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The Xiaohuangshan site is an early Neolithic settlement in the lower Yangzi River dating to 9000–7000 BP. In this paper, starch grains extracted from the surfaces of 9 pottery sherds and 6 grinding slabs unearthed from the early Xiaohuangshan phase (9000–8500 cal. BP) are identified from Oryza , Triticeae Tribe, Coix lacryma-jobi , Nelumbo sp., Dioscorea opposita Trunb , Vigna and Quercus spp. Based on the statistical analysis of percentage presence and the minimum numbers of plants identified by starch grains on the grinding slabs and potteries, it can be found that rice has become one of the major staple foods together with Triticeae grasses, Job's tears and acorns, which indicates rice should have been cultivated intentionally at Xiaohuangshan. The results also suggest that grinding slabs from Xiaohuangshan were used mainly for processing wild plants other than rice, and plant residues extracted from their surfaces cannot be utilized independently to explore human's subsistence strategies in that time. In addition, acorns probably were cooked whole in the pottery vessels before they were shelled or ground on the grinding slabs in the Xiaohuangshan site. This paper provides new evidence for the beginning of rice cultivation during the early Neolithic in the Lower Yangtze River. [ABSTRACT FROM AUTHOR]

The earliest pottery in East Asia, as is found in several cave sites in southern China, emerges in Upper Paleolithic contexts dating from the Last Glacial Maximum, ∼20 Ka cal BP. The making of simple pottery vessels in Late Pleistocene East Asia also has been noted in eastern Siberia and Japan but not yet in the Central Plains of China. This paper summarizes the better-reported evidence for early pottery sites across the vast region of China south of the Yangtze River, providing details on two dating projects conducted in the cave sites of Xianrendong (Jiangxi Province) and Yuchanyan (Hunan Province). The excavated contexts in these two caves and a few others clearly indicate that this early pottery was the creation of hunter-gatherers who hunted available game and foraged a variety of plant foods. The nature of the cave occupations is ephemeral, and where the published animal and plant remains allow, we suggest that there were repeated, seasonal occupations. In sum, there is no basis yet to suggest that the making of early pottery in South China marked sedentary or plant-cultivating communities. [ABSTRACT FROM AUTHOR]

The present paper focuses on the analysis of dryness/wetness in the Yangtze River Basin from 1960 to 2005 using monthly precipitation data observed at 135 gauges uniformly distributed over the area. The spatial and temporal variation of dryness/wetness has been assessed by means of the Standardized Precipitation Index (SPI). The principal component analysis (PCA) and wavelet transform analysis were applied to the SPI series computed on both 6-month and 12-month time scales. The results demonstrated noticeable spatial patterns with three sub-regions characterized by different climatic variability: the southeastern downstream part of the basin, the midstream and the western upstream part of the study area. In the upstream and lower reaches of the Yangtze River Basin, an obvious trend towards wetter conditions has been detected from 1990 onward. In addition, inter-decadal changes are obvious, indicating 7–8 years fluctuation in most parts of the region sporadically distributed in the studied period in 95% confidence level. The results of this paper will be helpful for an efficient water resources management under different conditions. Furthermore, three sub-regions should be separately considered in the watershed planning process for mitigating the adverse impacts of future extreme drought or flood occurrences. [ABSTRACT FROM AUTHOR]

The hydrological cycle is sensitive to the driving forces of climate change. Thus, impact assessment of climate change on water resources from the past to the present is of grave concern for basin management. In this study, water resource spatiotemporal patterns exposed to IPCC scenarios A2 and B2 in the upstream Yangtze River are assessed. Statistically downscaled precipitation and temperature are analyzed. Rainfall-runoff processes are modeled using a distributed hydrological model. Results show that the historical downscaled precipitation and temperature are consistent with observations. Mean air temperature increased for both scenarios. Precipitation generally declined over the region. Runoff is predicted to decrease in most rivers, especially in the wet season, and the variation of hydrographs is obvious. An increase in temperature likely caused the reduction of precipitation leading to the consequent rise of evapotranspiration and decline of surface water and groundwater recharge. Generally, surface water and ground water recharge declined faster in the A2 scenario than B2. Water resources will be in a considerable heterogeneous pattern driven by climate changes. Precipitation, surface water generation, and groundwater recharge share identical spatiotemporal patterns but are predicted to show larger spatial variation in future decades. B2 shows a larger future spatial variation, which may add risks for local droughts and floods. This paper emphasizes the evolution of spatiotemporal variations of water resources from 1999 to 2099 associated with discussions on implications and uncertainties in the upstream Yangtze River region. [ABSTRACT FROM AUTHOR]

The natural flow regime is confirmed to be the main driving factor in maintaining diverse species and abundant production of river floodplains. However, disturbance of human activities have affected natural hydro-geomorphical process, reduced habitat heterogeneity, and weakened ecological service functions. Thus, it is necessary to assess ecological water requirements and furthermore provide a quantitative operational basis for restoring natural flow regime. Macroinvertebrates are considered as good indicators of hydrological regime changes due to their confinement to the bottom, limited abilities of movement, and low tolerance. This paper deals with systematic ecological investigations in the Wuhan branch of the Yangtze River during 2007–2008. Altogether, 32 taxa of macroinvertebrates belonging to 13 families and 27 genera were identified. The density and biomass of total macroinvertebrates were 181 ind m −2 and 0.29 g dry mass m −2 , respectively. Canonical Correspondence Analysis (CCA) revealed that the important environmental factors influencing macroinvertebrate abundance were flow velocity (U), water depth (Z), and total nitrogen (TN). The relation between habitat weighted usable area and water discharge was analyzed on basis of creating suitability curves. Weighted usable area of habitat showed unimodal changes with increasing water discharge, i.e., first increased and then decreased, and weighted usable area of habitat reached the maximum when flow discharge was 21,000 m 3 s −1 . [ABSTRACT FROM AUTHOR]

