Prahova River Research Articles

Developing flood mapping procedure through optimized machine learning techniques. Case study: Prahova river basin, Romania

Study regionPrahova river basin located in the central-southern region of Romania. Study focusThis study aims to assess the susceptibility to flooding by using state-of-the-art machine learning and optimization procedures. To achieve this goal, we employed ten flood-related variables as independent variables in our machine learning models. These variables include slope angle, convergence index, distance from the river, elevation, plan curvature, hydrological soil group, lithology, topographic wetness index, rainfall, and land use. We used 158 flood locations as dependent variables in the training of four hybrid models: Deep Learning Neural Network-Statistical Index (DLNN-SI), Particle Swarm Optimization-Deep Learning Neural Network-Statistical Index (PSO-DLNN-SI), Support Vector Machine-Statistical Index (SVM-SI), and Particle Swarm Optimization-Support Vector Machine-Statistical Index (PSO-SVM-SI). Utilizing the Statistical Index method, we calculated coefficients for each flood predictor class or category. New hydrological insights for the regionThe PSO-DLNN-SI model demonstrated the best performance, achieving an AUC-ROC curve of 0.952. It's worth noting that the application of the PSO algorithm significantly enhanced the model's performance. Additionally, it's crucial to highlight that approximately 25 % of the study region exhibits a high to very high susceptibility to flood events. Taking into account the very precise results of the models applied in the present study, we can state that from a hydrological point of view, the current research contributes to a better understanding of the intensity with which floods can affect the different areas of the Prahova river basin.

Assessing the impact of an arch-dam breach magnitude and reservoir inflow on flood maps

Abstract Different scenarios of an arch-dam breach and their impact on the time-space evolution of flood waves are analysed using numerical modelling. As the accidents involving this type of dam are among the most catastrophic ones, the 108 m in height Paltinu arch-dam, Romania, was chosen as a case study due to its problems in the past. Three dam breach magnitudes and two inflow hydrographs for the worst-case scenario of Normal Operating Pool elevation in the reservoir were chosen as variable parameters, to assess their influence on the dam break wave characteristics and downstream flooded areas. The flood was routed along the 18 km reach of the Doftana River down to the confluence with the Prahova River. A 2D numerical model was set up with the help of HEC-RAS software, which was also used to analyse the resulting hazard maps under a GIS environment. Comparison of inundation boundary, maximum depths and velocities, as well as the arrival time at control sections allow for conclusions to be drawn. These predictive results of shape, magnitude, and time to peak of the flood waves are essential for flood risk management to obtain the risk maps, estimated damage costs, and possible affected areas.

Using fuzzy and machine learning iterative optimized models to generate the flood susceptibility maps: case study of Prahova River basin, Romania

In this work, the vulnerability to flooding in the Prahova River basin was calculated and analyzed using advanced methods and techniques. Thus, 2 hybrid models represented by Iterative Classifier Optimizer – Multiclass Alternating Decision Tree – Certainty Factor (ICO-LADT-CF) and Fuzzy-Analytical Hierarchy Process – Certainty Factor (FAHP-CF) were generated, which had as input data the values of 10 flood predictors and a number of 158 points where historical floods occurred. In the first step, the Certainty Factor values were calculated, which were then used in the Fuzzy-Analytical Hierarchy Process and Multiclass Alternating Decision Tree models. It should be mentioned that the Multiclass Alternating Decision Tree model was optimized with the help of the Iterative Classifier Optimizer. In the case of both ensemble models the slope angle was the most important flood conditioning factor. Moreover, according to Certainty Factor modelling the 8 classes/categories achieved the maximum value of 1. Next, the susceptibility to floods on the surface of the study area was derived. On average, about 20% of the study area has areas with high and medium susceptibility to flash floods. After evaluating the quality of the models through Receiver Operating Characteristics (ROC) Curve, the following results emerged: Success Rate for Flood Potential Index (FPI) Iterative Classifier Optimizer – Multiclass Alternating Decision Tree – Certainty Factor (ICO-LADT-CF) (Area Under Curve = 0.985) and Flood Potential Index (FPI) Fuzzy-Analytical Hierarchy Process – Certainty Factor (FAHP-CF) (Area Under Curve = 0.967); Prediction Rate for Flood Potential Index (FPI) Iterative Classifier Optimizer – Multiclass Alternating Decision Tree – Certainty Factor (ICO-LADT-CF) (Area Under Curve = 0.952) and Flood Potential Index Fuzzy-Analytical Hierarchy Process – Certainty Factor (FAHP-CF) (Area Under Curve = 0.913). At the same time, the accuracies of the models were: Training dataset − 0.943 (Iterative Classifier Optimizer – Multiclass Alternating Decision Tree – Certainty Factor) and 0.931 (Fuzzy-Analytical Hierarchy Process – Certainty Factor); Validating dataset − 0.935 (Iterative Classifier Optimizer – Multiclass Alternating Decision Tree – Certainty Factor) and 0.926 (Fuzzy-Analytical Hierarchy Process – Certainty Factor). As main conclusion, it can be mentioned that the 2 ensemble models outperform the previous machine learning models applied on the same study area before.

