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1

Applicability of TOPMODEL in the Mountainous Catchments in the Upper Nysa Kłodzka River Basin (SW Poland)

Jeziorska J., Niedzielski T.

Acta Geophysica

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2018

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Vol. 66, no. 2

203--222

EN

River basins located in the Central Sudetes (SW Poland) demonstrate a high vulnerability to flooding. Four mountainous basins and the corresponding outlets have been chosen for modeling the streamflow dynamics using TOPMODEL, a physically based semi-distributed topohydrological model. The model has been calibrated using the Monte Carlo approach—with discharge, rainfall, and evapotranspiration data used to estimate the parameters. The overall performance of the model was judged by interpreting the efficiency measures. TOPMODEL was able to reproduce the main pattern of the hydrograph with acceptable accuracy for two of the investigated catchments. However, it failed to simulate the hydrological response in the remaining two catchments. The best performing data set obtained Nash-Sutcliffe efficiency of 0.78. This data set was chosen to conduct a detailed analysis aiming to estimate the optimal timespan of input data for which TOPMODEL performs best. The best fit was attained for the half-year time span. The model was validated and found to reveal good skills.

2

HydroProg: a system for hydraulic forecasting in real time, based on the multimodelling approach

Niedzielski T., Miziński B., Kryza M., Netzel P., Wieczorek M., Kasprzak M., Migoń P., Szymanowski M., Jeziorska J., Witek M., Kosek W

Meteorology Hydrology and Water Management. Research and Operational Applications

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2014

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Vol. 2, Iss. 2

65--72

EN

Aleja Mickiewicza 24/28, 30-059 Kraków, Poland Abstract: The objective of this paper is to present the concept of a novel system, known as HydroProg, that aims to issue flood warnings in real time on the basis of numerous hydrological predictions computed using various models. The core infrastructure of the system is hosted by the University of Wrocław, Poland. A newly-established computational centre provides in real time, courtesy of the project Partners, various modelling groups, referred to as “project Participants”, with hydrometeorological data. The project Participants, having downloaded the most recent observations, are requested to run their hydrologic models on their machines and to provide the HydroProg system with the most up-to-date prediction of riverflow. The system gathers individual forecasts derived by the Participants and processes them in order to compute the ensemble prediction based on multiple models, following the approach known as multimodelling. The system is implemented in R and, in order to attain the above-mentioned functionality, is equipped with numerous scripts that manipulate PostgreSQL- and MySQL-managed databases and control the data quality as well as the data processing flow. As a result, the Participants are provided with multivariate hydrometeorological time series with sparse outliers and without missing values, and they may use these data to run their models. The first strategic project Partner is the County Office in Kłodzko, Poland, owner of the Local System for Flood Monitoring in Kłodzko County. The experimental implementation of the HydroProg system in the Nysa Kłodzka river basin has been completed, and six hydrologic models are run by scientists or research groups from the University of Wrocław, Poland, who act as Participants. Herein, we shows a single prediction exercise which serves as an example of the HydroProg performance.

3

An experimental approach to verifying prognoses of floods using an unmanned aerial vehicle

Witek M., Jeziorska J., Niedzielski T.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2014

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Vol. 2, Iss. 1

3--11

EN

The Department of Geoinformatics and Cartography of the University of Wrocław, Poland, is host in¬stitution of a project, financed by the National Science Centre in Poland, whose objective is to predict riverflow in real-time. If inundation is predicted, the problem of the verification of the overbank flow prognosis arises. This verification can be attained by utilizing an unmanned aerial vehicle that may be used for remote sensing applications. The unmanned aerial vehicle in question can take sequential photos with the unprecedented resolution of 3 cm/pix. Both the resolution and the opportunity for frequent flights – due to the low cost of the entire operation – allow us to compare prediction maps showing the forecasted overbank flow during an extreme hydrological event with the true observation obtained from the air. Although such verification is site- and event-specific, it can provide us with an objective technique for checking our system in a spatial domain. The main part of the system, known as HydroProg, produces multimodel ensemble hydrograph predictions and compares single-model prognoses; visualizations of them are then published in a web map service. The spatial predictions, along with the aerial orthophoto images, will also be presented online so that the user is able to observe the functioning of the system. Regular research flights have been carried out in Kłodzko County since 2012. The study areas correspond to sites where our Partner, the County Office in Kłodzko (SW Poland) – owner of the Local System for Flood Monitoring in Kłodzko County – has automatic gauges, and thus spatially reflect the hydrologic observation network. The aforementioned aerial module is experimental and will be incorporated into the entire system.

