Journal articles on the topic 'Variations in flood activity'
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1
Liu, Yesen, Yaohuan Huang, Jinhong Wan, Zhenshan Yang, and Xiaolei Zhang. "Analysis of Human Activity Impact on Flash Floods in China from 1950 to 2015." Sustainability 13, no. 1 (December 28, 2020): 217. http://dx.doi.org/10.3390/su13010217.
Abstract:
An early warning of a flash flood is essential to prevent the general public from the hazardous flooding events, however, the rapid variation of human activities has led to the uncertainty of risk in prone areas. The lack of a systematic record of flash flood events introduces challenges to flash flood-related research. Herein, we map spatial and temporal variations in flash floods in China from 1950 to 2015 and establish a general ordered logit model in a geographic information environment to estimate the association between the occurrence of flash flood events and natural conditions and the variation of human activities at the watershed level. The results showed that precipitation is an important cause of flash flooding, and demonstrate that anthropogenic intervention (heavy rainfall, density of villages, and vegetation cover) in the environment affect the likelihood of flash floods. We found that the likelihood of flash floods in China may increase with the air quality worsening and that the occurrence of flash floods is strongly correlated with vegetation cover. Our findings suggest a need for further investigation of the link between air quality and flash flooding in flood-prone areas.
2
SHALTOUT, M. A. MOSALAM, and M. T. Y. TADROS. "Variations of the solar activity and irradiance, and their influence on the flooding of the river Nile." MAUSAM 41, no. 3 (February 24, 2022): 53–62. http://dx.doi.org/10.54302/mausam.v41i3.2722.
Abstract:
Autocorrelation and power spectra analysis are carried out for different lengths of time series Of the following data:(l) Solar activity (sunspot, faculae and radio flux on 2800 MHz);(2) Irradiance (solar Constant measured at earth's surface and by the artificial satellite (Nimbus- 7); (3) River Nile flood (old water level, maximum flood level, and the difference between the both levels) measured at Cairo.
The results showing remarkable similarity between the power spectra of solar activity, irradiance (solar constant) and river Nile flood.
We conclude that any short or long-term variations in the solar activity lead to similar variations in the solar constant. Also, annual and secular variations of solar activity yield information’s on the suspected annual and secular variations of the river Nile flood.
3
Luz-Agostinho, KDG, AA Agostinho, LC Gomes, HF Júlio-Jr., and R. Fugi. "Effects of flooding regime on the feeding activity and body condition of piscivorous fish in the Upper Paraná River floodplain." Brazilian Journal of Biology 69, no. 2 suppl (June 2009): 481–90. http://dx.doi.org/10.1590/s1519-69842009000300004.
Abstract:
Flood pulses affect floodplain enrichment via the incorporation of nutrients and terrestrial biomass. As a result, they positively affect the body condition of aquatic organisms. This paper evaluates whether the absence of floods (resulting from dam control) affects the feeding activity and body condition of piscivorous fish. In addition, whether piscivores respond similarly to alterations in the flooding regime was assessed. Five piscivorous species were selected (Acestrorhynchus lacustris, Hoplias aff. malabaricus, Plagioscion squamosissimus, Rhaphiodon vulpinus, and Salminus brasiliensis). The fish were captured in four distinct years and in three river subsystems with differentiated water level fluctuations (Ivinheira = not regulated; Baía = regulated by the Paraná River level; Paraná = regulated by dams). Feeding activity and body condition were evaluated using the mean values of the standard residuals generated by regression models between body and stomach weights and standard length and body weight (all log-transformed). Differences among years and subsystems were evaluated via two-way analysis of variance. Pearson and Spearman correlations were performed between flooding attributes (duration, amplitude, timing, and daily variability) and feeding activity and body condition. Feeding activity differed across subsystems, whereas body condition varied across years, depending on the subsystem. Hoplias aff malabaricus (an ambusher adapted to starvation) presented feeding activity independent of the flooding regime and also presented better body condition in times of high water levels. Rhaphidon vulpinus exhibited variations in feeding activity but did not present alterations in body condition. The other species presented poorer body condition in years or subsystems with regular floods. Correlations identified that the duration and timing of floods had negative effects on body condition, whereas amplitude and mean annual water level improved feeding activity. Therefore, regular floods affect the feeding activity and body condition of piscivorous fish, and the response of each species depends on the existence or absence of pre-adaptation to long periods of starvation. Consequently, considering the role of the flood pulse in determining the availability of feeding resources for early life stages of piscivores, control of the flood pulse by dams is also disadvantageous for piscivorous fish.
4
Vannière, B., M. Magny, S. Joannin, A. Simonneau, S. B. Wirth, Y. Hamann, E. Chapron, A. Gilli, M. Desmet, and F. S. Anselmetti. "Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy." Climate of the Past 9, no. 3 (May 31, 2013): 1193–209. http://dx.doi.org/10.5194/cp-9-1193-2013.
Abstract:
Abstract. Two lacustrine sediment cores from Lake Ledro in northern Italy were studied to produce chronologies of flood events for the past 10 000 yr. For this purpose, we have developed an automatic method that objectively identifies the sedimentary imprint of river floods in the downstream lake basin. The method was based on colour data extracted from processed core photographs, and the count data were analysed to capture the flood signal. Flood frequency and reconstructed sedimentary dynamics were compared with lake-level changes and pollen inferred vegetation dynamics. The results suggest a record marked by low flood frequency during the early and middle Holocene (10 000–4500 cal BP). Only modest increases during short intervals are recorded at ca. 8000, 7500, and 7100 cal BP. After 4500–4000 cal BP, the record shows a shift toward increased flood frequency. With the exception of two short intervals around 2900–2500 and 1800–1400 cal BP, which show a slightly reduced number of floods, the trend of increasing flood frequency prevailed until the 20th century, reaching a maximum between the 16th and the 19th centuries. Brief-flood frequency increases recorded during the early and middle Holocene can be attributed to cold climatic oscillations. On a centennial time scale, major changes in flood frequency, such as those observed after ca. 4500/4000 and 500 cal BP, can be attributed to large-scale climatic changes such as the Neo-glacial and Little Ice Age, which are under orbital and possibly solar control. However, in the Bronze Age and during the Middle Ages and modern times, forest clearing and land use probably partially control the flood activity.
5
Czymzik, M., R. Muscheler, and A. Brauer. "Solar modulation of flood frequency in Central Europe during spring and summer on inter-annual to millennial time-scales." Climate of the Past Discussions 11, no. 5 (October 13, 2015): 4833–50. http://dx.doi.org/10.5194/cpd-11-4833-2015.
Abstract:
Abstract. Solar influences on climate variability are one of the most controversially discussed topics in climate research. We analyze solar forcing of flood frequency in Central Europe on inter-annual to millennial time-scales using daily discharge data of River Ammer (southern Germany) back to AD 1926 and revisiting the 5500 year flood layer time-series from varved sediments of the downstream Lake Ammersee. Flood frequency in the discharge record is significantly correlated to changes in solar activity during solar cycles 16–23 (r = −0.47, p < 0.0001, n = 73). Flood layer frequency (n = 1501) in the sediment record depicts distinct multi-decadal variability and significant correlations to 10Be fluxes from a Greenland ice core (r = 0.45, p < 0.0001) and 14C production rates (r =0.36, p < 0.0001), proxy records of solar activity. Flood frequency is higher when solar activity is reduced. These correlations between flood frequency and solar activity might provide empirical support for the solar top-down mechanism expected to modify the mid-latitude storm tracks over Europe by model studies. A lag of flood frequency responses in the Ammer discharge record to changes in solar activity of about one to three years could be explained by a modelled ocean–atmosphere feedback delaying the atmospheric reaction to solar activity variations up to a few years.
6
Vannière, B., M. Magny, S. Joannin, A. Simonneau, S. B. Wirth, Y. Hamann, E. Chapron, A. Gilli, M. Desmet, and F. S. Anselmetti. "Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy." Climate of the Past Discussions 8, no. 5 (September 24, 2012): 4701–44. http://dx.doi.org/10.5194/cpd-8-4701-2012.
Abstract:
Abstract. Two lacustrine sediment cores from Lake Ledro in Northern Italy were studied to produce chronologies of flood events for the past 10 000 yr. For this purpose, we have developed an automatic method that objectively identifies the sedimentary imprint of river floods in the downstream lake basin. The automatic counting of flood deposits was based on colour data extracted from processed core photographs, and the count data were processed to capture the flood signal. Automatic quantification was compared with naked-eye counting. Counts were performed twice on the proximal and distal cores to provide an objective and reproducible record of flood frequency. Geophysical and geochemical analyses made it possible to distinguish event deposits from background sedimentation. Flood frequency and reconstructed sedimentary dynamics were compared with lake-level changes and pollen dynamics inferred from vegetation data. The data suggest a record marked by low flood frequency during the early and middle Holocene (10 000–4500 cal BP). Only modest increases during short intervals are recorded at ca. 8000, 7500, and 7100 cal BP. The last third of the Holocene is characterised by a shift toward increased flood frequency at ca. 4500–4000 cal BP. With the exception of two short intervals around 2900–2500 and 1800–1400 cal BP, which show a slightly reduced number of floods, the trend of increasing flood frequency prevailed until the 20th century, reaching a maximum between the 16th and the 19th centuries. Brief-flood frequency increases recorded during the early and middle Holocene can be attributed to cold climatic oscillations. On a centennial time scale, major changes in flood frequency, such as those observed at ca. 4500 and 500 cal BP, can be attributed to large-scale climatic changes such as the Neo-glacial and Little Ice Age, which are under orbital and possibly solar control. The role of climate as the main forcing factor in flood activity is supported by the lake-level records: the major lake-level rises are synchronous with flood frequency increases. However, in the Bronze Age and during the Middle Ages and modern times, forest clearing and land use are indicated by pollen and archaeological data. These human activities have clearly affected the sediment record of flood activity, and they can partially explain the amplitude of the increases in flood activity.
