• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 1
  • 1
  • Tagged with
  • 5
  • 5
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studie prostorové aktivity lesních druhů savců obývajících remízy v zemědělské krajině se zaměřením na využívání okolních potravních zdrojů. / Study of spatial activity of small mammals inhabit isolated forest draws in agricultural landscape with a focus on the use of surrounding food sources.

HAVLOVÁ, Jitka January 2013 (has links)
Habitat fragmentation during 50s of 20th century caused decrease in food resource availibility for many small mammalian forest species. Despite all of the changes, those species managed to adapt to it - one of the adaptation mechanics has been migrating into agricultural areas. The main aim of this study was to describe the spatial activity of Apodemus sylvaticus and Myodes glaerolus inside two forst patches and compare it. My next aim was evaluate the significance of agricultural areas nearby the researched forest patches. One part of this was even the comparison of different marking techniques used for rodents in field. Data describing movement activity of researched species were collected using capture-mark-recapture (CMR) As expected the data differ - Greater mobility was found in A. sylvaticus, the M. glaerolus preffered to stay inside patches with larger vegetation cover. The raids into surrounding patches differed even in those two researched forest sites. In site "Samota" A. sylvaticus showed greater movement distance, however in "Hejtman" it were M. glaerolus expressing greater movement ability. Theirs movement were directed inside clover field. Both species of Samota site ventured into patches with dense plant cover, perhaps to minimise the risk of predation. The best method of marking proved to be the clipping the rodents ears with tags. As the next more efficient I would choose the ear-clipping.
2

Decision Support Systems for Water Environment Management in Rural Areas under Hydrological and Socio-Economic Uncertainties / 水文学的および社会経済学的不確実性下にある農村地域の水環境管理に対する意思決定支援システム

Goden, Mabaya 23 September 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20005号 / 農博第2189号 / 新制||農||1045(附属図書館) / 学位論文||H28||N5014(農学部図書室) / 33101 / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 藤原 正幸, 教授 村上 章, 准教授 宇波 耕一 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
3

Estimation de la rugosité du sol en milieux agricoles à partir de données Sentinel-1 / Estimation of surface roughness over bare agricultural soil from Sentinel-1 data

