Based on the statistic agricultural data with a county resolution and monthly mean temperature and precipitation data at 730 national basic weather stations for the period 1985-2004, it is focused in this paper to identify the susceptible regions to climate change on grain yield per unit. The following main conclusions can be drawn. (1) The linearity trends of grain yield per unit sown-area have increased remarkably in most regions since 1985, especially in northern China. Canonical Correlation Analysis (CCA) reveals that this kind of spatial pattern has high correlation with the change of temperature from April to October (α = 0.01). The impacts of precipitation change are less than those of temperature change in the corresponding period. Most notable yield-increased regions sensitive to the temperature change in April to October are located at the climate transitional zones in China. The fluctuation of temperature, as well as that of precipitation, plays important roles in changes of grain yield per unit sown-area. (2) 137 in 240 districts where the linearity trends of grain yield per unit sown-area are significantly (α = 0.05) subject to the changes of temperature from April to October analyzed by cointergration (EG-test), and most of them are located in the transitional zones of topography and the Changjiang River Valley. (3) There are 41.6% of valid statistic districts where grain yield is subject to both the changes of temperature from April to October and precipitation from May to September analyzed by cointergration (EG-test). Most of them are distributed in the three kinds of regions, with the largest one lying between the borderline of summer monsoon and the sideline of Chinese population geography from the Heihe City in Heilongjiang Province to Tengchong City in Yunnan Province, in which food shortage regions are superior in numbers; grain yield per unit shows high fluctuation with the stable amount of sown-area in Jilin, eastern Liaoning, Henan and Anhui, of which the amount of grain production is susceptible to climate change and are main grain-surplus regions in China. It shows that the stability of food production in China has declined in these regions over recent 20 years due to climate change in the corresponding period.
At present, there is no uniform standard of forecasting system and serving products for first-frost date forecasting studies and operations in China\'s meteorological departments in spite of agricultural autumn harvests depending greatly on the first frost occurring earlier or later in northern China, which restrained the development of prediction studies and operations on the first-frost dates. Therefore the study aims at the above problems and analyzes 3 aspects of them. The first is about the discrepancy analyses of the three kinds of first frost date data, in which two of them are defined by surface ground temperature and air temperature from instrument shelter, respectively, and the other data are from observing first frost dates. And then the study enlarges the number of the representative stations in northern China (north of 30oN) of National Climate Center operation from 65 in the past to 233 at present for improving the spatial resolving power of the prediction products. The second is the analyses of the climate features of the first frost dates based on the aforementioned surface ground temperature data of the 233 stations from 1961 to 2008. Finally, the study shows that it is outstanding for the significant effects of the climatic variability of the first frost dates on single outputs of rice and maize separately in Heilongjiang Province, as long as without the continuing and lasting cold days before the autumn, whereas the effects from anomalous air temperature before the autumn, for example from cool summer, are dominant.
Based on the fog, haze, air temperature and dew point temperature data of 449 weather stations, the land use data in 1980 and 2005 and remote sensing aerosol optical depth from MODIS data during 2000-2007 in eastern China, the change characteristics and causes of fog and haze days from 1961 to 2007 was studied with climatologically statistical diagnosis methods, remote sensing and geographic information system (GIS) technology. The results indicate that from 1961 to 2007, the number of fog days increased firstly and then decreased, but that of haze days increased gradually. The number of fog days was the most in the 1980s, but the least during 2001-2007. The number of haze days was the most during 2001-2007, but the least in the 1960s. In the past 47 years, the number of fog days increased in most northern parts of eastern China, including Shandong, the northern and western parts of Jiangsu and the northern part of Anhui, but decreased in most southern parts of eastern China, especially in Fujian province. The number of haze days increased in most parts of eastern China from 1961 to 2007. In most parts of eastern China, the number of fog days increased during the period 1961-1980, but decreased during 1981-2007, and the number of haze days increased during the two periods of 1961-1980 and 1981-2007. The change characteristics of fog and haze are consistent with other results of China. The increases of mean annual temperature, urban heat island effects and aerosol optical depth, and the decreases of air humidity and wind speed, which resulted mainly from the change of weather and climate conditions, regional urbanization and land use change, and the increase of air pollution disposal, are the main causes for the changes of fog and haze days.
