Laszlo Bertalan

Verified

Laszlo verified their affiliation via an institutional email.

Learn more

Verified

Laszlo verified their affiliation via an institutional email.

Learn more

• PhD
• Assistant Professor at University of Debrecen

Unoccupied aerial systems (UASs) are frequently used in the field of fluvial geomorphology due to their capabilities for observing the continuum rather than single sample points. We introduce a (semi‐)automatic workflow to measure river bathymetry and surface flow velocities of entire river reaches at high resolution, based on UAS videos and imager...

The quasi-natural meandering type of alluvial rivers is quite unusual in Central European watersheds. The lack of extensive regulation allows such rivers to shift along their floodplain and cause erosion of natural and agricultural lands. Description of channel morphometric parameters over decadal timescales allows a better understanding of such ri...

The extensive destruction of arable lands by the process of lateral bank erosion is a major issue for the alluvial meandering type of rivers all around the world. Nowadays, land managers, stakeholders, and scientists are discussing how this process affects the surrounding landscapes. Usually, due to a land mismanagement of agroforestry activities o...

Urban sprawl related increase of built-in areas requires reliable monitoring methods and remote sensing can be an efficient technique. Aerial surveys, with high spatial resolution, provide detailed data for building monitoring, but archive images usually have only visible bands. We aimed to reveal the efficiency of visible orthophotographs and phot...

We survey soil erosion processes using an index of connectivity and a non invasive and long-term assessment in situ technique: the ISUM (Improved Stock Unearthing Method). In this research, a vineyard of Castilla La Mancha under tillage management was selected. In 10 years, our results showed that the current total average soil surface level decrea...

16 different satellite soil moisture (SM) datasets (passive, active, combined, and model data) were compared at the European scale. We hypothesized that SM should be reflected by a variety of environmental factors, such as topography, hydroclimatology, soil characteristics, and biomass. Robust correlation was used to explore the relationship among...

Understanding the spatial distribution of topsoil properties in grassland ecosystems is essential for improving soil ecosystem services, quality, and erosion resilience. The availability of free, high-resolution satellite imagery and advanced data mining techniques offers new opportunities for efficient soil property assessment. This study aimed to...

Bevezetés A szélerózió a Föld számos területén, így hazánkban is komoly problémákat és jelentős károkat okoz (zHeNG, x. 2009). Ez a jelenség elsősorban a homoktalajokat veszélyezteti, de a kötöttebb talajok termőképességének leromlá-sában is fontos szerepet tölt be (Guo et al. 2014). A károk egy része lehet mezőgazdasági (talaj-veszteség, termőképe...

Vegetation structure data are essential for understanding the functioning of terrestrial ecosystems and for informing various science-policy interfaces. Recent years have seen a growing demand for high-resolution data on vegetation structure, driving the prediction of such metrics at fine resolutions (1 m - 30 m) at state, continental, and global s...

In this study, we investigated the accuracy of surface models and orthophoto mosaics generated from images acquired using different data acquisition methods at different processing levels in two urban study areas with different characteristics. Experimental investigations employed single- and double-grid flight directions with nadir and tilted (60°...

Aquatic vegetation species at the genus level in an oxbow lake were identified in Hungary based on a multispectral Uncrewed Aerial System (UAS) survey within an elongated oxbow lake area of the Tisza River under continental climate. Seven and 13 classes were discriminated using three different classification methods (Support Vector Machine [SVM], R...

Several studies investigated the occurrence of fires in Africa with numerical modeling or applied statistics; however, only a few studies focused on the influence of El Niño on the fire risk using a coupled model. The study aimed to assess the influence of El Niño on wildfire dynamics in Africa using the SPEEDY-HYCOM model. El Niño events in the Ea...

Badlands, often described as natural field laboratories, are landscapes of limited vegetation, with reduced or not existing human activity that are exposed to a wide range of geomorphological processes. These areas are made of mostly soft and poorly consolidated terrigenous, lacustrine or marine sediments of different age that were developed under...

Environmentally friendly biological mosquito control by Bacillus thuringiensis var. israelensis formulations needs appropriate breeding maps. The mapping accuracy depends on the quality of the used remote sensing data. Further, the mapping is expected to be cost-effective. Our aim was to study the effect of the quality of various remote sensing dat...

