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PubMed1997

Flood control embankments contribute to the improvement of the health status of children in rural Bangladesh.

Every year, Bangladesh experiences major floods that inundate about one-third of the country. Therefore, flood control projects that comprise earthen dikes and irrigation/drainage systems are built along the major rivers to protect the people living in low-lying areas, stabilize the river banks and improve agricultural productivity. However, the adverse effects of these projects are regularly emphasized, such as environmental degradation and reduction of fishing supplies. The Demographic Surveillance System of the International Centre for Diarrhoeal Diseases Research, Bangladesh (ICDDR,B) was used to assess the effect of a flood control programme on the mortality of 0-4-year-old children residing in the Matlab study area. Adjusted mortality rates were used in comparing four adjacent child populations residing either inside or outside a flood-control embankment and according to the type of health services provided in this area. Between the periods 1983-86 and 1989-92, the crude child mortality in the total study area decreased by 37%, from 185.9 per 1000 live births to 117.9 per 1000 live births. Following the construction of the embankment, death rates outside were up to 29% higher in 1-4-year-old children and 9% higher for 0-4-year age group compared to the flood-protected area (P < 0.001). Simultaneously, in the same study area, health interventions contributed to a 40% reduction in mortality among children less than 5 years of age in all causes of deaths (P < 0.001). Migration patterns and the effect of distances to the hospital are discussed.

Bangladesh↗
PubMed1999

[Biological infection of soil on the flooded areas of Wrocław City].

The distribution of geohelminth eggs on the appartment backyards of Wrocław city after flood disaster was studied. Out of 100 soil samples examined 17% were positive. Toxocara spp.eggs were present in 6% samples examined, Ascaris spp. in 2% and other eggs (Capilaria sp. and Trichuris vulpis) in 9% samples examined. Soil contamination of Wrocław area was much less than in other cities of Poland and Europe. The prevalence of geohelminth eggs on flooded areas was very similar to that on the not-flooded areas although the number of eggs recovered was twice as high on flooded areas.

Animals↗
PubMed1999

Tumour response to hypercapnia and hyperoxia monitored by FLOOD magnetic resonance imaging.

Flow and oxygenation dependent (FLOOD) MR images of GH3 prolactinomas display large intensity increases in response to carbogen (5% CO2/95% O2) breathing. To assess the relative contributions of carbon dioxide and oxygen to this response and the tumour oxygenation state, the response of GH3 prolactinomas to 5% CO2/95% air, carbogen and 100% O2 was monitored by FLOOD MRI and PO2 histography. A 10-30% image intensity increase was observed during 5% CO2/95% air breathing, consistent with an increase in tumour blood flow, as a result of CO2-induced vasodilation, reducing the concentration of deoxyhaemoglobin in the blood. Carbogen caused a further 40-50% signal enhancement, suggesting an additional improvement due to increase blood oxygenation. A small 5-10% increase was observed in response to 100% O2, highlighting the dominance of CO2-induced vasodilation in the carbogen response. Despite the large FLOOD response, non-significant increases in tumour pO2 were observed in response to the three gases. Tissue pO2 is determined by the balance of oxygen supply and demand, hence increased blood flow/oxygenation may not necessarily produce a large increase in tissue PO2. The FLOOD response is determined by the level of deoxygenation of blood, the size of this response relating to vascular density and the potential of high-oxygen content gases to improve the oxygen supply to tumour tissue.

Animals↗
PubMed2006

Flooding in GROMACS: accelerated barrier crossings in molecular dynamics.

The major bottleneck of today's atomistic molecular dynamics (MD) simulations is that because of the enormous computational effort involved, only processes at nanoseconds to microseconds time scales or faster can be studied directly. Unfortunately, apart from a few exceptions, relevant processes, such as chemical reactions or many large scale conformational transitions in proteins, occur at slower time scales and therefore are currently far out of reach for conventional MD. The flooding technique addresses this problem by inclusion of a flooding potential into the force field. This flooding potential locally destabilizes the educt state and thereby significantly accelerates the escape from the initial energy well without affecting the reaction pathway. Here, we summarize the theory and method for the computational chemistry community and detail the implementation within the official version 3.3 of the freely available MD program package GROMACS. Two examples shall demonstrate the application of flooding to accelerate conformational transitions and chemical reactions. The second example was carried out within a QM/MM framework.

