Solar radiation is a key factor in most climate processes. In surface hydrology, it controls the energy balance of the catchment, thus deeply influences the water balance. In this paper, the temporal and spatial variations of solar radiation and the cause of the variation have been analyzed based on meteorological data obtained from 46 national meteorological stations and aerosol index data from TOMS in the Haihe River Basin and surrounding areas. The results show that solar radiation and direct radiation significantly decreased, while the scatter radiation increased during the period 1957-2008. In terms of solar radiation, the densely populated areas have a greater decreasing trend than the scarcely populated ones. The spatial distribution of the increase in aerosol index is consistent with that of the decrease in aerosol index. The increase in aerosol resulting from human activities is the important reason for the decrease in solar radiation.
Since the 1970s, some meteorological observation stations in China 'entered'into cities passively due to urban expansion. The changes in underlying surface and building environment around the stations have had influences on the observation of air temperature,leading to overestimation on the regional air temperature. In this study, the surface underlying 756 meteorological stations across China was firstly identified based on the MSS images of the 1970s, TM images fore-and-aft 1990, and ETM images fore-and-aft 2000 and 2005, to distinguish the stations that 'entered' into cities. Then, after removing the observed data at these stations influenced by urban expansion, we built a dataset of background air temperature by interpolating the observed data at all the left stations. The average Urban Heat-island Intensity (HI) since 1970 was estimated by comparing the two datasets. The results show that overestimation on regional air temperature does occur due to urban expansion, with higher HI in autumn and winter than in spring and summer. Spatially, the overestimation is relatively higher in eastern China than in the middle part of China, however it is much higher in the above two regions than in western China. In the last 40 years the average temperature in China increased by about 1.58 oC, among which about 0.09 oC was attributed to urban expansion in some regions.
Yuxi and Dajiuhu profiles in the Three Gorges Region are chosen in this study, and based upon AMS14C dating (calibrated CY), we establish the high-resolution curves of various proxy indicators (δ13C, K, humification coefficient, total concentration of spore-pollen, Rb, Sr and Rb/Sr) during 9.3-2 kaBP. Besides we synthetically compare and analyze the records of climatic and environmental changes in Holocene sediments in the surrounding areas, we also obtain the materials of prosperity, decline and transition of ancient culture as well as the flood information from the Neolithic Age to historical periods by making statistical analysis of archaeological sites and paleoflood layers of the study area. The results show that: (1) Megatherma in Holocene appeared during 7.6-4 kaBP in the Three Gorges Region. During 9.3-7.6 kaBP, the climate in the study area was very unstable, drastically fluctuating, wet-cold in general, occurring cold or arid events more than once (approximately 9.1, 8.2 and 7.7 kaBP). During 4-2 kaBP, the climatic fluctuation was frequent, and trending slightly cold-dry than before. (2) The Megatherma during 7.6-4 kaBP can be divided into three stages: namely 1) the stage of 6-5 kaBP was the prime of Megatherma, when the climate was stable, warm-wet, with predominent vegetation and ecological environment as well as low frequency of flood events; 2) the stages of 7.6-6 kaBP and 5-4 kaBP were the transition periods with unstable characteristics in Megatherma, among them, during 5-4 kaBP as well as around 4 kaBP, the cold events were still remarkable and the flood events were also frequent. (3) The formation and development of ancient culture in the study area in prehistoric period was mainly corresponding to Megatherma, Daxi culture that the planting industry was the most prosperous appeared in the prime (6-5 kaBP) of Megatherma, other types of ancient culture before and after Daxi culture which were at the low tide or showing decline corresponded to the stages that the climate and environment were unstable. Response of ancient culture in study area to the climatic and environmental changes was achieved through altering the modes of subsistence.
Since the early 1900s, a tendency for some monsoonal temperate glaciers retreat has been observed in the Hengduan Mountains region. Against the background of climate change, 7 monsoonal temperate glaciers were in a stationary or an advancing state between the 1900s-1930s and the 1960s-1980s, and they were in a retreat state during the 1930s-1960s and from the 1980s to the present, which is consistent with the climatic fluctuations of China, the Northern Hemisphere and Hengduan Mountains region, and these glaciers were steady or advanced when the climate was characterised by cold-dry and vice versa. The variational extent is different among 7 glaciers owing to the locations and scales. The ablation water equivalent of glacier tongue in Dagongba Glacier, Xiaogongba Glacier and Hailuogou Glacier is 2710 mm, 3139 mm and 5281 mm in 1982/83, respectively, and the mean value in Hailuogou Glacier is 6157 mm during 1990/91-97/98, which is 876 mm more than that in 1982/83. The ablation of Baishui Glacier No.1 was in decline with the rise of altitude owing to the less debris cover in the summer of 2002. Based on the mass observation during 2008.9.19-30, the glacier started to accumulate after October 6, and the accumulation depth is 1 cm equal to 5 mm water equivalent per day during 9.30-10.13.
Based on the surface runoff, temperature and precipitation data over the last 50 years from eight representative rivers in Xinjiang, this paper, using the method of Mann-Kendall trend and jump detection, investigated the long-term trend and jump point of time series of surface runoff, mean annual temperature and annual precipitation. Besides, this paper analyzed the relationship between runoff and temperature and precipitation, and the frequency and peak flow of floods. Results showed that all parts of Xinjiang had experienced an increase in temperature and precipitation since the mid-1980s. Northern Xinjiang is the area that saw greatest change, followed by southern Xinjiang and eastern Xinjiang. Affected by temperature and precipitation variations, river runoff had both inter-annual and inner-annual changes. The surface runoff of most rivers had increased significantly since the early 1990s. And some of them had the phenomena of spring floods appearing ahead of time, summer floods lagging behind and flood peaks increasing. The variation characteristics were closely related with the replenishment types of rivers. The flood frequency and peak flow increased all over the Xinjiang region. Climate warming has had an effect on the regional hydrological cycle.
