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Drought is a common natural disaster in arid Central Asia, and the severity and frequency of drought and other hydroclimatic events are critical to the region's ecology and its residents' livelihoods. In particular, water resource management requires reliable knowledge of climatic variability and annual and centennial drought patterns. In this paper, we establish a 587-year tree ring chronology using 215 Schrenk spruce ( Picea schrenkiana Fisch. et Mey) samples and reconstruct a spring Palmer Drought Severity Index ( PDSI) for the inner Tianshan Mountains spanning the 1645-2008 period. The reconstruction explains 40.3% of the variance during the sub-period for which we also have reliable observational data (1938-2005). Cross-validation during this common period also supports our reconstruction model. Spatial correlation analyses with gridded PDSI data show that our PDSI reconstruction reveals a strong regional drought signal for the central and western Tianshan Mountains. [ABSTRACT FROM AUTHOR]

This paper reports an investigation into palaeoflooding along the upper reaches of the Hanjiang River valley, China. Based on the sedimentary evidence of the palaeohydrological regime, two bedsets of palaeoflood slackwater deposits (SWDs) were identified interbedded within the Holocene loess-soil sequence along the riverbanks of the Ankang east reach. Optical Stimulated Luminescence (OSL) dating and stratigraphical correlation with previously dated sites were used to reconstruct the chronology of the palaeoflood events. The results show that the palaeoflood events represented by SWD1 occurred between 13 000 and 12 400 a, coincident with the climatic transition from the Bølling-Allerød (BL+AL) stage to the Younger Dryas (YD) event. The palaeoflood events recorded by SWD2 were dated to 1000-800 a, corresponding to the later stages of the North Song Dynasty (AD 960-1127) and the subsequent South Song Dynasty (AD 1127-1279), which was a time of climatic decline according to historical documents. Palaeoflood discharges were estimated using the step-backwater method, and the peak discharges were estimated to be in the range 35 200-47 400 m3 s-1. These results are of significance to our understanding of the regional hydrological response to global climatic change, the utilization of water resources, hydraulic engineering, flood control and disaster reduction. [ABSTRACT FROM AUTHOR]

Recent investigations into relict periglacial phenomena in northern and western China and on the Qinghai- Tibet Plateau provide information for delineating the extent of permafrost in China during the Late Pleistocene. Polygonal and wedge-shaped structures indicate that, during the local Last Glacial Maximum ( LLGM, between ∼35 and 10.5 ka BP), the southern limit of latitudinal permafrost in northern China advanced southward at least to ∼38-40° N in the east and to ∼37-39° N in the west. This represents an advance of about 5-10° of latitude beyond present-day permafrost limits. The lower limits of elevationally controlled permafrost on the Qinghai- Tibet Plateau and its peripheries were about 1000 m lower: this permafrost was largely continuous during the LLGM. This suggests a cooling of between 4 and 10° C, or more. This paper discusses the extent of permafrost during the LLGM and presents maps that have been constructed on the basis of extensive and integrative analysis of all reliable and pertinent data. The results indicate that the extent of LLGM permafrost in China was between ∼3.8 and 4.3×106 km2. This is 80 to 100% more than that of ∼2.15×106 km2 in the 1970s, and 120 to ∼150% more than that of ∼1.75×106 km2 today. [ABSTRACT FROM AUTHOR]