7
Zúñiga, Emmanuel, Víctor Magaña, and Violeta Piña. "Effect of Urban Development in Risk of Floods in Veracruz, Mexico." Geosciences 10, no. 10 (October 9, 2020): 402. http://dx.doi.org/10.3390/geosciences10100402.
Abstract:
Urban floods have adverse effects on the population and the economy, and they are increasing in frequency and magnitude. The State of Veracruz is the region of Mexico with the highest number of disasters, more than 50% of the total number nationwide, in the 1970–2015 period. During the 1990s, disasters in this region increased from 5 to 10 events per year, mostly in relation to intense rains and floods. This study analyzes the factors that increase the risk of urban floods in the regions: (i) the Pánuco River, (ii) the Papaloapan River, and (iii) the Coatzacoalcos River regions, combining hazard data and estimates of vulnerability factors. The 95th percentile of daily precipitation (P95) is used as a threshold of heavy rain, i.e., the natural hazard. Vulnerability is estimated in terms of the percentage of natural vegetation loss due to changes in land cover and land use in the hydrological basins and the expansion of the urban areas in the regions under study. The risk of flood was compared with records of flood events focusing on the low-frequency variations of risks and disaster activity. The trends in urban flood activity are related to the loss of natural vegetation and deterioration of the basins leading to a loss of infiltration, i.e., larger runoffs. Even when the intensity of precipitation in recent decades remains without clear trends, or shows negative tendencies in the number of intense events, the number of floods is higher mostly because of the deterioration of hydrologic basins. Therefore, the risk of flooding in the state of Veracruz is mainly related to environmental factors that result in vulnerability rather than changes in the trends of extreme precipitation activity. This result means that disaster risk reduction actions should be mainly related to rehabilitation of the basins.
8
Barrera-Escoda, A., and M. C. Llasat. "The role of climatic factors in evolving flood patterns in a Mediterranean Region (1301–2012)." Hydrology and Earth System Sciences Discussions 11, no. 8 (August 1, 2014): 9145–82. http://dx.doi.org/10.5194/hessd-11-9145-2014.
Abstract:
Abstract. Data on flood occurrence and flood impacts for the last seven centuries in the northeast Iberian Peninsula have been analysed in order to characterise long-term trends, anomalous periods and their relationship with different climatic factors such as precipitation, general circulation and solar activity. Catastrophic floods do not present a statistically significant trend, whereas extraordinary floods have seen a significant rise, especially from 1850 on, and were responsible for the total increase in flooding in the region. This rise can be mainly attributed to small coastal catchments, which have experienced a marked increase in developed land and population, resulting in changes in land use and greater vulnerability. Changes in precipitation alone cannot explain the variation in flood patterns, although a certain increase was shown in late summer–early autumn, when extraordinary floods are most frequently recorded. The relationship between North Atlantic circulation and floods is not as strong, due to the important role of mesoscale factors in heavy precipitation in the northwest of the Mediterranean region. However it can explain the variance to some extent, mainly in relation to the catastrophic floods experienced during the autumn. Solar activity has some impact on changes in catastrophic floods with cycles related to the Quasi-Biennial Oscillation and the Gleissberg solar cycle. In addition, anomalous periods of high flood frequency in autumn generally occurred during periods of increased solar activity. The physical influence of the latter in general circulation patterns, the high troposphere and the stratosphere, has been analysed in order to ascertain its role in causing floods.
9
Czymzik, Markus, Raimund Muscheler, and Achim Brauer. "Solar modulation of flood frequency in central Europe during spring and summer on interannual to multi-centennial timescales." Climate of the Past 12, no. 3 (April 1, 2016): 799–805. http://dx.doi.org/10.5194/cp-12-799-2016.
Abstract:
Abstract. Solar influences on climate variability are one of the most controversially discussed topics in climate research. We analyze solar forcing of flood frequency in central Europe during spring and summer on interannual to multi-centennial timescales, integrating daily discharge data of the River Ammer (southern Germany) back to AD 1926 (∼ solar cycles 16–23) and the 5500-year flood layer record from varved sediments of the downstream Ammersee. Flood frequency in the River Ammer discharge record is significantly correlated to changes in solar activity when the flood record lags the solar signal by 2–3 years (2-year lag: r = −0.375, p = 0.01; 3-year lag: r = −0.371, p = 0.03). Flood layer frequency in the Ammersee sediment record depicts distinct multi-decadal variations and significant correlations to a total solar irradiance reconstruction (r = −0.4, p < 0.0001) and 14C production rates (r = 0.37, p < 0.0001), reflecting changes in solar activity. On all timescales, flood frequency is higher when solar activity is reduced. In addition, the configuration of atmospheric circulation associated with periods of increased River Ammer flood frequency broadly resembles that during intervals of reduced solar activity, as expected to be induced by the so-called solar top-down mechanism by model studies. Both atmospheric patterns are characterized by an increase in meridional airflow associated with enhanced atmospheric blocking over central Europe. Therefore, the significant correlations as well as similar atmospheric circulation patterns might provide empirical support for a solar influence on hydroclimate extremes in central Europe during spring and summer by the so-called solar top-down mechanism.
10
Suzuki, Yoshiaki, Ryuji Tada, Kana Nagashima, Takeshi Nakagawa, Katsuya Gotanda, Tsuyoshi Haraguchi, and Gordon Schlolaut. "Extreme flood events and their frequency variations during the middle to late-Holocene recorded in the sediment of Lake Suigetsu, central Japan." Holocene 31, no. 1 (October 8, 2020): 121–33. http://dx.doi.org/10.1177/0959683620961497.
Abstract:
Many studies are reconstructing flood records in the continental margins during the middle to late-Holocene. However, distinguishing the frequency and magnitude of flood events was difficult. Light gray event layers (GELs) in the sediment of Lake Suigetsu in Central Japan can solve this problem because they are recording the occurrence and magnitude of flood events during the last 80 years. Using these GELs, we aimed to reconstruct the frequency and magnitude of flood events during the last 8000 years. First, we verified whether GELs maintained the recording of flood events. We found that thin GELs (less than 40 mg/cm2 in mass) were rare, probably because of bioturbation, whereas thick GELs (larger than 40 mg/cm2 in mass) were rarely erased. We also found that GELs formed by the same amount of rainfall could have been thinner before 100 years ago. We revealed that the occurrence of extreme flood-origin event layers (EFELs: GELs thicker than 40 mg/cm2) during the last 8000 years may indicate the occurrence of extreme flood events (EFEs). Mass accumulation of EFELs may indicate the minimum estimation of rainfall on EFEs. There are several periods with higher frequency and magnitude of EFEs than those of the present level, agreeing with the periods of high flood activity in western Japan and East China. The frequency and magnitude of EFEs show different temporal variations. Northward and southward shifts in the westerly jet and monsoon fronts can partially explain such patterns.
11
Barrera-Escoda, A., and M. C. Llasat. "Evolving flood patterns in a Mediterranean region (1301–2012) and climatic factors – the case of Catalonia." Hydrology and Earth System Sciences 19, no. 1 (January 26, 2015): 465–83. http://dx.doi.org/10.5194/hess-19-465-2015.
Abstract:
Abstract. Data on flood occurrence and flood impacts for the last seven centuries in the northeastern Iberian Peninsula have been analysed in order to characterise long-term trends, anomalous periods and their relationship with different climatic factors such as precipitation, general circulation and solar activity. Catastrophic floods (those that produce complete or partial destruction of infrastructure close to the river, and major damages in the overflowed area, including some zones away from the channels) do not present a statistically significant trend, whereas extraordinary floods (the channel is overflowed and some punctual severe damages can be produced in the infrastructures placed in the rivercourse or near it, but usually damages are slight) have seen a significant rise, especially from 1850 on, and were responsible for the total increase in flooding in the region. This rise can be mainly attributed to small coastal catchments, which have experienced a marked increase in developed land and population, resulting in changes in land use and greater vulnerability. Changes in precipitation alone cannot explain the variation in flood patterns, although a certain increase was shown in late summer–early autumn, when extraordinary floods are most frequently recorded. The relationship between the North Atlantic circulation and floods is not as strong, due to the important role of mesoscale factors in heavy precipitation in the northwest of the Mediterranean region. However, it can explain the variance to some extent, mainly in relation to the catastrophic floods experienced during the autumn. Solar activity has some impact on changes in catastrophic floods, with cycles related to the quasi-biennial oscillation (QBO) and the Gleissberg solar cycle. In addition, anomalous periods of high flood frequency in autumn generally occurred during periods of increased solar activity. The physical influence of the latter in general circulation patterns, the high troposphere and the stratosphere, has been analysed in order to ascertain its role in causing floods.
12
Rahmadi, Rahmadi, Eka Purnama Indah, and Arie Rakhman. "DEVELOPMENT OF A PHYSICAL ACTIVITY LEARNING MODEL MULTIMEDIA BASED IN FLOOD PROne AREAS." Riyadhoh : Jurnal Pendidikan Olahraga 6, no. 2 (December 3, 2023): 202. http://dx.doi.org/10.31602/rjpo.v0i0.12945.
Abstract:
The background to this research comes from a school that adapts to natural situations, where sometimes when the tide is high it will submerge the entire school yard, causing physical education learning activities to be hampered. Based on survey results from the past 2 years, there are indeed several schools in the Banjar Regency area that have been submerged by high tides/are prone to flooding. The aim of this research is to create a learning model that is suitable for use during high tide by testing several learning models that have been designed related to multimedia-based physical activities. The method used in this research is research and deployment (RnD) with the ADDIE design (Analysis, Design, Development or Production, Implementation or Delivery and Evaluations). The research instruments used are tests and measurements, including testing learning models and finding out the results of validity tests and effectiveness tests. The research results show that the peer teaching and cooperative learning models are more dominantly used in flood conditions, but other variations of learning models also do not rule out the possibility of being used in post-floods with a usage intensity level of 73.5% for the peer teaching model and 73.1% for the cooperative model. dominantly used by physical education teachers at SMPN 2 Martapura Timur. In this way, these two learning models will provide activities for students with multimedia tools.
