Academic literature on the topic 'Rainfall sampler geomorpholog'

This contribution describes the creation of a landslide hazard assessment model for San Salvador, a department in El Salvador. The analysis started with an aerial photointerpretation from Ministry of Environment and Natural Resources of El Salvador (MARN Spanish acronym), where 4792 landslides were identified and georeferenced along with 7 conditioning factors including: geomorphology, geology, rainfall intensity, peak ground acceleration, slope angle, distance to road, and distance to geological fault. Artificial Neural Networks (ANN) were utilized to assess the susceptibility to landslides, achieving results where more than 80% of landslide were properly classified using in-sample and out of sample criteria. Logistic regression was used as base of comparison. Logistic regression obtained a lower performance. To complete the analysis we have performed interpolation of the points using the kriging method from geostatistical approach. Finally, the results show that is possible to derive a landslide hazard map, making use of a combination of ANNs and geostatistical techniques, thus the present study can help landslide mitigation in El Salvador.

This study was conducted to determine the seasonal variation of Cr, Ni, Cu, Zn, As, Cd and Pb concentrations in water from four coastal sites of Bangladesh. The mean concentrations of trace metals in the water samples in the range of each elements were Cr (2.6−15.3), Ni (5.1−77.5), Cu (10.2−510), Zn (5.0-1390), As (2.1−13.3), Cd (0.006−0.09), Pb (0.4−109 μg/l) in summer and Cr (3.6−43.7), Ni (10.8−42.4), Cu (7.3−45.2), Zn (18.0-73.9), As (4.0−19.7), Cd (0.025−0.087), Pb (2.8−34.8 μg/l) in winter. The mean concentrations of the metals in water followed a decreasing order of Zn > Cu > Pb > Ni > Cr > As > Cd in the summer and Zn > Ni > Cr > Cu >Pb > As > Cd in the winter. The water of Cox’s Bazar hatchery site showed the highest levels of Zn (1390), Cu (510) and Pb (109 μg/l) in summer while As (19.7 μg/l) showed highest in Cox’s Bazar Bakkhali estuary in the winter samples. The elevated level of Ni (77.5 μg/L) in the summer and Cr (43.7 μg/l) in the winter water samples were also found in the Sundarbans site. The mean concentrations of all estimated trace metals were higher in the winter than in the summer season. It was both in the Chittagong port and Meghna estuary. For the Meghna estuary, the highest concentration of Zn (36.0 μg/l) was observed in the water sample of winter season. Some trace metals exceeded the international quality guidelines. Suspended solid, temperature, rainfall, anthropogenic inputs and geomorphologic setup are influenced by seasonal vagaries which alter the variation of metal distribution. J. Biodivers. Conserv. Bioresour. Manag. 2018, 4(2): 67-80

This study reports the first example of major erosion from hurricanes degrading a rocky coastline anywhere around the Gulf of California, although other sources of evidence are well known regarding the effect of inland erosion due to catastrophic rainfall in the Southern Cape Region of the Baja California peninsula and farther north. The uplifted, 12-m terrace on the eastern shore of Isla del Carmen is the site of an unconsolidated coastal boulder deposit (CBD) consisting of large limestone blocks and boulders eroded from underlying Pliocene strata. The CBD stretches approximately 1.5 km in length, mostly set back 25 m from the lip of the terrace. The largest blocks of upturned limestone near the terrace edge are estimated to weigh between 5.8 and 28 metric tons. Waves impacting the rocky coast that peeled back slabs of horizontally-layered limestone at this spot are calculated to have been between 11.5 and 14 m in height. Analysis of sampled boulders from the CBD set back from the terrace edge by 25 m suggest that the average wave height responsible for moving those boulders was on the order of 4.3 m. Additional localities with exposed limestone shores, as well as other more common rock types of igneous origin have yet to be surveyed for this phenomenon elsewhere around the Gulf of California.

