River’s healthy life is a description of their living conditions, and it is also a comprehensive assessment of river’s functions and relations with the human society. Through analyzing the demands of human being and river ecosystem, the continuous flow, safe river channel for water and sediment transportation, good water quality, sustainable river ecosystem and water supply capacity are regarded as symbols of the healthy Yellow River. Minimum flow, maximum flood discharging capacity, bank-full discharge, transverse slope of floodplain, water quality degree, wetlands area, aquatic ecosystem, and water supply capacity, altogether eight quantitative indicators are set as symbols of healthy Yellow River, and their corresponding standards are determined based on the analysis with historical hydrological data and observed data of 1956–2004.
With the regional population growth, socioeconomic development, more and more attention has been paid to issues on the shared water allocation and the transboundary eco-security conservation during the development of water resources in the international rivers. In this paper, the existing major problems on transboundary waters in different sub-regions of Asia, such as water shortage, transboundary waters pollution, fragile eco-environment are discussed. Then, the key scientific issues to be concerned in the next study progress on the basis of the analyses of the new research directions and focus fields are raised: (1) unpredicted changes of the hydrologic and water system, and their impacts on the allocation of the sharing waters by global changes; (2) models of the international cooperation on the international rivers on the studies of international and national water laws or regulations, policies, the relative experiences and the case studies; (3) quantificational assessment on environmental flow, available water, and the comprehensive functions and values of the international watercourse system; (4) studies on transboundary aquatic bio-diversity maintenance, transboundary pollution supervision and treatment under the rules and principles accepted by the riparian states; (5) issues on transboundary compensation at the rules of “payments for using”, “payments for harm” and “compensation for benefit”; (6) using advanced 3S techniques to promote the integrated watershed development and management; and so on.
Northwest China includes Xinjiang Ugyur Autonomous Region, Qinghai Province, Gansu Province, Ningxia Hui Autonomous Region and Shaanxi Province, covering 308×104 km2. It is located in the warm-temperate zone and the climate is arid or semi-arid. Precipitation is very scarce but evaporation is extremely high. The climate is dry, the water resources are deficient, the eco-environment is fragile, and the distribution of water resources is uneven. In this region, precipitation is the only input, and evaporation is the only output in the inland rivers, and precipitation, surface water and groundwater change with each other for many times, which benefits the storage and utilization of water resources. The average precipitation in this region is 232 mm, the total precipitation amount is 7003×108 m3/a, the surface water resources are 1891×108 m3/a, the total natural groundwater resources are 1150×108 m3/a, the total available water resources are 438×108 m3/a, and the total water resources are 1996×108 m3/a and per capita water resources are 2278 m3/a. The water resources of the whole area are 5.94×104 m3/(a.km2), being only one-fifth of the mean value in China. Now, the available water resources are 876×108 m3/a, among which groundwater is proximate 130×108 m3/a.
Based on the cost-benefit data (1980–2002) of farm products and China Agriculture Yearbooks, this paper studies the regional disparity in the changes of the agricultural land use in China during the period 1980–2002 from three aspects such as the degree of intensity, the sown area and the abandoned farmland. The results show that: (1) The degree of intensity of land use in the western region during 1980–2000 has a strong uptrend, but in the eastern and central regions the degree of intensity descends obviously and has shown a continuous downtrend since 1997. (2) The total sown area shrinks notably in the eastern region, while it enlarges constantly in the western region. (3) The sown area in the eastern, central and western regions has gone through a similar cyclic process: down (1980–1985)–up (1985–1991)–down (1991–1994)–up (1994–1999)–down (1999–2002). However, there are obvious differences in amplitude variation and tendency among them. The sown area has shrunk in the eastern region and expanded in the central and western regions especially before 1999. (4) The most cases of abandoned farmland are reported in the central region, the second in the eastern region and the least in the western region. The abandonment phenomena chiefly occurred during 1992–1995 in the eastern region, and during 1998–2002 in the central region.