Choker, Mohammad 30 April 2018 (has links)
La télédétection spatiale est d’une importance primordiale pour la cartographie et la surveillance des problèmes environnementaux. Son intérêt réside dans la capacité des capteurs satellitaires spatiaux à fournir des informations globales et permanentes de la planète, aux échelles locale à globale. La télédétection radar a montré son grand potentiel ces dernières années dans la caractérisation des états de surface du sol. L’état de la surface du sol, et en particulier l’humidité et la rugosité, exerce une influence fondamentale sur la répartition de la pluie entre infiltration, rétention superficielle et ruissellement. Il a un rôle essentiel dans les processus hydrologiques de surface et ceux associés à l’érosion et aux processus d’évapotranspiration. La caractérisation et la prise en compte de ces conditions de surface constituent actuellement un enjeu important pour la modélisation à base physique des processus hydrologiques ou pour le couplage surface-atmosphère. Dans ce cadre et depuis plusieurs années, plusieurs études scientifiques ont montré le potentiel des données micro-ondes actives dans l’estimation de l’état hydrique du sol et de sa rugosité de surface.Les nouveaux systèmes radar (SAR ʺSynthetic Aperture Radarʺ) ont permis d’ouvrir de nouvelles perspectives pour l’observation de la terre grâce à l’amélioration de la résolution spatiale (métrique sur TerraSAR-X et COSMO-SkyMed) et temporelle (TerraSAR-X, COSMO-SkyMed, Sentinel-1). La disponibilité depuis peu des nouveaux capteurs radar bande C Sentinel-1 (Sentinel-1A et Sentinel-1B) rend indispensable l’évaluation des données Sentinel-1 pour la caractérisation des états de surface du sol et en particulier la rugosité de surface.Le travail de thèse se structure en trois parties. La première partie consiste à évaluer les modèles de rétrodiffusion de radar les plus utilisés (IEM, Oh, Dubois and AIEM) en utilisant un large ensemble de données de SAR et des mesures expérimentales des paramètres du sol. Cette évaluation permet de trouver le modèle de rétrodiffusion le plus robuste qui simule le mieux le signal radar afin de l'utiliser par la suite dans la procédure d'inversion du signal radar pour estimer la rugosité du sol. Le deuxième axe de recherche de cette thèse consiste à proposer un modèle de rétrodiffusion radar semi-empirique pour les polarisations HH, HV et VV. Ce nouveau modèle sera construit à l'aide d'une grande base de données réelle. Ce nouveau modèle sera également utilisé dans la procédure d'inversion du signal radar pour estimer la rugosité du sol. Le dernier axe de cette thèse consiste à construire une méthode d’inversion du signal radar en utilisant les réseaux de neurones afin d’évaluer le potentiel des données Sentinel-1 pour l’estimation de la rugosité des sols en milieux agricoles. Ces réseaux de neurones seront entrainés à l'aide d'un ensemble de données synthétiques élaborées à partir des modèles de rétrodiffusion radar choisis (IEM calibré par Baghdadi et du nouveau modèle proposé) et validés en utilisant deux ensembles de données: un ensemble de données synthétiques et une base de données réelle (images Sentinel-1 et mesures in situ d’humidité et de rugosité du sol). La base de données réelle a été collectée en Tunisie (Kairouan) et en France (Versailles). / Spatial remote sensing is of paramount importance for mapping and monitoring environmental problems. Its interest lies in the ability of space satellite sensors in providing permanent information of the planet, at local, regional and global scales. Also, it provides spatial and repetitive territories visions and ecosystem views. Radar remote sensing has shown great potential in recent years for the characterization of soil surface conditions. The state of the soil surface, in particular moisture and roughness, has a fundamental influence on the distribution of rainfall between infiltration, surface retention and runoff. In addition, it plays an essential role in surface hydrological processes and those associated with erosion and evapotranspiration processes. Characterization and consideration of these surface conditions have been recently considered as an important issue for physically based modeling of hydrological processes or for surface-atmosphere coupling. In this context and for several years, several scientific studies have shown the potential of active microwave data for estimation of the soil moisture and the surface roughness.New SAR (Synthetic Aperture Radar) systems have opened new perspectives for earth observation through improved spatial resolution (metric on TerraSAR-X and COSMO-SkyMed) and temporal resolution (TerraSAR-X, COSMO-SkyMed, Sentinel-1) . The recent availability of new Sentinel-1 C-band radar sensors (free and open access) makes it essential to evaluate the potential of Sentinel-1 data for the characterization of soil surface conditions and in particular surface roughness.The work revolves around three parts. The first part consist of evaluation of the most used radar backscattering models (IEM, Oh, Dubois, and AIEM) using a wide dataset of SAR data and experimental soil measurements. This evaluation gives the ability to find the most robust backscattering model that simulates the radar signal with good agreement in order to use later in the inversion procedure of the radar signal for estimating the soil roughness. The second research axe of this thesis consists of proposing an empirical radar backscattering model for HH, HV and VV polarizations. This new model will be developed using a large real dataset. This new model also will be used in the inversion procedure of the radar signal for estimating the soil roughness. The last axe of this thesis consists of producing a method to invert the radar signal using neural networks. The objective is to evaluate the potential of Sentinel-1 data for estimating surface roughness. These neural networks will be trained using wide synthetic dataset produced from the radar backscattering models chosen (IEM calibrated by Baghdadi and the new proposed model) and validated using two datasets: one synthetic dataset and one real (Sentinel 1 images and in-situ measurements). The real datasets are collected from Tunisia (Kairouan) and France (Versailles).
4

Modelo para simulação de nitrogênio e fósforo em sistemas de recursos hídricos, aplicação em região do alto curso do Rio Piranhas-PB.

