Applications of digital baseflow separation techniques for model validation, Wairarapa valley, New Zealand

<p>The representation of groundwater processes in hydrological models is crucial, as the connectivity between groundwater and surface water is significant. It is particularly important for regions such as the Wairarapa that experience high water stresses. Intensified agriculture has increased demand for irrigation, which can lead to depletion and degradation of reservoirs. This study compared observed streamflow records to TopNet-0 and TopNet-GW model outputs at points along the Mangatarere stream, a sub-catchment in the Wairarapa valley, New Zealand. Model performance was assessed using a suite of quantitative and qualitative comparisons. This analysis aimed to assess the similarities and differences between observed flow and the model outputs with respect to their model structures. Baseflow estimates from recursive digital filters were also compared at these sites to assess the groundwater representation of the models. The investigation can be considered representative of the wider Ruamahanga catchment, as the geology and hydrology in the region is relatively analogous. Flow infilling and baseflow separation was undertaken at 13 Wairarapa flow gauges to provide considerations to the model outputs. Options investigated for flow infilling included a straight infill or calculation of the flow difference at each point. Potential multipliers included a long-term or a monthly option. The difference infill, coupled with the long-term multiplier, was found to be the optimum method. Independent baseflow estimates included a Q90/Q50 flow duration curve index and indices generated from the Eckhardt and Bump & Rise recursive digital filters. The two digital filters produced similar statistics but were found to employ uncertain parameters that significantly affect outputs. TopNet-GW benefitted from up-to-date calibrations and as such produced generally excellent simulations in comparison to observed streamflow. With the addition of the deep groundwater conceptual reservoir in the structure of the model, simulated flow baseflow index estimates and graphical assessment of flow recession curves indicate TopNet-GW reproduces groundwater processes well despite potential over-representation of baseflow at the expense of high flow periods during peak flows. These findings highlight the importance of combining subsurface and surface flow dynamics to resolve water management issues and improve model performance at the catchment scale.</p>

Applications of digital baseflow separation techniques for model validation, Wairarapa valley, New Zealand

<p>The representation of groundwater processes in hydrological models is crucial, as the connectivity between groundwater and surface water is significant. It is particularly important for regions such as the Wairarapa that experience high water stresses. Intensified agriculture has increased demand for irrigation, which can lead to depletion and degradation of reservoirs. This study compared observed streamflow records to TopNet-0 and TopNet-GW model outputs at points along the Mangatarere stream, a sub-catchment in the Wairarapa valley, New Zealand. Model performance was assessed using a suite of quantitative and qualitative comparisons. This analysis aimed to assess the similarities and differences between observed flow and the model outputs with respect to their model structures. Baseflow estimates from recursive digital filters were also compared at these sites to assess the groundwater representation of the models. The investigation can be considered representative of the wider Ruamahanga catchment, as the geology and hydrology in the region is relatively analogous. Flow infilling and baseflow separation was undertaken at 13 Wairarapa flow gauges to provide considerations to the model outputs. Options investigated for flow infilling included a straight infill or calculation of the flow difference at each point. Potential multipliers included a long-term or a monthly option. The difference infill, coupled with the long-term multiplier, was found to be the optimum method. Independent baseflow estimates included a Q90/Q50 flow duration curve index and indices generated from the Eckhardt and Bump & Rise recursive digital filters. The two digital filters produced similar statistics but were found to employ uncertain parameters that significantly affect outputs. TopNet-GW benefitted from up-to-date calibrations and as such produced generally excellent simulations in comparison to observed streamflow. With the addition of the deep groundwater conceptual reservoir in the structure of the model, simulated flow baseflow index estimates and graphical assessment of flow recession curves indicate TopNet-GW reproduces groundwater processes well despite potential over-representation of baseflow at the expense of high flow periods during peak flows. These findings highlight the importance of combining subsurface and surface flow dynamics to resolve water management issues and improve model performance at the catchment scale.</p>

Advanced Digital Signal Processing Techniques on the Classification of the Heart Sound Signals