Butanes↗
PubMed1996

Influence of high-energy photons from cobalt-57 flood sources on scintillation camera uniformity images.

Cobalt-57 flood sources are often used for system flood-field uniformity checks of scintillation camera performance. Such sources are now available in large sizes and with high activities. Uniformity images using new 57Co sources have shown artefacts which are not present in uniformity images obtained from technetium-99m flood sources of the same activity. The high-energy photons emitted by 57Co and cobalt isotope impurities appear to influence the images obtained. This was investigated in three cameras using three 57Co sources of different age. The flood-field images obtained with the 57Co sources showed non-uniformity patterns that were dependent on the age of the cobalt source, the distance of the source to the collimator, and the specific camera type. Quantification of the uniformity images reflected these findings. Energy spectra of a new 57Co source, obtained with an external 1024-channel analyser connected to the camera, showed a broad tail of high-energy photons above the 122-keV photopeak, due to Compton scatter and collimator penetration. This tail diminished with older sources and with increased source to collimator distance, indicating that in both situations fewer high-energy photons were being measured by the camera system. This tail of high-energy photons contributes to the total count rate, but because this is not obvious from the counts observed in the photopeak window, the camera can unsuspectingly be operated at too high a total countrate where pile-up effects become significant. Caution is therefore advised when using 57Co sources. Problems may be minimized by purchasing low-activity sources (certainly no more than 370 MBq), by placing the source at a distance from the collimator, e.g. 50 cm, by allowing a new source to decay, and by manufacturers producing 57Co sources without detectable radioactive contaminants.

Cobalt Radioisotopes↗
PubMedDate not supplied

Physiological mechanisms of flooding (implosion) therapy.

Desensitization of psychological and physiological complex structures may be the most important element of flooding treatment. The implosive sessions are assumed to represent a supramaximal stimulation of pathologically excited and inert complex structures resulting in protective inhibition, irradiation of excitation, reduction of the excitation and inertness, and a decrease of the overshooting autonomic reactivity of the complex structures, leading to reduction of anxiety, aggression, and other pathologically increased feelings. Advantages such as stronger and improved flooding can be achieved by a flooding in hypnosis. The therapeutic indications go beyond the usual treatment of phobic states. In order to establish the psychological and physiological mechanisms in implosion there is a need for psychophysiological investigations. However, much is unknown about mechanisms. Controlled comparisons with other treatments give limited answers. Perhaps an international case history bank might establish which clinical conditions might benefit by technical modifications of flooding.

Animals↗
PubMed1999

Women's Awareness of and Attitudes Towards the Flood Action Plan (FAP) of Bangladesh: A Comparative Study.

/ Bangladesh has recently tested a program called the Flood Action Plan (FAP) to solve its chronic flood problem. The FAP envisages that all the major rivers of Bangladesh will eventually be embanked on both sides in order to prevent flooding. This paper reports on the responses of rural women to the possible impacts of the proposed embankment projects as outlined in the FAP. A further attempt is also made to compare their responses with the results of an earlier survey conducted among male respondents. Data for this study were collected from two rural areas of Bangladesh. It shows that almost all respondents had heard about the proposed construction and that they overwhelmingly support the embankment project of the FAP. Respondents are also aware of both positive and negative impacts of embankment construction. Similar findings were also reported by a previous study dealing with male responses to the embankment project. KEY WORDS: Flood Action Plan; Bangladesh; Women

Journal Article↗
PubMed1999

Simulation of lung lesions for validating the sonography of the flooded lung.

