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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 UAS-based thermal (TH) and multispectral (MS) cameras in SWC mapping.The study area for the analysis is situated at NE-Hungary near the town of Tépe. the plot is a part of a larger area of intensive agriculture, where the arable crop at the year of surveys was maize. The experimental AOI was set to a maximum size of 200 x 200 meters due to the time-demand and limitations of the multi-sensor surveys. On the plot 3 major soil types are found meanwhile relative relief differences are also notable. Soil samples were collected at the time of surveys to measure the reference SWC rates in laboratory conditions using the gravimetric method.The aerial mapping tasks were carried out using a DJI Matrice M210 payloads: 1) Micasense RedEdge-MX Dual, 2) Zenmuse XT2. High resolution DEM of the initial surface were mapped by a DJI Matrice M210 RTK v2 + a Zenmuse X7 lens. All imagery were processed in Pix4D Mapper. Machine Learning algorithms were then utilized to model the relationship between reflectance values, land surface temperature and the reference SWC values.Our surveys were dedicated to a sensitivity analysis on the different settings of Pix4D regarding the downscaling to different pixel resolution of the multispectral data and spectral reflectance calibration too. We have analyzed the differences on the SWC modeling accuracies on the different soil types and relief conditions to develop a more robust estimation for precision drainage designs.-----------The research is supported by the NKFI K138079 project.

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 the visibility of both shores. The interior geometry of both cameras were calibrated with an in-house designed target field. The image sequences were automatically co-registered to account for UAV movements during the image acquisition. The TIR data was processed to keep loss-free image information solely in the water area and to enhance the signal to noise ratio. Image velocimetry with PIV applied to the TIR data and PTV applied to the RGB data was utilised to retrieve surface flow velocities. Comparison between RGB and TIR data reveal an average deviation of about 0.01 m/s. Future studies are needed to evaluate the transferability to other non-regulated river reaches.

Airborne Laser Scanning (ALS) is a widely used method in Earth science, Agriculture or Forestry. This method could provide high resolution and accurate spatial data for the better understanding of surface structures, moreover, based on the laser pulses, it can even show important features of the ground below dense vegetation. However, these ALS surveys requires specially designed aircrafts, pilots and operators, detailed flight planning, which leads to an expensive way of data analysis. The application of laser scanners for Unmanned Aerial Systems (UAS) has started in the last few years. These sensor payloads provide less weight and size and decreased accuracy compared to the traditional ALS surveys but still serve as more reliable mapping technology contrary to the photogrammetric methods in many cases. However, several new UAS laser scanners are being developed but their accuracy conditions and applicability for agricultural monitoring must be studied in many ways.In our study we applied the novel Zenmuse L1 LiDAR sensor mounted on a DJI Matrice M300 RTK UAS. We surveyed a ~50 ha area of corn field near Berettyóújfalu, Hungary in the summer of 2021. Our aim was to reveal the applicability of UAS laser scanning for the precise ground surface reconstruction. In this period, the corn was under irrigated condition, therefore, extensive weed patches were observed between the paths. The laser scanner ground filtering data was compared to a photogrammetry-based aerial survey that we have carried out at the beginning of the vegetation cycle at the same parcel. Our results showed both the potentials and limitations of this sensor for precision agriculture. The laser beams produced significant amount of noise between the paths that had to be cleaned to extract the ground surface below the corn canopy. Based on our data processing methods we were able to delineate similar drainage networks within the parcel that was also processed from the initial aerial survey. However, the UAS LiDAR gained the most accurate surface reconstruction at the more clear grassland patches around the parcel. L. Bertalan was supported by the INKP2022-13 grant of the Hungarian Academy of Sciences. This research was funded by the Thematic Excellence Programme (TKP2020-NKA-04) of the Ministry for Innovation and Technology in Hungary. This research was also influenced by the COST Action CA16219 “HARMONIOUS - Harmonization of UAS techniques for agricultural and natural ecosystems monitoring”.