13
Tang, Yihan, Shufeng Xi, Xiaohong Chen, and Yanqing Lian. "Quantification of Multiple Climate Change and Human Activity Impact Factors on Flood Regimes in the Pearl River Delta of China." Advances in Meteorology 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/3928920.
Abstract:
Coastal flood regimes have been irreversibly altered by both climate change and human activities. This paper aims to quantify the impacts of multiple factors on delta flood. The Pearl River Delta (PRD), with dense river network and population, is one of the most developed coastal areas in China. The recorded extreme water level (m.s.l.) in flood season has been heavily interfered with by varied income flood flow, sea-level rise, and dredged riverbeds. A methodology, composed of a numerical model and the indexR, has been developed to quantify the impacts of these driving factors in the the PRD. Results show that the flood level varied 4.29%–53.49% from the change of fluvial discharge, 3.35%–38.73% from riverbed dredging, and 0.12%–16.81% from sea-level rise. The variation of flood flow apparently takes the most effect and sea-level rise the least. In particular, dense river network intensifies the impact of income flood change and sea-level rise. Findings from this study help understand the causes of the the PRD flood regimes and provide theoretical support for flood protection in the delta region.
14
Guo, Peng, Yingjie Wang, Yilin Yan, Fei Wang, Jiqiang Lyu, Wenyan Ge, Hao Chen, and Juying Jiao. "Assessing the Spatiotemporal Variations in the Hydrological Response of the Qin River Basin in Loess Plateau, China." Remote Sensing 16, no. 9 (April 30, 2024): 1603. http://dx.doi.org/10.3390/rs16091603.
Abstract:
In recent decades, the hydrological processes on the Loess Plateau have undergone significant changes due to the combined effects of climate change and human activities. This study investigates the Qin River basin, the core area of the Loess Plateau. Between 1971 and 2000, the hydrometeorology of the flood season in the Qin basin on the Loess Plateau in China changed abruptly in 1982 and 1992. This study uses distributed hydrologic modeling and statistical analysis to distinguish the spatial and temporal impacts of climate change and human activities. The fastest dynamic changes in land use occurred in grassland and construction land, accounting for 0.36% and −0.1%, respectively, from 1982 to 1991. From 1992 to 2000, it was 0.29% and 0.3%, respectively. The increase in basin area where the Normalized Difference Vegetation Index increased was 95%. However, except for significant changes in runoff from 1981 to 1992, there were no significant changes in precipitation, runoff, and temperature during other flood seasons. During the two studied variation periods, from 1982 to 1991 and from 1992 to 2000, the contribution rate of climate change to flood season runoff (CClimate) decreased from 83.26% to 74.47%, while the contribution rate of human activity disturbance to flood season runoff (Chuman) increased from 16.74% to 25.53%. In terms of spatial distribution, from 1982 to 1991, areas with a Chuman > 50% were primarily concentrated in the upper reaches of the basin, while from 1992–2000, these areas shifted to the lower reaches. This study offers valuable insights for water resource planning and soil conservation measures in the Loess Plateau and similar arid regions worldwide, aiming to ensure water resource safety and sustainability in response to climate change and human interference.
15
Abou Rjeily, Yves, Oras Abbas, Marwan Sadek, Isam Shahrour, and Fadi Hage Chehade. "Flood forecasting within urban drainage systems using NARX neural network." Water Science and Technology 76, no. 9 (July 10, 2017): 2401–12. http://dx.doi.org/10.2166/wst.2017.409.
Abstract:
Abstract Urbanization activity and climate change increase the runoff volumes, and consequently the surcharge of the urban drainage systems (UDS). In addition, age and structural failures of these utilities limit their capacities, and thus generate hydraulic operation shortages, leading to flooding events. The large increase in floods within urban areas requires rapid actions from the UDS operators. The proactivity in taking the appropriate actions is a key element in applying efficient management and flood mitigation. Therefore, this work focuses on developing a flooding forecast system (FFS), able to alert in advance the UDS managers for possible flooding. For a forecasted storm event, a quick estimation of the water depth variation within critical manholes allows a reliable evaluation of the flood risk. The Nonlinear Auto Regressive with eXogenous inputs (NARX) neural network was chosen to develop the FFS as due to its calculation nature it is capable of relating water depth variation in manholes to rainfall intensities. The campus of the University of Lille is used as an experimental site to test and evaluate the FFS proposed in this paper.
16
Pears, Ben, Antony G. Brown, Phillip S. Toms, Jamie Wood, David Sanderson, and Richard Jones. "A sub-centennial-scale optically stimulated luminescence chronostratigraphy and late Holocene flood history from a temperate river confluence." Geology 48, no. 8 (May 18, 2020): 819–25. http://dx.doi.org/10.1130/g47079.1.
Abstract:
Abstract River confluences can be metastable and contain valuable geological records of catchment response to decadal- to millennial-scale environmental change. However, in alluvial reaches, flood stratigraphies are particularly hard to date using 14C. In this paper, we use a novel combination of optically stimulated luminescence and multiproxy sedimentological analyses to provide a flood record for the confluence of the Rivers Severn and Teme (United Kingdom) over the past two millennia, which we compare with independent European climate records. The results show that by ca. 2000 yr B.P., the Severn-Teme confluence had stabilized and overbank alluviation had commenced. Initially, this occurred from moderately high flood magnitudes between ca. 2000 and 1800 yr B.P. (50 BCE–150 CE), but was followed from 1800 to 1600 yr B.P. (150–350 CE) by fine alluvial deposition and decreased flood intensity. From 1600 to 1400 yr B.P. (350–550 CE), the accumulation rate increased, with evidence of large flood events associated with the climatic deterioration of the Dark Age Cold Period. Following a period of reduced flood activity after ca. 1400 yr B.P. (ca. 550 CE), larger flood events and increase in accumulation rate once again became more prevalent from ca. 850 yr B.P. (ca. 1100 CE), coincident with the start of the Medieval Climate Anomaly, a period associated with warmer, wetter conditions and increased land-use intensity. This state persisted until ca. 450 yr B.P. (ca. 1500 CE), after which increased flood magnitudes can be associated with climatic variations during the Little Ice Age. We demonstrate that from the combination of high-resolution dating techniques and multiple analytical parameters, distinctive phases of relative flood magnitude versus flood duration can be determined to a detailed chronological precision beyond that possible from 14C dating. This permits the identification of the regional factors behind floodplain sedimentation, which we correlate with the intensification of land-use and climatic drivers over the last two millennia.
17
Legrand, Caroline, Benoît Hingray, Bruno Wilhelm, and Martin Ménégoz. "Assessing downscaling methods to simulate hydrologically relevant weather scenarios from a global atmospheric reanalysis: case study of the upper Rhône River (1902–2009)." Hydrology and Earth System Sciences 28, no. 9 (May 15, 2024): 2139–66. http://dx.doi.org/10.5194/hess-28-2139-2024.
Abstract:
Abstract. We assess the ability of two modelling chains to reproduce, over the last century (1902–2009) and from large-scale atmospheric information only, the temporal variations in river discharges, low-flow sequences and flood events observed at different locations of the upper Rhône River catchment, an alpine river straddling France and Switzerland (10 900 km2). The two modelling chains are made up of a downscaling model, either statistical (Sequential Constructive Atmospheric Analogues for Multivariate weather Predictions – SCAMP) or dynamical (Modèle Atmosphérique Régional – MAR), and the Glacier and SnowMelt SOil CONTribution (GSM-SOCONT) model. Both downscaling models, forced by atmospheric information from the global atmospheric reanalysis ERA-20C, provide time series of daily scenarios of precipitation and temperature used as inputs to the hydrological model. With hydrological regimes ranging from highly glaciated ones in its upper part to mixed ones dominated by snow and rain downstream, the upper Rhône River catchment is ideal for evaluating the different downscaling models in contrasting and demanding hydro-meteorological configurations where the interplay between weather variables in both space and time is determinant. Whatever the river sub-basin considered, the simulated discharges are in good agreement with the reference ones, provided that the weather scenarios are bias-corrected. The observed multi-scale variations in discharges (daily, seasonal, and interannual) are reproduced well. The low-frequency hydrological situations, such as annual monthly discharge minima (used as low-flow proxy indicators) and annual daily discharge maxima (used as flood proxy indicators), are reproduced reasonably well. The observed increase in flood activity over the last century is also reproduced rather well. The observed low-flow activity is conversely overestimated, and its variations from one sub-period to another are only partially reproduced. Bias correction is crucial for both precipitation and temperature and for both downscaling models. For the dynamical one, a bias correction is also essential for getting realistic daily temperature lapse rates. Uncorrected scenarios lead to irrelevant hydrological simulations, especially for the sub-basins at high elevation, due mainly to irrelevant snowpack dynamic simulations. The simulations also highlight the difficulty in simulating precipitation dependency on elevation over mountainous areas.
18
Razjigaeva, N. G., L. A. Ganzey, T. A. Grebennikova, L. M. Mokhova, and T. A. Kopoteva. "Origin, age and development of mountain lakes of southern Far East during the Holocene monsoon variations." Limnology and Freshwater Biology, no. 4 (2022): 1538–40. http://dx.doi.org/10.31951/2658-3518-2022-a-4-1538.