Influence of dam break scenarios on flood wave characteristics. Case study – Paltinu Dam, Romania

Among the various constructive types of dams, the arch dams breaches are the largest and the quickest to occur, leading to the most catastrophic flood waves. Therefore, prediction of the shape, magnitude and arrival time of the breach waves is of utmost importance for flood risk management. The study analyses in GIS environment the influence of different dam breach scenarios on the evolution in time and space of the flood wave. As a study case it was chosen the 108m in height, Paltinu arch-dam (Romania), built on Doftana River and its about 19km river reach down to the confluence with Prahova River. Several breach widths and depths are considered in the analysed scenarios, coupled with selected inflow hydrographs and initial reservoir water elevation, to assess their influence on the dam break wave characteristics and downstream flooded areas. To model the flood wave routing following the dam brake, HEC-RAS software is used. Inundation boundaries, characteristic depths and velocities, as well as arrival time in selected control sections are compared and conclusions are drawn.

Impact Of Channel Incision On Floods: A Case Study In The South-Eastern Subcarpathians (Romania)

Despite numerous researches on river channel incision, there are fewer studies on the impact of channel adjustments on floods. This paper aims to investigate channel adjustments and to analyse their impact on the frequency of floods by estimating the return period of the bankfull discharge of the Prahova River in the South-Eastern Subcarpathians (Romania). The study is based on the analysis of the maximum annual discharges and cross-section profiles of the Prahova River at Câmpina gauging station (1976–2015). To estimate the return period of the bankfull discharge, the log Pearson III distribution was used. Overall, the maximum depth and the cross-section area at the bankfull stage increased during the analysed period, indicating channel incision and lateral stability. The bankfull discharge of 1976 could be reached every year and the one of 2015 could occur almost every 5 years. Therefore, due to channel incision and increased channel capacity, overflowing the bankfull stage is a less frequent hazard on the Prahova River at Câmpina gauging station. River management appears to maintain this situation as no measure is taken to decrease channel incision.

Downstream coarsening of subsurface sediment grain size along upper Prahova River (Romania)

Downstream coarsening of subsurface sediment grain size along upper Prahova River (Romania)

Flood Susceptibility Assessment by Using Bivariate Statistics and Machine Learning Models - A Useful Tool for Flood Risk Management

In Romania, as in the rest of the world, the flood frequency has increased considerably. Prahova river basin is among the most exposed catchments of the country to flood risk. It also represents the area of the present study for which the identification of surfaces with high susceptibility to flood phenomena was attempted by applying 2 hybrid models (adaptive neuro-fuzzy inference system and fuzzy support vector machine hybrid) and 2 bivariate statistical models (certainty factor and statistical index). The computation of Flood Potential Index (FPI) was possible by considering a number of 10 flood conditioning factors together with a number of 158 flood pixels and 158 non-flood pixels. Generally, the high and very high flood potential appears on around 25% of the upper and middle basin of Prahova river. The validation of the results was made through the ROC Curve model. One of the novelties of this research is related to the application of Fuzzy Support Vector Machine ensemble for the first time in a study concerning the evaluation of the susceptibility to a certain natural hazard.

