinear methods, including multilayer perceptron artifcial neural network (MLP-ANN) and adaptive neuro-fuzzy inference systems (ANFIS). The uncertainty of the proposed method in this study was±0.105 compared to±0.114 and±0.126 for the best results of the ANN and the ANFIS models, respectively.

2

Runoff Hydrographs Using Snyder and SCS Synthetic Unit Hydrograph Methods: A Case Study of Selected Rivers in South West Nigeria

Salami A. W., Bilewu S. O., Ibitoye B. A., Ayanshola M. A.

Journal of Ecological Engineering

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2017

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Vol. 18, nr 1

25--34

EN

This paper presents the development of runoff hydrographs for selected rivers in the Ogun-Osun river catchment, south west, Nigeria using Snyder and Soil Conservation Service (SCS) methods of synthetic unit hydrograph to determine the ordinates. The Soil Conservation Service (SCS) curve Number method was used to estimate the excess rainfall from storm of different return periods. The peak runoff hydrographs were determined by convoluting the unit hydrographs ordinates with the excess rainfall and the value of peak flows obtained by both Snyder and SCS methods observed to vary from one river watershed to the other. The peak runoff hydrograph flows obtained based on the unit hydrograph ordinate determined with Snyder method for 20-yr, 50-yr, 100-yr, 200-yr and 500-yr, return period varied from 112.63 m3/s and 13364.30 m3/s, while those based on the SCS method varied from 304.43 m3/s and 6466.84 m3/s for the eight watersheds. However, the percentage difference shows that for values of peak flows obtained with Snyder and SCS methods varies from 13.14% to 63.30%. However, SCS method is recommended to estimate the ordinate required for the development of peak runoff hydrograph in the river watersheds because it utilized additional morphometric parameters such as watershed slope and the curve number (CN) which is a function of the properties of the soil and vegetation cover of the watershed.

3

The importance of calibration parameters on the accuracy of the floods description in the Snyder’s model

Wałęga A.

Journal of Water and Land Development

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2016

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no. 28

19--25

EN

Comparison of quality of Snyder’s model for determination flood waves was examination in this work. Model parameters were calibrated based on objective functions: percentage error in peak flow (PEPF), percentage error in volume (PEV), peak-weighted root mean square error (PWRMSE), sum of absolute residuals (SAR) and sum of squared residuals (SSR). Quality of model was calculating by Nash-Sutcliffe efficiency coefficient E. Additionally sensitivity of a model was characterized by its flexibility. The analyses were performed in the watershed of Grabinka. It has been found that the use PWRMSE as the objective function allows to obtain the best quality results of simulation. Furthermore, Snyder’s model is flexible to the change of Cp coefficient.

PL

W pracy porównano efektywność modelu Snydera w opisie wezbrań opadowych, którego parametry szacowano za pomocą różnych funkcji celu: procentowego błędu przepływu w kulminacji – PEPF, procentowego błędu objętości fali – PEV, ważonych średnich kwadratów błędu – PWRMSE, absolutnych sum reszt – SER i sum kwadratów reszt – SSR. Jakość modelu oceniono za pomocą współczynnika efektywności Nash– Sutcliffe’a. Dodatkowo zbadano wpływ zmiany wartości parametrów na wielkości przepływu uzyskane z modelu za pomocą współczynnika elastyczności. Analizy prowadzono w zlewni rzeki Grabinki. Stwierdzono, że zastosowanie PWRMSE jako funkcji celu umożliwia na uzyskanie najlepszej zgodności wyników z modelu z przepływami obserwowanymi. Ponadto model Snydera jest wrażliwy na zmiany parametru Cp, który może być utożsamiany z retencyjnością zlewni.

4

Chwilowy hydrogram jednostkowy. Metoda określania odpływu ze zlewni niekontrolowanej

Lorbiecka Z. A.

Inżynieria Morska i Geotechnika

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2006

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nr 4

204-209

PL

Analiza możliwości ograniczeń zastosowania metody chwilowego hydrogramu jednostkowego do określenia odpływu ze zlewni niekontrolowanej. Definicja zlewni niekontrolowanej oraz dwie postacie IUH stosowane do modelowania odpływu ze zlewni: model Nasha oraz alternatywny IUH. Dwa podejścia wykorzystywane do identyfikacji parametrów IUH - na podstawie charakterystyk zlewni oraz poprzez zastosowanie optymalizacji. Analizę poparto przykładami.

EN

The analysis of possibilities and limitations of the application of Instantaneous Unit Hydrograph (IUH) to a determination of the outflow from uncontrolled catchments. Definition of uncontrolled catchments and most common IUH forms represented by Nash's and the alternative models are shown. Identification of IUH parameters by two approaches i.e. catchments characteristics and optimization method. Some examples are also shown and discussed.