Abstract:
Abstract. A small mountain lakes-mire complex recorded in details Holocene environmental changes controlled by monsoon intensity and cyclogenesis activity. The reconstructions were based on multi-proxy studies (diatom, botanical and pollen analyses). We studied evolution of 8 lakes, located on different altitudes (from 320 to 1600 m). The studied lakes belong to four genetic types (on ancient basalt plateaus, depressions within large landslides on ancient volcano slopes and river valleys, and nival lakes on mountain peaks). Longest records (~9720 yr) of climatic changes was restored for East Manchurian mountains. Period long-term droughts 3050 1075 yr BP was connected with weaking of summer monsoon. Studied lakes of Sikhote-Alin were formed in late Holocene. The data clearly indicated drying events caused by precipitation deficits coincided with climate deterioration. Flood recurrence and cyclogenesis activity were recorded in the lake-mire complex developed on landslides within river valleys.
19
Harper, Joel T., Neil F. Humphrey, W. Tad Pfeffer, Tyler Fudge, and Shad O’Neel. "Evolution of subglacial water pressure along a glacier’s length." Annals of Glaciology 40 (2005): 31–36. http://dx.doi.org/10.3189/172756405781813573.
Abstract:
AbstractObservations from along the length of Bench Glacier, Alaska, USA, show that the subglacial water-pressure field undergoes a multiphase transition from a winter mode to a summer mode. Data were collected at the glacier surface, the outlet stream, and in a network of 47 boreholes spanning the length of the 7 km long glacier. The winter pressure field was near overburden, with low-magnitude (centimeter to meter scale) and long-period (days to weeks) variations. During a spring speed-up event, boreholes showed synchronous variations and a slight pressure drop from prior winter values. Diurnal pressure variations followed the speed-up, with their onset associated with a glacier-wide pressure drop and flood at the terminus stream. Diurnal variations with swings of up to 80% of overburden pressure were typical of mid-summer. Several characteristics of our observations contradict common conceptions about the seasonal development of the subglacial drainage system and the linkages between subglacial hydrology and basal sliding: (1) increased water pressure did not accompany high sliding rates; (2) the drainage system showed activity characteristic of the spring season long before abundant water was available on the glacier surface; (3) the onset of both spring activity and diurnal variations of the drainage system did not show a spatial progression along the length of the glacier.
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Rustomji, Paul. "Flood and drought impacts on the opening regime of a wave-dominated estuary." Marine and Freshwater Research 58, no. 12 (2007): 1108. http://dx.doi.org/10.1071/mf07079.
Abstract:
Wave-dominated estuaries are affected by floods generated in their hinterland catchments as well as marine tide and wave processes. The interaction of these terrestrial and marine influences controls the opening regime of the estuary. Despite the well documented environmental pressures on estuaries including elevated nutrient loadings and abstraction of river flows, little research concerning the variability and controls on estuary mouth opening regimes exists. From water level observations of Tuross Lake estuary in south-eastern Australia, the estuary’s recent opening regime is reconstructed and shown to vary significantly over time. Floodwaters fill the estuary and scour the estuary mouth, enhancing the exchange of marine water between the estuary and the ocean, which manifests as an increased tidal range within the estuary. Between floods, tide and wave activity caused aggradation of the estuary mouth such that the tidal range within the estuary declined by 0.5–0.7 mm per day as the mouth became more constricted. Under conditions of low river flow, high evaporative losses and seasonal reductions in ocean wave height, the estuary mouth can close completely. Using twentieth century streamflow estimates, it is shown that hydrologic variability is likely to have resulted in large variations in the estuary’s opening regime. Since 2000, there have been relatively few flood-driven scour events and this explains the relatively congested state of the current estuary mouth. Predicted hydrologic changes under enhanced atmospheric carbon dioxide concentrations are also likely to enhance the variability in the estuary’s opening regime.
21
Guiteras, Raymond, Amir Jina, and A. Mushfiq Mobarak. "Satellites, Self-reports, and Submersion: Exposure to Floods in Bangladesh." American Economic Review 105, no. 5 (May 1, 2015): 232–36. http://dx.doi.org/10.1257/aer.p20151095.
Abstract:
A burgeoning “Climate-Economy” literature has uncovered many effects of changes in temperature and precipitation on economic activity, but has made considerably less progress in modeling the effects of other associated phenomena, like natural disasters. We develop new, objective data on floods, focusing on Bangladesh. We show that rainfall and self-reported exposure are weak proxies for true flood exposure. These data allow us to study adaptation, giving accurate measures of both long-term averages and short term variation in exposure. This is important in studying climate change impacts, as people will not only experience new exposures, but also experience them differently.
22
Yu, Ran, Barth F. Smets, Ping Gan, Allison A. MacKay, and Joerg Graf. "Seasonal and spatial variations in microbial activity at various phylogenetic resolutions at a groundwater – surface water interface." Canadian Journal of Microbiology 60, no. 5 (May 2014): 277–86. http://dx.doi.org/10.1139/cjm-2014-0048.
Abstract:
We investigated the seasonal and spatial variation in activity and density of the metabolically active in situ microbial community (AIMC) at a landfill leachate-impacted groundwater – surface water interface (GSI). A series of AIMC traps were designed and implemented for AIMC sampling and microbial activity and density examinations. Measurements were made not only at the level of bacterial domain but also at the levels of alphaproteobacterial Rhizobiales order and gammaproteobacterial Pseudomonas genus, both of which included a large number of iron-oxidizing bacteria as revealed from previous analysis. Consistently higher microbial activities with less variation in depth were measured in the AIMC traps than in the ambient sediments. Flood disturbance appeared to control AIMC activity distributions at the gradually elevated GSI. The highest AIMC activities were generally obtained from locations closest to the free surface water boundary except during the dry season when microbial activities were similar across the entire GSI. A clone library of AIMC 16S rRNA genes was constructed, and it confirmed the predominant role of the targeted alphaproteobacterial group in AIMC activity and composition. This taxon constituted 2%–14% of all bacteria with similar activity distribution profiles. The Pseudomonas group occupied only 0.1‰–0.5‰ of the total bacterial density, but its activity was 27 times higher than the bacterial average. Of the 16S rRNA sequences in the AIMC clone library, 7.5% were phylogenetically related to putative IOB, supporting the occurrence and persistence of active microbial iron oxidation across the studied iron-rich GSI ecosystem.
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Chan, John W. Y., and Ronald S. Burton. "Variation in Alcohol Dehydrogenase Activity and Flood Tolerance in White Clover, Trifolium repens." Evolution 46, no. 3 (June 1992): 721. http://dx.doi.org/10.2307/2409640.
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Chan, John W. Y., and Ronald S. Burton. "VARIATION IN ALCOHOL DEHYDROGENASE ACTIVITY AND FLOOD TOLERANCE IN WHITE CLOVER,TRIFOLIUM REPENS." Evolution 46, no. 3 (June 1992): 721–34. http://dx.doi.org/10.1111/j.1558-5646.1992.tb02078.x.
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Shevnina, Elena, Ekaterina Kourzeneva, Viktor Kovalenko, and Timo Vihma. "Assessment of extreme flood events in a changing climate for a long-term planning of socio-economic infrastructure in the Russian Arctic." Hydrology and Earth System Sciences 21, no. 5 (May 23, 2017): 2559–78. http://dx.doi.org/10.5194/hess-21-2559-2017.
Abstract:
Abstract. Climate warming has been more acute in the Arctic than at lower latitudes and this tendency is expected to continue. This generates major challenges for economic activity in the region. Among other issues is the long-term planning and development of socio-economic infrastructure (dams, bridges, roads, etc.), which require climate-based forecasts of the frequency and magnitude of detrimental flood events. To estimate the cost of the infrastructure and operational risk, a probabilistic form of long-term forecasting is preferable. In this study, a probabilistic model to simulate the parameters of the probability density function (PDF) for multi-year runoff based on a projected climatology is applied to evaluate changes in extreme floods for the territory of the Russian Arctic. The model is validated by cross-comparison of the modelled and empirical PDFs using observations from 23 sites located in northern Russia. The mean values and coefficients of variation (CVs) of the spring flood depth of runoff are evaluated under four climate scenarios, using simulations of six climate models for the period 2010–2039. Regions with substantial expected changes in the means and CVs of spring flood depth of runoff are outlined. For the sites located within such regions, it is suggested to account for the future climate change in calculating the maximal discharges of rare occurrence. An example of engineering calculations for maximal discharges with 1 % exceedance probability is provided for the Nadym River at Nadym.
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Chen, Tsing-Chang, Jenq-Dar Tsay, Ming-Cheng Yen, and Jun Matsumoto. "Interannual Variation of the Winter Rainfall in Malaysia Caused by the Activity of Rain-Producing Disturbances." Journal of Climate 26, no. 13 (July 1, 2013): 4630–48. http://dx.doi.org/10.1175/jcli-d-12-00367.1.
Abstract:
Abstract Heavy rainfall/flood (HRF) cyclones contribute close to two-thirds of the total rainfall PT in both parts of Malaysia [peninsular Malaysia (M) and west Borneo (B)]. Judging by the rainfall variance produced by these cyclones and its correlation (~0.9) with the interannual PT variation, this variation is caused primarily by HRF cyclones through two factors: 1) their westward propagation properties and 2) their rain-producing efficiency. The former is regulated by the change of the cyclonic shear flow around the near-equator trough, while the latter is determined by the change of the convergence of water vapor flux toward tropical Southeast Asia. During November–December of cold (warm) ENSO phases, the westward propagation of the cyclone's parent cold surge vortices (CSVs) from the Philippine (P) vicinity (Borneo) to peninsular Malaysia CSVPMs (CSVBMs) and intensified (weakened) convergence of water vapor flux toward tropical South/Southeast Asia act to enhance (reduce) the rain-producing efficiency of HRFPM (HRFBM) cyclones. During winter cold (warm) phases, the deepening (filling) of the near-equator trough crossing west Borneo allows some CSVs formed/trapped in Borneo CSVBBs to develop into HRFBB (HRFBBM) cyclones (to propagate westward to peninsular Malaysia). The rain-producing efficiency of HRFBB and HRFBBM cyclones is also increased (reduced) by the intensified (weakened) convergence of water flux toward tropical South/Southeast Asia. Interannual variations of both PT(M) and PT(B) caused by the impacts of the circulation pattern changes on occurrences of HRFPM and HRFBB/HRFBBM cyclones, respectively, and their rain-producing efficiency may pose a new challenge to simulate the weather–climate relationship in climate modeling.