The quality of sonography of a unilaterally flooded lung needs to be validated on lesions of different echogenicity, size and subpleural position. Lesions were simulated in 12 young pigs with three different methods. After transbronchial (method 1) or transpleural puncture (method 2), diverse substances were injected into the lung. After 4 weeks, the thorax was opened and the lung flooded for the sonographic location of the lesions. In method 3, pulmonary lesions were simulated in an acute experiment after thoracotomy by transpleural injection or by filling of a Fogarty catheter balloon and were located sonographically. Transbronchial injection of alcohol invariably led to subsegment atelectasis. Only 25% of thoracoscopically controlled transpleural injections produced focal lesions in experiments in which the animals survived. Representative lesions were found only after alcohol injections. Transpleural injection of blood or a blood/Echovist suspension (method 3) simulated isoechogenic or echo-rich lesions with indistinct boundaries. By filling a Fogarty catheter balloon with saline solution or Echovist suspension, we succeeded in simulating echo-free or echo-rich lesions with smooth contours, located in different subpleural depths. After unilateral lung flooding, sonography successfully detected the locations of all these lesions and revealed their correlation with functional structures. Sonography of the flooded lung might be helpful in the intraoperative location of lesions, especially in the context of video-assisted thoracoscopic surgery.

Animals↗
PubMed2003

Preference and performance of a willow-feeding leaf beetle: soil nutrient and flooding effects on host quality.

The distribution and abundance of herbivores on plants growing under different environmental conditions may depend upon preference and/or performance. Soil nutrients and water availability are key determinants of herbivore distribution, as both influence plant growth and tissue quality. However, the effects of water on plant quality may depend upon the availability of nutrients and vice versa. Surprisingly few studies have examined the interactions between the two. We investigated the effects of soil nutrient and water availability on (1) the growth and chemistry of the silky willow (Salix sericea Marshall), and (2) the preference and performance of the imported willow leaf beetle (Plagiodera versicolora Laichartig). We conducted two common garden experiments using a similar 2x2 fully factorial design with two levels of soil nutrients (low, high) and two levels of water availability (field capacity, flooded). In the first experiment (larval performance), larval development time and pupal weight were not influenced by nutrient or water availability to the plant. This occurred despite the fact that plants in the high nutrient treatments had higher protein concentration and lower foliar concentrations of the phenolic glycoside 2'-cinnamoylsalicortin. In the second experiment (adult preference), we caged four plants (one from each treatment) and released beetles into cages. We found that plant growth and leaf protein depended upon the interaction between nutrient and water availability. Plant growth was greatest in the high nutrient-field capacity treatment and leaf protein was greatest in the high nutrient-flooded treatment. In contrast, adults settled and oviposited preferentially on the high nutrient treatment under flooded conditions, but we found no evidence of interactions between nutrients and water on preference. Thus, at least under flooded conditions nutrients affect adult preference. We also found that foliar protein was correlated positively with adult oviposition preference and per capita egg production. Our results, then, suggest that soil nutrients can influence adult preference, and that adults choose high-quality hosts (high protein) that promote egg production.

Animals↗
PubMed2005

Flood-deposited wood debris and its contribution to heterogeneity and regeneration in a semi-arid riparian landscape.

We investigated whether large woody debris (LWD) piles create nodes of environmental resources that contribute to the recovery of riparian vegetation and that also augment the heterogeneity and resilience of the riverine system. River and riparian systems are typified by a large degree of heterogeneity and complex interactions between abiotic and biotic elements. Disturbance such as floods re-distribute the resources, such as LWD, and thereby add greater complexity to the system. We examined this issue on a semi-arid savanna river where approximately a 100-year return interval flood in 2000 uprooted vegetation and deposited substantial LWD. We investigated the micro-environment within the newly established LWD piles and compared this with conditions at adjacent reference sites containing no LWD. We found soil nutrient concentrations to be significantly higher in LWD piles compared with the reference plots (total N +19%, available P +51%, and total C +36%). Environmental variables within LWD piles and reference sites varied with landscape position in the river-riparian landscape and with LWD pile characteristics. Observed differences were generally between piles located in the terrestrial and riparian areas as compared to piles located on the macro-channel floor. After 3 years the number and cover of woody species were significantly higher when associated with LWD piles, regardless of landscape position or pile type. We conclude that LWD piles formed after large floods act as resource nodes by accumulating fine sediments and by retaining soil nutrients and soil moisture. The subsequent influence of LWD deposition on riparian heterogeneity is discerned at several spatial scales including within and between LWD piles, across landscape positions and between channel types. LWD piles substantially influence the initial developmental of riparian vegetation as the system regenerates following large destructive floods.

