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The impact of anthropogenic actions on the environment and climate has recently increased the need to map the afforested areas. In this context, the three-dimensional (3D) measurement of vegetation structures plays an important role in having an efficient forest inventory and management. Nowadays, the airborne LiDAR (Light Detection And Ranging) system offers high horizontal resolution as well as vertical dimension information, making it possible to estimate both three-dimensional characteristics of individual trees and to identify the distribution of forest resources in the region. This study aims to present a processing approach for the determination of each tree’s position (X and Y location, as well as tree height) and its dimensions (crown diameter, area and volume) using geometrically accurate 3D point clouds (data sets were collected in a forested area in Argeș County, Romania). To a better understanding of the forest features and to explore the potential of remote sensing for such analysis, it was further exploited Digital Terrain Model (DTM), Digital Surface Model (DSM), and Canopy Height Model (CHM) derivation.

<p>Although anthropogenic emissions of trace gases have decreased over the last decades in Europe, strong additional reductions are required to reach the goals of the Paris climate agreements. In addition, air pollution is an issue of great concern for the inhabitants of the metropolitan area of Bucharest, as the local air quality is often poor. The rapid development of the city, increased traffic volume from a mixed vehicle fleet (different technologies and fuels), and other factors are strong contributors of emissions of greenhouse gases and air pollutants in Bucharest.</p><p>The goal of this research was the assessment of CO, CO<sub>2</sub> and CH<sub>4</sub> concentrations in Bucharest, identification of potential emissions hotspots and their causes (anthropogenic or natural/biogenic, local or distant) and determination of the background values.</p><p>Measurements were performed in summer 2019 in four districts of Bucharest covering about two thirds of the metropolitan area during the Romanian Methane Emissions from Oil&gas (ROMEO) campaign with high resolution (1 sec). These data sets were complemented with satellite observations of CO and CH<sub>4</sub> from Copernicus Sentinel-5P at a resolution of 7 km<sup>2</sup>.</p><p>Hourly meteorological data, temperature, relative humidity, wind speed and direction, and atmospheric pressure were added to the air pollutant data set because synoptic conditions can strongly influence the levels of pollution. Air mass origins were investigated by computing backward air mass trajectories using the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model for 72 hours back.</p><p>Points of high concentrations of CO, CO<sub>2</sub>, CH<sub>4</sub> near the surface were identified which are, most likely, linked to local anthropogenic activities in the nearby surroundings. We identified a variation of concentrations of CO from 0.01 to 101 ppm, of CO<sub>2</sub> from 388 to 6556 ppm, and of CH<sub>4</sub> from 1.89 to 246 ppm, while background levels are as follows: 0.071±0.042 ppm CO, 392.68±3.01 ppm CO<sub>2</sub>, and 1.93±0.016 ppm CH<sub>4</sub>.</p><p>Results of our study provide an up to date quantitative image of CO, CO<sub>2</sub>, CH<sub>4</sub> hotspots in the Bucharest area, which is important for modeling air quality and may also help to improve the relationships between column integrated air pollution data with in situ ground observations.</p><p><strong>Acknowledgement:</strong></p><p>This research is supported by ROMEO project, developed under UNEP’s financial support PCA/CCAC/UU/DTIE19-EN652. Partial financial support from UB198/Int project is also acknowledged.</p><p>The authors acknowledge the free use of tropospheric CO and CH<sub>4</sub> column data from TROPOMI (Sentinel-5P) sensor from https://s5phub.copernicus.eu and the NOAA Air Resources Laboratory for the provision of the HYSPLIT transport model available at READY website https://www.ready.noaa.gov</p><p>Special thanks to all INCAS technical staff for their support in performing the campaigns.</p>

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<p>In hydrogeological and pedoclimatic conditions, specific to the Danube River, there is a danger of secondary salinization of soil excluded from the floods. The drought, with an increasing frequency, affects agricultural production in areas where the largest irrigation systems are found. These systems were built during 1960-1990, but they are dysfunctional and unused for 20 years.</p><p>The purpose of this study is to insure a model using GIS technologies, in order to reduce the negative effects of the drought and to propose redevelopment of irrigation. Such model is presented in a form of five thematic maps where the main morphometric parameters (hypsometry, slope, slope orientation), in quantitative terms, the types of soils and land use were analyzed for the entire surface of the villages Gostinu-Greaca-Arges, located in the Danube Floodplain. The GIS model provides important information for the investigated area and it is a useful tool for risk assessment and early-warning.</p><p>This study is based on observations from the maps interpretation of the studied area, but also from reports and studies published over the years.</p><p> </p><p>Keywords: The Danube River, drought, soil, irrigation.</p>