4

Możliwości wykorzystania bezzałogowej fotogrametrii lotniczej do identyfikacji przekształceń antropogenicznych w korytach rzecznych

Witek M., Jeziorska J., Niedzielski T.

Landform Analysis

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2013

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Vol. 24

115--126

PL

Przestrzenny charakter antropogenicznych zmian w obrębie koryt rzecznych wymaga zastosowania metod i narzędzi umożliwiających nie tylko jakościową, ale i ilościową ich analizę. Pomiary geodezyjne są bardzo dokładne, lecz kosztowne i czasochłonne, co sprawia, że regularne pomiary, potrzebne do określenia dynamiki form fluwialnych, są trudne do zrealizowania. Tradycyjna fotogrametria lotnicza jest wartościowym źródłem informacji jedynie w przypadku analizy dużych obiektów. Skala, w jakiej najczęściej wykonywane są zdjęcia lotnicze, nie zapewnia wystarczającej szczegółowości do analizy niewielkich form rzeźby. W niniejszej publikacji zaprezentowane zostanie użycie bezzałogowego statku powietrznego (ang. UAV, Unmanned Aerial Vehicle), który wypełnia lukę między pomiarami naziemnymi a tradycyjną fotogrametrią czy analizą obrazów satelitarnych. Ultralekki bezzałogowy statek powietrzny swinglet CAM wyposażony jest w kompaktowy aparat fotograficzny wykonujący sekwencje zdjęć, które po przetworzeniu mogą służyć jako źródło kartometrycznych danych przestrzennych. Zniekształcenia geometryczne zdjęć oraz zniekształcenia spowodowane pochyleniem aparatu i rzeźbą terenu są usuwane w procesie wieloetapowego przetwarzania. Dzięki wysokiej rozdzielczości materiałów obserwacyjnych (do 3 cm px–1), wygenerowane ortofotomapy umożliwiają analizę niewielkich obiektów. Teren badań – Kotlina Kłodzka – jest doskonałym przykładem występowania zmian fluwialnych o podłożu antropogenicznym i – z uwagi na ten fakt – został wybrany jako obszar testowy do prezentacji możliwości bezzałogowego statku powietrznego w zakresie zdalnego wykrywania omawianych form. Wyniki potwierdzają dużą szczegółowość pozyskanych materiałów, co – w połączeniu z niskimi kosztami misji lotniczych oraz łatwością dostosowania parametrów i czasu realizacji lotów – jednoznacznie pokazuje, że zastosowana technologia jest odpowiednim narzędziem do obserwacji antropogenicznych form fluwialnych i może przyczynić się do rozwiązywania wielu problemów badawczych dotyczących ich roli w kształtowaniu procesów hydrologicznych.

EN

Spatial character of anthropogenic fluvial changes requires the use of methods and tools eligible for not only qualitative, but also quantitative analysis. Geodetic surveys are very accurate, but time and cost consuming, what makes repetitive measurements needed for determining the dynamics of fluvial landforms hard to perform. Traditional aerial photogrammetry is a valuable source only for examining features visible in a small cartographic scale. Hence, small fluvial forms cannot be observed using traditional aerial photogrammetry due to its limitations in resolution. Unmanned Aerial Vehicles (UAVs), presented extensively in this paper, serve as the additional source of high-resolution spatial information and thus fill the gap between terrestrial measurements and traditional aerial photogrammetry as well as satellite data. Ultra-light unmanned aircraft swinglet CAM, with consumer – grade camera onboard, provides sequences of pictures, which after geoprocessing can serve as source of spatial data eligible for quantitative measurements. Geometric incorrectness of the acquired pictures and distortions caused by tilt and relief are removed in the process of multistep processing. Due to high resolution of the observational material (up to 3 cm px-1) the generated orthophotomaps are appropriate for the analysis of small fluvial features. The study area – namely Kłodzko County – serves as a great example of assemblages of anthropogenic fluvial changes and – due to this fact – has been chosen as a test area to present potentials of UAV in observing the aforementioned landforms. The results confirm a great accuracy of the collected materials, which – in combination with low cost surveys, ease of parameter adjustment and flight schedule – unequivocally shows that the applied technology is an appropriate tool for observing anthropogenic fluvial forms, and thus may contribute to solutions of numerous research problems related to hydrological processes impacted by human interventions.

