Storm-generated Holocene and historical floods in the Manawatu River, New Zealand

This paper reports the first reconstruction of storm-generated late Holocene and historical river floods in the North Island of New Zealand. The sedimentary infills of nine palaeochannels were studied in the lower alluvial reaches of the Manawatu River. Floods in these palaeochannels were recorded as a series of sand-rich units set within finer-grained fills. Flood chronologies were constrained using a combination of radiocarbon dating, documentary sources, geochemical markers, and palynological information. Flood units were sedimentologically and geochemically characterised using high resolution ITRAXTM 16 X-Ray Fluorescence (XRF) core scanning and laser diffraction grain-size analysis. The longest palaeoflood record extends back ca.3000 years. The temporal resolution and length of the Manawatu record reflects accommodation space for fluvial deposits, channel dynamics and mobility, and high sediment supply. Floods that occurred in the Manawatu during the mid-1800s at the time of European land clearance and in the first decade of the twentieth century appear to be among the largest recorded in the last 3000 year

Interpreting historical, botanical, and geological evidence to aid preparations for future floods

River flooding is among the most destructive of natural hazards globally, causing widespread loss of life, damage to infrastructure and economic deprivation. Societies are currently under increasing threat from such floods, predominantly from increasing exposure of people and assets in flood-prone areas, but also as a result of changes in flood magnitude, frequency, and timing. Accurate flood hazard and risk assessment are therefore crucial for the sustainable development of societies worldwide. With a paucity of hydrological measurements, evidence from the field offers the only insight into truly extreme events and their variability in space and time. Historical, botanical, and geological archives have increasingly been recognized as valuable sources of extreme flood event information. These different archives are here reviewed with a particular focus on the recording mechanisms of flood information, the historical development of the methodological approaches and the type of information that those archives can provide. These studies provide a wealthy dataset of hundreds of historical and palaeoflood series, whose analysis reveals a noticeable dominance of records in Europe. After describing the diversity of flood information provided by this dataset, we identify how these records have improved and could further improve flood hazard assessments and, thereby, flood management and mitigation plans

Treatment of COVID-19 with remdesivir in the absence of humoral immunity: a case report

Abstract: The response to the coronavirus disease 2019 (COVID-19) pandemic has been hampered by lack of an effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antiviral therapy. Here we report the use of remdesivir in a patient with COVID-19 and the prototypic genetic antibody deficiency X-linked agammaglobulinaemia (XLA). Despite evidence of complement activation and a robust T cell response, the patient developed persistent SARS-CoV-2 pneumonitis, without progressing to multi-organ involvement. This unusual clinical course is consistent with a contribution of antibodies to both viral clearance and progression to severe disease. In the absence of these confounders, we take an experimental medicine approach to examine the in vivo utility of remdesivir. Over two independent courses of treatment, we observe a temporally correlated clinical and virological response, leading to clinical resolution and viral clearance, with no evidence of acquired drug resistance. We therefore provide evidence for the antiviral efficacy of remdesivir in vivo, and its potential benefit in selected patients

Treatment of COVID-19 with remdesivir in the absence of humoral immunity: a case report

Abstract: The response to the coronavirus disease 2019 (COVID-19) pandemic has been hampered by lack of an effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antiviral therapy. Here we report the use of remdesivir in a patient with COVID-19 and the prototypic genetic antibody deficiency X-linked agammaglobulinaemia (XLA). Despite evidence of complement activation and a robust T cell response, the patient developed persistent SARS-CoV-2 pneumonitis, without progressing to multi-organ involvement. This unusual clinical course is consistent with a contribution of antibodies to both viral clearance and progression to severe disease. In the absence of these confounders, we take an experimental medicine approach to examine the in vivo utility of remdesivir. Over two independent courses of treatment, we observe a temporally correlated clinical and virological response, leading to clinical resolution and viral clearance, with no evidence of acquired drug resistance. We therefore provide evidence for the antiviral efficacy of remdesivir in vivo, and its potential benefit in selected patients

Depositional development of the Muskeg Lake crevasse splay in the Cumberland Marshes (Canada)

Crevasse splays are common geomorphological features in alluvial and deltaic floodplains. Although crevasse splays can develop into full avulsions, thereby transforming large areas of floodbasins, little is known about their sedimentary and geomorphological development at the decadal scale and their avulsion potential. We used aerial photography and lithological cross-sections to reconstruct crevasse-splay formation in the largely unmanaged floodplain of the Saskatchewan River in the Cumberland Marshes (Saskatchewan, Canada). Based on surface geomorphology and subsurface deposits, various stages of crevasse-splay development were described which were linked to both external forcing and internal morphodynamics. Initial splay deposition, following a levee breach during a large flood, occurred as a broad but relatively thin sandy sheet in a down-basin direction in the receiving backswamp area. In a next phase, these primary crevasse-splay deposits blocked local down-basin flow, thereby forcing the crevasse-splay channel in a direction perpendicular to the parent channel and original floodbasin gradient. This created an asymmetrical splay sequence composition, which differs in appearance from more commonly observed dendritic crevasse splays. It is concluded that sedimentation patterns in the splay have been influenced by inherited effects of previously formed deposits. Feedbacks of the original floodbasin gradient and earlier stages of splay formation are suggested as prominent mechanisms in creating the current morphology, orientation, and architecture of its deposits

Flood-related variations in provenance of fine-grained palaeochannel sediments in the Rhine river basin