Dear Colleagues, monitoring water resources at high resolution and with large spatial coverage is essential in order to achieve sustainable development at a global scale. Many regions suffer a critical lack of hydrological observations or present discontinuous measurements from sparse in situ monitoring networks. In recent years, advances in Remote...

The current research aims to predict the velocity distribution and discharge rates in rivers based on the entropy concept using only one surface velocity measurement. In this direction, first, the uncrewed aerial vehicle (UAV)‐based image acquisition technique was applied to collect the surface velocity distribution along two European rivers, the S...

Soil water content (SWC) estimation is a crucial issue of agricultural production, and its mapping is an important task. We aimed to study the efficacy of UAV-based thermal (TH) and multispectral (MS) cameras in SWC mapping. Soil samples were collected and the SWC content was determined in a laboratory as reference data and four machine learning re...

Riparian zones are dynamic ecosystems that form at the interface between the aquatic and terrestrial components of a landscape. They are shaped by complex interactions between the biophysical components of river systems, including hydrology, geomorphology, and vegetation. Remote sensing technology is a powerful tool useful for understanding riparia...

Sommario/Abstract The present study aims to estimate cross sectional velocity distribution and discharge rate in rivers based on the Entropy concept using only one surface velocity measurement. In this case study, UAV-based image acquisition was applied to collect the surface velocity distribution along the Sajó River near the city of Nagycsécs, Hu...

This study assesses the suitability to use RGB and thermal infrared imagery acquired from an UAV to measure surface flow velocities of rivers. The reach of a medium-scale river in Hungary is investigated. Image sequences with a frame rate of 2 Hz were captured with two sensors, a RGB and an uncooled thermal camera, at a flying height that ensures t...

Gullies reduce both the quality and quantity of productive land, posing a serious threat to sustainable agriculture, hence, food security. Machine Learning (ML) algorithms are essential tools in the identification of gullies and can assist in strategic decision-making relevant to soil conservation. Nevertheless, accurate identification of gullies i...

Prehistoric mounds of the Great Hungarian Plain often function as refuges for relic loess steppe vegetation and their associated fauna. The Zsolca mounds are a typical example of kurgans acting as refuges, and even though they are surrounded by agricultural land, they harbour a species rich loess grassland with an area of 0.8 ha. With a detailed fi...

Beside industrial scale large wind turbines there is an increasing demand for lower capacity, household scale wind turbines recently. An important advantage of such small wind turbines is that they can be established in urban locations and they can produce electricity in online and offline mode either. While the height of the towers of industrial s...

Identification of roofing material is an important issue in the urban environment due to hazardous and risky materials. We conducted an analysis with Discriminant Function Analysis (DFA) and Random Forest (RF) on WorldView-2 imagery. We applied a three- and a six-class approach (red tile, brown tile and asbestos; then dividing the data into shadowe...

The alluvial meandering Sajó River (or Slaná in Slovakian) is a transboundary river of Slovakia and Hungary with a total length of 229 km, of which 124 km is located in the Hungarian territory. Regarding the river regulation and management, Sajó River shows one of the highest rate of free forming sections in compare with other alluvial rivers in Hu...

In present study the land use evolution in two sides of Talar River that is one of the most important rivers in Caspian Sea watershed, have been investigated during about a 60 years period by interpretation of archive aerial photographs. The effects of land use change on bank retreat of the study reach have been considered too. Results show that du...

The Itaipu reservoir had been established in 1984 on the Parana River, along the Brazil-Paraguay border region. The reservoir has a total length of 181 km, mean width of 7 km, the capacity exceeds 29,109 m3 while the coastline covers 2,919 km. In the reservoir area, Serra Geral Basalt Group, a Cretaceous age continental flood basalt flow outcrops e...

This chapter will be more practical in nature. It will discuss two fields in which UAV-based photogrammetry proves a particularly efficient tool in geographic and architectural surveys. We will also reflect on the expectable accuracy of these relatively low-cost instruments.

The aim of this chapter is to provide a general overview about the main components of a developed UAS mapping system, the survey, and processing procedure. At first (4.1), a brief introduction is given about basic operational elements and accessories of UAS. Then, recent camera/sensor technologies allowing various survey solutions are going to be d...

