According to the analysis of the climate materials including the topographic map in 1975, the TM and CBERS satellite remote sensing materials from the 1980s to 2005 as well as the air temperature, precipitation, evaporation rate, maximum depth of snow and the biggest depth of frozen soil in the past 45 years, the water level area of four lakes at the southeast of Nagqu, Tibet including Bam Co, Pung Co, Dung Co and Nuripung Co show a distinct trend of expansion in the past 30 years. In 2005, the water level area of the above four lakes increased by 48.2 km2, 38.2 km2, 19.8 km2 and 26.0 km2 respectively compared to 1975, with the respective increase rate of 25.6%, 28.2%, 16.2% and 37.6%. That is closely related to the warming and humidified climate change in the recent years such as rise of the air temperature, increase of the precipitation, decrease of the evaporation rate and permafrost degradation.
Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index (SPI) based on monthly precipitation data for 1873–2005. The SPI on scales of 3, 6, 12 and 24 months has been calculated. The SPI on 3, 6, 12 and 24 months present 4 wet periods prevailed during 1873–1885, 1904–1923, 1938–1960 and 1983–2005, and 3 dry episodes during 1886–1903, 1924–1937 and 1961–1982. Significant periods of higher wavelet power in the SPI-24 months occurred on the time scales of 2–7-year band in around 1880–1890, 1910–1950 and 1970–1990, and at 8–15-year band in 1920–1960 and 1965–2000 respectively. Periodicities in the SOI and ENSO indices are similar to those in SPI-24 months with little difference, namely, in the SPI-24 months, there are significant periods at the 2–7- and 8–15-year bands during 1930–1940. The periodicity components in individual SPI-24 months, SOI and ENSO indices are more complicated, showing the wetness and dryness variability in Shanghai is controlled by more than one physical factors. The research results indicate that the Shanghai area has experienced dryness and wetness variability on different time scales during the past 133 years.
The characteristics of water vapor transport (WVT) over China and its relationship with precipitation anomalies in the Yangtze River Basin (YRB) are analyzed by using the upper-air station data in China and ECMWF reanalysis data in summer from 1981 to 2002. The results indicate that the first mode of the vertically integrated WVT is significant whose spatial distribution presents water vapor convergence or divergence in the YRB. When the Western Pacific Subtropical High (WPSH) is strong and shifts southward and westward, the Indian Monsoon Low Pressure (IMLP) is weak, and the northern part of China stands behind the middle and high latitude trough, a large amount of water vapor from the Bay of Bengal (BOB), the South China Sea (SCS) and the western Pacific forms a strong and steady southwest WVT band and meets the strong cold water vapor from northern China in the YRB, thus it is likely to cause flood in the YRB. When WPSH is weak and shifts northward and eastward, IMLP is strong, and there is nearly straight west wind over the middle and high latitude, it is unfavorable for oceanic vapor extending to China and no steady and strong southwest WVT exists in the region south of the YRB. Meanwhile, the cold air from northern China is weak and can hardly be transported to the YRB. This brings on no obvious water vapor convergence, and then less precipitation in the YRB.
In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation (CHNIP). During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O. The established local meteoric water line δD=7.42δ18O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region. The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions. The monthly δ18O values were characterized by a positive correlation with surface air temperature (δ18O (‰) =0.33 T (℃)–13.12). The amount effect visualized during summer period (δ18O (‰) = –0.04P (mm)–3.44) though not appeared at a whole yearly-scale. Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China. The quantitative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops. Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor. Multiple linear regression equations and a δ18O–T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data. The established δ18O–T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.
