Two-Dimensional Flood Simulation of the Lower Yellow River from Huayuankou to Jiahetan

黄河下游花园口至夹河滩河段系典型的游荡型河段.在该河段,黄河大堤内范围宽广,一般洪水频率年份,水流主要限制在主槽内,因此大堤内分布有不少居民点以及纵横交错的保护居民点的生产堤和不少高于地面的灌溉渠堤和公路,使洪水行洪范围受到了很大的限制.当洪峰流量很大时,洪水将造成生产堤溃决,极大地危害滩区居民的生活.因此,设计模拟模型计算网格时需要考虑大堤、生产堤、明显高于地面的道路等阻水建筑物的影响,使这些堤及公路成为计算格网的边.不规则四边形网格能够很好地拟合黄河这种复杂的计算域.数值模拟时采用有限体积法,为确保通量的单向性,文中使用Osher格式计算通量.通过对1982年洪水的模拟,模拟结果表明了模型的合理性.

Studies of the effects of industrial pollution in the lower Patapsco river area: 1. Curtis Bay Region 1941

Industrial effluents in the lower Patapsco area, which constitutes the navigable portion of the river and includes Baltimore Harbor, are many and include waste acid, distillery waters, tannery wastes and copper as (ferrous sulphate) from pigment and steel industries. (PDF contains 22 pages (2 on 1)

The role of women in artisanal fisheries along the Lower Benue River

A questionnaire survey was carried out to assess the role of women in the artisanal fisheries of fish markets sector along the Lower Benue River. Four (4) fishing settlement communities of fish markets along the Lower Benue were selected. They are namely North Bank, Wadata, Abinse and Gbajimba . Structure and unstructured questionnaire were administered to cover areas of personal data, fish production activities, processing and marketing among others. The study revealed that women along the Lower Benue River participate activity in the artisanal fisheries sub-sector. However, the major role played by the women was in the area of processing and preservation, marketing and distribution. These accounted 52 and 42% respectively. The distribution of the women was not tribally based however, Jukun women accounted for 66.20% followed by Agatu women 13.00%. The age bracket of the women mostly involved in fisheries activities was between 31-40 years. About 86% of them was married. The initial capital base was low and mostly by personal saving accounting for 52%. Need for government assistance was the highlight in this study. About 86% sought for Federal Government intervention from the National Poverty Eradication Programme. This they felt will be a welcome development to boost women participation in the Artisanal fisheries sub-sector along the Lower Benue River

A traditional floodplain fishery of the lower Amazon River, Brazil

This paper describes fishing activities of households in four communities located in a floodplain lake system of the lower Amazon river. An average of 42 households were interviewed about their fishing activity on a monthly basis. The fishery is a typical multi-gear, multi-specific artisanal fishery. Approximately ten types of fishing gear are utilized, of which the three main types of gillnets account for 51% of the total catch. The catch per trip averaged 15 kg, for an annual total of 2,295 kg per household. Some 40 species or groups of species are caught, although four species account for 50% of the total. There is a strong seasonal pattern to the fishery, with catch per trip and catch per unit effort (CPUE) highest in the low water season (September-November). While there are marked differences between subsistence and commercially oriented fishing strategies, these differences are more in degree than in type, since fishers use the same types of gear and most fishers regularly sell part of their catch.

Seasonal and interannual variation in juvenile salmonids and associated fish assemblage in open waters of the lower Columbia River estuary

The transition between freshwater and marine environments is associated with high mortality for juvenile anadromous salmonids, yet little is known about this critical period in many large rivers. To address this deficiency, we investigated the estuarine ecology of juvenile salmonids and their associated fish assemblage in open-water habitats of the lower Columbia River estuary during spring of 2007–10. For coho (Oncorhynchus kisutch), sockeye (O. nerka), chum (O. keta), and yearling (age 1.0) Chinook (O. tshawytscha) salmon, and steelhead (O. mykiss), we observed a consistent seasonal pattern characterized by extremely low abundances in mid-April, maximum abundances in May, and near absence by late June. Subyearling (age 0.0) Chinook salmon were most abundant in late June. Although we observed interannual variation in the presence, abundance, and size of juvenile salmonids, no single year was exceptional across all species-and-age classes. We estimated that >90% of juvenile Chinook and coho salmon and steelhead were of hatchery origin, a rate higher than previously reported. In contrast to juvenile salmonids, the abundance and composition of the greater estuarine fish assemblage, of which juvenile salmon were minor members, were extremely variable and likely responding to dynamic physical conditions in the estuary. Comparisons with studies conducted 3 decades earlier suggest striking changes in the estuarine fish assemblage—changes that have unknown but potentially important consequences for juvenile salmon in the Columbia River estuary.

