Flood Land Research Articles

Alpha track analysis and fission track analysis for localizing actinide-bearing micro-particles in the Yenisey River bottom sediments

Distribution of actinides in bottom sediment and flood land soil cores collected from the Yenisey River near the Krasnoyarsk Mining and Chemical Combine (MCC) were analyzed. Actinide-bearing micro-particles were localized using alpha track analysis (ATA) and fission track analysis (FTA). Different types of radioactive micro-particles were found by analysis of the ratios of fission tracks to α -tracks from single particles. The different origin of these particles was confirmed by scanning electron microscopy with energy dispersed microanalysis (SEM-EDX), secondary ion mass-spectrometry (SIMS) and single-particle α -spectrometry. It is established that for most of the radioactive micro-particles ATA and FTA are the only possible techniques to obtain information concerning their origin. For the studied samples of bottom sediments and flood land soils, it was established that 80–90% of alpha radioactivity is attributed to hot-particles with 238Pu and 239,240Pu as the major radionuclides. According to the sequential extraction data most of 238Pu and 239,240Pu is found in the residual low-soluble fraction.

Mean sea-level rise impacts on Santos Bay, Southeastern Brazil – physical modelling study

The greenhouse effect and resulting increase in the Earth's temperature may accelerate the mean sea-level rise. The natural response of bays and estuaries to this rise, such as this case study of Santos Bay (Brazil), will include change in shoreline position, land flooding and wetlands impacts. The main impacts of this scenario were studied in a physical model built in the Coastal and Harbour Division of Hydraulic Laboratory, University of São Paulo, and the main conclusions are presented in this paper. The model reproduces near 1,000 km(2) of the study area, including Santos, São Vicente, Praia Grande, Cubatão, Guarujá and Bertioga cities.

Os Efeitos no Ambiente Marinho da Elevação do Nível do Mar em Regiões da Baixada Santista, Brasil

The greenhouse effect and resulting increase in the earth’s temperature may accelerate the mean sea level rise. Knowledge regarding the relative sea-level rise and its effects on coastal areas is reviewed here. Hydraulic processes, such as tidal forcing, prism, currents and storm surges, salinity intrusion and littoral processes, will be modified. The natural response of bays and estuaries to this rise, such as this case study on Santos (SP), will include change in shoreline position, land flooding and impacts on wetlands

BIOECONOMICS OF RESERVOIR AQUACULTURE IN VIETNAM

Reservoir aquaculture has developed in an ad hoc manner in Vietnam to date. A bioeconomic model of reservoir aquaculture in northern Vietnam is presented in this paper to highlight issues of developmental importance of reservoir aquaculture in Vietnam. The biological model is based on a conventional von Bertalanffy growth function and the economic model is a net revenue function. The greatest source of costs for the operation are restocking costs (75%) and contract labor costs (18 percent). Benchmark net revenue is approximately 8.7 million VND (approximately US$539). The stocking density, length of time between stocking and harvest and harvesting efficiency have the largest impact on net revenue. The inclusion of aquaculture into government fisheries development plans with research focused on development of fingerling production, preparation of flooded land for aquaculture production and strengthening institutional arrangements for reservoir leasing and credit arrangements, is likely to lead to increased capitalization and investment, and therefore greater revenues for local fishing populations.

Impact of small-holder irrigation on the agricultural production, food supply and economic prosperity of a representative village beside the Senegal River, Mauritania

