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The vast Dongting Lake in the middle Yangtze River basin, China, was occupied by Chinese Neolithic settlements starting 10 000 years ago, and rice cultivation there is probably the earliest in the world. The numerous Neolithic settlements identified by previous archaeological surveys represent the five major Neolithic cultural stages, i.e. the Pengtoushan (9000–7900 cal. yr BP), Zaoshixiaceng (7900–6800 cal. yr BP), Daxi (6800–5500 cal. yr BP), Qujialing (5500–5000 cal. yr BP), and Shijiahe (5000–4000 cal. yr BP). Using sedimentological and geoarchaeological approaches, this paper analyses the drivers of basin-scale settlement relocation in relation to lake-level fluctuations and monsoon climate variations in the Holocene. The relocation of Neolithic sites around the lake shoreline and on the adjacent floodplain, together with radiocarbon-dated stratigraphy, clearly indicates that the shape of the lake basin was an incised and elongated valley occupied by a lake in the early Holocene, which became a broader and shallower depression in the mid to late Holocene. The established lowest habitable base of the settlements positioned on the lake shore assists reconstruction of the change in lake level from 22 m at 9000 cal. yr BP to 26 m at 5500–4000 cal. yr BP, although higher and lower lake levels occurred during the intervening cultural stages. The pollen spectra reveal a warming trend throughout the Holocene with at least four major temperature cycles, driven by monsoon variations between temperate- and warm-humid conditions. In the early Holocene the climate changed from cool-dry to warm-humid, and this played a key role in developing the earliest Pengtoushan culture in the region. Subsequent climate fluctuations fit well with the advance and retreat of the lake shore, also coevally with Neolithic site movements in the lake region. In this study we show how geoarchaeological evidence can be used in environmental reconstruction during the Holocene. [ABSTRACT FROM AUTHOR]

Wetland ecosystem is an essential ecosystem in the world. Its organic carbon stock and carbon cycle are important basis of global carbon cycle researches and also major contents of global climate change researches. Researches have shown that wetland protection and restoration can promote carbon accumulation and reduce emission of greenhouse gases. This paper discussed influence of carbon stock and carbon balance of wetland ecosystem and emission of greenhouse gases, as well as the relationship between wetland and global climate changes. Finally, it made prospect on researches about carbon cycle of Dongting Lake. [ABSTRACT FROM AUTHOR]

The Dongting Lake Basin (DTLB) of China is a flood prone area. Knowledge of the spatiotemporal characteristics and risks of precipitation extremes is essential for flood mitigation. Based on the precipitation amount (R), precipitation intensity (Ri), max 1 day precipitation amount (Rx1) and max 5 day precipitation amount (Rx5), this study analyzed the spatial-temporal patterns, risks and investigated the influences of the precipitation extremes at seasonal scale. The distributed high values of R, Ri, Rx1, Rx5 and their 5-year return levels (R5, Ri5, Rx15, Rx55) indicated high flood risks in the eastern and northern parts of the basin, and the general upward trends of these indices suggested increasing flood risks, except for some areas in southwestern part in spring and autumn. The precipitation extremes were related to the topographic and circulation factors, within which the latter might have greater roles. Furthermore, the trend directions of the 5-year return levels (R5, Ri5, Rx15, Rx55) were not always the same as the initial indices (R, Ri, Rx1, Rx5), suggesting that overall decreasing (increasing) precipitation extremes do not always represent decreasing (increasing) risks of floods. Hence, policy makers should pay more attention to the risks of precipitation extremes rather than their overall tendencies. [ABSTRACT FROM AUTHOR]

With global climate change and impacts of human activity, the water cycle, which has a close relationship with local water resources, has changed rapidly. Based on different greenhouse gas emission scenarios, five relatively independent global climate models are selected from 47 CMIP5 models to simulate future climatic conditions. Data are downscaled to the local projection, with bias neutralized before applying them to the hydrological models, by which availability of future water resources are calculated for the Dongting Lake basin. The results show that the water resources of the Dongting Lake basin are likely to increase in the future, but be distributed more unevenly. All scenarios indicate that water availability will increase during the flood season and decrease during the dry season, with a prominent increase in annual discharge. The scenarios also predict that the greater the greenhouse gas emissions, the more uneven the water distribution becomes. Overall, the water resources of the Dongting Lake catchment show the same increasing and unevenly distributed trend in the future, which could be further accelerated by human activities.Editor Z.W. Kundzewicz; Associate editor Q. Zhang [ABSTRACT FROM AUTHOR]

Climate variability and human activity were regarded as two contributors to streamflow alteration. However, the contributions of the two factors were still unclear in Dongting Lake. Therefore, it was crucial to quantify the relative impact of climate variability and human activity on streamflow alteration. The time series (1961-2010) was divided into three periods, namely, natural period (1961-1980), change period I (1981-2002) and change period II (2003-2010). Sensitivity analysis based on Budyko-type equations was applied to reveal the contributions of climate variability and human activity in those two change periods, respectively. The results showed that during the change period I, climate variability was the main factor responsible for streamflow alteration in most parts of Dongting Lake, accounting for 60.07-67.27%. However, the impact of climate variability was slightly smaller than that of human activity in West Dongting Lake (the former accounting for 43.20% while the latter accounting for 56.80%). For the change period II, human activity was the dominate factor for streamflow alteration, accounting for 58.89-78.33%. The impact of climate variability gradually decreased while the impact of human activity gradually increased. Along with the intensification of the human activity, the impact of it became more dominant. The results could provide a reference for water resources planning and management decisions. Under the condition of uncontrollable climatic factor, effective measures should be put forward in controlling human activity, such as reservoir/dam operation, closed management of protected area and so on. Besides, it is essential to study the impact of climate variability on future water resources and water resource management under different climate change scenarios. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]