GIS-Based Relief Compartment Mapping of Fluvio-Karst Landscape in Central Brazilian Highlands

The present study describes the preliminary findings of a research project aiming at creating a knowledge-base for the protection of caves heritage at Rio Vermelho preservation area in the central Brazilian highlands. A GIS-based relief compartment mapping was conducted using readily available data (e.g., satellite images, geological, and cave location maps). Four resultant geomorphological domains were identified, including (i) lowlands (282 km2) with a baselevel in silicates and carbonates, (ii) the karst terrains (994 km2) which were developed in carbonates trapped by siltstone lenses, (iii) the talus (1483 km2) having colluvial and alluvial units deposited by the escarpment retreat (Urucuia Formation) and (iv) the highlands (1143.7 km2) developed over the sandstone of the Urucuia Group. The intersection of landform and geological maps resulted in delineating two abrupt contacts, the first between lowland and karst terrains and the second between the talus and highlands that formed canyon escarpment. For sustainability perspective, this study proposed two types of cave systems in the region as superior/vadose (top-bottom) that collect floods from hillslopes and deep Epigene fluvial-karst (bottom-up)

Site characterization and analysis of landslide dynamics under the influence of triggering factors by geophysical methods

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2018.Deslizamentos de terra são resultados de processos geomorfológicos naturais que alteram as propriedades físicas do local. Essas alterações anômalas nos materiais podem levar a emissões micro-sísmicas e também podem alterar as propriedades das ondas de ruído ambiente se propagando através delas, sendo que ambas podem ser detectadas pela aplicação de técnicas geofísicas (mais baratas, não invasivas e aplicáveis). A caracterização subsuperficial (técnicas geofísicas) do sítio de escorregamento é feita no primeiro estágio, onde são utilizados os métodos Análise Multicanal de Ondas de Superfície (MASW), Tomografia de Resistividade Elétrica (ERT) e Relação Espectral Horizontal para Vertical (HVSR). Na segunda etapa, a análise dinâmica do escorregamento é feita com ruído ambiente e microssismicidade emitida. As mudanças sazonais na rigidez da massa de escorregamento são analisadas por HVSR com lapso de tempo (frequência natural) e interferometria de ruído ambiente (mudança de velocidade relativa). Os resultados são otimizados por um experimento de talude normal de campo, em escala de campo, no campo experimental da Universidade de Brasília, Brasil, onde a carga normal foi mantida na elevação do solo. Finalmente, uma análise tipológica dos registros sísmicos de escorregamentos e em um experimento em escala controlada. A superfície de escorregamento resultante e os caminhos permeáveis foram identificados bem nas seções de resistividade modeladas, enquanto a seção estratigráfica de velocidade de onda de cisalhamento 2D de três camadas é obtida pelo MASW onde uma tendência de rigidez crescente contínua e diminuição da velocidade na escarpa é observada. O ruído sísmico registrado em diferentes locais no escorregamento é analisado para reconstruir a geometria do escorregamento e sua dinâmica sazonal. As curvas de HVSR resultantes são divididas em três grupos com base nos valores de pico de frequência, cada um representando as zonas dinâmicas aleatoriamente dispersas e mutuamente separadas criadas pelos efeitos erosionais (fluviais) do rio de Capetinga subjacente. O HVSR juntamente com as curvas de ruído ambiente f-k são usados para a estimativa da velocidade de onda de cisalhamento 1-D também. Os resultados do experimento protótipo mostram dois picos de frequência na curva HVSR, as variações de amplitude no pico de maior frequência em diferentes acumulações de estresse no solo são observadas. Uma diminuição de -0,6% em dV / V foi observada antes do colapso do solo no teste de carga da placa. Nem o ANI nem o HVSR mostram a resposta sazonal no deslizamento. Os sinais de curta duração, com uma tipologia única, são observados durante os testes de retirada da pilha do corpo de expansão. A mesma análise foi aplicada ao deslizamento de terra de Sobradinho, onde os sinais de uma tipologia particular são observados durante a estação chuvosa, possivelmente relacionados com a dinâmica do escorregamento ou as cargas de sedimentos do rio. O estudo será eficaz na compreensão da dinâmica pré-colapso de encostas instáveis em formações argilosas em termos de variações sazonais na rigidez, alteração nas propriedades físicas, fases de acumulação de tensão no solo, mudanças sazonais na ressonância e tipologia dos registros sísmicos.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) e A Fundação de Apoio à Pesquisa do Distrito Federal (FAP-DF).Landslides are results of natural geomorphological processes that alter the physical properties of the site. These anomalous alterations in the geomaterials can lead to microseismic emissions and can also change the properties of ambient noise waves propagating through them both of which can be detected by the application of geophysical techniques (cheaper, noninvasive and applicable). The subsurface characterization (geophysical techniques) of landslide site is done in the first stage where Multi-Channel Analysis of Surface Waves (MASW), Electrical Resistivity Tomography (ERT) and Horizontal to Vertical Spectral Ratio (HVSR) methods are used. In the second stage, the dynamic analysis of landslide is done with ambient noise and emitted microseismicity. The seasonal changes in stiffness of landslide mass is analyzed by time-lapse HVSR (natural frequency) and ambient noise interferometry (relative velocity change). The results are optimized by a field scaled prototype experiments in the experimental field of the University of Brasilia, Brazil where the normal load was kept on rising on the soil. Finally, a typological analysis on the seismic records of landslide and at a controlled scale experiment is performed. Resultant slip surface and permeable paths were identified well on the modeled resistivity sections, while a three layered 2D shear wave velocity stratigraphic section is obtained from MASW where a continuous increasing rigidity trend and a decrease in velocity at landslide scarp are observed. The seismic noise recorded at different sites in the landslide is analyzed in order to reconstruct the landslide geometry and its seasonal dynamics. Resultant HVSR curves are divided into three groups based on the frequency peak values, each one is a representative of a mutually detached randomly scattered dynamic zones created by the erosional (fluvial) effects of the underlying Capetinga river. The HVSR along with ambient noise f-k curves are used for the estimation of 1-D shear wave velocity as well. Results of the prototype experiment show two frequency peaks at HVSR curve, the amplitude variations at higher frequency peak at different stress levels in the soil are observed. A decrease of -0.6 % in dV/V was observed before the soil collapse in plate loading test. Neither ANI nor HVSR shows the seasonal response at the landslide. The short duration signals having a unique typology are observed during pull out tests on expander body pile. The same analysis was applied at Sobradinho landslide where signals of particular typology are observed during the rainy season which are possibly related with the landslide dynamics or the sediments loads of the river. The study will prove effective in understanding precollapse dynamics of unstable slopes in clayey formations in terms of seasonal variations in rigidity, alteration in physical properties, stress accumulation phases in the soil, seasonal changes in resonance, and typology of the seismic records