The hydrological regime of the Prahova River along Carpathian and Subcarpathian stretch

The hydrological regime of the Prahova River along Carpathian and Subcarpathian stretch

Modeling Hydrodynamic Changes Induced by Run-of-River Hydropower Plants along the Prahova River in Romania

AbstractThe purpose of the study is to reveal changes of the hydrodynamics and sediment transport induced into the river channel by the operation of small hydropower plants (SHPs). A 36-km reach of...

Spatial temporal variability of maximum flow in Slănic, Teleajen and Prahova River Basins

AbstractThe present study analyzes the spatial temporal variation of maximum flow in Slănic Teleajen and Prahova river basins (upper basin). Maximum flow rates were analyzed in relation to the threshold values corresponding to the Defence Levels respectively the maximum flow which determines exceeding Warning and Flooding Levels. The series of major floods events, selected on the basis of the threshold values mentioned above, were then statistically analyzed to determine trends (Mann-Kendall test) and the variations in the level of frequency, analysis which was applied seasonally and annually. The analysis made revealed that trends in terms of maximum flow rates in the Prahova upper basin were generally negative (decreasing), statistically significant for the February, May, July, August and the annual average, while in Slanic river basin, the trend was mostly positive, statistically significant for October.

Using a multi-criteria analysis to identify rivers with hydromorphological restoration priority: Braided rivers in the south-eastern Subcarpathians (Romania)

In order to systematically plan river restoration actions at a regional scale, this paper develops a multi-criteria analysis that classifies rivers, based on their priority for hydromorphological restoration. This priority is defined by severe human pressures within the erodible corridor of the river, drastic alteration of the stream channel, and low intensity of river pattern functioning. Based on relevant indicators for three groups of features (human pressures, channel changes, and river functionality), a Hydromorphological Restoration Priority Index (HRPI) was designed. The high values (>66%) of HRPI reflect an urgent need for hydromorphological restoration while low values (<33%) reveal a less immediate necessity for restoration. The proposed methodology was applied on braided sectors of rivers crossing the south-eastern (Curvature) Subcarpathians (Romania). The values of the total HRPI ranged between 21% (Zăbrăuţ River) and almost 44% (Prahova River). According to our results, most of the analyzed sectors have a low need for hydromorphological restoration of the braided pattern, while some have a moderate necessity for restoration. Whereas the Prahova River has the highest HRPI, it should be given priority for restoration at a regional scale, which corresponds to the objectives of River Basin Management Plans for the interval beyond 2021.

Mapping flood and flooding potential indices: a methodological approach to identifying areas susceptible to flood and flooding risk. Case study: the Prahova catchment (Romania)

Given that floods continue to cause yearly significant worldwide human and material damages, flood risk mitigation is a key issue and a permanent challenge in developing policies and strategies at various spatial scales. Therefore, a basic phase is elaborating hazard and flood risk maps, documents which are an essential support for flood risk management. The aim of this paper is to develop an approach that allows for the identification of flash-flood and flood-prone susceptible areas based on computing and mapping of two indices: FFPI (Flash-Flood Potential Index) and FPI (Flooding Potential Index). These indices are obtained by integrating in a GIS environment several geographical variables which control runoff (in the case of the FFPI) and favour flooding (in the case of the FPI). The methodology was applied in the upper (mountainous) and middle (hilly) catchment of the Prahova River, a densely populated and socioeconomically well-developed area which has been affected repeatedly by water-related hazards over the past decades. The resulting maps showing the spatialization of the FFPI and FPI allow for the identification of areas with high susceptibility to flash-floods and flooding. This approach can provide useful mapped information, especially for areas (generally large) where there are no flood/hazard risk maps. Moreover, the FFPI and FPI maps can constitute a preliminary step for flood risk and vulnerability assessment.