27
DAWSON, CHRISTIAN W., MARTIN R. BROWN, and ROBERT L. WILBY. "INDUCTIVE LEARNING APPROACHES TO RAINFALL-RUNOFF MODELLING." International Journal of Neural Systems 10, no. 01 (February 2000): 43–57. http://dx.doi.org/10.1142/s0129065700000053.
Abstract:
Trying to model the rainfall-runoff process is a complex activity as it is influenced by a number of implicit and explicit factors — for example, precipitation distribution, evaporation, transpiration, abstraction, watershed topography, and soil types. However, this kind of forecasting is particularly important as it is used to predict serious flooding, estimate erosion and identify problems associated with low flow. Inductive learning approaches (e.g. decision trees and artificial neural networks) are particularly well suited to problems of this nature as they can often interpret underlying factors (such as seasonal variations) which cannot be modelled by other techniques. In addition, these approaches can easily be trained on the explicit factors (e.g. rainfall) and the inexplicit factors (e.g. abstraction) that affect river flow. Inductive learning approaches can also be extended to account for new factors that emerge over a period of time. This paper evaluates the application of decision trees and two artificial neural network models (the multilayer perceptron and the radial basis function network) to river flow forecasting in two flood prone UK catchments using real hydrometric data. Comparisons are made between the performance of these approaches and conventional flood forecasting systems.
28
Montety, Laure de, Bernard Long, Gaston Desrosiers, Jean-François Crémer, Jacques Locat, and Georges Stora. "Utilisation de la scanographie pour l'étude des sédiments : influence des paramètres physiques, chimiques et biologiques sur la mesure des intensités tomographiques." Canadian Journal of Earth Sciences 40, no. 7 (July 1, 2003): 937–48. http://dx.doi.org/10.1139/e03-027.
Abstract:
In July 1996, a flash flood resulted in the input of 9 million m3 of sediment toward the Bay of Ha! Ha!, leading to the elimination, partly or totally, of the benthic fauna of the bay. In this study, the CT scanner has been used in a highly perturbed environment, the Bay of Ha! Ha!, to both assess (i) the relationships between the variations of tomographic intensities and the sedimentologic parameters of the sedimentary column and (ii) to quantify the biogenic structures resulting from the activity of benthic organisms. Compaction, CaCO3 contents, and granulometry of sediments are the most important influences on the variation of tomographic intensities. The scanner allowed the study and quantification, in a non destructive way, of the sediment occupation by biogenic structures and, more particularly, allowed to further assess most of the relative importance of the fine fraction of biogenic structures (0.2501 mm) in the surface sediment layer (05 cm). Sediment occupation by biogenic structures reached maximal values at the upper part of the sedimentary column and decreased with depth. If sedimentary reworking leads to an increase in the sediment porosity, destabilization generated by the activity of organisms is balanced by the consolidation of the wall of the biogenic structures. Bioturbation resulting from the activity of benthic organisms into the sediments has a significant role on the sedimentary structure and biogeochemical processes. It is therefore necessary to quantify the volume of sediments occupied by biogenic structures to assess the activity of benthic organisms in the sedimentary column.
29
Wan, Zhiwei, Xi Chen, Min Ju, Chaohao Ling, Guangxu Liu, Siping Lin, Huihua Liu, Yulian Jia, Meixin Jiang, and Fuqiang Liao. "Streamflow Reconstruction and Variation Characteristic Analysis of the Ganjiang River in China for the Past 515 Years." Sustainability 12, no. 3 (February 6, 2020): 1168. http://dx.doi.org/10.3390/su12031168.
Abstract:
River flow reconstruction under the background of long-term climate change is of great significance for understanding the regional response to future drought and flood disasters, and the sustainable development of water resources. Investigating the basic characteristics and changing trends of the streamflow of the Ganjiang River is scientifically important to mitigate drought and flood disasters in the future. This study reconstructed drought and flood grade series of five regional stations of the Ganjiang River based on spatially explicit and well-dated local chronicle materials and used a linear regression model of modern drought/flood grades and precipitation to reconstruct historical precipitation for the past 515 years. The relationships between the modern precipitation of five regional stations and streamflow of Waizhou Station, which is the last hydrological station of the Ganjiang River were analyzed through principal component regression. The adjusted R2 is 0.909, with a low relative bias of −1.82%. The variation of streamflow from AD 1500 to AD 2014 was reconstructed using the proposed model. Result shows that high flows occur in nine periods and low flows occur in 11 periods. Extremely low stream flow in 515 years appears during the middle and late 17th century. Cumulative anomaly and Mann-Kendall mutation test results reveal that a transition point from predominantly low to high flows occur in AD 1720. Redfit power spectrum analysis result shows that the variation periods of streamflow are 2–5, 7–8 years, and approximately 32 years, where the most significant period is 2–3 years. Continuous wavelet transform indicates that the corresponding relation occurs between streamflow and El Niño/Southern Oscillation for eight years. Streamflow is affected by temperature and East Asian monsoon that is controlled by solar activities. The flood may be related to strong solar activity, monsoon failure, and vice versa. Hydrological frequency curve analysis shows that the streamflow of the Ganjiang River once in a hundred years may reach up to 1031 × 108 m3 for flood or 485 × 108 m3 for drought and the standard of once in a millennium runoff may reach up to 1188 × 108 m3 for flood or 450 × 108 m3 for drought. These results may provide basic hydrological data for the sustainable development of society and serve as a reference for mitigating the impact of drought and flood disasters in the future.
30
Danandeh Mehr, Ali, and Ozgun Akdegirmen. "Estimation of Urban Imperviousness and its Impacts on Flashfloods in Gazipaşa, Turkey." Knowledge-Based Engineering and Sciences 2, no. 1 (May 2, 2021): 9–17. http://dx.doi.org/10.51526/kbes.2021.2.1.9-17.
Abstract:
The paper examines flooding issues under rapid urbanization in Gazipasa city during the past seven years 2013-2019. The Storm Water Management Model (SWMM) integrated with the satellite images representing temporal variation in the land use and land cover (LULC) characteristics of the city were used to determine the variation in the runoff generation capacity, flood volume, and associated risks. The Google Earth software together with GIS technology were utilized to create and handle spatial data required for SWMM simulation. Standard design storm intensity derived from the local intensity-duration-frequency curves was used as the stationary input parameter for SWMM simulation in both the past and current LULC conditions. The comparison between LULC maps showed that the extent of urban imperviousness area has been approximately increased by 80% in average. The SWMM simulations showed the peak flood value of 51.3 m3/sec and 61.4 m³/sec for the year 2013 and 2019, respectively. Moreover, under the same design storm, Rational Method has been applied and 39 m3/sec of peak flow rate has been calculated by disregarding the urbanization activity. The results indicate that the LULC variation during the past seven years resulted in almost 20% (18%) increase in peak flow (flood volume).
31
Csizmarik, Gábor, Ferenc Ligetvári, Csaba Juhász, and Péter Simándi. "Monitoring the oxygen level in the Szarvas-Kákafok Deadarm." Acta Agraria Debreceniensis, no. I (October 5, 2010): 170–73. http://dx.doi.org/10.34101/actaagrar/i/8397.
Abstract:
The water quality of the Szarvas-Békésszentandrás Dead Körös is generally meso-eutrophic, and meso-saprobic. However, particularlyunder higher temperature conditions, the water body may change toward the eutrophic state, even algal blooms could be observedpreviously.The present measurements were conducted during a two week period, twice a day. Three water samples were taken horizontally, fromthe surface, bottom and the middle of the water body. The samples were examined in situ. The oxygen content, the temperature, the pH andthe conductivity were measured by potentiometric methods.Increasing pH was detected in correlation to the temperature, which indicated a rising photosynthetic activity. Also, the O2concentration showed high variations, especially, when the fresh water supply from the river was stopped, due to a small flood in the riverKörös.These results indicate the increasing eutrophication processes in the deadarm, and the high load and instability of the ecosystem.
32
Scanlon, Annette T., and Sophie Petit. "Effects of site, time, weather and light on urban bat activity and richness: considerations for survey effort." Wildlife Research 35, no. 8 (2008): 821. http://dx.doi.org/10.1071/wr08035.
Abstract:
To maximise bat retention in urban environments, efficient bat monitoring is needed, but the factors that influence survey results for urban bats are unclear. We used echolocation call detectors (n = 378 detector-nights from November 2005 to October 2006) to assess bat activity among different sites in the Adelaide City parklands, temporal variations in activity (hourly, nightly, monthly), and responses to weather and light (artificial and moon). Bat species did not occur evenly in urban conditions; dark parks were more important for bat diversity and activity (six species groups in the darkest park) than were artificially lit parkland areas (three species groups in the flood-lit park). Gould’s wattled bat (Chalinolobus gouldii) and Mormopterus species 4 (94% of calls) were advantaged in urban parklands, being the only species recorded when lights were on at sports parks, whereas five species groups occurred when the lights were off. Minimal bat activity was recorded in the first 2 h after civil twilight, suggesting that bats may roost outside the city and commute nightly into parklands. Bat activity increased with temperature, with a burst in activity occurring after 7°C. Rainfall (>1 mm/24 h) and moon illumination at midnight did not influence activity. Urban environments should provide diversity to attract a diverse assemblage of bat species. Activity fluctuated among sites, nights, and across the year, indicating that large sample sizes over long periods of time are required to monitor and survey bats reliably with detectors.