Analysis of Variance↗
PubMed1993

Effect of liming on plant accumulation of cadmium under upland or flooded conditions.

Liming a Cd-amended red earth (typical hapludalf) decreased plant shoot Cd content both in upland and in flooded conditions. The effect was due to the restriction of the total uptake of Cd from soil and the Cd transfer from roots to shoots following liming. Pot soil samples were sequentially extracted with 1 M ammonium acetate, 0.125 M Cu(II) acetate, and 1 m HNO3 to fractionate Cd into exchangeable, complexed, and acid-soluble forms. Results showed that soil flooding decreased exchangeable Cd and increased Cd in the complexed fraction. Liming also transferred Cd from exchangeable fraction to other lower available fractions depending on water regimes. With upland conditions, the Cd was transferred to the residual fraction, and to a lesser extent to the acid-soluble fraction, whereas in flooded soil the lost exchangeable Cd was recovered mainly in complexed fraction where the Cd was potentially more available for plants compared with that in residual and in acid-soluble fractions. Therefore, soil liming for controlling plant Cd uptake would be more favourable in upland rather than flooded conditions.

Journal Article↗
PubMed2006

Tolerance of transgenic canola plants (Brassica napus) amended with plant growth-promoting bacteria to flooding stress at a metal-contaminated field site.

The growth of transgenic canola (Brassica napus) expressing a gene for the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase was compared to non-transformed canola exposed to flooding and elevated soil Ni concentration, in situ. In addition, the ability of the plant growth-promoting bacterium Pseudomonas putida UW4, which also expresses ACC deaminase, to facilitate the growth of non-transformed and transgenic canola under the above mentioned conditions was examined. Transgenic canola and/or canola treated with P. putida UW4 had greater shoot biomass compared to non-transformed canola under low flood-stress conditions. Under high flood-stress conditions, shoot biomass was reduced and Ni accumulation was increased in all instances relative to low flood-stress conditions. This is the first field study to document the increase in plant tolerance utilizing transgenic plants and plant growth-promoting bacteria exposed to multiple stressors.

Biomass↗
PubMed2005

Evaluation of the use of capillary numbers for quantifying the removal of DNAPL trapped in a porous medium by surfactant and surfactant foam floods.

The capillary number is used to quantify the mobilization potential of organic phases trapped within porous media. The capillary number has been defined in three different forms, according to types of flow velocity and viscosity used in its definition. This study evaluated the suitability of the capillary number definitions representing surfactant and surfactant foam floods by constructing capillary number-TCE saturation relationships. The results implied that the capillary number should be correctly employed, according to scale and fluid flow behavior. This study suggests that the pore-scale capillary number should be used only for investigating the organic-phase mobilization at the pore scale because it is defined by the pore velocity and the dynamic viscosity. The Newtonian-fluid capillary number using the Darcy velocity and the dynamic viscosity may be suitable for quantifying flood systems representing Newtonian fluid behavior. For viscous-force modified flood systems such as surfactant-foam floods, the apparent capillary number definition employing macroscopic properties (permeability and potential gradient) may be used to appropriately represent the desaturation of organic phases from porous media.

Journal Article↗
PubMed2005

Regional scale flood modeling using NEXRAD rainfall, GIS, and HEC-HMS/RAS: a case study for the San Antonio River Basin Summer 2002 storm event.