Studying the process of riverine sediment at mouths and continental shelves is a critical subject for many engineering applications, such as dredging, navigation, dispersal and remobilization of contaminants. Sediment deposits also determine seabed properties, coastal geomorphology, and the health of coastal habitat/ecology. During extreme conditions, episodic river discharge triggered by large rainfall due to tropical cyclones may contribute significant amount of riverine sediment into the ocean. In the past decade, evidence of severe seabed erosion (up to 1m/year) along the sandy coast of Yunlin County has raised concerns regarding the sustainability of coastal structures. The exposed riverine sediment from the Jhuoshuei River is considered as one of major sources for sediment supply in this region. Bottle samples collected from bridge station in the Jhuoshuei River during the passage of tropical cyclones suggest sediment concentration can exceed 40 g/l for the major duration of the storm (Milliman et al. 2007). To mitigate the damage caused by shoreline retreat, 600,000 cubic meters per month of sand has been placed in two specific locations near the offshore industry park. The overarching goal of this study is to clarify the contribution of exposed riverine sediment and beach nourishment to enhance our understanding on the observed sediment transport and morphological evolution.

Abstract. Understanding the timescales of water flow through catchments and the sources of stream water at different flow conditions is critical for understanding catchment behaviour and managing water resources. Here, tritium (3H) activities, major ion geochemistry and streamflow data were used in conjunction with lumped parameter models (LPMs) to investigate mean transit times (MTTs) and the stores of water in six headwater catchments in the Otway Ranges of southeastern Australia. 3H activities of stream water ranged from 0.20 to 2.14 TU, which are significantly lower than the annual average 3H activity of modern local rainfall, which is between 2.4 and 3.2 TU. The 3H activities of the stream water are lowest during low summer flows and increase with increasing streamflow. The concentrations of most major ions vary little with streamflow, which together with the low 3H activities imply that there is no significant direct input of recent rainfall at the streamflows sampled in this study. Instead, shallow younger water stores in the soils and regolith are most likely mobilised during the wetter months. MTTs vary from approximately 7 to 230 years. Despite uncertainties of several years in the MTTs that arise from having to assume an appropriate LPM, macroscopic mixing, and uncertainties in the 3H activities of rainfall, the conclusion that they range from years to decades is robust. Additionally, the relative differences in MTTs at different streamflows in the same catchment are estimated with more certainty. The MTTs in these and similar headwater catchments in southeastern Australia are longer than in many catchments globally. These differences may reflect the relatively low rainfall and high evapotranspiration rates in southeastern Australia compared with headwater catchments elsewhere. The long MTTs imply that there is a long-lived store of water in these catchments that can sustain the streams over drought periods lasting several years. However, the catchments are likely to be vulnerable to decadal changes in land use or climate. Additionally, there may be considerable delay in contaminants reaching the stream. An increase in nitrate and sulfate concentrations in several catchments at high streamflows may represent the input of contaminants through the shallow groundwater that contributes to streamflow during the wetter months. Poor correlations between 3H activities and catchment area, drainage density, land use, and average slope imply that the MTTs are not controlled by a single parameter but a variety of factors, including catchment geomorphology and the hydraulic properties of the soils and aquifers.

R E S U M O O conhecimento sobre as fragilidades potencial ambiental de uma bacia hidrográfica possibilita identificar e analisar os ambientes em seus diferentes níveis de organização, auxiliando nos trabalhos de zoneamento ambiental, gestão territorial e na compreensão da relação dinâmica entre os componentes naturais e os fatores antrópicos. Nesse sentido, o objetivo deste trabalho foi avaliar as fragilidades potencial e ambiental na bacia hidrográfica do rio Catolé Grande, sudoeste da Bahia, acrescentando-se parâmetros relativos à malha hídrica e qualidade da água à metodologia estabelecida na literatura. A fragilidade potencial foi definida com base em informações sobre a declividade, tipo de solo, pluviosidade, geologia, geomorfologia e malha hídrica. A fragilidade ambiental foi obtida através dos resultados da fragilidade potencial acrescido de dados sobre o uso do solo e qualidade da água através da utilização do Índice de Qualidade da Água, que foi determinado em amostras de água coletadas em oito pontos ao longo da malha hídrica da bacia. Todos os parâmetros foram integralizados utilizando-se ferramentas do software ArcGis 9.3, gerando os mapas sínteses das fragilidades potencial e ambiental. A inclusão do IQA influenciou a definição da fragilidade ambiental, aumentando as áreas com baixa fragilidade, provavelmente devido às condições boas e ótimas da água encontradas nos locais amostrados. O nível de vulnerabilidade dos recursos hídricos superficiais influenciou negativamente a fragilidade potencial e em menor escala a fragilidade ambiental. O trabalho mostrou a importância da inclusão de novos fatores ambientais para o estabelecimento das fragilidades potencial e ambiental de bacias hidrográficas proporcionando a obtenção de informações importantes para o um manejo integrado da área. A B S T R A C T The knowledge about the potential and environmental fragilities of watersheds makes possible to identify and to analyze the environment, their different organization levels, being relevant in the environmental zoning, territorial administration and in the understanding of the dynamic relationship between the natural components and the anthropic factors. In that sense, the objective of this work was to develop the evaluation of the potential and environmental fragilities of the rio Catole Grande watershed located in the southwest of the Bahia state. The used methodology was the one proposed by Ross (1994), modified by including environmental factors related to the quality of the superficial water resources and he hydric network. The potential fragility was defined based on information about slope, soil type, geology, geomorphology, rainfall and the hydric network. The environmental fragility was obtained through the results of the potential fragility, use of the soil and the Water Quality Index determined by the analysis of water samples collected in eight sampling points. All the parameters were integrated using the available tools of the software ArcGis 9.3, generating the syntheses maps of the potential and environmental fragilities. The inclusion of the IQA influenced the definition of the environmental fragility, increasing the areas with low fragility, probably due to the good and very good water conditions found in the sampled places. The vulnerability levels of the superficial water resources influenced negatively the potential fragility and in smaller scale the environmental fragility. The work showed the importance of including new environmental factors for the establishment of the potential and environmental fragilities of watersheds, providing important information for an integrated management of the area. Keywords: environmental fragility, potential fragility, rainfall, slope, soil type, water quality, geology, geomorphology

