Under the background of human activity and global environmental change, the research of traditional geographical-ecological processes are undergoing fundamental change over the past few decades. Based on the general overview of the research situation, the development and perspective of geographical-ecological processes are discussed in the paper. From the research progress of geographical-ecological processes, it can be inferred that the basic science research issues of geographical-ecological processes include: (1) structure and processes, which consist of structure, function, dynamic, driving forces, processes and mechanism; (2) synthesis and integration, involving elements integration, processes integration, regional integration, and other scientific points. And the studies of geographical-ecological processes focus on the scale-structure-process interactions, natural-economic-social interactions, topographical-hydro-ecological processes mutual coupling, geographical-ecological processes and the combination with resources environmental effects. The research of geographical-ecological processes in the development is showing a systematic, integrated, cross-cutting and applied development trend. And the critical issues of geographical-ecological processes in the future study can be summarized as follows: (1) the processes of materials, energy and biological flows in earth surface systems; (2) the driving forces, procedure, effects of earth's surface environment; (3) regional composition and regional heterogeneity; (4) scale and scaling; (5) holistic synthesis of geography; (6) innovation of methodology; and (7) application of the geographical-ecological processes research. To promote geographical-ecological processes study in the future, more attentions should be paid to the following issues: (1) observation, experimentation, investigation and simulation; (2) integration of remote sensing and field observation; (3) regional integration and global research; and (4) interdisciplinary research.
Based on the analysis of the relationship among environmental flows of river requirements, the efficiency of water resource utilization and the consumption coefficient, and discharge concentration of waste water, the water quantity and water quality calculation method of environmental flows of river requirements in dualistic water cycle is developed, and the criteria for environmental flows of river requirements are established. Taking Liaohe River as demonstration, the environmental flows of river requirements for Xiliao River, Dongliao River, Liaohe River artery, Huntai River and northeast rivers along Huangbohai (Huanghai and Bohai seas) in unitary water cycle make up 39.3%, 63.0%, 43.9%, 43.3% and 43.5% of runoff, respectively. Evaluated according to Tennant recommended flow and grade, the results show that: except Xiliao River which is "median", the rest are all above "good", and even the Dongliao River is "very good". The corresponding proportion of environmental flows for each river in dualistic water cycle is 57.5%, 74.1%, 60.8%, 60.3% and 60.4%, respectively. The combined evaluation results show that evaluated from the angle of "quantity", except Xiliao River, the rest rivers can all achieve the "quantity" criterion of environmental flows requirements, but if evaluated from the angle of "quality", only Dongliao River can meet the "quality" standard, and by water quantity/quality combined evaluation method, only Dongliao River can achieve the criterion.
Water supply of the Karuxung watershed is mainly from melt water and rainfall, therefore both climate warming and precipitation increasing have positive impacts on runoff. Mann-Kendall trend analysis, the Sen's slope estimate and correlation analysis are employed to analyze data from Wengguo hydrometric station and Langkazi meteorological station. The results indicate that runoff, air temperature, precipitation and evaporation all have showed significant upward trends. Of which runoff change is most sensitive to climate change, especially during fall and winter. It is concluded that more trends are observed than are expected to occur by chance. In recent 20 years, the annual mean temperature has increased dramatically with a rate of 0.34 oC every 10 years, which is higher than that of Xizang (Tibet) region which is 0.26 oC every 10 years, and the extremely high temperatures all appeared in the 1990s. For the temperature, the latter 10 years is 0.5 oC higher than the former 10 years, whereas the runoff increased by 26%. Different periods have different growth extents. October to February, July to September and March to June increased by 44%, 27% and 24%, respectively. During ablation period, the runoff change is affected mostly by climate change from April to June, whereas the runoff is affected by climate and precipitation jointly when monsoon comes, and the rainfall influences the runoff with uncertainty. During non-ablation period, runoff change is more obvious for it is influenced by the former months, and its key supply is base flow.