1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China; 2. College of Resources and Environment, Southwest University, Chongqing 400716, China; 3. Institute of Tibetan Plateau Research, CAS, Beijing 100085, China)
Based on the data of δ18O in surface snow, snow pits, meltwater and the glacier-fed river water at Baishui Glacier No.1, Mt. Yulong, the isotopic fractionation behaviors in the typical monsoonal temperate glacier system in winter and summer were compared. The results indicate that the isotopic fractionation degree in summer is greater than that in winter, suggesting that the snow/ice melting is more intense in summer. Moreover, whenever it is in winter or summer, from surface snow to meltwater, and to glacier-fed river water, the gradient of δ18O with altitude gradually increases. This shows that the degree of isotopic fractionation gradually strengthens when surface snow is being converted into meltwater and finally into glacial river water, which suggests that the influence of post-depositional processes on δ18O gradient in the monsoonal temperate glacier region differs spatially.
Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity (NPP). We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement (R2 = 0.85, P<0.001) between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to arid ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.
Using monthly average, maximum, minimum air temperature and monthly precipitation data from 5 weather stations in Mt. Qomolangma region in China from 1971 to 2004, climatic linear trend, moving average, low-pass filter and accumulated variance analysis methods, the spatial and temporal patterns of the climatic change in this region were analyzed. The main findings can be summarized as follows: (1) There is obvious ascending tendency for the interannual change of air temperature in Mt. Qomolangma region and the ascending tendency of Tingri, the highest station, is the most significant. The rate of increasing air temperature is 0.234 oC/decade in Mt. Qomolangma region, 0.302 oC/decade in Tingri. The air temperature increases more strongly in non-growing season. (2) Compared with China and the global average, the warming of Mt. Qomolangma region occurred early. The linear rates of temperature increase in Mt. Qomolangma region exceed those for China and the global average in the same period. This is attributed to the sensitivity of mountainous regions to climate change. (3) The southern and northern parts of Mt. Qomolangma region are quite different in precipitation changes. Stations in the northern part show increasing trends but are not statistically significant. Nyalam in the southern part shows a decreasing trend and the sudden decreasing of precipitation occurred in the early 1990s. (4) Compared with the previous studies, we find that the warming of Mt. Qomolangma high-elevation region is most significant in China in the same period. The highest automatic meteorological comprehensive observation station in the world set up at the base camp of Mt. Qomolangma with a height of 5032 m a.s.l will play an important role in monitoring the global climate change.
As the “Third Pole” of the world, the Tibetan Plateau has important effects on climate of its surrounding areas and even the whole world. Many results have been achieved on climate change since the last inter-glacial period in recent decades from ice core, tree-ring and lake sediment records over the Tibetan Plateau. In this paper, we review these achievements, especially those in the special periods. During the last inter-glacial period, temperature went down rapidly and went up slowly. The temperature record of the last glacial period is consistent with Greenland ice core records, also having own features over the Tibetan Plateau. Younger Dryas event agrees with the records from Europe and Greenland. Generally speaking, it is warm in the Holocene, and temperature has been rising gradually in the last 2000 years and gone up rapidly in recent decades. Climate changes on different time scales on the Tibetan Plateau occurred earlier and the change amplitude is larger than those in other parts of China.
The spatial distribution and monthly/annual variation of foggy days in China are analyzed based on the monthly mean fog data collected from 604 observational stations for the period 1961–2000. Results show that there are six fog regions in China: the middle reaches of the Yangtze River, coastal areas, Yunnan-Guizhou Plateau, eastern Gansu–Shaanxi region, Huaihe River valley, Tianshan mountainous area and northern Xinjiang. On the whole the interannual variation trend of foggy days is descending, especially an obvious decline after the 1980s. The areas where the foggy days have obvious tendency present a southwest-northeast direction. The rising trend regions alternate with descending trend regions, forming a SE-NW directional wave structure. In general, the number of foggy days in autumn and winter is larger than in spring and summer over most fog regions. The monthly variation curves of foggy days are bimodal in the coastal area of the Yellow Sea and northern Xinjiang, and unimodal in other regions.