R E S U M O O conhecimento sobre as fragilidades potencial ambiental de uma bacia hidrográfica possibilita identificar e analisar os ambientes em seus diferentes níveis de organização, auxiliando nos trabalhos de zoneamento ambiental, gestão territorial e na compreensão da relação dinâmica entre os componentes naturais e os fatores antrópicos. Nesse sentido, o objetivo deste trabalho foi avaliar as fragilidades potencial e ambiental na bacia hidrográfica do rio Catolé Grande, sudoeste da Bahia, acrescentando-se parâmetros relativos à malha hídrica e qualidade da água à metodologia estabelecida na literatura. A fragilidade potencial foi definida com base em informações sobre a declividade, tipo de solo, pluviosidade, geologia, geomorfologia e malha hídrica. A fragilidade ambiental foi obtida através dos resultados da fragilidade potencial acrescido de dados sobre o uso do solo e qualidade da água através da utilização do Índice de Qualidade da Água, que foi determinado em amostras de água coletadas em oito pontos ao longo da malha hídrica da bacia. Todos os parâmetros foram integralizados utilizando-se ferramentas do software ArcGis 9.3, gerando os mapas sínteses das fragilidades potencial e ambiental. A inclusão do IQA influenciou a definição da fragilidade ambiental, aumentando as áreas com baixa fragilidade, provavelmente devido às condições boas e ótimas da água encontradas nos locais amostrados. O nível de vulnerabilidade dos recursos hídricos superficiais influenciou negativamente a fragilidade potencial e em menor escala a fragilidade ambiental. O trabalho mostrou a importância da inclusão de novos fatores ambientais para o estabelecimento das fragilidades potencial e ambiental de bacias hidrográficas proporcionando a obtenção de informações importantes para o um manejo integrado da área. A B S T R A C T The knowledge about the potential and environmental fragilities of watersheds makes possible to identify and to analyze the environment, their different organization levels, being relevant in the environmental zoning, territorial administration and in the understanding of the dynamic relationship between the natural components and the anthropic factors. In that sense, the objective of this work was to develop the evaluation of the potential and environmental fragilities of the rio Catole Grande watershed located in the southwest of the Bahia state. The used methodology was the one proposed by Ross (1994), modified by including environmental factors related to the quality of the superficial water resources and he hydric network. The potential fragility was defined based on information about slope, soil type, geology, geomorphology, rainfall and the hydric network. The environmental fragility was obtained through the results of the potential fragility, use of the soil and the Water Quality Index determined by the analysis of water samples collected in eight sampling points. All the parameters were integrated using the available tools of the software ArcGis 9.3, generating the syntheses maps of the potential and environmental fragilities. The inclusion of the IQA influenced the definition of the environmental fragility, increasing the areas with low fragility, probably due to the good and very good water conditions found in the sampled places. The vulnerability levels of the superficial water resources influenced negatively the potential fragility and in smaller scale the environmental fragility. The work showed the importance of including new environmental factors for the establishment of the potential and environmental fragilities of watersheds, providing important information for an integrated management of the area. Keywords: environmental fragility, potential fragility, rainfall, slope, soil type, water quality, geology, geomorphology