A considerable effort to rehabilitate and extend degraded irrigation schemes is taking place along the Mauritanian side in the Senegal River Valley. To increase understanding of the effects of these activities on the population, a model was used to analyse how the irrigated agriculture production interacts with other production systems, human food supply, and economic prosperity in a representative village in the Middle Valley. The activities in the village comprise grazing of mostly goats and sheep on shrubland, rain fed cropping, partly on saturated soil as river or plain floods recede, and an irrigation area of 32 ha soon to be enlarged to 90 ha. The production environment is characterized by a long dry winter, small, highly variable summer rainfall, and high temperatures and evaporative conditions. River flooding is variable and dependant on rainfall at great distance from the village. Using a generated weather series, the model evaluates the fodder supply for livestock on the shrubland, the productivity of grain and stubble for human and animal consumption, respectively, together with the human labour, and fertilizer and fuel requirements to maintain optional production scenarios. A financial sector calculates cash balance. Established cropping practice uses cowpea, sorghum, millet and rice, the latter on irrigated land. All families have equal access to grazing on the shrubland but different access to rain fed, flood land, and irrigation cropping. The model evaluates the impact of production scenarios on identified family types with distinct resources, extending current practice to a more diverse use of irrigated land by introducing alternative summer (sorghum) and new winter (cowpea) crops. The analysis of the current scenarios reveals the small and variable productivity of the shrubland, the precarious situation facing a family with access to rain-fed cropping only, and the stabilizing, although still inadequate, impact of the initial irrigation project. Expansion of the irrigation area, and more diversified cropping, will provide more families with access to irrigation but the small area available to each family (0.50 ha) will not produce sufficient grain or straw unless cropping is intensified to include a second winter crop. With that, additional benefits will flow indirectly to villagers without access to irrigation, through increased requirement for labour and sale of grain and fodder. The expanded irrigation area increases the stock carrying capacity of the village, raising concerns for the sustainable management of the shrubland.

Monitoring Sahelian floodplains using Fourier analysis of MODIS time‐series data and artificial neural networks

Fourier analysis of Moderate Resolution Image Spectrometer (MODIS) time‐series data was applied to monitor the flooding extent of the Waza‐Logone floodplain, located in the north of Cameroon. Fourier transform (FT) enabled quantification of the temporal distribution of the MIR band and three different indices: the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Water Index (NDWI), and the Enhanced Vegetation Index (EVI). The resulting amplitude, phase, and amplitude variance images for harmonics 0 to 3 were used as inputs for an artificial neural network (ANN) to differentiate between the different land cover/land use classes: flooded land, dry land, and irrigated rice cultivation. Different combinations of input variables were evaluated by calculating the Kappa Index of Agreement (KIA) of the resulting classification maps. The combinations MIR/NDVI and MIR/EVI resulted in the highest KIA values. When the ANN was trained on pixels from different years, a more robust classifier was obtained, which could consistently separate flooded land from dry land for each year.

Brackish water ecosystem restoration based on integrated water system design

Brackish water ecosystem restoration based on integrated water system design Despite their current location within a primary agricultural area, most of the creek remnants in the Dutch clay polder areas have a high potential for recovery into healthy ecosystems. Like most areas in the Netherlands the clay polders are densely populated. Therefore multifunctional land use is encouraged and different types of land use coexist within small distances from each other. As a result water conflicts occur: agricultural land use requires deep groundwater levels and causes eutrophication by spreading nutrients into the water system, while existing ecosystems within and around the creek remnants need wetland conditions and low nutrient levels. Furthermore periods of high discharge cause flooding of arable land. Extreme measures like filling in ditches and increasing water levels are needed to achieve the water targets for wetlands around the creeks. On the other hand, the effects of these measures easily cause water logging in nearby agricultural areas. We introduce an integrated approach for the restoration of creek ecosystems. Both the complex interaction of groundwater, surface water and ecology and the limiting conditions imposed by adjacent agricultural land use, spatial developments and regulatory settings like the European Water Framework Directive are thereby taken into account. A highly integrated set of measures is proposed creating optimal conditions for both high agricultural production and flourishing creek ecosystems.

Effects of Hurricane Ivan on water quality in Pensacola Bay, Florida

Pensacola Bay, Florida, was in the strong northeast quadrant of Hurricane Ivan when it made landfall on September 16, 2004 as a category 3 hurricane on the Saffir-Simpson scale. We present data describing the timeline and maximum height of the storm surge, the extent of flooding of coastal land, and the magnitude of the freshwater inflow pulse that followed the storm. We computed the magnitude of tidal flushing associated with the surge using a tidal prism model. We also evaluated hurricane effects on water quality using water quality surveys conducted 20 and 50 d after the storm, which we compared with a survey 14 d before landfall. We evaluated the scale of hurricane effects relative to normal variability using a 5-yr monthly record. Ivan's 3.5 m storm surge inundated 165 km2 of land, increasing the surface area of Pensacola Bay by 50% and its volume by 230%. The model suggests that 60% of the Bay's volume was flushed, initially increasing the average salinity of Bay waters from 23 to 30 and lowering nutrient and chlorophylla concentrations. Additional computations suggest that wind forcing was sufficient to completely mix the water column during the storm. Freshwater discharge from the largest river increased twentyfold during the subsequent 4 d, stimulating a modest phytoplankton bloom (chlorophyll up to 18 μg l−1) and maintaining hypoxia for several months. Although the immediate physical perturbation was extreme, the water quality effects that persisted beyond the first several days were within the normal range of variability for this system. In terms of water quality and phytoplankton productivity effects, this ecosystem appears to be quite resilient in the face of a severe hurricane effect.