Based on the distributed model for calculating astronomical solar radiation of the rugged topography and the terrain shield model, by using meteorological observation data of the Yangtze River Basin (including the routine meteorological data and the solar radiation data), NOAA-AVHRR of remote sensing data (offering surface Aledo) and the digital elevation model (DEM) data with a resolution of 1 km × 1 km as a terrain response of the main data, a distributed direct solar radiation model, a distributed diffuse radiation model and a distributed terrain reflectance radiation model of the Yangtze River Basin are set up separately, and a distributed model for calculating global solar radiation over rugged terrains is developed for the Yangtze River basin. This paper deeply analyzes simulation results errors and variations of global solar radiation due to locality and terrains. The results suggest that the global solar radiation to be affected, owing to different seasons, is followed by spring > winter > summer > autumn and the impact degree was enhanced owing to increases of altitude, slope, latitude, trend, from the aspect perspective, the global solar radiation quantity over mountainous areas for the Yangtze Rive Basin influenced by local topographic factors has a clear spatial difference and subsists sunny slope (or southern slope) obviously larger than shady slope (or northern slope). Simulation error analysis shows that average absolute error of simulation is 13.04177 MJm-2, average relative error 3.655%, and in site authentication method shows an absolute error of simulation of 22.667 MJ m-2, while relative error of 4.867%.
Scenario modeling and risk assessment of natural disaster is one of the hotspots of disaster research. However, urban natural disaster risk assessment, so far, is lack of common procedures and program. This paper selects rainstorm water-logging as research disaster, which is one of the most frequent occurring hazards in most cities of China, and sets up a small-scale based integrated methodology for hazards risk assessment of rainstorm water-logging, taking Jing\'an District in Shanghai as an example. Based on the basic concept of disaster risk, this paper applies scenario modeling to express the risk of the small-scale urban rainstorm water-logging disasters in different return periods. Through the analysis of hazards, vulnerability and exposure, we simulate different disaster scenarios and propose a comprehensive analysis method and procedure for the small-scale urban storm water-logging disaster risk assessment. A grid-based GIS approach, including urban terrain model, urban rainfall model, urban rainfall model and urban drainage model, was applied to simulate inundation area and depth. And then, stage-damage curves for residential buildings and contents were generated by the loss data of water-logging from the field surveys and the insurance company, which were further applied to analyze the vulnerability, exposure and loss assessment. Finally, the exceedance probability curve for disaster damage was constructed by using the damages of each simulated event and its respective exceedance probabilities. A framework was also developed for coupling the water-logging risk with the risk planning and management through exceedance probability curve and annual average of water-logging loss. And this is a new exploration for small-scale urban natural disaster scenario simulation and risk assessment.
Based on daily temperature and precipitation data of 27 stations in the Mts. Hengduan region, methods of spline interpolation, regression analysis, least square, moving average were employed to analyze the climatic changing trend and spatial differences under the background of global warming. Results indicated that temperature patterns are consistent with warming at statistical significance level during 1960-2008, and relatively low in the 1960s and 1980s, whereas it started to rise after the 1980s which can be proved by a 0.46 oC temperature increase in 2000-2008. The average temperature of all the year, spring, summer, autumn and winter exhibited an obvious increasing trend roughly centered in the area of Mt. Meili and the southernmost between Mt. Shaluli and Mt. Daxue with the velocity of 0.15 oC 10a-1, 0.589 oC 10a-1, 0.153 oC 10a-1, 0.167 oC 10a-1 and 0.347 oC 10a-1, respectively. And what\'s more, temperature increase is more obvious from lower to higher altitude. Precipitation is relatively more after the 1980s, which can be confirmed by a 29.84 mm increase in the 1990s, but it started to decrease after 2000. The average precipitation of all the year, spring, summer, autumn and winter changed by 9.09 mm 10a-1, 8.62 mm 10a-1,-1.5 mm 10a-1, 1.53 mm 10a-1 and 1.47 mm 10a-1, respectively, roughly centered in the area of Mt. Meili and the southernmost between Mt. Shaluli and Mt. Daxue, and only the spring is significant at the 0.05 level. Under the influence of the longitudinal range-gorge, the regional trend in precipitation was on the decrease from southwest to northeast and from south to north in the Mts. Hengduan region. In summer monsoon, the regional trends of temperature and precipitation are 0.117 oC 10a-1 and 6.01 mm 10a-1, respectively, but the precipitation also started to decrease after 2000. There is also a 0.25 oC 10a-1 and 7.47 mm 10a-1 increase of temperature and precipitation in winter monsoon.