33
Pacheco-Blas, Lucero, Gabriela González-González, and Alicia Ortega-Aguilar. "Sex-Related Variations in the Brain Motor-Network Connectivity at Rest during Puberty." Applied Sciences 13, no. 18 (September 5, 2023): 10006. http://dx.doi.org/10.3390/app131810006.
Abstract:
The development of functional neuroimaging technologies has resulted in a flood of mathematical models that investigate functional brain connections in health and disease. Motor network activity in the resting state and its response to puberty remains to be investigated. Variations between sexes in puberty may appear not just in brain regions involved in sexual and emotional activities, but also in cognitive and motor abilities that are active even when the individual is resting. The aim of this study was to investigate the interactions of the motor subnetwork in the resting state of healthy males and females aged 12 and 16. This study used the OpenNeuro Dataset ds004169:1.0.7, Queensland Twin IMaging. The MRI signals were preprocessed to get adjacency matrices from the sensory/somatomotor and cerebellar networks in the Power atlas. Network topology was analyzed using the centrality measures of strength, hubness, and leverage. The strength of the nodes increases with age in both sex groups. Both sexes had right hemisphere dominance in the cerebellar-mouth subnetwork and left dominance in the cerebellar-hand subnetwork. Eleven leverage centrality regions were common to all groups, the most relevant were the Precuneus, the cingulum postcentral and the supplementary motor area. In both sexes, hubs at age 12 were detected only in the right hemisphere. This dominance was reduced at age 16. Understanding connectivity changes in the brain during rest may enable the identification of neurophysiological mechanisms of cognitive and behavioral development that may contribute to long-term psychological well-being in adolescents.
34
Miller, Jerry R., Danvey Walsh, and Lionel F. Villarroel. "Use of Paleoflood Deposits to Determine the Contribution of Anthropogenic Trace Metals to Alluvial Sediments in the Hyperarid Rio Loa Basin, Chile." Geosciences 9, no. 6 (May 31, 2019): 244. http://dx.doi.org/10.3390/geosciences9060244.
Abstract:
Toxic trace metals are a common and significant contaminant in riverine ecosystems, and are derived from both natural and anthropogenic sources. Determining the contributions of metals from these sources has proven difficult, in part, because physical and biogeochemical processes alter the nature (e.g., grain size, mineral composition, organic matter content) of the source materials as they are transported through the drainage network. This study examined the use of paleoflood deposits located along the hyperarid Rio Salado, a tributary to the Rio Loa of northern Chile, to construct local background functions and enrichment factors (LEFs) to differentiate between natural and anthropogenic metal sources. Significant variations in metal content occurred between river reaches and flood deposits of a given reach; these variations were primarily related to changes in sediment source that may reflect differences in El Niño and La Niña precipitation patterns. Three conservative elements (Al, Fe, Co) were examined to construct background functions for seven trace metals. Cobalt yielded the most effective background functions for As, Cd, Ni, Pb, and Zn; Fe was selected for Cr, and Al for Cu. The resulting LEFs approximated 1, illustrating that paleoflood deposits produced effective background functions, and could be applied to downstream sites contaminated by mining activity.
35
Zhang, Tongwen, Mamatkanov Diushen, Ermenbaev Bakytbek, Huaming Shang, Yaqi Gao, Liping Huang, Ruibo Zhang, et al. "Tree ring record of annual runoff for Issyk Lake, Central Asia." Journal of Water and Climate Change 10, no. 3 (April 5, 2018): 610–23. http://dx.doi.org/10.2166/wcc.2018.232.
Abstract:
Abstract Revealing hydrologic variations in the past is helpful to understand the dynamic changes and evolution of a given water body. The widespread long-lived spruce forests growing in the mountainous area around Issyk Lake in Central Asia provide a good opportunity for dendrohydrologic studies about that lake. A regional tree-ring width chronology developed for Picea schrenkiana was used to reconstruct 345-year annual runoff for Issyk Lake. Based on frequency of the wettest/driest years and decades, the 20th century was identified as having the most frequent hydrologic fluctuations among the last three centuries. After applying a 21-year moving average, seven wet and six dry periods were found in the runoff reconstruction. The 10- and 2.1–5.4-year cycles of this reconstruction revealed that annual runoff variability of Issyk Lake may be influenced by solar activity and the atmosphere–ocean system. Spatial correlation proves that the runoff reconstruction contains climatic signals representative of a large area, including the western Tien Shan Mountains and Junggar Basin. A comparison between the annual runoff reconstruction and other hydroclimatic reconstructions reveals similar variations, particularly in the high-frequency domain. The annual runoff reconstruction also accurately captures some flood/drought events noted in the meteorological records and hydroclimatic reconstructions of Central Asia.
36
Carlson, Claire Elizabeth, Paul A. Isihara, Roger Sandberg, David Boan, Kaile Phelps, Kyu Lim Lee, Danilo R. Diedrichs, et al. "Introducing PEARL." Journal of Humanitarian Logistics and Supply Chain Management 6, no. 2 (August 1, 2016): 202–21. http://dx.doi.org/10.1108/jhlscm-07-2015-0031.
Abstract:
Purpose – The need in disaster response to assess how reliably and equitably funding was accounted for and distributed is addressed by a standardized report and index applicable to any disaster type. The paper aims to discuss this issue. Design/methodology/approach – Data from the Nepal earthquake (2015), Typhoon Haiyan (2013), the Haiti earthquake (2010), Sri Lankan flood (2011), and Hurricane Sandy (2012) illustrate uses of a public equitable allocation of resources log (PEARL). Drawing from activity-based costing and the Gini index, a PEARL spreadsheet computes absolute inequity sector by sector as well as a cumulative index. Response variations guide index value interpretation. Findings – Index values indicates major inequity in Nepal hygiene kit distribution and Haiti earthquake (both PEARL indices near 0.5), moderate inequity for the Sri Lankan flood (index roughly 0.75) and equitable distributions for Typhoon Haiyan and Hurricane Sandy (both indices approximately 0.95). Indices are useful to approximate proportions of inequity in the total response and investigate allocation under uncertainty in sector need specification. Originality/value – This original tool is implementable using a website containing a practice PEARL, completed examples and downloadable spreadsheet. Used across multiple sectors or for a single sector, PEARL may signal need for additional resources, correct inequitable distribution decisions, simplify administrative monitoring/assessment, and foster greater accounting transparency in summary reports. PEARL also assists historical analysis of all disaster types to determine completeness of public accounting records and equity in fund distribution.
37
Davis, D. W., and J. C. Green. "Geochronology of the North American Midcontinent rift in western Lake Superior and implications for its geodynamic evolution." Canadian Journal of Earth Sciences 34, no. 4 (April 1, 1997): 476–88. http://dx.doi.org/10.1139/e17-039.
Abstract:
Volcanism in the Midcontinent rift system lasted between 1108 and 1086 Ma. Rates of flood-basalt eruption and subsidence in the western Lake Superior region appear to have been greatest at the beginning of recorded activity (estimated 5 km/Ma subsidence rate at 1108 Ma) and rapidly waned over a period of 1–3 Ma during a magnetically reversed period. The age of the paleomagnetic polarity reversal is now constrained to be between 1105 ± 2 and 1102 ± 2 Ma. A resurgence of intense volcanism began at 1100 ± 2 Ma in the North Shore Volcanic Group and lasted until 1097 ± 2 Ma. This group contains a ca. 7 Ma time gap between magnetically reversed and normal volcanic sequences. A similar disconformity appears to exist in the upper part of the Powder Mill Group. The average subsidence rate during this period was approximately 3.7 km/Ma. Latitude variations measured from paleomagnetism on dated sequences indicate that the North American plate was drifting at a minimum rate of 22 cm/year during the early history of the Midcontinent rift. An abrupt slowdown to approximately 8 cm/year occurred at ca. 1095 Ma. These data support a mantle-plume origin for Midcontinent rift volcanism, with the plume head attached to and drifting with the continental lithosphere. Resurgence of flood-basalt magmatism at 1100 Ma may have been caused by extension of the superheated lithosphere following continental collision within the Grenville Orogen to the east.
38
Nour, Ali Mahamat, Masrabé Djimtolgar, and Galmai Orozi. "Inter-annual variation of the mean temperature and rainfall in Chad and the solar activity during the period from 1950 to 2020." Journal of Applied and Natural Science 15, no. 3 (September 19, 2023): 1292–98. http://dx.doi.org/10.31018/jans.v15i3.4836.
Abstract:
Given the increased variability of rainfall, the resurgence of extreme meteorological phenomena such as droughts, floods, heat waves, and violent winds and considering the influence of solar activity on certain meteorological parameters, a study on the variation of temperature and rainfall in relation to solar activity is necessary. The present study aimed to analyze the inter-annual evolution of meteorological parameters (mean temperature and rainfall) in Chad over the period from 1950 to 2020 in two geographically distinct areas (Sudanian and Sahelian zone) and then to establish a link between these parameters and solar activity to predict the variations of these two parameters over time. The rainfall results showed that the wettest years were 1959 in N'Djamena and 1951 in Moundou. On the other hand, the driest years recorded were 1984 in N'Djamena and 1998 in Moundou. The study of the mean temperature in these two areas during the same period led to the conclusion that the hottest year was 2010 in N'Djamena; however, in Moundou the hottest year recorded was 1997. Globally, in the two zones concerned, analysis of the results on variations in rainfall showed a downward trend. However, the study of average temperature showed a steady rise over the same period. The superposition of rainfall and mean temperature with the sunspot numbers Rz led to the conclusion that high sunspot activity increases temperature and thus warming, while low sunspot activity brings high precipitation.
