1362 archaeological sites from the Paleolithic age to the Warring States time in Hubei Province increase gradually from west to east and from high to low. The number of Paleolithic sites with altitudes of 50-500 m account for 78% of the total, while 71%-95% of the sites from the Neolithic age to the Warring States time are distributed at the areas of 0-200 m. The temporal-spatial distribution of archeological sites in this area is mainly affected by two factors. For one thing, the human beings of every age need to choose the first on the second terrace as living sites which are near to the water source and are easy to withstand flood. Additionally, since downcutting of rivers can form new river valley and lateral erosion and accumulation of river in stable time of tectonic movement can result in gathering of many new terraces. So, the human beings migrated to adapt to the change of terrace location, which led to the number of sites increasing gradually in the lower areas of the central and eastern parts of this province. For other things, the temporal-spatial distribution of archeological sites in this area is affected by the climate condition. The Paleolithic sites are distributed mostly in the Hanjiang River Basin in northeastern Shiyan, southeast of Jingzhou and east of Jinmen, which is because rivers were distributed in higher areas in this period. During Chengbeixi cultural period, the sites are rare in the quondam Paleolithic sites distribution area, but manifold obviously along the Yangtze River near the southwest Yichang contrarily. The pollen record of Dajiuhu Lake indicates that only 23 Chengbeixi cultural sites may be related to more precipitation and flood during the Holocene wet and hot period. Daxi Culture, Qujialing Culture and Shijiahe Culture are corresponding to middle and top of the Dajiuhu pollen Zone IV, during which the climate is in order as a whole and is propitious to agricultural development. In the Qujialing Culture period, 32 of the former 34 Daxi Cultural sites disappeared, while 90 sites increase abruptly in the higher highlands in the north of Xiangfan-Jinmen-Xiaogan, which may respect with enlarging of water areas. Chu Culture period is corresponding to Dajiuhu pollen Zone V, which is warm and dry Holocene phase, but it seems that the climate condition is propitious to agricultural cultivation and the number of archeological sites increases heavily to 593. In addition, there are the least archaeological sites in the lake areas of the southeast Hubei Province because of low-lying topography with altitudes of 1-50 m and severest flood.
Archaeological excavations over many years show that there are many culture interruptions among archaeological strata of many sites in the Yangtze River Basin. Therefore, the investigation of culture interruption is one of the important research fields dealing with the relationship between human and environment since Holocene. Based on some chronological data, archaeological cultures before the Qin and Han dynasties in the Three Gorges region can be divided into six cultural periods: Chengbeixi Culture (8200-6300 a BP) →Daxi Culture (6300-5000 a BP)→Qujialing Culture (5000-4600 a BP)→Baimiao and Weijialiangzi Culture (4600-4000 a BP) →Earlier Ba Culture coming from the western part of the Yangtze River Basin (4000-3000 a BP) and Chu Culture (3000 a BP-278 BC). By the comparison between archaeological stratigraphy, sediment characteristics of cultural layers and culture interruptions, the synthetical analysis of the distribution of sites, and references from other scholars, we can see that there are 5 culture interruptions in the Three Gorges region. They are from the last stage of Chengbeixi Culture to the initial stage of Daxi Culture(5800~5500 a BP)-Xia dynasty (4000~3500 a BP)-the last stage of Chunqiu and Zhanguo stage (2500~2200 a BP)-since the Song dynasty (since 960 A.D.) in the Three Gorges. The 5 cultural interruptions relate to catastrophic events during the prehistoric and historic period to a certain extent.