Microtremor response of a mass movement in Federal District of Brazil

The present study provides a brief description of the ambient noise recorded at a slow moving mass movement in Ribeirão Contagem Basin. The area is an interesting natural laboratory as river detachment processes in a number of different stages can be identified and are easily accessible. We investigate the site dynamic characteristics of the study area by recording ambient noise time-series at nine points, using portable nine three-component short period seismometers. The time-series are processed to give both horizontal to vertical spectral ratio (HVSR) curves as well as time-frequency plots of noise power spectral density (SPD). The HVSR curves illustrate and quantify aspects of site resonance effects due to underlying geology. Probability density function (PDF) shows that noise level lies well between new high noise model (NHNM) and new lower noise model (NLNM) and their probabilities are higher above 2 Hz. HVSR curves present a uniform lithologically controlled peak at 2 Hz. Directional properties of the wavefield are determined by beamforming method. The f-k analysis results in the E-W component show that at 5 Hz phase velocities are close to 1700 m/s while at 10 Hz dropped to 250 m/s. We observed that between 5 and 16 Hz the incoming wavefield arrive from 260 degrees. Further studies will apply a detailed noise analysis for the understanding of dynamics of the mass movement, which is triggered by the river erosion

Polavtomatski pristop za kartiranje vrtač na brazilskem pokritem krasu: pot do ocene ranljivosti