This paper develops a framework for regional scale flood modeling that integrates NEXRAD Level III rainfall, GIS, and a hydrological model (HEC-HMS/RAS). The San Antonio River Basin (about 4000 square miles, 10,000 km2) in Central Texas, USA, is the domain of the study because it is a region subject to frequent occurrences of severe flash flooding. A major flood in the summer of 2002 is chosen as a case to examine the modeling framework. The model consists of a rainfall-runoff model (HEC-HMS) that converts precipitation excess to overland flow and channel runoff, as well as a hydraulic model (HEC-RAS) that models unsteady state flow through the river channel network based on the HEC-HMS-derived hydrographs. HEC-HMS is run on a 4 x 4 km grid in the domain, a resolution consistent with the resolution of NEXRAD rainfall taken from the local river authority. Watershed parameters are calibrated manually to produce a good simulation of discharge at 12 subbasins. With the calibrated discharge, HEC-RAS is capable of producing floodplain polygons that are comparable to the satellite imagery. The modeling framework presented in this study incorporates a portion of the recently developed GIS tool named Map to Map that has been created on a local scale and extends it to a regional scale. The results of this research will benefit future modeling efforts by providing a tool for hydrological forecasts of flooding on a regional scale. While designed for the San Antonio River Basin, this regional scale model may be used as a prototype for model applications in other areas of the country.

Computer Simulation↗
PubMed2005

Force analysis and visualization of NAPL removal during surfactant-related floods in a porous medium.

Governing mechanisms of dense non-aqueous phase liquid (DNAPL) removal during surfactant and surfactant-foam (SF) flooding were studied by porous-patterned glass model experiments. Physical forces, viscous forces and capillary forces, acting on trichloroethylene (TCE) blobs were quantified to understand DNAPL removal mechanisms during the floods, simultaneously visualizing the removal mechanisms. The viscous force of the remedial fluid was intimately related to TCE removal from the porous medium. The remedial fluid with a high viscous force displaced more TCE blobs. Displacement of residual TCE by the remedial fluid began as viscous pressure of flooding was closed to the capillary pressure of the porous medium. In the region of viscous pressure less than the capillary pressure, residual TCE was either retained or solubilized, not displaced, implying that TCE solubilization was the dominant TCE removal process. Glass porous model visualization validated a dominance of the capillary forces during a surfactant flush and a dominance of the viscous forces of the displacing fluid during a SF flood.

Models, Chemical↗
PubMed2005

Contamination of the alluvial plain, feeding-stuffs and foodstuffs with polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DL-PCBs) and mercury from the River Elbe in the light of the flood event in August 2002.

Meadow soils, feeding-stuffs and foodstuffs from the alluvial plain of the river Elbe were analyzed in respect of PCDD/Fs, DL-PCBs and mercury with a view to assessing the consequences of the extreme flood of August 2002. The PCDD/F concentrations in the soils range from 3 to 2100 ng WHO-TEQ/kg dm, and for the DL-PCBs the range was 0.32 to 28 ng WHO-TEQ/kg dm. On the basis of established threshold values >40% of the areas are only fit for restricted usage. Mercury concentrations range from 0.11 to 17 mg/kg dm, whereby the action value of 2 mg/kg dm is exceeded in about 50% of the soil samples. A cumulative memory effect from past floods rather than a recent contamination from August 2002 is documented. Soils taken from behind broken dykes showed significantly lower concentrations. Grass, hay and grass silage originating from pasture land in Lower Saxony were taken before and immediately after the flooding. PCDD/Fs range from 0.29 to 16 ng WHO-TEQ/kg, the maximum permitted value of 0.75 ng WHO-TEQ/kg was exceeded in about 50% of the samples. Muscle-tissue from cattle, sheep, lamb and a roe deer as well as untreated milk from individual cows returned values ranging from 0.76 to 5.9 pg WHO-PCDD/F-TEQ/g fat, and 10% of the samples returned values higher than the permitted maximum of 3 pg WHO-PCDD/F-TEQ/g fat. The action value of 2 pg WHO-PCDD/F-TEQ/g fat was exceeded in 33% of the samples. No direct connection between these results and the effects of the flood could be established. A major input path for PCDD/Fs is the tributary Mulde, which discharges contaminated sediments from its catchment area into the Elbe.