Based upon the ages inferred by cultural relicts, AMS 14C dating, phenomena of human activitices and characteristics of magnetic susceptibility (SI) curves of profiles at Zhongba Site in Chongqing, we find that the contribution of climate change and soil formation to the distribution of magnetic susceptibility values in stratum is concealed by the impact of the abnormally strong human activitices for a long time. The results of analysis indicate that the sources of accumulation at Zhongba Site include mainly enormous ceramics fragments, natural scrap materials from human activities and flood deposits. The cultural layers gathered with a large number of ceramics fragments (red pottery particularly) show high magnetic susceptibility values, among them, the especially abnormal high values may be concerned with the increase of the magnetic materials caused by mankind's using the fire and burning on a large-scale at that time; on the other hand, the "flood disturbed layers" usaully show low magnetic susceptibility values. Based on further analyses of the magnetic susceptibility curves, we can still find that the active epoches of human activities was from the final stage of the Neolithic Age to the Tang Dynasty, and human activities began to tend to be weakening after the Song Dynasty. During the active epoch, the final stage of the Neolithic Age, the middle period of the Xia and Shang dynasties, the early and middle periods of Western Zhou Dynasty, Spring and Autumn Period, middle and late stages of the Warring States, the middle period of the Six Dynasties and Tang Dynasty were in the periods of great prosperity. However, there are obvious flood disturbed deposits included in the layers of the late stage of the Neolithic Age, the early period of the Xia and Shang dynasties, the early period of Western Zhou Dynasty, the late period of Spring and Autumn Period, the early period of the Warring States , Song Dynasty, Ming and Qing dynasties and modern period, which can be inferred to be the ages of the occurrence of severe floods.
Mount Qomolangma , the highest peak on Earth, is often referred to as the third pole of the globe. The Nyainqentanglha is one of the closest remote parts of mountain range north to the Himalayas. As such the two places are relatively inaccessible on the southern Tibetan Plateau and little is known about their meteorology. In 2003, an auto weather station was deployed at the north col of western Nyainqentanglha (WNQ) range (30o24'44.3"N, 90o34'13.1"E, 5850 m a.s.l.). In 2005, the other station was operated at the north col of Mount Qomolangma (28o01'0.95"N, 86o57'48.4"E, 6523 m a.s.l.). We believe that these represent the high elevation at which continuous weather data have never been collected and thus are valuable datasets with which to investigate the meteorology of the high altitude southern Tibetan Plateau. In this paper, we compare the observations with the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis, in order to understand the reliability of NCEP/NCAR reanalysis data on Mount Qomolangma and Nyainqentanglha Range. We find that the reanalysis captures much of the synoptic-scale variability in temperature and pressure, although the reanalysis values are systematically lower than the observations. Furthermore, most of the variability magnitude is, to some extent, underestimated. In addition, the weather event extracted from the NCEP/NCAR reanalyzed pressure and temperature prominently appears one-day lead to that from the observational data on Mount Qomolangma , while on the WNQ range it frequently occurs on the same day and there is no obvious lead or lag. Influenced by the same atmosphere circulation, Mount Qomolangma and the WNQ range have close correlations both in the observational data and reanalyzed data.
Xinjiang is divided into three regions: the Altay Mountains-Tacheng, the Tianshan Mountains and the northern slope of the Kunlun Mountains by the climatic feature and their runoff. Based on the daily observed materials from 12 air sounding meteorological stations and the annual runoff materials from 34 hydrological stations during the period of 43 years from 1960 to 2002, the mean height change at the 0 oC level, the changing trend of runoff and their deviation of spacial distribution were researched in Xinjiang according to the methods of the combination of qualitative and quantitative analyses and the contrast with the five-year smoothing mean curve. The results show that there exists a better coherence between the height change at the 0 oC level and the annual runoff amount of the rivers in Xinjiang, and this kind of correlation has especially turned closer since 1970. Each region had its own unique feature that the heights have been significantly ascending over Altay Mountains-Tacheng and Tianshan Mountains, and that the height has been lowering over the northern Kunlun Mountains since 1990. Correspondingly the runoff over the former two regions has been increasing and over the latter has been slightly decreasing in the same period of time. In terms of relativity, there exist better linear correlations at the significance level of 0.01 between the height at the 0 oC level in summer and the runoff over Xinjiang as well as the Tianshan Mountains and the northern slope of the Kunlun Mountains. Recently, the height change at the 0 oC level has been resulted not only from the climate change on the ground but also from the upper climate change in Xinjiang. Along with the climate warming, the ascend of the height at the 0 oC level and the increase of melting snow in mountains, the runoff is accordingly gaining so that Xinjiang is witnessing the period of abundant water, and vice versa. So the runoff is directly resulted from the lifting of the height at the 0 oC level in summer. The increase of temperature in the upper air is one of the immediate factors during the course that the climate in Xinjiang is getting warmer and wetter.