The groundwater level of 39 observation wells including 35 unconfined wells and 4 confined wells from 2004 to 2006 in North China Plain (NCP) was monitored using automatic groundwater monitoring data loggers KADEC-MIZU II of Japan. The automatic groundwater sensors were installed for the corporation project between China and Japan. Combined with the monitoring results from 2004 to 2006 with the major factors affecting the dynamic patterns of groundwater, such as topography and landform, depth of groundwater level, exploitation or discharge extent, rivers and lakes, the dynamic regions of NCP groundwater were gotten. According to the dynamic features of groundwater in NCP, six dynamic patterns of groundwater level were identified, including discharge pattern in the piedmont plain, lateral recharge– runoff–discharge pattern in the piedmont plain, recharge–discharge pattern in the central channel zone, precipitation infiltration–evaporation pattern in the shallow groundwater region of the central plain, lateral recharge–evaporation pattern in the recharge-affected area along the Yellow River and infiltration–discharge–evaporation pattern in the littoral plain. Based on this, the groundwater fluctuation features of various dynamic patterns were interpreted and the influencing factors of different dynamic patterns were compared.
Competitive use of transboundary freshwater resources is becoming one of the key factors influencing regional peace and political relationship among states. In China, 18 major international river basins are concentrated in three regions, of which the total annual outflow at the border is 7320×108 m3, occupying 26.8% of the total annual runoff of China, and the inflow at the border is only 172×108 m3. In this paper, we analyzed the major drivers affecting shared water vulnerability in China, namely: (1) changes in physical conditions affecting the availability of water; (2) competing objectives between economic development and ecological conservation; (3) lack of emergency response mechanisms; (4) unsound administrative institutions; and (5) shortcomings in the development of regional cooperation based on transboundary waters. We concluded by identifying four pathways for reducing vulnerability: (1) encouraging scientific research cooperation; (2) constructing information-sharing channels; (3) establishing early-warning mechanisms; and (4) promoting further coordination and negotiation.
Eco-geographic regional system is formed by division or combination of natural features based on geographic relativity and comparison of major ecosystem factors (including biological and non-biological) and geographic zonality. In previous studies, soil types were often taken as a basis for soil regionalization. However, the quantitative characteristics of soil indicators are fitter than the qualitative ones of soil types for modern regionalization researches. Based on the second China’s national soil survey data and the provincial soil resource information, by principal analysis and discriminant analysis, this paper discusses the appropriate soil indicators as the complement of eco-geographic region indicator systems and the relationships between these soil indicators and soil types in regionalization. The results show that five indicators are used in eco-geographic zonality in mid-temperate zone of eastern China which are organic matter content, cation exchange capacity, pH, clay content and bulk density in topsoils. With a regression-kriging approach, the maps of soil indicators in mid-temperate zone of eastern China are compiled with a resolution of 1 km in every grid and the indicative meanings of these soil indicators are discussed. By cluster analysis it is proved that these soil indicators are better than the soil types and soil regionalization in delineating eco-geographic regions.
Urbanization has been the most important process that changed land cover landscape in Guangzhou since reformation, especially since 1990. It is essential for monitoring and assessing ecological consequences of urbanization to understand landscape quantitative characteristics and its changes. Based on four land-cover type maps interpreted from remote sensing TM images of 1990, 1995, 2000 and 2005, combining gradient analysis with landscape metrics, the quantified spatial pattern and its dynamics of urbanization in Guangzhou was got. Three landscape metrics were computed within different regional areas including the whole study area, two transects along two highways (one N–S and the other W–E) and radiation zones with equal distance outwards the city center were set. Buffer zones for transects N–S and W–E were outlined along highways. The following questions should be answered in this paper: What responses were implied with changing spatial grain size or extent for landscape pattern analysis? Could gradient progress of urbanization be characterized by landscape pattern analysis? Did landscape metrics reveal urban expanding gradually? Were there directional differences in land cover landscape pattern during urbanizing development? The results gave some affirmative answers. Landscape pattern exhibited obviously scale-dependent to grain size and extent. The landscape metrics with gradient analysis could quantitatively approach spatial pattern of urbanization. A precise location for urbanized area, like city center and sub-center, could be identified by multiple landscape metrics. Multiple adjunctive centers occurred as indicated by analysis of radiation zones around the city center. Directional differences of landscape pattern along the two transects (N–S and W–E) came into being. For example, fragmentation of landscape in the transect W–E was obviously higher than that in the transect N–S. All in all, some interesting and important ecological implications were revealed under landscape patterns of two transects or radiation zones, and that was the important step to link pattern with processes in urban ecological studies and the basis to improve urban environment.