Doline mapping is paramount in the vulnerability and risk assessment of the underground karst environment by identifying cave-ground connectivity points at the surface. However, manual mapping is labour-intensive, slow and subjective, especially on a large scale. Therefore, the present study adopted a GIS-based semi-automatic approach for mapping large and medium-sized depressions/dolines in the Corrente river basin in Brazil, with a particular focus on the environmentally preserved areas of river Vermelho (APANRV Portuguese abbreviation) using remote sensing (DEM and Google Earth imagery) and field-based observations. Seven typical dolines forms (e.g., cockpit with drain insertion, collapse, collapse with river capture, suffosion, solution, cover collapse, and buried) are found from extensive field surveys. As an outcome of the proposed approach, two hundred and thirty-two medium to large-sized dolines have been identified and categorised into three main groups based on the cave density and local geology G1, G2, and G3. The high density of identified dolines (164 known caves) in G1 provides reconnaissance for future speleological works in the preserved areas. Additionally, the presence of a considerable number of dolines in the adjoining areas (G2 and G3) stresses the need to revise the existing boundaries of the APANRV. Results correlate well with the dolines sites marked using field surveys and Google Earth images. This doline mapping may help researchers in the groundwater vulnerability assessment and the protection of speleological heritage preserved in the caves.Kartiranje vrtač je nadvse pomembno za oceno ranljivosti in tveganja podzemnega kraškega okolja, saj določa točke povezanosti med jamami in tlemi na površju. Vendar je ročno kartiranje zelo zahtevno, časovno zamudno in subjektivno, zlasti v velikih merilih. Zato je bil v tej študiji uporabljen polavtomatski pristop z uporabo orodij GIS za kartiranje velikih in srednje velikih kraških globeli/vrtač v porečju reke Corrente v Braziliji s posebnim poudarkom na okoljsko ohranjenih območjih reke Vermelho (portugalsko APANRV) z uporabo daljinskega zaznavanja (posnetki DEM in programa Google Earth) in na podlagi terenskih opazovanj. Na podlagi obsežnih terenskih raziskav je ugotovljenih sedem značilnih oblik vrtač (npr. kokpit z drenažo, udornica, udornica z zajezitvijo reke, sufozija, škavnica, udornica, nastala z udorom/rušenjem jamskega stropa, in udornice, nastale z zasutjem). Kot rezultat predlaganega pristopa je bilo opredeljenih 232 srednje velikih do velikih vrtač, ki so bile glede na gostoto vrtač in lokalno geologijo razvrščene v tri glavne skupine G1, G2 in G3. Velika gostota opredeljenih vrtač (164 znanih jam) v skupini G1 zagotavlja predhodni pregled za prihodnja speleološka dela na ohranjenih območjih. Poleg tega prisotnost velikega števila vrtač na sosednjih območjih (G2 in G3) poudarja potrebo po ponovnem pregledu zdajšnjih meja APANRV. Rezultati se dobro ujemajo z lokacijami vrtač, kartiranimi na podlagi terenskih raziskav in posnetkov programa Google Earth. To kartiranje vrtač lahko raziskovalcem pomaga pri oceni ranljivosti podzemne vode in pri zaščiti speleološke dediščine, ohranjene v jamah

Movement for the Restoration of Democracy (MRD): Reflection and Resistance against Dictatorial Regime in Punjab

The Movement for Restoration of Democracy (MRD) emerged when General Zia-ul-Haq could not fulfill the promise of conducting elections and prolonged his dictatorial regime instead of fulfilling his promise. He drew his power from a controlled system of government. In those circumstances, the democrats formed an alliance against the martial law administration. They neglected their internal differences and focused on their goal to achieve freedom of expression and liberty which was snubbed by the regime. MRD main demands were the restoration of democracy, under 1973 Constitution, conduction of election and handing over the system of administration to representatives of people. MRD continued struggled till the end of dictatorial regime in 1988

Microtremor Response of a Mass Movement in Federal District of Brazil

The present study provides a brief description of the ambient noise recorded at a slow moving mass movement in Ribeirão Contagem Basin. The area is an interesting natural laboratory as river detachment processes in a number of different stages can be identified and are easily accessible. We investigate the site dynamic characteristics of the study area by recording ambient noise time-series at nine points, using portable nine three-component short period seismometers. The time-series are processed to give both horizontal to vertical spectral ratio (HVSR) curves as well as time-frequency plots of noise power spectral density (SPD). The HVSR curves illustrate and quantify aspects of site resonance effects due to the local geological setting. Probability density function (PDF) shows that noise level lies well between new high noise model (NHNM) and new lower noise model (NLNM) and their probabilities are higher above 2 Hz. HVSR curves present a uniform lithologically controlled peak at 2 Hz. Directional properties of the wavefield are determined by beamforming method. The f-k analysis results in the E-W component show that at 5 Hz phase velocities are close to 1700 m/s while at 10 Hz dropped to 250 m/s. We observed that between 5 and 16 Hz the incoming wavefield arrive from 260 degrees. Further studies will apply a detailed noise analysis for relating the dynamics of the landslide (which can be retriggered by river erosion as well as rainfalls and seismic shaking) to possible changes in detectable physical properties