Impacts from the 2004 Indian Ocean Tsunami: analysing the potential protecting role of environmental features

The tsunami that deeply impacted the North Indian Ocean shores on 26 December 2004, called for urgent rehabilitation of coastal infrastructures to restore the livelihood of local populations. A spatial and statistical analysis was performed to identify what geomorphological and biological configurations (mangroves forests, coral and other coastal vegetation) are susceptible to decrease or increase coastal vulnerability to tsunami. The results indicate that the width of flooded land strip was, in vast majority, influenced by the distance to fault lines as well as inclination and length of proximal slope. Areas covered by seagrass beds were less impacted, whereas areas behind coral reefs were more affected. The mangroves forests identified in the study were all located in sheltered areas, thus preventing to address the potential protecting role of mangroves forests.

Chemical characterization and 210Pb dating in wetland sediments from the Nhecolândia Pantanal Pond, Brazil

Pantanal, located in the central region of South America, is recognized as one of the world's largest freshwater wetlands. In order to verify possible changes in this environment, a study was undertaken in Nhecolândia Pantanal, Mato Grosso do Sul State, Brazil. Two sediment cores from the Salina do Meio pond (SM1 and SM2) and one core from a small flood land named Baia (B5) were collected in 2001. The elements As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, Zn and Zr were determined by instrumental neutron activation analysis (INAA). Cluster and factorial analysis were applied to the chemical data. The sedimentation rate in the SM2 core was determined by 210Pb method and the mean value found was 0.61 cm . y-1. The results obtained in the present study showed that recent geochemical processes such as desorption, precipitation and dissolution can contribute for the high water alkalinity and salinity in the saline ponds.

The Three Gorges Dam Project—Religious Practices and Heritage Conservation

Yunyang, in the heart of the Three Gorges region, is bearing the brunt of the consequences of the dam’s construction, through the flooding of agricultural lands, the resettlement of families, the wholesale rebuilding of urban centres and the relocation of the famous Zhang Fei temple. At the core of vital economic, ideological and symbolic interests are historical and religious relics and the worship of local deities. From local development policies to citizen initiatives, these fundamental markers of community identity are the subject of many different investments and reworkings. They are showing themselves to be particularly crucial for consolidation of the identity of the inhabitants frayed by the trauma that the region is currently undergoing.

Seasonal differences in the incidence of infection with Fasciola gigantica in cambodian cattle

Farmer's cattle were treated with triclabendazole and used as tracer animals to detect new infections with Fasciola gigantica in three villages located on the bank of the Bassac River (a major tributary of the Mekong River) and in a fourth village located on farmland away from the river, from April 1999 until January 2001. The month of infection was estimated by subtracting 4 months from the date when eggs of F. gigantica were detected in faeces. Farmers were interviewed each month to record the nature of the agricultural and animal husbandry activities that occurred during the previous month, especially events that might have exposed cattle to infection with F. gigantica. Results support the conclusions that infection of cattle in riverbank villages acquired from about August or September until November originated from herbage and water in irrigation canals and dams on the riverbank, and that the progressively increasing monthly incidence from December until April (up to 87% per month in April 2000) was derived from herbage and water in recently harvested rice fields and lakes adjacent to the riverbank. The abrupt cessation of new infection in riverbank villages in May coincided with flooding of low-lying land, the movement of cattle to land above flood height on the riverbank, and a change of diet to dry-land crop residues, stored dry rice stalks, and herbage and water that were unlikely to contain metacercariae. It was concluded that snails in dams and canals on the riverbank became infected with E gigantica after cattle were moved to the riverbank in May, and cercariae shed from these snails provided the new infections that occurred in cattle in August and September. In the village located away from the river, infection of cattle between September and March coincided with the rice harvest, supporting the conclusion that feeding of fresh rice stalks and stubble after the rice was harvested was the main source of infection. The low monthly incidence observed (up to 6.4% per month) was consistent with the hypothesis that snails did not survive in the dry rice fields between crops and that few snails would have been available from the small number of aquatic refuges that persisted through the dry season to recolonize rice fields during the wet season. Between April and August there was no opportunity for new infection because cattle were fed forage from around houses and headlands, and on dry-land crop residues and stored dry rice stalks. Control of fasciolosis was proposed using a single treatment of cattle with triclabendazole in riverbank villages in May when cattle were moved to the riverbank, and after harvest of the last rice field in villages located away from the river.