Bao Loc is one of two cities of Lam Dong province. Located on Di Linh – Bao Loc plateau about 800 – 1000m elevation, Bao Lọc has the complex mountainous terrain. The authors have surveyed and collected information and samples in the landslide area. This area occurred the cracks, damaged several buildings within 1.2 ha. The authors have also identified causes of landslide such as geomorphotogy, stratigraphic slope, slope materials, hydrogeology, climate, etc. However, the main cause was soil extraction activities at toe of slope which lost the counterweight berm, associated with the moisture increase of soil due to heavy rainfall in rainy season. It reduced the shear strength of slope materials. Based on data analysis of surveyed location, the authors applied GeoStudio software by SLOPE/W module so as to calculate the slope stability under the sections. Analyzed results showed that the slope was stable in dry season with the minimum factor of safety (FS) around 1.474, in rainy season the slope was unstable with minimum the factor of safety around 0.896 commensurate with groundwater present model. The minimum factors of safety in the model with the appearance of groundwater table are represented by the distance among the slope sections following the relationship function with correlation coefficient (R2) is 0.9915. According to the interpolated result from the relationship function showed that the width of unstable area or the width of sliding mass is 35.1m. As the obtained results, the authors proposed realizable solutions to stabilize the slope in order to minimize the effect of landslide at the study area.

ABSTRAK Penelitian ini bertujuan untuk mengetahui kondisi karakteristik lahan dan tingkat bahaya longsor di daerah penelitian. Hasil penelitian sebagai berikut: 1. Karakteristik lahan: a) iklim: curah hujan 2.224 mm/tahun, b) geologi: struktur lapisan batuan dengan bentuk miring dan miring bergelombang, c) geomorfologi: bentuklahan pegunungan dan perbukitan, satuan bentuklahan lereng kaki gunung api, kemiringan lereng yang sangat curam 43% dan curam 40% dengan panjang lereng yang sedang 45 m, panjang 100 m, sangat panjang 210 m, bentuk lereng lurus, cembung, cekung, bervariasi cembung cekung, d) tanah: tekstur tanah lempung berpasir dan pasir berdebu, struktur tanah remah, gumpal, bukit tunggal, konsistensi tanah sangat gembur, lepas-lepas, permeabilitas tanah sangat cepat 21 cm/jam dan cepat 7,09 cm/jam e) hidrologi: kedalaman muka air tanah <500 cm f) penggunaan lahan: semak belukar/alang-alang, tegalan/kebun campuran dan pemukiman. 2. Tingkat bahaya longsor: a) sedang: Pada daerah Batang Hari, Aia Dingin, Cubadak, Lolo. b) Tinggi: Pada daerah Aia Ampu. Kata kunci : lahan, longsor. ABSTRACT This research of aims are determine the condition of land characteristics and the level of landslide hazard in the research area. The sample of this research is purposive sampling, the sample is taken in accordance with the research objectives. The research show as follows: 1. Land characteristics: a) climate: rainfall 2.224 mm / year, b) geology: rock layer structure with an oblique shape and tilted wavy, c) geomorphology: form of mountainous and hilly land, landform unit of the foot slope volcano, very steep slope of 43% and steep 40% with medium slope length 45 m, length 100 m, very long 210 m, and the shape of the slope is straight, convex, concave, irregular. d) soil: soil texture sandy loam, and dusty sand, structure of land crumb,lumpy, single hill, consistency of land very loose, loose , soil permeability very fast 21 cm/h and fast 7,09 cm/h e) hydrology: groundwater depth <500 cm f) land use: shrubs / reeds and moor / seasonal gardens and settlement 2. the level of landslide hazard: a) medium: At Batang Hari, Aia Dingin, Cubadak, Lolo. b) high: At Aia Ampu. Keyword: land, hazard.