In this research, we survey soil erosion processes using an index of connectivity and a non-invasive and long-term assessment in situ technique: the improved stock unearthing method (ISUM), for whi...

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 field survey of their geomorphology, soil, flora and fauna, we describe the most relevant attributes of the mounds regarding their maintenance as valuable grassland habitats. We recorded 104 vascular plant species, including seven species that are protected in Hungary and two species (Echium russicum and Pulsatilla grandis) listed in the IUCN Red List and the Habitats Directive. The negative effect of the surrounding cropland was detectable in a three-metre wide zone next to the mound edge, where the naturalness of the vegetation was lower, and the frequency of weeds, ruderal species and crop plants was higher than in the central zone. The ancient man-made mounds harboured dry and warm habitats on the southern slope, while the northern slopes had higher biodiversity, due to the balanced water supplies. Both microhabitats had different assemblages of ground-dwelling invertebrates.

Unmanned Aerial Vehicles (UAV) have become a commonly used measurement tool in geomorphology due to their affordable cost, flexibility, and ease of use. They are regularly used in fluvial geomorphology, among other fields, because the high spatiotemporal resolution of UAV data makes it possible to assess the continuum rather than relying on single samples.In this study, UAV data are used to hydro-morphologically describe three different river reaches of lengths between 150 and 1000 m. Specifically, the surface flow velocity and bathymetry of the rivers were reconstructed. The flow velocities were calculated using the Particle Tracking Velocimetry (PTV) method applied to UAV video sequences. In addition, UAV-based imagery was acquired to perform 3D reconstruction above and below the water surface using SfM (Structure from Motion) photogrammetry, taking into account refraction effects as well as frame processing to increase the visibility of underwater features. Reference data for flow velocities were generated at selected positions using current meters as well as ADCP (Acoustic Doppler Current Profiler) readings. The image-based calculated bathymetry was compared with RTK-GNSS sampling depth measurements and also ADCP data.The developed workflow enables rapid and regular measurement of hydrological and morphological data of river channels. This ultimately enables multi-temporal assessment and significantly improves hydro-morphodynamic modelling, in particular their calibration.

The Sajó River in Hungary is a medium-sized sand-bed river along which intensive meander development and bank erosion occur. The process threatens agricultural lands and populated areas extensively. Therefore, preventive river management is needed.Main geomorphological features, processes and in-channel flow conditions have to be studied in detail in order to reveal main driving factors. Datasets with high spatio-temporal resolution are necessary to identify relevant parameters. However, so far data density at this river is sparse and gauging stations are distributed poorly.The aim of this study is the improvement of data availability to measure and model hydromorphodynamics of single reaches of the Sajó River. Therefore, multi-temporal field campaigns along selected sub-reaches are conducted with Unmanned Aerial Vehicles (UAV) and Unmanned Water Vehicles (UWV) to survey the topography, the river bed and flow conditions. The channel bathymetry is measured by a single-beam echo sounder mounted on a self-designed remotely controlled boat. The boat also integrates a Mobile Laser Scanner (MLS) to measure the river banks. Furthermore, a panorama camera system is installed to improve the pose estimation of the UWV functioning as a calibrated multi-sensor platform. UAV surveys were performed, using RGB and Thermal Infrared image sequences, to apply image velocimetry algorithms to characterize the river flow at selected cross-sections. ADCP measurements and Terrestrial Laser Scans (TLS) are used for accuracy assessment of the novel datasets.Eventually, data captured over a 2-years period will be implemented into hydrodynamic modeling of the studied sub-reaches to better understand seasonal variations in channel morphodynamics.----The project has been founded by the DAAD (57448822) and (Tempus Public Foundation & DAAD 307670). The research is also influenced by the HARMONIOUS COST Action (CA16219).

