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Huang C.C.,Shaanxi Normal University | Pang J.,Shaanxi Normal University | Zha X.,Shaanxi Normal University | Su H.,Xian International Studies University | Jia Y.,Shaanxi Normal University
Quaternary Science Reviews | Year: 2011

Palaeo-hydrological study was carried out in the Qishuihe River valley in the middle reaches of the Yellow River. Several bedsets of flood slackwater deposit were identified in the Holocene loess-soil sequences on the riverbanks. They were differentiated from aeolian loess and soils by the parallel and waving beddings and the distinctive stratigraphic breaks separating individual palaeoflood events. Chronology of the flood events was established by OSL dating, checked by archaeological identification of the anthropogenic remains retrieved from the sequences. The results show that successive floods occurred between 4300 and 4000 a BP in association with the abrupt climatic event of 4200 a BP. These overbank floods had the riverbank settlement inundated repeatedly. Another series of extraordinary floods occurred between 3200 and 3000 a BP when monsoonal climate shifted from the mid-Holocene Climatic Optimum toward late Holocene dry conditions. The climatic event of 4200 a BP and the climatic decline at 3100 a BP were believed to be characterized by droughts previously. This work provides solid evidence that both severe droughts and extreme floods were parts of the climatic variability during abrupt climatic event and climatic decline in the semi-arid to sub-humid zones over the world. © 2010 Elsevier Ltd.

Huang C.C.,Shaanxi Normal University | Pang J.,Shaanxi Normal University | Zha X.,Shaanxi Normal University | Zhou Y.,Shaanxi Normal University | And 4 more authors.
Journal of Quaternary Science | Year: 2012

Palaeoflood slackwater deposits (SWDs), are the natural record of overbank flooding and are often found within aeolian loess-soil profiles along the river valleys of the middle Yellow River basin. These pedo-stratigraphic sequences are studied using a multi-disciplinarily approach to reconstruct Holocene hydro-climatic variations. Our field investigations along the lower Jinghe River valley have identified palaeoflood SWDs at several sites along the riverbanks based on sedimentological criteria. Analytical results, including magnetic susceptibility, particle-size distribution and concentrations of chemical elements, indicate that these well-sorted palaeoflood SWD beds were deposited from the suspended sediment load in floodwaters. We identify two episodes of extraordinary palaeoflood events along the Jinghe River valley. These hydro-climatic events were dated to 4200-4000 and 3200-2800 a BP, by using the optically stimulated luminescence method in combination with archaeological dating of retrieved anthropogenic remains, and with pedo-stratigraphic correlations with the previously studied Holocene pedo-stratigraphy in the Jinghe River drainage basin. The flooding events are therefore considered to be a regional expression of known climatic events in the northern hemisphere and demonstrate Holocene climate was far from stable. This study provides important data in understanding the interactions between regional hydro-climatic systems and global change in semi-arid and sub-humid regions. © 2012 John Wiley & Sons, Ltd.

Cao F.,Nanyang Technological University | Cao F.,Xian International Studies University | Hu G.,Nanyang Technological University
Journal of Pragmatics | Year: 2014

This article reports a comparative study of interactive metadiscourse in quantitative and qualitative research articles across the disciplines of applied linguistics, education, and psychology. Drawing on Hyland's metadiscourse framework, the study examined the use of five types of interactive metadiscourse, together with their subtypes, in a corpus of 120 research articles. Quantitative and qualitative analyses revealed clear cross-paradigmatic differences in the incidence of reformulators, comparative and inferential transitions, sequencers, and non-linear references. The analyses also identified marked cross-disciplinary differences in the use of exemplifiers, comparative transitions, linear references, and integral citations. These observed differences are interpretable in terms of the contrasting epistemologies underlying the qualitative and quantitative research paradigms and the different knowledge-knower structures prevailing in the disciplines under investigation. © 2014 Elsevier B.V.

Wang X.-H.,Xian International Studies University
Fangzhi Gaoxiao Jichukexue Xuebao | Year: 2014

Let D be a positive integer, and let p be an odd prime. Using certain elementary methods, the number of positive integer solutions (m,x) of the equation p2m - Dx2 =1 is discussed. It proved that the equation has at most one positive integer solution (m,x).

Huang C.C.,Shaanxi Normal University | Huang C.C.,CAS Institute of Earth Environment | Pang J.,Shaanxi Normal University | Zha X.,Shaanxi Normal University | And 3 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2010

Holocene palaeohydrological investigations were carried out in the middle reach of the Jinghe River that drains the central part of the Loess Plateau. A set of palaeoflood slackwater deposits was found interbedded in the Holocene loess-soil sequence within the cliff riverbanks. Both the sedimentary criteria and the analytical results show that this sediment was sourced from a suspended sediment load of floodwater. The major cultural layer of a late Neolithic settlement (4300-4000 a BP) occurring at the same site is blanketed by this flood deposit directly. Slopewash with pottery shards, charcoal and burnt earth occurs in between the palaeoflood slackwater deposit beds. It indicates that each of the slackwater deposit beds has recorded one individual flood event, and that these extraordinary floods occurred when the late Neolithic people occupied the riverbank terrace land. This pre-historical settlement was abandoned after the floods eventually due presumably to repeated inundation by overbank floodwater. The flood events were OSL dated to between 4100 and 4000 a BP and checked by archaeological dating of the anthropogenic remains retrieved from the sequences. Peak discharges of the floods were estimated to between 19,500 and 22,000 m3 s- 1, which is several times gauged maximum floods. During the 4200-4000 a BP climatic event, severe droughts were documented in China's monsoonal regions and great floods were known from an ancient legend. This study provides a well-dated sediment record of pre-historical floods which occurred at the transition from the Neolithic to the Bronze Age in the Yellow River basin. It shows that extraordinary floods were part of the abrupt climatic variability during the 4200-4000 a BP climatic event. The highly variable, unstable and catastrophic climate typified by both droughts and floods resulted in settlement abandonment, and possibly the decline of the highly developed late Neolithic civilizations in China's monsoonal regions. © 2010 Elsevier B.V. All rights reserved.

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