Effects of flooding in southern Poland on heavy metal concentrations in soils

Abstract. Total concentrations of heavy metals in soils were measured before and after the catastrophic floods of 1997, which devastated most districts within the commune of Racibórz in southern Poland. The assays covered lead, zinc, cadmium, chromium, nickel and copper. Analyses on soil samples taken in 2002, after the floods, were compared with those of 1992, taken as part of regular monitoring. There was an increase in the mean concentrations of heavy metals as a consequence of the flooding. Only a small part of this increase may be due to changes in the method of analysis between the two dates. The mean concentrations of heavy metals after flooding did not exceed the permissible levels for Polish soils. Permission was therefore granted to continue using much of the flooded land for farming. However, the investigations located a number of places where heavy metals were above permissible levels. Some of these were a consequence of the floods, but others were considered to be due to contamination from previous industry. Where high concentrations were found, land was excluded from agricultural use.

Effects of flooding in southern Poland on heavy metal concentrations in soils

. Total concentrations of heavy metals in soils were measured before and after the catastrophic floods of 1997, which devastated most districts within the commune of Raciborz in southern Poland. The assays covered lead, zinc, cadmium, chromium, nickel and copper. Analyses on soil samples taken in 2002, after the floods, were compared with those of 1992, taken as part of regular monitoring. There was an increase in the mean concentrations of heavy metals as a consequence of the flooding. Only a small part of this increase may be due to changes in the method of analysis between the two dates. The mean concentrations of heavy metals after flooding did not exceed the permissible levels for Polish soils. Permission was therefore granted to continue using much of the flooded land for farming. However, the investigations located a number of places where heavy metals were above permissible levels. Some of these were a consequence of the floods, but others were considered to be due to contamination from previous industry. Where high concentrations were found, land was excluded from agricultural use.

Activité potentielle de méthanogenèse dans les sols, tourbières, sédiments lacustres et du réservoir hydroélectrique Robert-Bourassa dans le moyen Nord-Canadien

Flooding of land associated with the creation of reservoirs may increase, at least in the short term, methane flux to the atmosphere. To evaluate the potential contribution of such land use on methane production, field samples were studied in vitro for the potential activity of methanogenic bacteria in unflooded or flooded boreal forest soils, together with lacustrine sediments. From this comparative study, periodically flooded or flooded peats contribute more to methane production than do unflooded peats, soils, and natural lake sediment. The intensity and temporal changes in the activity of methanogenic archaea in the different systems depended on a combination of environmental factors, such as the amount and quality of organic carbon, the water level, and the concentration of oxidizing ions (SO42-, Fe3+).

Unequal respiratory health risk: Using GIS to explore hurricane-related flooding of schools in Eastern North Carolina

This cross-sectional study investigated whether schools serving populations at high risk of developing respiratory infections in the state of North Carolina (USA) were disproportionately burdened by flooding from Hurricane Floyd. We used geographic information systems (GIS) to overlay a satellite-derived image of the flooded land with school locations. We identified 77 flooded schools and 355 schools that were not flooded in 36 counties. These schools were then characterized based on the income, race/ethnicity, and age of their student populations. Prevalence ratios (PRs) revealed that low-income schools in which a majority of students were Black had twice the risk of being flooded (PR 2.01; 95% confidence interval, 1.28, 3.17) compared to the referent group (non-low-income schools with a majority of non-Black students). This analysis suggests that schools serving populations already at elevated risk of respiratory illness were disproportionately affected by the flooding of Hurricane Floyd. GIS can be used to identify and prioritize schools quickly for remediation following natural disasters.