The aim of our study was to collect hydrological datasets representing the spatio-temporal trends at the Sajó River watershed. A UAV-based meander development monitoring was carried out from 2014 to 2016 at selected river bends where we compared the rate of lateral erosion with the water levels. Our results showed that the hydrological variables pl...

Poster presented at the VIII. GIS Conference and Exhibition in Debrecen 2017.

Flume experiments are common tools in investigations of fluvial geomorphology. There is often a need to capture the actual phase of fluvial surface development. Terrestrial laser scanner was used as reference data and compared to three different type of photogrammetric model. The three type were based on three different camera type (Panasonic, GoPro...

A remarkable badland valley is situated near Kazár, NE-Hungary, where rhyolite tuff outcrops as greyish white cliffs and white barren patches. The landform is shaped by gully and rill erosion processes. We performed a preliminary state UAS survey and created a digital surface model and ortophotograph. The flight was operated with manual control in...

Fluvial geomorphologists have tried to describe the outstanding tectonically affected avulsion process of Tisza River at the Great Hungarian Plain by various theoretical concepts. Flume experiments provide the ability to examine the main characteristic processes of a highlighted surface development theory under controlled settings within an acceler...

The aim of our study was to analyze the changes in channel planform geometry of River Sajó between 1952 and 2011. Long term morphological changes were evaluated on the basis of maps and aerial photographs. In every investigated periods the bank edges were vectorized in ArcMap 10. Our results showed that the channel width had a decreasing trend; whi...

Poster presented at the VII. GIS Conference and Exhibition in Debrecen 2016.

Poster presented at the VII. GIS Conference and Exhibition in Debrecen 2016.

Poster presented at the VII. GIS Conference and Exhibition in Debrecen 2016.

Recently, various researches have focused on the environmental condition assessment of oxbow lakes along rivers. In this study we investigated the bed morphology, conductivity and the changes of macro-and microelements in the oxbow, named Kacsa-tó, that was formed by the 45 th cutoff on Tisza River, then the results were plotted using GIS softwares...

Decreasing population density is a current trend in the European Union, and causes a lower environmental impact on the landscape. However, besides the desirable effect on the regeneration processes of semi-natural forest ecosystems, the lack of traditional management techniques can also lead to detrimental ecological processes. In this study we inv...

The aim of our investigations is to analyse meander and river bank development influenced by natural processes and human activity on the alluvial Sajó River of Hungary. Long term morphological changes of Sajó River were evaluated on the basis of maps aerial photographs (1952, 1956, 1972, 1988, 2000, 2005 and 2011) and the 1:10.000 scale topographic...

The aim of our investigations was to analyse meander and river bank development influenced by natural processes and human activity on the alluvial Sajó (Slaná) River of Hungary. The rate and pattern of meander development was evaluated by analysing horizontal meander parameters. Long term morphological changes of Sajó River were evaluated on the ba...

Flume and plotting board experiments have been used in fluvial geomorphology for decades. Our goal was to examine a photogrammetric method of creating digital elevation models and ortophotos from digital photographs of a surface development experiment. Our examinations showed that the DEM and the ortophotos can be created by a short period of time...

The aim of this paper is to provide a brief overview about some experiments that we have performed at our department’s fluvial processes laboratory. Actually, this laboratory has a large plotting board which is 10meters long, 3meters wide and 2,5meters deep concrete basin. It has a slight slope for the natural river runoff-processes and it is fille...

The aim of this presentation is to provide a brief overview about some experiments that we performed at our department for my PhD-researches. The areas of my research are fluvial geomorphology and GIS technologies. Fluvial geomorphology is a very popular topic and many scientists investigated the relationship between river systems and the surface d...

A tájváltozásban és a területhasználatban megmutatkozó jellegzetességek megértéséhez a jelenkori állapotok felmérése mellett nagyon fontos, hogy megismerjük annak korábbi viszonyait, s az azokat kialakító folyamatok hátterét. Dolgozatomban egy 243km2 területű, a Tokaj-Zempléni-hegyvidék, Hegyköz és a Hegyalja egyes vidékeit magába foglaló mintaterü...