Ice-rich permafrost landscapes are sensitive to ongoing changes in climate. Permafrost retrogressive thaw slumps (RTSs) represent one of the more abrupt and prolonged disturbances, which occur along Arctic river and lake shorelines. These features impact local travel and infrastructure, and there are many questions regarding associated impacts on biogeochemical cycling. Predicting the duration and magnitude of impacts requires that we enhance our knowledge of RTS geomorphological drivers and rates of change. Here we demonstrate the utility of remotely piloted aircraft systems (RPAS) for documenting the volumetric change, associated drivers and potential impacts of the largest active RTS along the Old Crow River in Old Crow Flats, Yukon, Canada. RPAS surveys revealed that 29,174 m3 of sediment was exported during the initial evacuation in June 2016 and an additional 18,845 m3 continued to be exported until June 2019. More sediment export occurred during the warmer 2017 summer that experienced less cumulative rainfall than summer 2018. However, several rain events during 2017 were of higher intensity than during 2018. Overall mean soil organic carbon (SOC) and total nitrogen (TN) within sampled thaw slump sediment was 1.36% and 0.11%, respectively. A combination of multispectral, thermal and irradiance (derived from the RPAS digital surface model) data provided detailed classification of thaw slump floor terrain types including raised dry clay lobes, shaded and relatively stable, and low-lying evacuation-prone sediments. Notably, the path of evacuation-prone sediments extended to a series of ice wedges in the northern headwall, where total irradiance was highest. Using thaw slump floor mean SOC and TN values in conjunction with sediment bulk density and thaw slump fill volume, we estimated that 713 t SOC and 58 t TN were exported to the Old Crow River during the three-year study. Findings showcase the utility of high-resolution RPAS datasets for refining our knowledge of thaw slump geomorphology and associated impacts.

Numerical lake hydrological and geochemical models are valuable tools for interpreting and quantifying palaeoclimate reconstructions derived from lake sediment archives, and the sensitivity of lakes under future climate scenarios. This study details the development and calibration of a holistic lake model, alongside related projects focussed on the development of tools and datasets associated with lake modelling. Lake monitoring was conducted over three years at twelve sites in the Newer Volcanic Province, south-eastern Australia on a bi-monthly basis, collecting water levels, and water samples for analysis of oxygen and hydrogen isotopes and major/minor ions. A correlation was identified between the lake morphology and the 18O and 2H isotopic enrichment of lake water, visible as variations in the regression slopes of !18O and !2H (local evaporation lines). Cl-/Br- and HCO3 - /Cl- ratios were used to partition the source of water for each lake between groundwater and direct precipitation. Lakes high in the landscape, above the regional aquifers, were found to have lower Cl-/Br- ratios, suggesting they are predominantly rainfall fed, whereas the other lakes have Cl-/Br- ratios similar to groundwater. HCO3 -/Cl- ratios were ambiguous, likely due to the variability of HCO3 -/Cl- in groundwater. Deuterium excess (d-excess) data were used to assess the degree to which lakes exhibited through-flow or terminal hydrology. The d-excess results showed strong seasonal variability as a function of lake depth, suggesting that a more conservative solute may be better suited to determine the groundwater regime for these lakes. One challenge encountered throughout this research was the need to monitor the isotopic composition of daily precipitation feeding into lake systems. To address this challenge in future research, an autonomous rainfall sampler was developed. A computational method using hydrologic-isotopic modelling to estimate the original isotopic composition and volume of evaporated samples was also described. An important yet poorly constrained component of lake hydrological models is the interaction between lakes and their surrounding groundwater. A single layer, finite difference groundwater model was developed to simulate and investigate this interaction. The model was designed to operate using spreadsheet software, and is able to model transient groundwater flows, confined and unconfined aquifers incorporating recharge, abstraction and injection, no-flow, fixed-head and head-dependent boundary conditions. The model was validated using nine groundwater scenarios and applied to demonstrate that the use of a specified saturated thickness for unconfined aquifers beneath lakes may give more realistic results. A holistic lake hydrological and geochemical model was developed, coupling mass and energy balances, hydrology, groundwater, catchment processes, geochemistry and water isotopes. The model was applied to Lake Bullen Merri and Lake Gnotuk, neighbouring maar crater lakes in Victoria, Australia. The model was able to simulate lake hydrology from 1889–2018, water temperatures and chemistry from ~1965–2018, and water isotopes from 2015–2018. The simulations suggest that both lakes experienced through-flow hydrology at high water levels, transitioning to terminal lakes at lower water levels. The potential for the isotopic composition of the lake water to become disconnected from the hydrological balance of the lake was also identified. The newly developed model offers significant potential to constrain past climates and to forecast the trajectory of lake hydrological and geochemical change under future climate scenarios.
Thesis (Ph.D.) -- University of Adelaide,School of Physical Sciences, 2020