39
Gui, Shu, and Ruowen Yang. "Quasi-Biweekly Oscillation of the Bay of Bengal–East Asia–Pacific Teleconnection in Boreal Summer." Journal of Climate 33, no. 17 (September 1, 2020): 7643–62. http://dx.doi.org/10.1175/jcli-d-19-0856.1.
Abstract:
AbstractThe study reported in this paper used ERA-Interim reanalysis data to investigate the intraseasonal variability of the Bay of Bengal (BOB)–East Asia–Pacific teleconnection (BEAP) during the summer between 1979 and 2016. Over this period, the intraseasonal oscillation of the BEAP fell mainly within the quasi-biweekly oscillation (QBWO) band. Variations in atmospheric circulation and precipitation, which may contribute to extreme weather events, showed a significant correlation with the phase transition of the BEAP from the BOB to East Asia and the Pacific. The evolution of the BEAP–QBWO is closely associated with the westward propagation of convective anomalies to the southwestern BOB. Dynamical analysis revealed that anomalous vertical motion coupled with anomalous convective activity over the southern BOB plays an important role in leading the phase propagation of the BEAP–QBWO, and that the horizontal advection anomalies can strengthen the BEAP–QBWO. Linear baroclinic model experiments confirmed that variations in convection over the southern BOB play a leading role in the BEAP–QBWO phase changes. Further research suggests that the boreal summer intraseasonal oscillation can trigger the BEAP–QBWO through downstream propagation of convective disturbances to the southern BOB. This study provides insights into the cause and effect of the BEAP–QBWO, which will help to improve understanding of flood and drought patterns in the Asia–Pacific region.
40
Picado, Ana, Joana Mendes, Rui Ruela, João Pinheiro, and João Miguel Dias. "Physico-Chemical Characterization of Two Portuguese Coastal Systems: Ria de Alvor and Mira Estuary." Journal of Marine Science and Engineering 8, no. 7 (July 19, 2020): 537. http://dx.doi.org/10.3390/jmse8070537.
Abstract:
The present study aims to research the physico-chemical processes in two under-researched coastal systems located on the west and south Portuguese coast—Mira Estuary and Ria de Alvor—through the development and exploitation of dedicated coupled physical and water quality models. Both systems are highly dynamic, supporting a wide range of biological diversity; however, they are characterized by distinct environmental and oceanographic conditions, enhancing the importance of a comparative approach. In this context, the Delft3D modeling suite was implemented and successfully calibrated and validated for both systems, accurately reproducing their hydrodynamic, hydrographic, and chemical features. A broad characterization of Mira Estuary and Ria de Alvor was carried out. Results show that the tidal wave interacts differently with the different geomorphology of each estuary. The tidal wave amplitude decreases as it propagates upstream for both estuaries; however, the magnitude for Ria de Alvor is higher. A flood tidal dominance was found for Mira Estuary, allowing the transport of well-oxygenated water into the estuary, contributing to high residence times in the middle estuary and therefore to poor dissolved oxygen (DO) replenishment. Ria de Alvor shifts from ebb dominance at the central area to flood dominance upstream with low residence times, allowing an effective exchange of water properties. Results also reveal that the water temperature is the dominant driver of seasonal dissolved oxygen variations in both estuaries, with the lowest levels occurring during the late summer months when the water temperature is highest. In addition, pH is influenced by biological activity and freshwater inflow.
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Leonardi, Federica, Teresa Botti, Giuliana Buresti, Anna Paola Caricato, Alberto Chezzi, Carlo Pepe, Sabina Spagnolo, Sabrina Tonnarini, Miriam Veschetti, and Rosabianca Trevisi. "Radon Spatial Variations in University’s Buildings Located in an Italian Karst Region." Atmosphere 12, no. 8 (August 15, 2021): 1048. http://dx.doi.org/10.3390/atmos12081048.
Abstract:
In the framework of a collaboration between INAIL and University of Salento, an indoor radon survey in 54 buildings belonging to the UniSalento University (Southeast Italy) was carried out. The monitored buildings differ by type, construction period, materials, etc., and are located in an area with a morphology characterized mainly by marls, calcareous marls, and calcarenites (karst area). The sample of the survey includes 963 rooms at different floors: it consists in rooms mainly located at ground floor (67%), first floor (12%), and below ground (12%). SSNTD passive dosimeters measured the average radon activity concentration for two consecutive semesters (spring/summer and autumn/winter) from which annual radon averages were estimated for each room. The spatial variability within buildings was investigated in terms of variation between floors and among rooms at the same floor. Data analysis provides evidence that the distributions (in terms of arithmetic mean, standard deviation, median, and geometric mean) of indoor radon annual averages at ground floor and at first floor within building are very similar. This highlights that the karstic characteristics of soil and building materials affect radon levels not only below ground and at ground floor, but also at first floor. Moreover, to evaluate the spatial variability of radon among buildings or floors, the analysis of the distribution of coefficient of variation (CV) was carried out: the results show a low spatial variability with median and average values of CVs ≤ 30% both for the whole building and at different floor levels.
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Greenwood, Charles, Arne Vogler, and Vengatesan Venugopal. "On the Variation of Turbulence in a High-Velocity Tidal Channel." Energies 12, no. 4 (February 19, 2019): 672. http://dx.doi.org/10.3390/en12040672.
Abstract:
This study presents the variation in turbulence parameters derived from site measurements at a tidal energy test site. Measurements were made towards the southern end of the European Marine Energy Centre’s tidal energy test site at the Fall of Warness (Orkney, Scotland). Four bottom mounted divergent-beam Acoustic Doppler Current Profilers (ADCPs) were deployed at three locations over an area of 2 km by 1.4 km to assess the spatial and temporal variation in turbulence in the southern entrance to the channel. During the measurement campaign, average flood velocities of 2 ms−1 were recorded with maximum flow speeds of 3 ms−1 in the absence of significant wave activity. The velocity fluctuations and turbulence parameters show the presence of large turbulent structures at each location. The easternmost profiler located in the wake of a nearby headland during ebb tide, recorded flow shielding effects that reduced velocities to almost zero and produced large turbulence intensities. The depth-dependent analysis of turbulence parameters reveals large velocity variations with complex profiles that do not follow the standard smooth shear profile. Furthermore, turbulence parameters based on data collected from ADCPs deployed in a multi-carrier frame at the same location and time period, show significant differences. This shows a large sensitivity to the make and model of ADCPs with regards to turbulence. Turbulence integral length scales were calculated, and show eddies exceeding 30 m in size. Direct comparison of the length scales derived from the streamwise velocity component and along-beam velocities show very similar magnitudes and distributions with tidal phase.
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Owen, Marc R., Robert T. Pavlowsky, and Derek J. Martin. "Spatial and Temporal Characteristics of Channel Disturbance Zones in Big River, Southeast Missouri (1937–2018)." Southeastern Geographer 64, no. 1 (March 2024): 30–53. http://dx.doi.org/10.1353/sgo.2024.a920706.
Abstract:
abstract: Ozarks watersheds have responded to land clearing and settlement disturbances by transporting large amounts of gravel and sediment to main valleys of medium-large river systems. Historical gravel and sediment accumulate in disturbance zones, which are areas of excessive channel activity that can be detected over time using historical aerial photographs. This project uses a series of aerial photos from 1937–2018 to identify disturbance zones in the Big River of southeast Missouri, which has a history of lead mining and ore processing that has caused widespread contamination of the channel and floodplain deposits. Variations in active areas of the historical meander belt show that disturbance zones account for 24 percent of the channel length at an interval of one per 2.5 km of channel. Megabars and extensions are the most prominent types of disturbance zones, but translations and cutoffs are larger with higher potential for sediment storage. From 1937 to 1976, areas of channel activity have cycled between expansion and contraction. However, after a period of recovery prior to 1976, disturbance zone areas have been expanding over the last 40 years likely in response to an increase in flood magnitude and frequency from more high intensity rainfall events since 1973.
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Thorin, S., T. Robinet, P. Laffaille, and B. Vincent. "Shape and surface variations of syphon openings during complete tidal cycles in Mya arenaria in the intertidal zone." Journal of the Marine Biological Association of the United Kingdom 81, no. 3 (June 2001): 505–15. http://dx.doi.org/10.1017/s0025315401004155.
Abstract:
Since the degree of syphonal opening can be an index of the pumping activity, the shape and the surface of syphon openings in Mya arenaria were filmed with an underwater camera at two stations in the middle of the intertidal zone. The individuals were perpendicularly oriented to the main current direction or parallel with the inhalant syphon upstream during flood tide, causing refiltration risks during ebb tide. The surface of the inhalant opening (SI) was strongly reduced with increasing current speeds. Its shape (XI) varied with the individual's orientation and had a tendency to become more circular with time. The surface of the exhalant opening (SE) decreased and its shape (XE) flattened with increasing current velocity and with time. However, variations of XI and XE were weak. Current direction had no significant effect on SI, SE, and XE, but did cause a strong decrease of the SE/SI ratio during ebb in individuals exposed to important refiltration risks during ebb tide. Significant negative correlations between stomach content in phaeopigments and SI and SE suggest that a syphonal constriction could contribute to more efficient feeding. For parallel oriented individuals, the decreases of SE, SE/SI, and XE during ebb can then be interpreted as an attempt to deviate or increase the excurrent velocity relative to the incurrent so as to limit refiltration. We suggest that decreases in opening surface and shape may serve, above all, to increase syphon current jet velocity in syphonate bivalves.
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Guo, Jingpeng, Kebiao Mao, Yinghui Zhao, Zhong Lu, and Lu Xiaoping. "Impact of Climate on Food Security in Mainland China: A New Perspective Based on Characteristics of Major Agricultural Natural Disasters and Grain Loss." Sustainability 11, no. 3 (February 7, 2019): 869. http://dx.doi.org/10.3390/su11030869.