As the representation of the typical river basin of headwater of the Yangtze River, Tibetan Plateau, Dongkemadi River Basin has glacier and snow accumulation. This paper uses the Snowmelt Runoff Model to simulate effects of different divisions of Dongkemadi River Basin to the hydrological process and simulate temperature at different stations as the driving factor to the effects of hydrological simulation, based on the hydrological data and meteorological data observed from May to October in 2005. According to the simulations, a final simulation scheme is selected as the final decision. The simulation result of different divisions of Dongkemadi River Basin shows its effect to the simulation. Simulation using different temperatures as driving factor shows that the SRM model is very sensitive to the effects of different temperatures. The correlation analysis shows that the correlation between runoff and air temperature is relatively good with best linear correlation coefficient reaching 0.72, but it can only reach 0.20 between runoff and precipitation. Based on the simulation and correlation analysis, the appropriate division and representative air temperature are selected to simulate the Dongkemadi River Basin's hydrological process. The coefficient of Nash Sutcliffe (R2) is 0.83 and the volume difference of streamflow is 0.95%. Considering the sensitivity of the SRM model to air temperature, we simulated the relationship among air temperature, precipitation and runoff when the temperature rises by 1oC. The simulation result shows that: (1) The total amount of streamflow in the simulation period changed from 25.5 × 106 m3 to 33 × 106 m3; (2) The glacial mass balance line ascended from 5600 m to 5750 m and the area of ablation in Dongkemadi enlarged from 5.8 km2 to 13.5 km2, so that the contribution of the streamflow from glacial ablation is much greater; (3) because of the rise of air temperature, the speedup of snowmelt and the change of precipitation state are the main reasons of the runoff increase from May to June. The rise of runoff from July to October is mainly caused by the melting of glacier.
Sustainable land use models are prerequisites of sustainable development of regional ecology and economy. It is especially true for arid land areas where environment is wholly fragile thanks to very limited precipitation and where human activities have greatly transformed natural desert system by clearing natural vegetation, expanding oases and even building dams. However, the up-to-data study of land use models is still in a stage of investigation and case study, lacking solid scientific basis. This paper holds that land types and their combination patterns are the principal basis for designing sustainable land use models, and that GIS and RS-based large-scale land type mapping and their spatial combination structure study should be coordinated with the demand of social development and carried out in the near future. The existing environmental problems induced by irrational land use mostly result from their deviation from the natural properties of land types. This paper, taking the northern Tianshan Mountains as an example and considering land type patterns as the basis of land use patterns, improves the vertical oasis and middle mountain two belt development model and mountain land use model for arid land put forward in recent years, and, in terms of oases patterns, outlines oasis development models, including diluvial-alluvial fan intensive land use model, alluvial plain moderate-scale agricultural development model, and river-end oasis ecological use model.
Based on the analysis about actual land-use map of Changsha City in different times, this article analyzed the characteristic of urban spatial expansion of Changsha from time sequence, spatial form and structure evolution systemically by studying indexes such as city land-use structure proportion, expansion intensity index, economy flexibility index, population flexibility index, compaction degree changing index and so on. And then it discussed the dynamic mechanism of urban land expansion by integrating the regional socioeconomic development situation and many aspects such as physiographical environment, population growth and economic development, traffic infrastructure, planning and regional development strategies and system innovation. The research indicated that the urban land expansion speed and intensity got higher step by step in Changsha from 1949 to 2004, the whole trend became more and more reasonable, and the expansion form changed from a single external expansion to a combination form of external and internal expansion, from a circular or linear continuous form to a speckled or clustered discontinuous pattern. Overall, the urban land expansion of Changsha is a phasic, diversified and complex process. And no matter what the stage is, it is an organic system containing multiple speed, pattern and shape, which are driven by multiply impetuses. The dominant features in different stages presented clearly because of balance and fluctuation between different forces, and the existing urban land border and shape were formed finally under the joint efforts of these phasic forces.
Previous study on karst processes was always focused on karstification intensity and its variation under different geological settings, climatic and hydrologic conditions in view of macroscale, or on contribution of carbonate rock weathering to the atmospheric CO2 sink. Lesser attention was paid to impact of land-use types on karst processes. The direction and intensity of karst processes could be deeply affected by soil physical and chemical variations which were resulted from land cover. Taking Nongla Fengcong depression area, Mashan County, Guangxi as an example, the authors discussed the impact of landuse cover on karst processes based on the data of field standard limestone tablet. Almost all the land-use types occurred in a small study area, so the present study is also typical and representative. The results showed that the corrosional ratio at varied soil depth is quite different. Corrosional ratio in woodland and orchard is mostly bigger than 20mg/a, which is much higher than that in cultivated land and shrubs. Generally, corrosional ratio decreased from orchard, woodland, tilled land, fallow and shrubs successively, in which soil organism and soil CO2 are two major controlling factors: corrosion process is controlled remarkably by soil organism in woodland and orchard, the higher the organism content is and the less the pH value is, the higher the corrosional ratio is. Owing to lower organism content, the corrosional ratio affected mainly by soil CO2 in tilled land and shrubs. The impacts of land-use types on karst processes could be active to improve corrosional rate, for example organic fertilization in orchard resulted in soil organic matter increase; or negative to retard corrosional rate, for example surface disturbance in tilled land resulted in soil porosity increase and CO2 emission. Moreover, organism activities and their offspring could be the most active factor, vegetation succession can improve the three-phase condition of karst dynamics system, and thus accelerate the karst processes. Accordingly, the results of this paper have significance of protecting karst fragile soil resources and readjusting land-use structure in Fengcong mountainous area.