5

Non-linear sea level variations in the eastern tropical Pacific

Niedzielski T.

Artificial Satellites : Journal of Planetary Geodesy

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2010

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Vol. 45, No. 1

1--10

EN

The objective of this paper is to provide an insightful interpretation for the non-linearity of the inter-annual signal in sea level change in the eastern tropical Pacific. Such a non-linearity has been already discussed elsewhere for global ocean. Herein, the residual sea level anomaly time series from TOPEX/Poseidon and Jason-1 altimetry is obtained by removing the significant deterministic signals from the original sea level anomaly data. Since the eastern tropical Pacific is a profound region where many processes responsible for driving the El Niño/Southern Oscillation (ENSO) act, it is possible to link a few of them with the non-linearity of sea level change. In particular, not only local, usually weak, oceanatmosphere interactions exist in the eastern equatorial Pacific but this region is also remotely impacted by climatic processes acting in the western equatorial Pacific where the oceanatmosphere coupling is the strongest. The detected non-linearity of sea level change is due to the asymmetry between warm and cold ENSO episodes. Such an asymmetry can be driven by the non-linear dynamical heating associated with strong ENSO events.

6

Empirical hydrologic predictions for southwestern Poland and their relation to ENSO teleconnections

Niedzielski T.

Artificial Satellites : Journal of Planetary Geodesy

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2010

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Vol. 45, No. 1

11--26

EN

Recent investigations confirm meaningful but weak teleconnections between the El Niño/Southern Oscillation (ENSO) and hydrology in some European regions. In particular, this finding holds for Polish riverflows in winter and early spring as inferred from integrating numerous geodetic, geophysical and hydrologic time series. The purpose of this study is to examine whether such remote teleconnections may have an influence on hydrologic forecasting. The daily discharge time series from southwestern (SW) Poland spanning the time interval from 1971 to 2006 are examined. A few winter and spring peak flows are considered and the issue of their predictability using empirical forecasting is addressed. Following satisfactory prediction performance reported elsewhere, the multivariate autoregressive method is used and its modification based on the finite impulse response filtering is proposed. The initial phases of peak flows are rather acceptably forecasted but the accuracy of predictions in the vicinity of local maxima of the hydrographs is poorer. It has been hypothesized that ENSO signal slightly influences the predictability of winter and early spring floods in SW Poland. The predictions of flood wave maxima are the most accurate for floods preceded by normal states, less accurate for peak flows after La Niña episodes and highly inaccurate for peak flows preceded by El Niño events. Such a finding can be interpreted in terms of intermittency. Before peak flows preceded by El Niño there are temporarily persistent low flows followed by a consecutive melting leading to a considerable intermittency and hence to difficulties in forecasting. Before peak flows preceded by La Niña episodes there exist ENSO-related positive temperature and precipitation anomalies in SW Poland causing lower, but still considerable, intermittency and thus better, but not entirely correct, predictability of hydrologic time series.

7

An application of low-order ARMA and GARCH models for sea level fluctuations

Niedzielski T., Kosek W.