Effects of temperature change on water discharge, and sediment and nutrient loading in the lower Pearl River basin based on SWAT modelling

National Natural Science Foundation of China [U0633002, 30670385]

A climate of control: flooding, displacement and planned resettlement in the Lower Zambezi River valley, Mozambique

In recent years, the potential role of planned, internal resettlement as a climate change adaptation measure has been highlighted by national governments and the international policy community. However, in many developing countries, resettlement is a deeply political process that often results in an unequal distribution of costs and benefits amongst relocated persons. This paper examines these tensions in Mozambique, drawing on a case study of flood-affected communities in the Lower Zambezi River valley. It takes a political ecology approach – focusing on discourses of human-environment interaction, as well as the power relationships that are supported by such discourses – to show how a dominant narrative of climate change-induced hazards for small-scale farmers is contributing to their involuntary resettlement to higher-altitude, less fertile areas of land. These forced relocations are buttressed by a series of wider economic and political interests in the Lower Zambezi River region, such dam construction for hydroelectric power generation and the extension of control over rural populations, from which resettled people derive little direct benefit. Rather than engaging with these challenging issues, most international donors present in the country accept the ‘inevitability’ of extreme weather impacts and view resettlement as an unfortunate and, in some cases, necessary step to increase people’s ‘resilience’, thus rationalising the top-down imposition of unpopular social policies. The findings add weight to the argument that a depoliticised interpretation of climate change can deflect attention away from underlying drivers of vulnerability and poverty, as well as obscure the interests of governments that are intent on reordering poor and vulnerable populations.

Cytogenetic and DNA barcoding reveals high divergence within the trahira, Hoplias malabaricus (Characiformes: Erythrinidae) from the lower Amazon River

Dados moleculares e citogenéticos tem evidenciado especiação críptica na traíra sul-americana, Hoplias malabaricus. No presente estudo, cariótipos e sequências de DNA barcode de espécimes de sete populações, habitando a região do baixo rio Amazonas, foram analisadas a fim de caracterizar o nível de divergência genética dentro de um único cariomorfo. Todos os espécimes possuem 2n = 40 cromossomos (20m+20sm) os quais são inseridos no grupo de traíras do cariomorfo C. DNA barcode revelou seis haplogrupos, com clara divergência entre populações do Brasil e da Argentina. Os resultados apoiam a hipótese de complexo de espécies e indicam que um único cariomorfo de Hoplias malabaricus pode conter mais de uma espécie.

Temporal Differences in the Hydrologic Regime of the Lower Platte River, Nebraska, 1895–2006

In cooperation with the Lower Platte South Natural Resources District for a collaborative study of the cumulative effects of water and channel management practices on stream and riparian ecology, the U.S. Geological Survey (USGS) compiled, analyzed, and summarized hydrologic information from long-term gaging stations on the lower Platte River to determine any significant temporal differences among six discrete periods during 1895-2006 and to interpret any significant changes in relation to changes in climatic conditions or other factors. A subset of 171 examined hydrologic indices (HIs) were selected for use as indices that (1) included most of the variance in the larger set of indices, (2) retained utility as indicators of the streamflow regime, and (3) provided information at spatial and temporal scale(s) that were most indicative of streamflow regime(s). The study included the most downstream station within the central Platte River segment that flowed to the confluence with the Loup River and all four active streamflow-gaging stations (2006) on the lower Platte River main stem extending from the confluence of the Loup River and Platte River to the confluence of the Platte River and Missouri River south of Omaha. The drainage areas of the five streamflow-gaging stations covered four (of eight) climate divisions in Nebraska—division 2 (north central), 3 (northeast), 5 (central), and 6 (east central).

Active tectonics in the NW-German Basin: Evidence from correlations between the modern landscape and deep geological structures (Lower Saxony, river Hunte)

KurzfassungIm Einzugsgebiet der Hunte (NW-Deutsches Becken, Niedersachsen) wurde untersucht, ob die Landschaftsgenese durch tektonische Bewegungen der Oberkruste beeinflußt ist. Krustenbewegungen führten im Bereich einer Hauptschollengrenze zu einer Hebung der weichselzeitlichen Niederterrasse (durchschnittliche Hebungssrate von ~0,5 mm/a über die letzten 12000 Jahre). Tektonischer Einfluß auf die heutige Landoberfläche ist über einem permischen Salzkissen zu verzeichnen, wo sich das Gefälle der holozänen Aue umkehrt. Krustenbewegungen haben mit großer Wahrscheinlichkeit Vorzugsrichtungen verursacht, die an der Tertiärbasis und in der heutigen Landschaft nachweisbar sind (0-5° und 90-95°). Das Abfließen der Hunte nach Norden scheint durch eine aktive, nordwärts gerichtete Kippung des NW-Deutschen Beckens verursacht zu sein. Hohe lineare Korrelationskoeffizienten zwischen Tiefenlage der Tertiärbasis und Höhenlage der heutigen Landoberfläche weisen auf eine aktive Kippung des Beckens hin. Beckensubsidenz hat möglicherweise die Akkumulation der weichselzeitlichen Niederterrasse gesteuert, da eine Übereinstimmung zwischen rezenter Beckensubsidenz und durchschnittlicher Sedimentationsrate des Niederterrassenkörpers besteht. Untersuchungen an einer geschlossenen Hohlform deuten auf eine aktive Sackungsstruktur hin, da sich Anomalien des geologischen Untergrundes mit der topographischen Lage der Struktur decken.