FINDING THE BEST LOCATIONS FOR FURROWS IN SOIL BERMS OF DRAINAGE DITCHES USING LIDAR DATA

Soil berms are typically built on the sides of ditches and are designed to purify water from agricultural fertilizers and to limit the transport of sediments to water bodies. However, for soils with fine particles, water filtration is limited and wet soil conditions can occur, which in turn reduces the soil's hydrologic conductivity capacity and hinders tree growth in the forest. The aim of the study is to develop a methodology for automatic modeling of the furrows in soil berms. Open source software QGIS and GRASS GIS is used in data processing. LiDAR data with minimum ground point density of 1.5 points per square meter were used in DEM creation. Local maximum analysis and further data filtration were used in determination of locations of soil berms. The results show that by making one furrow for every 185 m of ditches it is possible to reduce the area of the depressions by up to 91.8%. &nbsp

Identification of wet areas in forest using remote sensing data

ArticleAim of this study is to evaluate different remote sensing indices to detect spatial distribution of wet soils using GIS based algorithms. Ar ea of this study represents different soil types on various quaternary deposits as well as different forest types. We analyzed 25 sites with the area of 1 km 2 each in central and western part of Latvia. Data about soil characteristics like thickness of pea t layer and presence of reductimorphic colors in soil was collected during field surveys in 228 random points within study sites. ANOVA test for comparing means of different soil wetness classes and binary logistic regression analysis for evaluating the ac curacy of different remote sensing indices to model spatial distribution of wet areas are used for analysis. Main conclusion of this study is that for different quaternary deposits and soil texture classes different algorithms for soil wetness prediction s hould be used. Data layers for predicting soil wetness in this study are various modifications and resolutions of digital elevation model like depressions, slope and SAGA wetness index as well as Sentinel - 2 multispectral satellite imagery. Accuracy of soil wetness classification of soils on moraine, fluvial and eolian sediments exceeds 94%, whereas on the clayey sediments it is close to 80%

METHOD FOR SHALLOW DRAINAGE DITCH NETWORK GENERATION USING REMOTE SENSING DATA

Aim of this study is to develop a method for automatic shallow drainage ditch generation to drain terrain depressions using four factor least cost surface which is obtained using LiDAR (light detection and ranging) data and Sentinel-2 multispectral satellite imagery. LiDAR data are used for depression mapping in DEM, flow accumulation and slope modelling as well as CHM (canopy height model) to obtain relative vegetation height. Sentinel-2 imagery was used for land cover type identification as well as separating coniferous and deciduous forest stands. Study area is located in western Latvia and is 25 km2 large. Least cost surface connects DEM depressions and already existing drainage ditches by best possible path for shallow ditch network digging. Different methods are applied to determine depressions which can be drained as well as changes of affected drained area and depression depth. This results in suitable areas where to create shallow ditches to improve water runoff. Results show that using this method average reduction of area of depressions is 79% and average length of shallow ditches on each drained depression hectare is 370 m

Aerial LiDAR Technology in Support to Avalanches Prevention and Risk Mitigation: AN Operative Application at "colle della Maddalena" (italy)

Abstract. Snow avalanches are the result of unstable snow masses that detach from steep slopes as consequence of changes in snowpack structure. Nowadays, remote sensing technologies can improve the knowledge of avalanches phenomenon. This work focuses on the use of high point density aerial LiDAR (Light Detection And Ranging) technology as support to avalanche events prevention and risk mitigation, by presenting an operative application at Colle della Maddalena (Italy), along the road SS n. 21, nearby the French state border. The area is often involved in intense avalanche events that adversely impact on traffic and freight transport. For this reason, regional administrations will activate the Avalanche Artificial Detachment Intervention Plan (PIDAV, 2012) in order to prevent and manage the avalanche risk in the study area, also adopting artificial detachment systems. Main aim of the present work was to generate high resolution information related to geomorphological characterization (i.e. digital elevation models, slope and aspect) of avalanche sites derived from LiDAR data processing, that will help involved authorities in the management of the avalanche control plan. Digital elevation models at 0.5 m of spatial resolution were generated together with relative tridimensional models. Secondly, a preliminary investigation about capabilities and limits of LiDAR technology was done in the identification of avalanche sites only relying on geomorphological information directly derived by LiDAR data processing. Results showed that position of avalanche sites were correctly identified while no information could be obtained about the extension of the sliding area and identification of detachment areas

Digitale Geländemodelle aus Laserscandaten: neue Herausforderungen und Anwendungsmöglichkeiten in den Geowissenschaften

Digitale Geländemodelle (DGM) aus Laserscanmessungen bilden das Relief der Erdoberfläche in nie gekannter Präzision ab. Dies eröffnet einerseits neue und verbesserte Anwendungsmöglichkeiten in den Geowissenschaften, andererseits stellen sich aber auch neue Herausforderungen an die Aufbereitung der Laser-DGM. Für viele Anwendungen ist es erforderlich, das originale Laser-DGM aufzubereiten, um die Ergebnisse zu optimieren oder eine Berechnung überhaupt erst zu ermöglichen. So werden u.a. innovative Verfahren zum Filtern von Rauschen und anthropogenen Reliefformen, sowie zur Herstellung konsistenter Abflussverhältnisse – eine Grundvoraussetzung für die Ermittlung von Einzugsgebieten – vorgestellt. Die Anwendungsbeispiele für Laser-DGM beziehen sich auf die Ableitung morphometrischer Reliefparameter und die Erstellung von Geomorphographischen Karten zur Unterstützung der Bodenkartierung, die Berechnung von Einzugsgebieten für digitale Fließgewässernetze und die Ermittlung von Dolinen.Digital Terrain Models ( DTM) from laser scanning measurements form the relief of the earth’s surface in unprecedented precision. This opens on the one hand, new and improved applications in the earth sciences, on the other hand, but also represent new challenges to the pre-processing of laser DTM. For many applications it is necessary to modify the original laser DGM to optimize or to enable calculations. Thus, innovative methods for filtering noise and anthropogenic relief forms, and for the production of consistent discharge conditions - a prerequisite for the determination of catchment areas – are presented. The application examples for laser-based DTM refer to the derivation of morphometric terrain parameters and geomorphographic maps to support soil mapping, the calculation of catchment areas for digital rivernetworks and the identification of dolines

Pembuatan Digital Elevation Model Resolusi 10m dari Peta RBI dan Survei GPS dengan Algoritma ANUDEM

This study proposes the generation of Digital Elevation Model (DEM) with spatial resolution of 10m x 10m by re-interpolation of elevation data. Data input for this study includes: (1) digitized datum coordinate from RBI map, (2) sample points surveyed by GPS, (3) digitized contour data fromSRTM DEM and ASTER GDEM2, and (4) digitized stream-network layer from RBI. All collected data were converted to mass point coordinats. On the top of Topogrid-ArcGIS, all points data were interpolated to produce DEM. After that the produced DEM were compared and evaluated to the SRTM and ASTER DEMvisually. The result shows that produced DEM are more accurate to represent the detailed topography of the study areas

An Hierarchical Labeling Technique for Interactive Computation of Watersheds

International audience—The watershed computation is a prevalent task in the geographical information systems. It is used, among other purposes, to forecast the pollutant concentration and its impact on the water quality. The algorithm to compute the watershed can be hard to parallelize and with the increasingly data growth, the need for parallel computation increases. In this paper we propose a new method to parallelize the watershed computation. Our algorithm is decomposed into two tasks, the parallel watershed segmentation into a hierarchy that allows in a second task to retrieve randomly large watersheds at run-time in interactive time