Using Pressure and Alteration Indicators to Assess River Morphological Quality: Case Study of the Prahova River (Romania)

River morphological quality assessment, derived from quantification of human pressures as well as river channel alteration, is a demand of the Water Framework Directive (WFD) in terms of integrating hydromorphological elements in defining ecological status. Our study’s aim is to contribute to the hydromorphological evaluation by proposing indicators and separating classes, based on a revisited Morphological Quality Index (rMQI) protocol. The rMQI is based on 12 indicators of human pressures, 10 indicators of channel form adjustments, and 11 indicators of functionality. The rMQI scoring system allows for the quantification of changes when compared to reference conditions, be they undisturbed or nearly undisturbed by human interventions, with absent channel adjustments and a functioning natural river style. We used the lower, meandering sector of the Prahova River to demonstrate our assessment methodology. The Lower Prahova River suffers from a minor local intervention and a diminishing intensity of fluvial processes specific to a meandering style. Meanders geometry was affected by significant changes that included a decrease in the radius of curvature, width and width–to–mean–depth ratio. We concluded that the Lower Prahova River has a good morphological quality, which is rated as second class on a scale of five levels, from natural to severely modified. We recommend an improvement in the hydromorphological evaluation protocol in Romania by additional indicators for morphological alterations specific to each channel pattern.

Maintenance of the Romanian National Transportation System of Crude Oil and Natural Gas

In this paper we present a view on the organization of maintenance to the Romanian National Transportation System of crude oil and natural gas.Currently, Romania has an important system of pipelines for transporting crude oil and petroleum products, built and equipped with up to date levels of technology, and a well developed network of gas pipelines, interconnected, forming the National Transportation System. Depending on the needs of mining, processing and consumption the transportation of fluid hydrocarbons continues to grow.The primary means of transportation, for both liquid hydrocarbons and gas, it is thru the pipelines. Existing pipeline network in Romania continued to grow, reaching higher lengths, diameters and transport capacities. Thus the Romanian transportation system grew and now it integrates the activities of collection and preparation of oil and gas for transport and storage and those of distribution to consumers. In such a system, the central place it is occupied by the transportation activity with an array of specific issues that require careful consideration in order to find the best solutions both technically and economically.The lack of a proper maintenance method used at a point where the crude oil pipelines overpass Prahova River in the village of Cartojani, after a heavy rainfall, has lead to damage to the pipeline supportive pillars, resulting in heavy repair costs.

Landslide susceptibility deterministic approach using geographic information systems: application to Breaza town, Romania

The study is a deterministic-based approach on landslide susceptibility. The purpose of the paper is to create quantitative susceptibility maps by joining the one-dimension infinite slope stability model with a raster-based GIS (ILWIS) and taking into account the spatial distribution of input parameters. A landslide-prone area, with relative homogeneous geology and geomorphology, located in the Subcarpathian sector of the Prahova River, Romania, was selected for the study. There are frequent problems caused by active landslides in the studied area, especially in years with heavy precipitation, often causing destruction of houses and roads situated on the slopes (1992, 1997, and 2005). Detailed surveys covering a 7-year period provided the necessary input data on slope parameters, hydrological components, and the geotechnical background. Two simulations were used: one on dry soil conditions and one on fully saturated soil conditions. A third test was based on the level of the groundwater table mapped in summer 2008. Detailed analyses were particularly focused on landslides to compare predicted results with actual results using field measurements. The model is very suitable for use in raster GIS because it can calculate slope instability on a pixel basis, each raster cell being considered individually. The drawback of the model is the highly detailed data of input parameters. Despite this disadvantage, in conclusion, the usefulness of slope stability models on a large-scale basis was emphasized under infinitely high failure plain conditions and lithological homogeneity.

Linking morphological settings and hydrodynamic river behaviour. Prahova River, Romania

The purpose of this study is to analyze, using GIS, the relationship between hydrodynamic characteristics during high intensity flood periods and geomorphological controls on channel and valley morphology of the Carpathian and Subcarpathian Prahova River. In order to acquire Prahova River’s topographic information, on its channel and valley from Predeal (upstream) to Campina (downstream), in August 2006 a GIS ground-based survey was used. The survey consisted of 192 topo-bathymetrical cross-section profiles over 55 Km distance (river length) covering the Carpathian and Subcarpathian reaches.