The spatial and temporal variability of ocean primary productivity in the China seas from 2003 to 2005 was estimated by size-fractionated primary productivity model. Satellite primary productivity showed spatial and temporal variability. Annual averaged primary productivity levels were 564.39, 363.08, 536.47, 413.88, 195.77 and 100.09 gCm-2a-1 at the Bohai Sea, the northern Yellow Sea (YS), the southern YS, the northern East China Sea (ECS), the southern ECS, and the South China Sea (SCS), respectively. Peaks of primary productivity appeared twice, in spring (April to June) and fall (October and November), in the northern YS, southern YS and southern ECS, while a single peak (June) appeared in the Bohai Sea and northern ECS. Two peaks of primary productivity also appeared in the SCS, one was in winter (January) and the other in summer (August), and the peak in winter was far higher than that in summer. The monthly averaged primary productivity from 2003 to 2005 in the Bohai Sea and southern YS was higher than that in the other four areas during most months, while that in the southern ECS and SCS was lower than that in the other four areas the whole year. The primary productivity during spring period (March to June in the southern ECS and April to July in the other five sea areas) contributed about 41% on average to the annual primary productivity in the above five areas except SCS. Furthermore, satellite primary productivity during that period showed an interannual variability that was also the largest, and the averaged standard deviation was 6.68. Meanwhile, the contribution during fall period (October to January in the southern ECS and August to November in other sea areas) was about 33% on average; and the primary productivity during this period also showed an interannual variability. However, in SCS, the contribution during winter period (December to March) was the highest (about 42%), while that during spring period (April to July) was the lowest (28%). But SCS and the other five areas have one thing in common: the larger the contribution, the larger the interannual variability.
The river terraces of the Changjiang River in the Three Gorges Reservoir area are key to the study on the evolution of the water system of the Chuanjiang River and the Xiajiang River. These terraces mainly develop in the western part of the reservoir area, i.e., the hill and low mountain region in the eastern part of Sichuan. Up to 6 levels of terraces are identified. The main problem encountered in terrace related studies is the lack of reliable temporal controls on the terrace formation. We measured the terrace ages by using the TL and ESR methods. The results show that the ESR method is likely unsuitable for dating fluvial sediments in the Three Gorges Reservoir area. Although the TL method has intrinsic flaws, the ages of terrace T1-T4 given by this method are supported by independent dating results. The TL ages of terrace T1-T4 are estimated to be 7-17 ka, 28-46 ka, 62-81 ka and 103-105 ka respectively. In addition, we infer that terrace T4 is older than 101 ka, terrace T5 older than 392 ka and terrace T6 younger than 780 ka based on the chronostratigraphic and the reported paleomagnetic study. Consequently, an approximate time series of terrace accumulation is established.
The Huangqihai Lake, a small enclosed lake in Inner Mongolia of China, lies at the northern boundary of Eastern Asian Summer Monsoon and in the central part of Asian Winter Monsoon. Thus, its lacustrine sediment sensitively recorded the climate change of the above two monsoon systems. Based on the geochemical elements Rb and Sr of three different grain size fractions sediment from profile H3 on the northern lacustrine bottomland 13 m above the Huangqihai Lake surface in 1986, this paper investigates the record of palaeolake stand state, sedimentary environment evolution, and winter monsoon change. First, these samples are divided into three different grain size fractions, i.e., total sediments, 77-20 μm and < 20 μm. Second, the chemical elements, Rb and Sr of the grain size separation, are tested and analyzed systematically in this paper. Then these elements compositions of these samples are measured using VP-320 mode fluorescence spectrum instrument, respectively. The magnetic susceptibilities of these samples are measured using Kappabridge KLY-3 mode instrument made in Czech AGICO Company. The results showed the elements of Rb and Sr and the ratios of Rb/Sr vary regularly with the grain size. But the ratios of Rb/Sr in the sediments with < 20 μm correlate positively with the magnetic susceptibility of these samples. Therefore, the ratios of Rb/Sr in the fraction < 20 μm from the lake sediments reflect the weathering intensity in the deposition sites. It is a good indicator of the summer monsoon-induced weathering and pedogentic fluctuations and can be used to reconstruct the conditions of the paleoclimate and paleoenvironment.