A Comparative Study of Magnetic Fabric Characters Between Flooded Sediments and Normal River Sediments

AbstractFlooded sediments and normal river sediments have similar sedimentary features in stratigraphic profiles. It is difficult to distinguish these two types of sediments only based on sedimentary features. In order to identify the ancient flood disaster events, it is significant to establish identification marks of sediments from the environment magnetism. We have made a systematic sampling and measuring, and compared the magnetic fabric character of Paizhouwan dam‐broken fan deposits of 1998 with that of modern flood land deposits of the Yangtze River nearby Paizhouwan. Combined with the magnetic fabric character of flood land sediments in lower reaches of the Yangtze River, we reveal that the features of magnetic fabric of normal river sediments in middle and lower reaches of the Yangtze River are greatly different from that of dam‐broken fan deposits. And they are closely related with the sedimentary environments. So it is an effective method for distinguishing flood sediments and normal river sediments through measuring magnetic fabric parameters of sediments in the middle reaches of the Yangtze River and studying the shape of magnetic anisotropy susceptibility magnitude ellipse.

Malacocoenoses of large lowland dam reservoirs of The Vistula River basin and selected aspects of their function

Spatio-temporal variation in qualitative and quantitative occurrence of malacofauna was analysed in three large lowland dam reservoirs. Differences between the malacofauna of flooded land areas and former river beds persist even in middle-aged reservoirs. Quick turnover of water has a positive effect on mollusc abundance and species richness of the whole reservoir, and on the frequency of occurrence in the former river bed. Considerable dynamics of the malacocoenoses and a possibility to revert to earlier development stages, as a result of considerable disturbance, were observed at an advanced stage of biocoenosis development. Besides water dynamics and composition and distribution of bottom deposits, a significant effect on the malacocoenoses is exerted by dominant species, especially D. polymorpha. Abundance and dominance structure of malacocoenoses determine their role in the ecosystem, including accumulation of phosphorus and heavy metals, and their cycling as a result of filtration activity, faeces production, excretion and trophic transfer. Generally, the quantities of elements, especially heavy metals, accumulated in molluscs, are much smaller than the quantities which flow through the malacocoenoses. A large part of the pool of these elements contained in the shells is excluded from circulation for many years. Food chains seem to have relatively little effect on the transfer of heavy metals in the reservoir.

Impact of climate change on ecotopes of the rivers Rhine and Meuse.

Climate change, resulting in changes in temperature, precipitation, river discharge regime and sea level rise, may affect the ecosystems of the large rivers of the Netherlands in this century. This note discusses the method used to assess the impact of climate change on riparian ecosystems along the large rivers and presents the results of an application for the rivers Rhine and Meuse in the Netherlands. For this purpose, the effects of different climate change and land use scenarios on characteristic ecotopes have been compared with the current situation. The climate change scenarios were derived from the temperature rise estimation of the Intergovernmental Panel on Climate Change (IPCC). These have been translated into a sea level rise and changes in river discharge regime using results from earlier climate studies. Flood durations were derived by combining current contour maps of altitude and future sedimentation loads. For each type of ecotope a transition matrix has been developed to relate changes in flood duration and land use to changes in the types of ecotopes. The results indicate that climate change has a significant impact on several characteristic riverine ecotopes and therefore on the ecological quality of floodplains. However, the effect of natural land use is more dramatic and may therefore compensate for some of the negative effects of climate change.

Long-term effects of stream management on plant communities in two Danish lowland streams

Submerged macrophytes grow abundantly in most shallow streams common in the cultivated lowlands of northwestern Europe. Weed-cutting has been practised for years in many of these streams to reduce the risk of flooding of adjacent land. Our objective was to quantify long-term impacts of weed-cutting on macrophyte communities in two Danish rivers. We found that the total macrophyte coverage was similar in the weed-cut and uncut reaches in the two rivers, but species richness, diversity and patch complexity were higher in the uncut reaches. The spatial distribution of macrophytes on the stream bottom was also more heterogeneous in the uncut stream reaches. We also found evidence of a strong effect of weed-cutting on macrophyte species composition. P. natans was abundant in the uncut reaches in both streams but practically eliminated in the cut reaches, despite the fact that its basic habitat requirements were met. Also, the established phase strategy of the macrophyte community was affected by weed-cutting. Species displaying characteristically ruderal traits were more abundant in the cut reaches and species with competitive abilities were only abundant in the uncut stream reaches. We suggest that important species traits in streams, where the weed is cut regularly, are associated with rapid growth and high dispersal-capacity. Our results indicate that weed-cutting can contribute significantly to a decline in species diversity in streams. To provide optimal conditions for diverse stream macrophyte communities, we therefore suggest that weed-cutting should be minimised.