The water quality of Dianchi Lake declines quickly and the eutrophication is getting serious. To identify the internal pollution load of Dianchi Lake it is necessary to evaluate its sediment accumulation. Sedimentation rates of Dianchi Lake are determined by 137Cs dating. However, 137Cs vertical distribution in sediment cores of Dianchi Lake has special characteristics because Dianchi Lake is located on the southeast of the Qinghai-Tibet Plateau, the Kunming quasi-stationary front is over the borders of Yunnan and Guizhou where the specific precipitation is distributed. Besides 1954, 1963 and 1986 137Cs marks can be determined in sediment cores, a 137Cs mark of 1976 representing the major period of 137Cs released from China unclear test can be determined and used for an auxiliary dating mark. Meanwhile Dianchi Lake is divided into seven sections based on the water depth, basin topography, hydrological features and supplies of silt and the lakebed area of each section is calculated. The mean annual sedimentation rates for seven sections are 0.0810, 0.1352, 0.1457, 0.1333, 0.0904, 0.1267 and 0.1023 g/cm2a in 1963–2003, respectively. The gross sediment accumulation of the lake is 26.18×104 t/a in recent 17 years and 39.86×104 t/a in recent 50 years.
On top of Shigujian Peak (1477 m a.s.l.) of the Dayangshan Mountain in Jinyun County, Zhejiang Province, large amounts of granite pits with diameters ranging from several dozens of centimeters to around one meter and depth from 10 cm to 45 cm are found on rock surface. These pits mainly appear on the NE and SE sides, and their drainage mouths are in the same direction. The identification results through micropolariscope and X-ray fluorescence spectrometer reveal that bedrock of pits is from middle to fine-grained moyite being apt to be weathered and modified. In Dayangshan region the annual mean temperature is 9.2℃ and annual precipitation is over 1700 mm. On the one hand, there always experiences a period of periglacial action with temperature oscillating near 0℃ for 4 months, i.e., from December to March next year. As a consequence, the freezing-thawing cycles may be remarkable to disintegrate the bedrock. On the other hand, the windward slope of Shigujian Peak meets typhoon of over force 10 on the Beaufort scale in summer, therefore, the blowing makes suspending sands or pebbles grind in swirling form. Based on field investigation and periglacial geomorphic theory, the pits on top of Shigujian Peak are attributed to freezing- thawing of periglacial action. Meanwhile, storm and strong wind accelerate the process. Observation shows that both the actions are still undergoing and variant directions of wind are the main cause for making different shapes of the pits. Because the top of Shigujian is 1500 m lower than the present snow line, some scholars considered that “glacial pothole” formed in the Quaternary is hard to work, even though in the Last Glacial Maximum (LGM).
The concentrations of heavy metals Ba, Pb, Cu, Zn and Co in snow pit collected in September, 2005 from the accumulation area of the East Rongbuk Glacier (6523 m a.s.l.), which lies on the northern slope of Mt. Qomolangma, were determined by inductively coupled plasma mass spectrometry (ICP-MS). Concentrations (pg/ml) of heavy metals are Ba2-227, Co2.8-15.7, Cu10-120, Zn29-4948 and Pb14-142, respectively. The δ18O was determined by MAT-252. The time period of the snow pit spans from autumn 2005 to summer 2004. Seasonal variations of the concentrations and δ18O are observed, of which Pb, Cu, Zn and Co are much lower in summer monsoon season than that in non summer monsoon season, suggesting that different sources of heavy metals contributed to the site. EFc (crustal enrichment factors) is Co3.6, Cu27, Pb33 and Zn180, respectively. Higher EFc values of Pb, Cu and Zn suggest that Pb, Cu especially Zn are mainly contributed by anthropogenic sources.