Animal Feed↗
PubMed2006

Radiological consequences of the extreme flooding on the lower course of the Rhone valley (December 2003, south east France).

In early December 2003 unusual weather conditions led to major flooding of the lower Rhone valley. When it floods, the Rhone carries large masses of solid matter in suspension, which potentially includes associated artificial (anthropogenic) radioactive contaminants from soil drainage in the catchment area and from re-uptake of sedimentary matter that has been contaminated with low-level radioactive liquid effluents from almost twenty nuclear facilities situated along the Rhone valley. A sampling campaign was carried out to investigate the level and spread of both sediment mass and associated radioactive contamination across the flooded areas. An attempt was made to assess the radiological consequences of such an extreme event on contamination of the food chain. Our results show that almost 700,000 tons of sediment was transported onto the floodplain, of which 80% were coarse and fine sands. These materials transferred 6660 MBq of 137Cs, 93 MBq of (239+240)Pu, 13 MBq of 238Pu and 204 MBq of 60Co over a surface area of 60 km2. More than 90% of deposited sediments are concentrated in a 10 km2 area of agricultural soils, and we estimated that 18% were plowed into the soil. Nevertheless, the level of activity measured in the vegetable crops and milk was not significantly different from the level measured in similar samples from regions that were not affected by the December 2003 floods.

Animals↗
PubMed2006

Nitrogen and phosphorus dynamics of a re-wetted shallow-flooded peatland.

Minerotrophic peatlands play an important role in the regulation of water quality and quantity but due to drainage and agricultural land use most of these systems have lost this function. In Central Europe, many re-wetting projects have been implemented to restore wetlands for multifunctional purposes during the last years. The Pohnsdorfer Stauung (Northern Germany) is a eutrophic fen which was used for intensive agriculture for 40 years. The peatland is divided in two subareas by a small stream. In the scope of re-wetting measures, one subarea (westpolder) was flooded by blockading the main drainage ditch in 1996/97, a second subarea (eastpolder) was re-connected to the stream by an inlet and outlet in 2001. Nitrogen and phosphorus dynamics were investigated in the surface water of these systems over a 5-year (westpolder) and 3-year (eastpolder) period, and balances were calculated. In both polders high dynamics of nitrogen and phosphate concentrations were observed in the surface water. Nitrate peaked in the winter months, whereas ammonium, phosphate and organically bound nitrogen (N(org)) revealed highest values during summer. Daily balances for the eastpolder and annual balances for both polders were calculated. In both polders nitrate was retained but phosphate and N(org) were exported. Differences of the nutrient dynamics and the absolute and relative balances between the polders were due to the different hydrology: the eastpolder received a high nitrate load by the stream, in the westpolder nutrient loads are low and internal nutrient cycles are dominating. During the summer months, high ammonium concentrations, oxygen depletion, and phosphate release occur in the warm, stagnant water of both polders. Normally, high phosphate and ammonium concentrations did not coincided with discharge phases from the polders. However, in August 2002 after heavy rainfall high phosphorus and ammonium discharge was observed. One important factor influencing the detected nutrient dynamics and balances is the change from a drained and fertilized peatland to a flooded wetland in only a few years. We conclude that continuous water flow and stable water levels are desired for flooded peatlands to prevent high concentrations of ammonium and phosphate and to utilize the potential for nitrate retention. In degenerated peatlands, flooding should only be regarded as an easy technological solution in order to conserve the peat mineralization, and to form the foundation for the further development of the peatland to a more efficient nutrient retaining system.

Conservation of Natural Resources↗