Abstract:
Under the background of global warming, China has experienced frequent natural disasters that have seriously affected grain production in recent decades. Based on historical documents from 1978-2014, we explored the spatio-temporal variation of five major kinds of natural disasters and grain losses in China using statistical techniques: the Mann-Kendall (MK) test, social network analysis (SNA), and geographic information system (GIS) tools. The disaster intensity index (Q) clearly showed the variation of natural disasters; all of China experienced a significant increasing trend at an annual scale, reaching its peak (27.77%) in 2000. The step change points in floods, droughts, hail, and low-temperature events began to occur in 1983, 1988, 1988, 1992, respectively, while no obvious trend was detected for typhoon activity from 2001 to 2014. Drought and flood were the most serious types of disaster over the last four decades, accounting for more than 50% of total grain losses. Eight major provinces were identified with severe grain losses: Heilongjiang, Shandong, Henan, Hebei, Anhui, Sichuan, Jiangsu, Hunan, and Hubei. Five studied natural disaster types were identified throughout the seven physical geographical regions. Spatial distribution for the different disaster types showed significant geographical distribution characteristics. Natural disasters gradually became more diverse from north to south. Droughts, hail, and low-temperature disasters were randomly distributed throughout China; flood and typhoon disasters exhibited significant spatial auto-correlation and clustering patterns. Finally, in accordance with the intensity of natural disaster, the annual grain losses at the provincial scale initially increased (ranging from 0.14 million to 3.26 million tonnes in 1978-2000), and then decreased after 2000 (ranging from 3.26 million to 1.58 million tonnes in 2000-2014). The center of gravity of grain losses gradually moved northward. These results emphasize that developing different strategies for disaster prevention and mitigation programs in the major grain producing areas (e.g., Heilongjiang, Shandong, and Henan) are critical and important to China's food security.
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Cheng, Yang, Hongming He, Nannan Cheng, and Wenming He. "The Effects of Climate and Anthropogenic Activity on Hydrologic Features in Yanhe River." Advances in Meteorology 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/5297158.
Abstract:
This paper aims to analyze the effects of precipitation and anthropogenic activity on hydrologic features in Yanhe River so as to provide support for regional water management and evaluation of water and soil conservation measures. Thiessen Polygon was created to calculate mean values of watershed, and Mann-Kendall statistic test and Sen’s slop estimator test were adapted to analyze variation trend and interaction between precipitation, runoff, and sediment discharge. When 1961~1970 was set as reference period (ignoring human effects), the double mass curve quantified the effects of precipitation and anthropogenic activity on runoff and sediment discharge in Yanhe River during 1961~2008. The result showed that the monthly distribution of precipitation, runoff, and sediment discharge was extremely uneven. 78.1% of precipitation, 64.1% of runoff, and 98.6% of sediment discharge occurred in the flood season. Precipitation, runoff, and sediment discharge performed significant downward trends during 1961–2008. Therein, anthropogenic factors contributed 66.7% and 51.1% to sediment discharge reduction during 1971–1994 and 1995–2008, respectively. They contributed 103.8% and 82.9% to runoff reduction during these two periods, respectively.
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Frost, RH, and N. Murtagh. "Encouraging planting in urban front gardens: a focus group study." Perspectives in Public Health 143, no. 2 (March 2023): 80–88. http://dx.doi.org/10.1177/17579139231163738.
Abstract:
Aims: Encouraging planting in front gardens offers mental and physical health benefits, as well as positive local environmental impacts such as reducing flood risk and improving air quality. However, urban front garden greenery has reduced in recent years. We aimed to explore adults’ views regarding planting greenery in front gardens, barriers and facilitators, and their understanding of health and environmental impacts, to identify appropriate intervention mechanisms for behaviour change. Methods: We carried out five online focus groups with 20 participants aged 20–64 in England, purposively sampled for variation according to age, gender, home ownership, income, ethnicity and residing in an urban or suburban area. We audio recorded each focus group, transcribed it verbatim and analysed transcripts using thematic analysis. Results: Front gardening was a relaxing activity that provided benefits including increased wellbeing, fresh air and vitamin D. Planting in front gardens depended heavily on available time and space, garden orientation, local security and the weather. Front gardens could be a place for social interaction. Participants tended to prioritise neatness and tidiness over greenery. Lack of knowledge and low self-efficacy were key barriers. There was little awareness of the environmental benefits of front garden greenery; however, reducing flood risk and encouraging biodiversity were viewed positively. Conclusion: Initiatives to encourage front garden planting should focus on plants that require little knowledge to acquire and care for, are suitable to the local environmental conditions and with a visual impact of neatness and bright colour. Campaigns should draw attention to local flood risk reduction and increasing biodiversity, in addition to personal health benefits.
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Li, C., Y. Zhong, and W. Zhang. "STUDY ON SPATIAL-TEMPORAL VARIATION OF HONG LAKE BASED ON VIIRS AND MODIS IMAGES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W7 (September 13, 2017): 797–802. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w7-797-2017.
Abstract:
Hong Lake is the largest lake in Hubei Province. With the increase of Hong Lake economic activity, the area, spatial location and shape of Hong Lake have changed greatly in the past. In this paper, we used the images, which is from the visible infrared imaging radiometer (VIIRS). First, we selected the images of Hong Lake waters on December 6, 2016 and December 26, 2015. Then we extracted the water bodies by the single-band method, spectral relationship method, normalized difference water index (<i>NDWI</i>) were used, and the effect-s were compared. Second, the images of Hong Lake waters in summer and winter were selected from 2012 to 2016, respectively. Last, The <i>NDWI</i> was used to extract the water body and compared with the MODIS image extraction effect in the same period. As a result of the vegetation around Hong Lake, the water is extracted by <i>NDWI</i> and normalized difference vegetation index (<i>NDVI</i>). It is found that for the VIIRS image, the <i>NDWI</i> is the best in the water extraction of Hong Lake. The <i>NDVI</i> + <i>NDWI</i> method is beneficial to the extraction of water covered with aquatic plants. VIIRS image extraction is better than MODIS image. In addition, from the study of VIIRS and MODIS to Hong Lake waters in the five years of water extraction and area calculation, 2012&ndash;2016 period, Hong Lake’s average area of 348.213&thinsp;km<sup>2</sup> in flood season, in dry season average area of 349.163&thinsp;km<sup>2</sup>. The largest area for the 2012 flood season 389.751&thinsp;km<sup>2</sup>, the smallest area of 2016 flood season 306.177&thinsp;km<sup>2</sup>. Overall, Hong Lake’s area changes little.
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Liu, Congcong, Yuanfang Chai, Boyuan Zhu, Yunping Yang, Jinyun Deng, and Yong Hu. "River regulation and resilience: an approach for the Yangtze watershed." Water Supply 21, no. 4 (February 2, 2021): 1817–33. http://dx.doi.org/10.2166/ws.2021.035.
Abstract:
Abstract Many studies have focused on analyzing variation characteristics of the watershed resilience based on different indicators, while few efforts have been made to quantificationally evaluate contributions of climatic and anthropogenic factors to the varied resilience. In this study, we investigate changes in the seasonal runoff resilience of the entire Yangtze River basin during 1961–2014 by using a convex model and a resilience indicator (Pi). The MIKE 11HD model and the regression method were adopted to further differentiate effects of climate variations and human activities. Results show that climate variation (especially droughts and floods) and human activities exert negative and positive effects, respectively, and become primary reasons for falling and increasing trends in entire watershed resilience. These impacts grow with time under the gradually intensified climate variability and human activity. HIGHTLIGHTS Effects of climatic and anthropogenic factors on the varied watershed runoff resilience are quantificationally estimated. Investigating the changes in the watershed resilience in the entire Yangtze River.
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Aubert, A. H., C. Gascuel-Odoux, G. Gruau, N. Akkal, M. Faucheux, Y. Fauvel, C. Grimaldi, et al. "Solute transport dynamics in small, shallow groundwater-dominated agricultural catchments: insights from a high-frequency, multisolute 10 yr-long monitoring study." Hydrology and Earth System Sciences 17, no. 4 (April 11, 2013): 1379–91. http://dx.doi.org/10.5194/hess-17-1379-2013.
Abstract:
Abstract. High-frequency, long-term and multisolute measurements are required to assess the impact of human pressures on water quality due to (i) the high temporal and spatial variability of climate and human activity and (ii) the fact that chemical solutes combine short- and long-term dynamics. Such data series are scarce. This study, based on an original and unpublished time series from the Kervidy-Naizin headwater catchment (Brittany, France), aims to determine solute transfer processes and dynamics that characterise this strongly human-impacted catchment. The Kervidy-Naizin catchment is a temperate, intensive agricultural catchment, hydrologically controlled by shallow groundwater. Over 10 yr, five solutes (nitrate, sulphate, chloride, and dissolved organic and inorganic carbon) were monitored daily at the catchment outlet and roughly every four months in the shallow groundwater. The concentrations of all five solutes showed seasonal variations but the patterns of the variations differed from one solute to another. Nitrate and chloride exhibit rather smooth variations. In contrast, sulphate as well as organic and inorganic carbon is dominated by flood flushes. The observed nitrate and chloride patterns are typical of an intensive agricultural catchment hydrologically controlled by shallow groundwater. Nitrate and chloride originating mainly from organic fertilisers accumulated over several years in the shallow groundwater. They are seasonally exported when upland groundwater connects with the stream during the wet season. Conversely, sulphate as well as organic and inorganic carbon patterns are not specific to agricultural catchments. These solutes do not come from fertilisers and do not accumulate in soil or shallow groundwater; instead, they are biogeochemically produced in the catchment. The results allowed development of a generic classification system based on the specific temporal patterns and source locations of each solute. It also considers the stocking period and the dominant process that limits transport to the stream, i.e. the connectivity of the stocking compartment. This mechanistic classification can be applied to any chemical solute to help assess its origin, storage or production location and transfer mechanism in similar catchments.