Search results for "Waters"

Trans-boundary land cover changes and its influences on water crisis: Case study of the Aras River

2020

Abstract In a watershed, disturbing land covers (LCs) are one of the most important factors in the balance and flow rate of water. This study aimed to monitor and model LC changes in the upstream of the Aras River Basin in Turkey over 1984, 2002, 2010 and 2016. The main ground to conduct such an analysis was to mitigate severe economic, social and ecological consequences driven by agricultural activities and dam construction along with probable climate change, which would decrease the water flow from the Aras River to Caspian Sea. The study approach consisted of four main steps: 1) producing LC maps using Landsat satellite images, 2) performing the change analysis, 3) identifying the change…

Mūsas upes ūdens ķīmiskā kvalitāte

2015

Ūdeņu ķīmijas pētījumiem ir liela nozīme, jo ūdens ir viens no nepieciešamākajiem resursiem cilvēkiem. Ūdens ķīmiskais sastāvs nosaka ūdens kvalitāti, kuru ir jāpārzina, lai pārvaldītu, racionāli izmantotu un aizsargātu ūdeņus. Latvijas virszemes ūdeņu ķīmisko sastāvu ietekmē dažādi faktori – ģeogrāfiskais novietojums, teritorijas ģeoloģiskā uzbūve, klimats, hidroloģiskie, ģeoķīmiskie procesi un antropogēnā darbība. Lielākoties Mūsas upes ūdeņu ķīmiskais sastāvs veidojas Lietuvā. Upes garums Latvijā ir vien 20 km no kopējiem 164 km un baseina lielums Latvijā ir vien 2 % no kopējās baseina platības. Darba mērķis ir novērtēt Mūsas upes ūdens ķīmisko kvalitāti un apskatīt punktveida piesārņotā…

Vertical diversity of bacteria in an oxygen-stratified humic lake, evaluated using DNA and phospholipid analyses

2009

Microbes play a particularly important role in the food web in lakes with high dissolved organic carbon content. The bacterial community of a polyhumic lake, Mekkojarvi, was studied using DNA techniques and phospholipid fatty acid (PLFA) analysis during the mid-summer period of water column strati- fication. According to the 16S rRNA gene clone libraries and length heterogeneity analysis (LH-PCR), heterotrophic bacteria dominated only in the oxic epilimnion, in which various Actinobacteria (mostly cluster acI-B) and Betaproteobacteria (especially Poly- nucleobacter subcluster PnecC) were common. Se- quences assigned to heterotrophic, methylotrophic, photoautotrophic, and chemoautotrophic ge…

Comprehensive dataset of shotgun metagenomes from oxygen stratified freshwater lakes and ponds

2021

Stratified lakes and ponds featuring steep oxygen gradients are significant net sources of greenhouse gases and hotspots in the carbon cycle. Despite their significant biogeochemical roles, the microbial communities, especially in the oxygen depleted compartments, are poorly known. Here, we present a comprehensive dataset including 267 shotgun metagenomes from 41 stratified lakes and ponds mainly located in the boreal and subarctic regions, but also including one tropical reservoir and one temperate lake. For most lakes and ponds, the data includes a vertical sample set spanning from the oxic surface to the anoxic bottom layer. The majority of the samples were collected during the open wate…

Linking the Molecular Signature of Heteroatomic Dissolved Organic Matter to Watershed Characteristics in World Rivers

2015

Large world rivers are significant sources of dissolved organic matter (DOM) to the oceans. Watershed geomorphology and land use can drive the quality and reactivity of DOM. Determining the molecular composition of riverine DOM is essential for understanding its source, mobility and fate across landscapes. In this study, DOM from the main stem of 10 global rivers covering a wide climatic range and land use features was molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). FT-ICR mass spectral data revealed an overall similarity in molecular components among the rivers. However, when focusing specifically on the contributi…

Watersheds management (Transylvania/Romania): implications, risks, solutions

2007

An optical classification tool for global lake waters

2017

Shallow and deep lakes receive and recycle organic and inorganic substances from within the confines of these lakes, their watershed and beyond. Hence, a large range in absorption and scattering and extreme differences in optical variability can be found between and within global lakes. This poses a challenge for atmospheric correction and bio-optical algorithms applied to optical remote sensing for water quality monitoring applications. To optimize these applications for the wide variety of lake optical conditions, we adapted a spectral classification scheme based on the concept of optical water types. The optical water types were defined through a cluster analysis of in situ hyperspectral…

Comparison of machine learning models for gully erosion susceptibility mapping

2020

© 2019 China University of Geosciences (Beijing) and Peking University Gully erosion is a disruptive phenomenon which extensively affects the Iranian territory, especially in the Northern provinces. A number of studies have been recently undertaken to study this process and to predict it over space and ultimately, in a broader national effort, to limit its negative effects on local communities. We focused on the Bastam watershed where 9.3% of its surface is currently affected by gullying. Machine learning algorithms are currently under the magnifying glass across the geomorphological community for their high predictive ability. However, unlike the bivariate statistical models, their structu…

Hydrological Analysis of Loess Plateau Highland Control Schemes in Dongzhi Plateau

2020

Gully Consolidation and Highland Protection (GCHP) Project is a major soil and water conservation and land remediation project implemented in the Chinese Loess Plateau (CLP). As the connection between the mechanisms of erosion and practical applications for addressing it is not clear, the implementation of engineering measures to combat the problem has been insufficient to date. This study used field investigation and descriptive statistics, together with hydrological analysis modeling to gain an understanding of the impact of the Loess Plateau Highland Control Schemes on the evolution of the Dongzhi Plateau as the largest, most well-preserved, and the thickest loess deposit region in China…

Improving stock unearthing method to measure soil erosion rates in vineyards

2018

Abstract Vineyard soils experience high erosion rates compared to soils from other agricultural land uses. The high soil losses in vineyards limits the sustainability of traditional production schemes and warrants comprehensive research aimed at thwarting the main erosion processes affecting vineyard systems. However, long-term measurements, which include spatial variability of soil erosion rates at the plot scale, are uncommon, as most of the measurements have taken place either at the hillslope or watershed scales. Against this background, the stock unearthing method (SUM) can be considered a useful methodology. However, the current method falls short because it assumes that the topograph…