NEPOMUCENO, Thiago Cabral. 13 April 2018 (has links)
Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-13T20:32:36Z No. of bitstreams: 1 THIAGO CABRAL NEPOMUCENO – DISSERTAÇÃO (PPGECA) 2018.pdf: 5961539 bytes, checksum: ea3a80835b67c0d1615b111f56921a4a (MD5) / Made available in DSpace on 2018-04-13T20:32:36Z (GMT). No. of bitstreams: 1 THIAGO CABRAL NEPOMUCENO – DISSERTAÇÃO (PPGECA) 2018.pdf: 5961539 bytes, checksum: ea3a80835b67c0d1615b111f56921a4a (MD5) Previous issue date: 2018-02-27 / Capes / O lançamento de efluentes domésticos em ambientes aquáticos sem o devido tratamento vem comprometendo a qualidade da água de reservatórios e rios. Esta torna-se ainda mais relevante quando, em torno desses corpos hídricos superficiais, existe uma intensa prática agrícola, com aplicação de fertilizantes a base de nitrogênio e fósforo, onde a ocorrência de eventos chuvosos pode gerar escoamento superficial e encaminhar o excesso desses nutrientes presentes no solo para os rios e reservatórios próximos. Portanto, o presente trabalho propôs o desenvolvimento e aplicação de um modelo para simulação de nitrogênio e fósforo em sistemas de recursos hídricos, que permita simular a interação de rios, reservatórios e áreas agrícolas em termos desses parâmetros de qualidade de água. No arranjo estrutural do modelo desenvolvido, duas etapas metodológicas merecem destaque, são elas: modelagem de nitrogênio e fósforo nas áreas agrícolas, considerando os principais fluxos de entrada e saída desses macronutrientes no solo, e definição dos sistemas de equações diferenciais ordinárias que possam representar a dinâmica comportamental de nitrogênio e fósforo nos corpos hídricos, ou seja, rios e reservatórios integrantes de um determinado sistema estudado. Como estudo de caso, foi selecionado um sistema de recursos hídricos localizado na unidade de planejamento hidrológico do Alto Piranhas-PB, compreendendo áreas agrícolas, rios e reservatórios, juntamente com as principais contribuições de nutrientes para o respectivo sistema, além de ser levado em consideração o aporte das águas da transposição do rio São Francisco, proveniente do Eixo Norte da transposição. Para a aplicação do modelo desenvolvido, foram analisados cenários que possibilitassem uma melhor avaliação da resposta do sistema estudado ao lançamento dos efluentes domésticos e agrícolas, além do impacto das águas da transposição. Os resultados das simulações indicaram que os recursos hídricos analisados são sensíveis a ação dos efluentes domésticos e agrícolas, principalmente nos períodos de seca, onde o volume dos reservatórios e vazões nos trechos dos rios são reduzidos. Com o acréscimo das águas da transposição, foram observadas atenuações significativas nos níveis de nitrogênio e fósforo nos corpos hídricos, devido ao maior poderio de diluição dos efluentes proporcionado por esse aporte hídrico, embora foram observados níveis críticos em alguns meses. Desta forma, medidas preventivas e corretivas devem ser adotadas a esse tipo de sistema, de maneira a evitar o comprometimento da biota aquática e dos múltiplos usos as quais as águas estão destinadas. / The release of domestic effluents in aquatic environments without the proper treatment has compromised the water quality of reservoirs and rivers. This becomes even more relevant when, around these surface water bodies, there is an intense agricultural practice, with the use of nitrogen and phosphorus base fertilizers, where the occurrence of rainfall events can generate runoff and return the excess nutrients present in the soil to nearby rivers and reservoirs. Therefore, this work proposed the development and application of a model for simulation of nitrogen and phosphorus in water resources systems, allowing the interaction of rivers, reservoirs and agricultural areas in terms of water quality parameters. In the structural arrangement of the developed model, two methodological steps are worth mentioning: nitrogen and phosphorus modeling in agricultural areas, considering the main input and output flows of these macronutrients in the soil, and definition of the systems of ordinary differential equations that can represent the behavioral dynamics of nitrogen and phosphorus in the water bodies, ie, rivers and reservoirs that are part of a given system studied. As a case study, a water resource system was selected, located in the Alto Piranhas-PB hydrological planning unit, comprising agricultural areas, rivers and reservoirs, together with the main nutrient contributions to the respective system, besides being taken into account the contribution of the waters of the transposition of the São Francisco river, coming from the Eixo Norte of the transposition. For the application of the developed model, scenarios were analyzed to enable a better evaluation of the response of the studied system to the release of domestic and agricultural effluents, besides the impact of the transposition waters. The results of the simulations indicated that the analyzed water resources are sensitive to the action of domestic and agricultural effluents, mainly in periods of drought, where the volume of the reservoirs and flows in the stretches of the rivers are reduced. With the addition of the transposition waters, significant attenuations were observed in the nitrogen and phosphorus levels in the water bodies, due to the higher dilution power of the effluents provided by this water supply, although critical levels were observed in some months. Therefore, preventive and corrective measures should be adopted for this type of system in order to avoid compromising the aquatic biota and the multiple uses to which the waters are destined.
5

Assessing the relationship between soil health/quality and water quality in the Mississippi delta

Sarmiento Rodriguez, Laura Andrea 08 December 2023 (has links) (PDF)
Several studies have reported agronomic benefits by improving soil health/quality, but uncertain knowledge remains when determining specific impacts on water quality off-field. This study investigated the links between runoff water quality and soil health/quality in agricultural fields of the Mississippi delta under three land management scenarios: Conservation Reserve Program (CRP), vegetative buffer (VB), and row crops (RC). Using the Soil Management Assessment Framework (SMAF), a Soil Quality Index (SQI) was obtained based on ten soil health/quality indicators from 2008 and 2012 datasets. The SMAF identified significant differences in soil health/quality improvements among scenarios over a four-year period. Varied relationships between water quality parameters, SQI, and soil health/quality indicators were determined. Individually, physical and chemical soil indicators were also correlated with runoff water quality. Overall, the evidenced relationship between soil health/quality and water quality parameters was stronger in areas under CRP.

Page generated in 0.0645 seconds