The agricultural climate risk in the geographical transitional zones is very sensitive to climate change. Based on previous researches, this article established the cotton climate suitability model and the risk index to analyze the cotton climate risk degree in Henan Province. The result shows that, in the last 40 years, the cotton climate risk degree has a gradual increasing trend in which the precipitation plays a very important role, and the climate suitability and its deviation have different performances in the influence on the risk change in different phases; the increase rate of risk degree has significant regional and transitional characteristics, for example, from the eastern plain to the western mountains, the risk change rate becomes slower and slower, so the contrast between the central-southern Huang-Huai plain and the Funiu mountains is the most remarkable; and in the north-south direction, the contrast between the fast increase belt from the central-southern Huang-Huai plain to the middle Yellow River and the slow increase belt near the Yellow River is particularly remarkable, which is possibly the results of topographic and climatic transitional belt; and the risk change process also has obvious regional difference. For instance, abrupt change is an important characteristic in eastern Henan where this sudden change type has notable latitudinal difference, while in the western mountainous area it is very rare. Although the temperature change over the 40 years is still increasing in this area, the trend has reduced gradually since the end of the 1980s.
Chinese National Committee for the International Human Dimensions Programme on Global Environmental Change (CNC-IHDP) is a newly founded academic organization in China aiming at promoting the research on Human Dimensions of Global Environmental Changes (HDGEC). International cooperation is an important part of CNC-IHDP’s activities. This paper makes a brief review on current international cooperation that has been developed, and introduces some aspects on which to focus in future.
The Tibetan Plateau (TP) plays a unique role in Earth System Sciences. It represents a key area to understand not only basic geodynamic processes linked with the formation and uplift of mountains and plateaus, but also the interaction between plateau uplift and environmental changes. Over the last 50 million years the formation of the TP has considerably influenced the global climate and monsoon system. Moreover, the TP proves to be extremely sensitive to present-day global change phenomena. Based upon the foundation of the new Institute of Tibetan Plateau Research (ITP) by the Chinese Academy of Sciences (CAS) and through the Memorandum signed by the CAS and DFG (Deutschen Forschungsgemeinschaft), both CAS and DFG provide opportunities to intensify TP research and to develop coordinated research programs. “The Tibetan Plateau – Geodynamics and Environmental Evolution” consisting of one big projects funded by CAS and five projects funded by DFG that cover the pre- and early-collision history of the TP, the Palaeogene/Neogene uplift and climatic dynamics as well as the Late Quaternary and recent environmental and climatic changes on the TP. The projects are linked through several levels of interactions.
It has been widely accepted that human activities, especially burning fossil fuels and land use change, have altered the climate on earth and anthropogenic carbon fluxes have become comparable in magnitude with the natural fluxes in the global carbon cycle. The present and potential threat of adverse consequences has focused the attention of the scientists, policy makers and general public on the interaction among carbon cycle, climate change and human system. Asia is a hot spot from environmental change and sustainable development perspectives. The development pathways and environmental changes in the region have obvious consequences for the regional carbon cycle, even for global carbon budget, and the complex, diverse social, economic and environmental conditions make it highly difficult to understand and quantify these consequences. The GCP Beijing Office “will have a supporting and coordinating role and will provide coordination, leadership and capacity building on carbon cycle sciences in China and to the larger region of Asia” and “liaise with the two International Project Offices based in Canberra and Tsukuba to coordinate a regional and global strategy consistent with the GCP Science and Implementation Framework”.
Since 2001, the French and Chinese researchers have done a cooperative research on the comparison of integrated development of large river basins. The Yangtze River was chosen as a crux of this research and linked with other older river experiments like the Rhone, the Nile and the Mississippi. This research includes not only the environmental issues but also economic and social issues. One special issue journal has been published in French for our research results. Other two collective and comparative books in French and Chinese will be finished at the end of this year. In the future, the comparison should be widened to Italy (the Po), Egypt (the Nile development planning) and the United States (the Mississippi Basin) and we would like to enlarge our research group and want to link up different teams and research projects, in order to get a global understanding of large river regions phenomenon.