To project future river discharge in the Yangtze River basin, artificial neural networks were used in this study. Based on observed precipitation, temperature, and river discharge data from 1961 to 2000, artificial neural networks were trained and calibrated. The paper projects river discharges at Yichang and Datong hydrological stations under three greenhouse gas emission scenarios from 2011 to 2050 in the Yangtze River basin, by applying climate projections of global climate model ECHAM5/MPI-OM. The results show that annual river discharges at two hydrological stations have no obvious trends and their decadal variations are also small under three emission scenarios. Seasonal discharges at Yichang and Datong have different trends during 2011–2050. Ratios of river discharge in four seasons within a year tend to change. [ABSTRACT FROM AUTHOR]

Abstract: Changes on water resources volume of 1960–2007 in the Upper Reaches of the Yangtze River are discussed in this paper. A time series (1960–2007) and its spatial patterns of actual evapotranspiration (ETa) estimation are analyzed based on Advection-Aridity model (A–A model) with selected parameters for 72 meteorological stations in the upper reaches of the Yangtze River Basin. The result indicates that average ETa of the basin changed in stages: slight increases in the first decade; a drop followed by fluctuations and lower increases in the next ten years; and then a dramatic decline in the latest decade, with three abrupt change years detected in the early 1970s, 1990s, and 2000s. ETa increases from mountainous northwest areas to plains in eastern areas, with significant decreases in plain regions and increases in the mountain region. ETa in the Sichuan Basin is found to decrease at the most rapid rate, and ETa in the sub-area to the south of the upland mountain region is increasing significantly. Such patterns of spatial trend in ETa result in reductions in regional variation, both annually and in all seasons. The change in ETa of this area is believed to be related to local water resource changes, and is impacted by the changes in climate factors. Temperature of this area has increased, and sunshine duration hours have shortened, leading to a reduction in net radiation. Relative humidity also has decreased. Comprehensively, reduction in both energy and moisture supply for evapotranspiration result in an increasing ETa. Moreover, a sharp drop of ETa occurred in the early 2000s, and meteorological factors including wind speed also show abrupt change to different extents. The impact of ETa on regional water balance at both inter-annual and intra-annual scales is also discussed in this study. [Copyright &y& Elsevier]

Abstract: With the increasing accumulation of data on early rice farming in the middle and lower reaches of the Yangtze River, this region has become one of the most important places to trace the origin and development of agriculture. This paper gives a general evaluation of some early rice sites, including the Hemudu, Majiabang, Kuahuqiao, and Shangshan cultures in the lower reaches of the Yangtze River; the Pengtoushan and Chengbeixi cultures, and the Xianrendong, Diaotonghuan and Yuchanyan sites in the middle reaches of the Yangtze River; and the Jiahu site in North China, and recognizes three main development stages of the prehistoric rice forming in China, i.e. initial stage (before 8000 BC, approximately equal to Mesolithic Age), developing stage (between 8000 BC and 5000 BC) and maturating stage (since 5000 BC). The initiation of agriculture is suggested to come with the establishment of more or less sedentary residences, which coexists with the occurrence of pottery making. Warming climate after the last glaciations is considered as a major factor that allowed the distribution of the wild rice northward. Food requirement and storage are another factor in initiating early rice farming, while the increasing population and the Holocene Maximum warm climate condition might greatly promote its development. Evidence from the middle and lower Yangtze River area exhibits the transitional process from a hunting and gathering society to an agriculture-oriented society. [ABSTRACT FROM AUTHOR]

Abstract: Floods often are accompanied by intensified soil erosion and thus high sediment supply from the catchment into the main channel of the river. This paper examined the sediment processes, especially deposition and erosion, during the two extreme flood years in 1954 and 1998, in the middle and low reaches of the Yangtze River. The total amount of sediment supplied to the middle and lower reaches from Yichang–Hankou and Hankou–Datong, was 1095 Mt in 1954 and 855.9 Mt in 1998, or 176% and 137% of the averaged 622 Mt/a from 1950 to 2006. A high deposition occurred in the floodplains, lakes and channels along the section Yichang–Hankou, both in 1954 and 1998. The total deposition reached 635 Mt and 499 Mt in 1954 and 1998 or 138% and 124% of the sediment load measured at the Datong station, respectively. However, different processes in the downstream section Hankou–Datong during the two flood events were found. Severe erosion (−140 Mt) happened in 1954, but only a slight erosion occurred (−22 Mt) in 1998. Thus, the floodplains and channels in the middle and lower reaches of the Yangtze River play an important role in regulating sediment discharge during extreme flood events. The heavy deposition in the middle reaches effectively reduced the amount of sediment discharged into the river mouth and thus acted as a major depocenter in the extreme flood year. The results also suggested that the Yichang–Hankou tended to shift from a depositional section to an erosional section, whereas the Hankou–Datong changed from an erosion-dominated section to a deposition-dominated section even before the Three Gorges Reservoir infilling in 2003. It is anticipated that this tendency would be accelerated and the historical role of sediment regulation by the two reaches could eventually be changed due to the reduced sediment supply from the Upper Yangtze. [ABSTRACT FROM AUTHOR]