In this study, we examine flood-related variations in provenance of fine-grained palaeochannel sediments from the Bienener Altrhein (Germany), an abandoned river channel close to the apex of the Rhine river delta. Geochemical and grain size analyses were conducted on channel-fill sediments from multiple core sections, ranging from 1.15 m to 8.48 m depth, which represents pre-industrial sediment deposited from approximately 1550 AD to 1850 AD. In addition, four sediment cores of ~ 1 m length were retrieved from channel-fills or overbank deposits along the Upper Rhine and the three main tributaries of the Rhine in Germany (Neckar River, Main River and Moselle River). Sediment geochemistry was analysed using an Itrax X-Ray Fluorescence (XRF) core scanner. Four elements (Ti, Co, Rb, W) were selected for further analysis based on the following a priori criteria: (1) The elements must be associated with minerals in the fine particle size fractions; 2) they must not be susceptible to precipitation-dissolution reactions during early diagenenis of the sediment; 3) the elements must be detected in the vast majority of the measurements; 4) the difference between the minimum and maximum number of the XRF counts for the upstream cores must be greater than 50% of the average number of counts. The XRF counts for these elements were standardised to z-scores and were subsequently corrected for the variation clay content ( 150 μm), which was primarily deposited during historical flood events. The results show the Mahalanobis distances are larger than 1 for most increments, which indicates that the four sampled upstream sites do not entirely cover all sources of sediment deposited in the Bienener Altrein channel. The logtransformed Mahalonibis distance correlates significantly (α = 0.05) with the >150 μm particle size fraction for the Upper Rhine River (negative) and the Moselle River (positive). This implies that the proportion of fine sediment that originates from the upper parts of the river basin and, hence, the sediment transport distance increases with flood magnitude. These results provide an excellent starting point to reconstruct the origin of historic flood events as documented in the sedimentary records of channel fills and dike breach ponds

The influence of Late Pleistocene geomorphological inheritance and Holocene hydromorphic regimes on floodwater farming in the Talgar catchment, southeast Kazakhstan, Central Asia

In comparison to Southwest Asia and the Indian subcontinent, the relationship between Holocene river dynamics, climate change and floodwater farming in Central Asia is significantly under researched. To address this, a multi-disciplinary research project was begun in 2011 centred on the Talgar catchment, a south-bank tributary of the Ili River, southeast Kazakhstan. Building on archaeological excavations and surveys conducted over the past 20 years, we have undertaken investigations of Holocene human ad-aptations to changing hydromorphic regimes in the Tien Shan piedmont region, Central Asia. Fluvial geochronologies have been reconstructed over the last 20,000 years using Optically Stimulated Lumi-nescence and 14C dating, and are compared with human settlement histories from the Eneolithic to the medieval period. Phases of Late Pleistocene and Holocene river aggradation at c. 17,400e6420, 4130 e2880 and 910e500 cal. BC and between the mid-18th and early 20th centuries were coeval with cooler and wetter neoglacial episodes. Entrenchment and floodplain soil development (c. 2880e2490 cal. BC and cal. AD 1300e1640) coincided with warmer and drier conditions. Prior to the modern period, floodwater farming in the Talgar River reached its height in the late Iron Age (400 cal. BC e cal. AD 1) with more than 70 settlement sites and 700 burial mounds. This period of agricultural expansion cor-responds to a phase of reduced flooding, river stability and glacier retreat in the Tien Shan Mountains. Late Iron age agriculturists appear to have been opportunistic by exploiting a phase of moderate flows within an alluvial fan environment, which contained a series of partially entrenched distributary channels that could be easily ‘engineered’ to facilitate floodwater farming. Holocene climate change was therefore not a proximate cause for the development and demise of this relatively short-lived (c. 200 years) period of Iron Age farming. River dynamics in the Tien Shan piedmont are, however, strongly coupled with regional hydroclimatic fluctuations, and they have likely acted locally as both ‘push’ and ‘pull’ factors for riparian agriculturists

A new model of river dynamics, hydroclimatic change and human settlement in the Nile Valley derived from meta-analysis of the Holocene fluvial archive

Abstract not availableMark G. Macklin, Willem H.J. Toonen, Jamie C. Woodward, Martin A.J. Williams, Clement Flaux, Nick Marriner, Kathleen Nicoll, Gert Verstraeten, Neal Spencer, Derek Welsb

Holocene fluvial history of the Nile's west bank at ancient Thebes, Luxor, Egypt, and its relation with cultural dynamics and basin-wide hydroclimatic variability

In the Theban area around modern Luxor (Egypt), the River Nile divides the temple complexes of Karnak and Luxor from New Kingdom royal cult temples on the western desert edge. Few sites have been archaeologically identified in the western flood plain, despite its presumed pivotal role in the ancient ritual landscape as the territory that both physically divided and symbolically connected the areas inhabited by the living and the areas occupied by the dead. Using borehole data and electrical resistivity tomography, the current investigation of subsurface deposits reveals the location of an abandoned channel of the Nile. This river course was positioned in the western, distal part of the Nile flood plain. Over 2100 ceramic fragments recovered from boreholes date the abandonment of the relatively minor river channel to the (late) New Kingdom. This minor river branch could have played an important role in the cultural landscape, as it would have served to connect important localities in the ritual landscape. Changes in the fluvial landscape match with established periods of basin-wide hydroclimatic variability. This links cultural and landscape changes observed on a regional scale to hydroclimatic dynamics in the larger Nile catchment, in one of the focal areas of Ancient Egyptian cultural development