Speech processing subject primarily depends on the digital signal processing (DSP) methods, such as convolution, discrete Fourier transform (DFT), fast Fourier transforms (FFT), finite impulse response (FIR) and infinite impulse response (IIR) filters, FFT recursive and non-recursive digital filters, FFT processing, random signal theory, adaptive filters, upsampling and downsampling, etc. Recursive and non-recursive digital filters are primarily deployed to absorb the signal of interest signals and to block the unwanted signals (noise). Broadly, low-pass, high-pass, band-pass, and band-stop filters are implemented for filtering functions. In frequent, the DSP theories can be used for further biomedical engineering domains like biomedical imaging (MRI, ultrasound, CT, X-ray, PET) and genetic signal analysis-cum-processing too. In this article, the experiments such as voiced/unvoiced detection, formants estimation using FFT and spectrograms, pitch estimation and tracking and yes/no sound classification are used. Also, the analysis of normal/abnormal heart sound signals using simple energy computation and the zero-crossing rate and their results are obtained. For the entire study, the Matlab R2018a tool is used to obtain the simulation results. At last, the criticism, feedbacks, comments, reactions from the student are detailed for the exceptional development of the course.

Calculus of the fractional order operators in a discrete time domain

The article presents the elementary theory of differential and integral operators of the fractional order in a discrete time approach. A notion of a simple proper fraction operator has been introduced. It has been done for the time equivalent by applying the Taylor series. On this basis a new theory of a certain complexity operators has been formed which includes differential operators of the fractional order. Somewhat more general approach has been presented in the later part of the article by introducing a rational power of the convolution operator. Both approaches to the fractional operators are realized by non–recursive digital filters of infinite impulse responses. The stability of such filters is also being considered. The article also contains the application to the distributed parameters electrical circuits theorem.

Application of recursive digital filter (RDF) methods for baseflow separation: study at Brantas watershed

Baseflow is an important component affecting the availability of water in the river during the dry season. Availability of water in the dry season is useful for water resources management. This research aims to test and to compare six recursive digital filters (RDF) methods for calculating baseflow and baseflow index. This research was conducted in Brantas Watershed. Two outlets (sub-watersheds) located at Kertosono and Ploso were used. Daily discharge from 1996 to 2015 of the two outlets above was used as main input for this study. While rainfall data were used to determine the calibration period. The sequence procedures of this research, consist of: (1) inventory of daily discharge and rainfall data, (2) data processing, (3) calibration, (4) validation, and (5) evaluation of models’ performances. Six (6) methods of baseflow separation based on recursive digital filters were evaluated. The calibration process was carried out for periods 1996 to 2005. The periods from July to September was assumed to be the peak of the dry season and then selected for calibration process. The parameter values were calibrated using the data from dry season for each year. Furthermore, the average value of parameters obtained from calibration period then used to separate baseflow in validation process (periods 2006 to 2015). The result of separation both in calibration and validation are then evaluated using root mean square error (RMSE), coefficient of determination (R²) and FDC. This research shows that the Lyne-Hollick and EWMA filters perform better than other methods. In Brantas Kertosono sub-watershed, the optimal parameter value for Lyne Hollick algoritmh (αly) = 0.995 dan for EWMA filter (αew) = 0.003 and in Brantas Ploso sub-watershed (αly ) = 0.99 dan (αew) = 0.003.

Group Delay Equalization of Polynomial Recursive Digital Filters in Maximal Flat Sense

The paper presents the development of an algorithm to obtain stable allpass filter, which acts as a group delay equalizer, with the aim to equalize group delay of the polynomial IIR filter in a maximal flat sense. The proposed method relies on a set of nonlinear equations, derived directly from the flatness conditions of the group delay response at the origin in the [Formula: see text]-plane, with the order to obtain the unknown values of the allpass filter coefficients. The algorithm implemented in the MATLAB platform returns the coefficients of allpass filter. In the given example, first we construct a minimum phase polynomial IIR digital filter with a maximally flat magnitude at origin, next we augment the system with cascade connection of nonminimum allpass digital filter with order to equalize the group delay response of the whole filter in a maximally flat sense.