Elective induction for pregnancies at or beyond 41 weeks of gestation and its impact on stillbirths: a systematic review with meta-analysis

<p>Abstract</p> <p>Background</p> <p>An important determinant of pregnancy outcome is the timely onset of labor and birth. Prolonged gestation complicates 5% to 10% of all pregnancies and confers increased risk to both the fetus and mother. The purpose of this review was to study the possible impact of induction of labour (IOL) for post-term pregnancies compared to expectant management on stillbirths.</p> <p>Methods</p> <p>A systematic review of the published studies including randomized controlled trials, quasi- randomized trials and observational studies was conducted. Search engines used were PubMed, the Cochrane Library, the WHO regional databases and hand search of bibliographies. A standardized data abstraction sheet was used. Recommendations have been made for input to the Lives Saved Tool (LiST) model by following standardized guidelines developed by the Child Health Epidemiology Reference Group (CHERG).</p> <p>Results</p> <p>A total of 25 studies were included in this review. Meta-analysis of 14 randomized controlled trials (RCTs) suggests that a policy of elective IOL for pregnancies at or beyond 41 weeks is associated with significantly fewer perinatal deaths (RR=0.31; 95% CI: 0.11-0.88) compared to expectant management, but no significant difference in the incidence of stillbirth (RR= 0.29; 95% CI: 0.06-1.38) was noted. The included trials evaluating this intervention were small, with few events in the intervention and control group. There was significant decrease in incidence of neonatal morbidity from meconium aspiration (RR = 0.43, 95% CI 0.23-0.79) and macrosomia (RR = 0.72; 95% CI: 0.54 – 0.98). Using CHERG rules, we recommended 69% reduction as a point estimate for the risk of stillbirth with IOL for prolonged gestation (> 41 weeks).</p> <p>Conclusions</p> <p>Induction of labour appears to be an effective way of reducing perinatal morbidity and mortality associated with post-term pregnancies. It should be offered to women with post-term pregnancies after discussing the benefits and risks of induction of labor.</p

A semi-automatic approach for doline mapping in Brazilian covered karst: the way forward to vulnerability assessment

peer reviewedDoline mapping is paramount in the vulnerability and risk assessment of the underground karst environment by identifying cave-ground connectivity points at the surface. However, manual mapping is labour-intensive, slow and subjective, especially on a large scale. Therefore, the present study adopted a GIS-based semi-automatic approach for mapping large and medium-sized depressions/dolines in the Corrente river basin in Brazil, with a particular focus on the environmentally preserved areas of river Vermelho (APANRV Portuguese abbreviation) using remote sensing (DEM and Google Earth imagery) and field-based observations. Seven typical dolines forms (e.g., cockpit with drain insertion, collapse, collapse with river capture, suffosion, solution, cover collapse, and buried) are found from extensive field surveys. As an outcome of the proposed approach, two hundred and thirty-two medium to large-sized dolines have been identified and categorised into three main groups based on the cave density and local geology G1, G2, and G3. The high density of identified dolines (164 known caves) in G1 provides reconnaissance for future speleological works in the preserved areas. Additionally, the presence of a considerable number of dolines in the adjoining areas (G2 and G3) stresses the need to revise the existing boundaries of the APANRV. Results correlate well with the dolines sites marked using field surveys and Google Earth images. This doline mapping may help researchers in the groundwater vulnerability assessment and the protection of speleological heritage preserved in the caves

Suitability Analysis of Groundwater for Eco-friendly Agricultural Growths in Food Basket of Pakistan

Water is an important component of earth’s atmosphere and it sustains ecosystems, agriculture and human settlements on earth (Samson et al., 2010). Salinity, sodicity and toxicity generally need to be considered for the evaluation of suitable quality of groundwater for irrigation (Khan et al., 2014; Cobbina et al., 2012; Todd and Mays, 2005). In Thal Doab Aquifer (TDA) groundwater occurs as a layer of fresh water over saline water and its availability is subjected to recharging potency of the Indus and Chenab rivers (Hussain et al., 2017 a, 2016 a)