Palaeoflood hydrologic study was a leading subject in the global change study. Using sediment physiognomy, archaeology and OSL chronology, the palaeoflood slacking deposits were found and analyzed on T2 terrace between the Qishuihe and Weihe rivers. The results showed that 20 palaeoflood events happened in the 4 periods of 4650-4600 a BP, 4400-4300 a BP, 4200-4100 a BP and 3100-3010 a BP since 11500 a BP, respectively. Then their peak discharges were calculated according to the hydrology principle, which greatly prolonged the flood data sequence in the Qishuihe river valley. And the flood frequency curve was established to enhance the reliability to control and reduce flood disasters in this valley. This research result is not only practical to the flood control, water resources exploitation and eco-environmental construction for Yangling, a well-known agricultural and high-tech city in Northwest China, but also fills in the blank of the palaeoflood hydrologic study in the Weihe River Basin, which is of great scientific significance to the comprehensive improvement of the eco-environment of the river basin.
Based upon the 1970 aero-photo topographic map and TM/ETM satellite images taken in 1976, 1991 and 2000, the authors artificially interpret boundary of lake water and glaciers and calculate their areas in different stages with the support of GIS. Results show that from 1970 to 2000, lake area increased from 1941.64 km2 to 1979.79 km2 with a rate of 1.27 km2/a, while glacier area decreased from 167.62 km2 to 141.88 km2 with a rate of 0.86 km2/a. The increased rate of lake area in 1991-2000 was 1.76 km2/a that was faster than 1.03 km2/a in 1970-1991, while in the same period of time, the shrinking rates of glaciers area were 0.97 km2/a and 0.80 km2/a respectively. Climatic factors such as air temperature, precipitation, maximum possible evaporation and their values in warm seasons and cold seasons over the past 30 years are analyzed with linkage of the lake and glaciers variations. The results suggest that temperature increasing is the main reason for accelerated melting of glaciers. Lake area enlargement is mainly induced from the increase of glacier melting water, while slight increase of precipitation and obvious decrease of evaporation are also important factors. Regional precipitation and evaporation and their linkages with lake area enlargement need to be thoroughly studied under the global warming and glaciers retreating.
Taking the source region of the Yellow River as a study area and based on the data from Madoi Meteorological Station and Huangheyan Hydrological Station covering the period 1955-2005 in the study area, this paper analyses the changing trends of surface water resources, climate and frozen ground and reveals their causes. Some conclusions can be drawn as follows: (1) Results show there exist frequent fluctuations from high to low water flow in recent 51 years. Generally speaking, the discharge has shown a declining trend in the 51 years especially since the 1990s. The annual distribution shows one peak which, year on year is getting smaller. (2) Precipitation has a significant and sustained influence on discharge. (3) A sharp rise of temperature in the source region resulted in the increase of evaporation and the decrease of discharge supply, which has a greater effect than on ice-snow melting, as indicated by the fact that the rising spring temperatures played the most important role in this process. (4) Frozen ground tends to be degraded markedly. Permafrost is impermeable so there is a negative correlation between the thickness of the active layer and permeability, whereas there is a significant positive correlation between the permafrost thickness and the discharge. (5) Evaporation rates are significantly increasing, leading to the decrease of discharge. (6) 70% of the discharge reduction resulted from climate change, and the remaining 30% may have been caused by intensified human activities. The major factors influencing the discharge are, in the order of their effects, frozen ground, precipitation, evaporation and temperature. It is evident that permafrost is of utmost importance in the formation and development of surface water resources in the source region of the Yellow River.
This paper examines quantitatively farmers' vulnerability to flood in the Poyang Lake Region (PLR) using GIS technique. The spatial unit for this analysis is township. The analysis consists of three major steps. First, the spatial extent and characteristics of flood risk areas were determined using a digital elevation model (DEM) derived from a 1:50,000 topographic map. Second, for each of the township values of six indices reflecting the economic activities of local farmers were computed. These indices are: percentage of rural population, percentage of farmland, GDP per acreage, percentage of employment in the first industry, net income per farmer and percentage of agricultural income. The values of these six indices were then normalized and used for vulnerability assessment. Third, the normalized indices (as GIS data layers) were overlaid with the flood risk areas to obtain the risk coefficient of each township and to calculate the overall vulnerability of each township. The analysis results show that there are large-scale flood risk areas which have a great impact on livelihood of the farmers in the PLR. 55.56% of 180 townships among flood risk areas have a high degree of vulnerability to flood. These townships stand at the lakefront around the Poyang Lake and the alongshore zones at the 'Five Rivers'.