Based on the measured hydrological data from 1951 to 2008, the linkage hydrological effect between Jingjiang River and Dongting Lake was analyzed by comparative method after the operation of Three Gorges Project. Firstly, the results showed that the scour amount in Jingjiang River was 78.9% of the total scour amount from Yichang to Chenglingji, and that its average scour intensity was higher than the total scour intensity from Yichang to Chenglingji, too. Secondly, the dividing-water and dividing-sand ratios in the three bayous of the Jingjiang River were reduced by 2.33% and 2.78% separately. Thirdly, the average runoff and sediment in the three bayous flowing into the Dongting Lake were reduced by 7.7% and 24.4%, respectively. Fourthly, the speed of sediment filling-up was lowered by 26.7%, which would prolong natural life of the Dongting Lake. In flood season, the runoff amount of the Jingjiang River flowing into the Dongting Lake was 20.2% less than the multi-year average value. The decreases of runoff amount induced droughts in summer and fall, as well as shortage of drinking water and industry water, shipping safety, similarly led to the decrease of birds and the increase of the oriental field mice. Finally, the multi-year average values of sediment and flood discharge capacity in bayous were respectively increased by 26.6% and 3.7%, which protected embankment effectively.
In order to find out the variation process of water and sediment and its effect on the Yellow River Delta, this paper, by means of statistics, analyzed the water and sediment discharge from 1950 to 2007 at Lijin and the reduction of water and sediment in Yellow River Basin caused by human activities. Results show that the water and sediment discharge into sea decreased from 1950 to 2007 with serious fluctuation. The human activities were the main cause for the reduction of water and sediments into sea. From 1950 to 2005, the multiyear average reduction of water and sediment by means of water and soil conservation were 2.02×109 m3 and 3.41×108 t, respectively, while the multiyear average usage of water and sediment for industry and agriculture were 2.52 × 1010 m3 and 2.42 × 108 t, respectively. From 1960 to 2007, the multiyear average sediment silted in the Sanmenxia Reservoir was 1.45×108 t and that silted in the Xiaolangdi Reservoir was 2.398×108 t. Compared to the data of Huayuankou, in the lowere reaches, the water and sediment discharge into sea decreased with siltation and increased with erosion. The coastline near the estuary extended and the delta increased when the ratio of total water and sediment into sea was about 0.0257 t/m3 in different periods.
The forefront of physical geography research is driven by social needs. The global concern on resources and environment issues and major issues facing sustainable development of China has a series of demands for physical geography. International Geosphere-Biosphere Program, International Human Dimensions Program of Global Environmental Change, World Climate Research Program, Biological Diversity Program and Earth System Science Partnership contain the forefront of physical geography research. China's State Key Basic Research Program, the priority area of development of Earth Sciences Department of National Natural Science Foundation of China, State Science and Technology Support Program etc. have conducted a series of cutting-edge physical geography research. A number of new methods and techniques for physical geography research have emerged in data collection, model simulation, laboratory analysis, studies on physical geographical processes and environmental change and global physical geographical research.
In recent years, promoted by tremendous demands from national economic construction, great progress has been made in geomorphology and Quaternary geology in China. This article generalizes the recent progresses, mainly those in the period 2006-2008, including the progress in the fields of tectonic landforms, fluvial landforms, eolian landforms, glacial landforms, estuary and coastal landforms and Quaternary environmental evolution. Furthermore some suggestions are proposed to develop the discipline in the following aspects: (1) Studies of basic theories; (2) Research into applied geomorphology and Quaternary geology concerning the key construction projects; (3) Experimental studies, both in laboratories and in field surveys; (4) Training of young geomorphologists and Quaternary geologists.
Wetland research in landscape ecology, as a new hot field in recent years, has resulted in the development of wetland science. However, wetland research on landscape scale is a complex process which integrates wetland ecology with landscape methodology. So some problems have emerged in the development of wetland in landscape research, and significantly blocked the progress for wetland research in advance. This paper elaborates the current situation and problems in landscape studies on wetlands, and discusses future of wetland research in landscape ecology. We believe that wetland research into landscape ecology is still the main field in conservation and rational utilization of wetlands. Especially, we have obtained latest conclusions in landscape structure and pattern, process and function, evaluation and management of wetlands. But some new problems are increasingly emerged, including the concept of wetland landscape, classification, precision of information of wetlands from remote sensing imagine, application of multi-scale data, methodology of structure and pattern and scale choice for process and function of wetlands. How can we solve these problems, and how can we apply the theory of landscape ecology to the practice of wetland research? In future, five aspects are to be addressed: (1) to focus attention on wetland classification system with special ecological characteristics and distribution features in a given geographical condition; (2) to strengthen studies on landscape fragmentation of wetlands to exhibit changes in landscape patterns of wetlands impacted by human activities; (3) to develop new methodology for landscape patterns by integrating ecological process and functions of wetlands; (4) to conduct multi-scale biodiversity of wetlands study to exhibit maintaining capacity of wetland landscape in different patch-corridor-metrics models influenced by natural or human activities in a given region; and (5) to place emphasis on landscape management research in applying principles of pattern-process-function for conservation, planning and design of wetlands.