Artificial Satellites : Journal of Planetary Geodesy

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2010

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Vol. 45, No. 1

27--39

EN

The paper presents the analysis of geographically-dependent irregular sea level fluctuations, often referred to as residual terms around deterministic signals, carried out by means of stochastic low-order autoregressive moving average (ARMA) and generalised autoregressive conditional heteroscedastic (GARCH) models. The gridded sea level anomaly (SLA) time series from TOPEX/Poseidon (T/P) and Jason-1 (J-1) satellite altimetry, commencing on 10th January 1993 and finishing on 14th July 2003, has been examined. The aforementioned models, limited to low-orders being combinations of 0,1 and 2, have been fitted to the SLA data. The root mean square and the Shapiro-Wilk test for the normal distribution have been used to calculate statistics of the residuals from these models. It has been found that autoregressive (AR) models as well as ARMA ones serve well the purpose of adequate modelling irregular sea level fluctuations, with a successful fit in some patchy bits of the equatorial Pacific. In contrast, GARCH models have been shown to be rather inaccurate, specifically in the vicinity of the tropical Pacific, in the North Pacific and in the equatorial Indian Ocean. The pattern of the Tropical Instability Waves (TIWs) has been noticed in the statistics of AR and ARMA model residuals indicating that the dynamics of these waves cannot be captured by the aforementioned linear stochastic processes.

8

On the probability distribution of Earth Orientation Parameters data

Niedzielski T., Sen A. K., Kosek W.

Artificial Satellites : Journal of Planetary Geodesy

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2009

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Vol. 44, No. 1

33--41

EN

Earth Orientation Parameters (EOPs), i.e. pole coordinates (xp, yp), Universal Time (UT1-UTC), and celestial pole offsets (dX, dY ), are the transformation parameters between the International Terrestrial Reference Frame (ITRF) and the International Celestial Reference Frame (ICRF). It is customarily assumed that each of the EOP time series follows the normal distribution. The normality assumption has been used specifically in EOP prediction studies. The objective of this paper is to investigate the normality hypothesis in detail. We analysed the daily time series of xp, yp, UT1-UTC, length-of-day (Δ), dX, and dY in the time interval from 01.01.1962 to 31.12.2008. The UT1-UTC data were transformed to UT1R-TAI by removing leap seconds and the tidal signal using the IERS model. The tidal effects δΔ were also removed from the Δ time series and Δ−δΔ data were obtained. Furthermore, we constructed the residuals of these time series using least-squares fit. We evaluated the skewness and kurtosis and tested their statistical significance by the D’Agostino and the Anscombe-Glynn tests, respectively. In addition, the Anderson-Darling test for the normal distribution was applied. It was found that the xp, yp time series and their residuals slightly depart from the normal distribution, but this departure is rather due to marginal flattening/narrowing of the probability density function than due to extreme values. The UT1R-TAI time series and its residuals were also classified as non-Gaussian, however, the deviations from the normal distribution are again slight. The similar results hold for the Δ - δΔ data, but some of its residuals were found to be Gaussian. We noticed that the celestial pole offsets, dX and dY , tend to deviate from the Gaussian distribution. In addition, we examined the determination errors of EOP data and found them to depart significantly from the normal distribution.

9

A Required Data Span to Detect Sea Level Rise

Niedzielski T., Kosek W.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2008

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Vol. 2, no. 2

143--147

EN

Altimetric measurements indicate that the global sea level rises about 3 mm/year, however, in various papers different data spans are adopted to estimate this value. The minimum time span of TOPEX/Poseidon (T/P) and Jason-1 (J-1) global sea level anomalies (SLA) data required to detect a statisti-cally significant trend in sea level change was estimated. Seeking the trend in the global SLA data was per-formed by means of the Cox-Stuart statistical test. This test was supported by the stepwise procedure to make the results independent of the starting data epoch. The probabilities of detecting a statistically significant trend within SLA data were computed in the relation with data spans and significance levels of the above-mentioned test. It is shown that for the standard significance level of 0.05 approximately 5.5 years of the SLA data are required to detect a trend with the probability close to 1. If the seasonal oscillations are removed from the combined T/P and J-1 SLA data, 4.3 years are required to detect a statistically significant trend with a probability close to 1. The estimated minimum time spans required to detect a trend in sea level rise are ad-dressed to the problem of SLA data predictions. In what follows, the above-mentioned estimate is assumed to be minimum data span to compute the representative sample of SLA data predictions. The forecasts of global mean SLA data are shown and their mean prediction errors are discussed.