Morpho-dynamic evolution patterns of Subcarpathian Prahova River (Romania)

Abstract The Prahova River (Romania) at the Southern Carpathian Mountains was affected by a number of measureable changes in its planform pattern and longitudinal profile over the past 200 years. The mountain river has been incising into bedrocks, narrowing its valley, abandoning its lateral channels and straightening its path while crossing the Subcarpathian study section. The purpose of this study is to analyze, using GIS, the relationship between short-term (less than 200 years) lateral and vertical morphological adjustments observed over the 18 km length Subcarpathian Prahova River and specific long-term evolutionary patterns (more than 200 years). Human disturbances and hydrodynamic characteristics during high intensity flood periods are assessed in the context of existing neotectonics and lithology controls on channel and valley morphology. Surveyed cross-section profiles were used to construct the geometry of a 1D hydraulic model. Simulations were performed using the HEC-RAS software (USACE) under steady flow conditions for flow values between bankfull and the peak discharge value of typical flood events with a return period of 20 and 50 years. Three main areas with high values of computed shear stresses and velocities and corresponding low values of width to depth ratio (W/D) were identified. These areas were found to match the observed erosion areas, where the river has incised into bedrock and eroded its banks. Other potentially aggradation areas of low shear stress values and high W/D were confirmed by field observations. The evolutional patterns of Prahova River channel are tectonic-structurally determined, developed and maintained during the Quaternary mainly by the principles of river morphodynamics. The evolution over shorter timescale bears the mark of the man-induced impact (changes in sediment and hydrologic regimes). In a long-term perspective, the overall channel evolution of this river is expected to be strongly influenced by human activity.

Landslide Susceptibility for the Administrative Area of Breaza, Prahova County, Curvature Subcarpathians, România

Please click here to download the map associated with this article. The evaluation of landslide susceptibility requires understanding of the spatial distribution of the factors that control slope instability. It is known that the behaviour of landslides is difficult to evaluate because of the various factors that trigger mass movements. The methodology used is very diverse, based on statistical methods, probabilistic methods, deterministic methods, empirical methods or a combination of them. The main factors used for landslide susceptibility assessment are composed from basic morphometric parameters, such as slope gradient, curvature, aspect, solar radiation etc in combination with lithology, land-use/land-cover, soil types or soil properties. For this study it was decided to use only four factors: slope gradient, lithology, land-use/land-cover and a topographic wetness index. The study area spreads over approximate 50 km and represents the administrative area of Breaza town, located along the Prahova River in the Curvature Subcarpathians, Romania. This area is highly affected by mass movements, spread on the entire hillslopes. Over 70% of the area is moderately or highly susceptible to landslides.

The Geomorphotechnical Map: a highly detailed geomorphic map for railroad infrastructure improvement. A case study for the Prahova River Defile (Curvature Carpathians, Romania)

Please click here to download the map associated with this article. The paper proposes a new type of geomorphic map, a selective fusion of geomorphic data with land engineering and transport infrastructure features at the detailed scale of 1:5,000. The map focuses on the interaction between landforms, morphodynamics and transport infrastructure, having as interface the land engineering works. The “geomorphotechnical map” as it was named was developed in a digital format as a GIS project for the Prahova River Defile (Curvature Carpathians, Romania), a sector along the main transcarpathian route which links Bucharest with Brasov and Transylvania. Geomorphic data was collected through detailed field mapping, during summer and autumn periods, together with GPS surveying. The technical infrastructure elements were located also using orthophotos from different time periods. The map reflects the main favourable geomorphic conditions (and limitations) for the improvement of a difficult sector along the Bucharest-Brasov main railway; this has national and European importance (a sector of the 4th Pan European Corridor). Since 2008 this railway (double and electrified since 1969) is the subject of complex and costly improvement works supported by European Financed Projects.

Evolution 2D de la bande active de la Haute Prahova (Roumanie) durant les 150 dernières années

Cet article traite de l’evolution de la Haute Prahova (Carpates et Subcarpates en Roumanie) durant les 150 dernieres annees en relation avec les facteurs responsables. L’analyse est basee sur une etude cartographique diachronique realisee a partir de cinq series de cartes et orthophotoplans de 1855, 1900, 1955, 1980, 2005. Les parametres pris en compte ont ete la sinuosite et la bande active de tressage, ce qui a permis de determiner le style fluvial de la Prahova et de quantifier ses variations. Les principaux resultats montrent que la Prahova se caracterise par une contraction importante de la largeur de son chenal fluvial/bande active et par une tres faible evolution de sa sinuosite. Cela est du a l’action conjuguee de plusieurs types de facteurs naturels et anthropiques qu’il est difficile de departager du fait de leurs effets simultanes.