A remarkable badland valley is situated near Kazár, NE-Hungary, where rhyolite tuff outcrops as greyishwhite cliffs and white barren patches. The landform is shaped by gully and rill erosion processes. Weperformed a preliminary state UAS survey and created a digital surface model and ortophotograph. Theflight was operated with manual control in order to perform a more optimal coverage of the aerial images.The overhanging forests induced overexposed photographs due to the higher contrast with the baretuff surface. The multiresolution segmentation method allowed us to classify the ortophotograph andseparate the tuff surface and the vegetation. The applied methods and final datasets in combination withthe subsequent surveys will be used for detecting the recent erosional processes of the Kazár badland

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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 or urbanization plans, river regulations are designed to reduce anthropogenic impacts such as bank erosion, but many of these regulations resulted in a degradation of habitat diversity. Regardless, there is a lack of information about the possible positive effects of meandering from the ecological point of view. Therefore, the main aim of this study was to investigate a 2.12 km long meandering sub-reach of Saj&oacute, River, Hungary, in order to evaluate whether the process of meander development can be evaluated as a land degradation processes or whether it can enhance ecological conservation and sustainability. To achieve this goal, an archive of aerial imagery and UAV (Unmanned Aerial Vehicle)-surveys was used to provide a consistent database for a landscape metrics-based analysis to reveal changes in landscape ecological dynamics. Moreover, an ornithological survey was also carried out to assess the composition and diversity of the avifauna. The forest cover was developed in a remarkable pattern, finding a linear relationship between its rate and channel sinuosity. An increase in forest areas did not enhance the rate of landscape diversity since only its distribution became more compact. Eroding riverbanks provided important nesting sites for colonies of protected and regionally declining migratory bird species such as the sand martin. We revealed that almost 70 years were enough to gain a new habitat system along the river as the linear channel formed to a meandering and more natural state.

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 discussed. Once these hardware components are presented, the detailed workflow of a basic UAV-based mapping procedure is described (4.2). A further discussion focuses not only on the analytical or planning phases but also on providing useful information on the operational and processing parts as well (4.3). Then, there comes image acquisition and project planning (4.4). The photogrammetry-based image processing requires detailed expertise and attention; Sect. 4.5 maybe helpful to avoid potential mistakes. The last section (4.6) summarizes some aspects of the use of LiDAR technologies in UAV-based surveys.

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 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 river systems like Sajo River (Slovakia-Hungary) where no preliminary work is available regarding channel dynamics. In addition, to just describing the geomorphic processes, the environmental management implications of these meandering rivers need to be investigated as well. Thus, this study represents a bend-scale morphological analysis on the 124 km long section of the Sajo River in the Hungarian territory in eight different periods between 1952 and 2011. Archive aerial imagery, orthophotographs and topographical maps were organized into a database, then GIS-based analyses were performed to quantify the rate and extent of channel shifts, bend development and the area of erosion/accretion. On the bend scale, we have calculated several morphometric parameters (bend length, chord, amplitude, the radius of curvature) to quantify the evolutionary trajectory of reaches. Hydrological time series data were evaluated to reveal its possible role in the processes. Based on the available GIS-data of natural elements and anthropogenic intervention, we delineated 12 different reaches showing similar characteristics, from which six reaches were defined as natural. According to the morphometric parameters of the natural reaches, channel widths became narrower and the planform became more concentrated spatially in most of the reaches while the overall sinuosity of almost all natural reaches increased. Although artificial cutoffs mainly reduced the reach complexity, in some cases, they have accelerated the bend development downstream in the following few years. Erosion and accretion activity were higher in the periods when the discharge was higher than the effective discharge but its effect became less apparent in the second half of the investigated time period. By 1980, major artificial cutoffs and bank protection works were carried out that could have an impact in reducing the potential channel shifting. Based on our results, we propose a possible preservation and some modifications along the Hungarian part of the Sajo River reaches to be carried out by the local river management authorities. We conclude that this study provides a detailed demonstration of the Sajo River morphodymanics which can be used for further land planning to avoid harmful consequences of recent bank erosion processes not only along the Sajo River, but other similar rivers in Europe.