The paper defines the resource system of Leye geological relics as 7 landscape types, 10 landscape fields, 19 landscape segments, 32 landscape cells and numerous typical landscape entities. On the basis of analysis and investigation about the background of the formation of scenic spots, the formation of scenery in Leye is categorized into four epochs in terms of different geological stages and the typical karst landform formed during the specific geological stage, namely, the epoch of Fengcong, the epoch of underground river and cave, the epoch of Tiankeng and the epoch of modern karst. During the four epochs, as the formation of scenery in Leye is macro-controlled and affected by the cyclical evolution of tectonic movement which involves multiple cycles from tremendously strong to relatively strong, to feeble, finally to stable, and specifically by climatic factors, formation lithology and the process of karst, different "Tectonic-Surface-Climate" responses occur: (1) the S-shaped massif always grows from both surface and underground; (2) the clastic rock massif mostly develops from the surface. However, both of the formation processes evolve in the same direction, starting from the anisotropic, scattered and independent system to the anisotropic, sole network system, finally to the uniform network system. During these four epochs, the clastic rock massif always serves as the base level of erosion and drainage of the S-shaped massif; the two massifs always exert mutual restriction and influence on the direction, intension and dimensions of formation of their own, which is quite similar to the mode between island and ocean. Based on the above-mentioned process and mechanism, the paper puts forward the island-style model of formation for Leye geological relics.
The Ailao Mountains were considered as the natural borderline between the east and the west of Yunnan for a long time. Are there any differences showed by social and economic elements between the two sides? In view of this, in the region between 22°50'-24°50'N and 100°46'-103°47'E where the Ailao Mountains and the Yuanjiang-Red River Valley were mainly located, 10 counties along both sides of 5 sections with a distance of around 0.5 latitude each were considered as the research spots. Some factors, including natural conditions, economic development, farming structure and net income were contrasted and analyzed. The major research results were obtained in the following. (1) The height fall, land suitable for farming, rainfall and water resource in the west were bigger, less and richer than the ones in the east, showing that the natural condition had obvious differences between the two sides; (2) The farming structure, the planting proportions of cash crops and rainfed crops in the east were higher than the ones in the west, indicating that the farming structure between the east and the west had obvious differences, and the farming structure on each side had a similar changing tendency among the 5 latitude sections; (3) The economic development status, per capita GDP, output value of agriculture and net income of farmers in the east were much higher than the ones in the west, which proved that the development level and the developing tendency at the spatial and temporal scales between the two sides had larger differences, and on each side, they were more consistent. According to the above analysis, the Ailao Mountains-Yuanjiang River Valley was not only the natural borderline, but also the social-economic borderline in the region.
Based on data from field investigations and laboratory research work in 2008 and 2009, this paper, by variance analysis, studies the distribution and storage of soil organic carbon contents of typical types of vegetation in the Ili river valley including alp meadow, meadow grassland, typical steppe, desert steppe, temperate coniferous forest and so on. The results show that soil organic carbon contents varied with the changes of plant types. At 0-50 cm soil layer, soil organic carbon contents of alp meadow and meadow grassland are the highest, followed by temperate coniferous forest, typical steppe, and desert steppe. Deciduous broad-leaved forest and secondary forest almost have the same content of organic carbon, which is higher than that of typical steppe, the soil organic carbon content is the lowest in intrazonal vegetation and desert vegetation. Soil organic carbon contents of different types of vegetation, with the exception of intrazonal vegetation, have a descending trend with the decrease of soil depth. There are differences in soil organic carbon density of different types of vegetation. A higher density of soil organic carbon occurs in alp meadow, meadow grassland and temperate coniferous forest, while the lowest density is observed in desert vegetation. In the Ili river valley, soil organic carbon contents of grassland at surface soil layer are higher, so it is very important to protect surface soil of grassland and to prevent soil organic carbon change in surface layer, which is very useful to keep stability of soil carbon pool.
There are distinctive responses of the lower Yellow River to water-sediment variation, and river course transfer into the lower reaches have been changed notably since 1950 due to the water-sediment conditions, which is the result of human activities and climate changes, and the river course into the sea has been transferred several times. The paper analyzed the water-sediment data (1950-2007) and the water level variation under the same flow (3000 m3/s) at hydrological stations in different courses into the sea. Results show that the lower Yellow River has displayed an alternation between siltation and scouring. It would keep a dynamic balance when the suspended sediment concentration into the lower reaches is about 18.6 kg/m3. Besides controlled by water-sediment with siltation or scouring, the variation process of reaches downwards Aishan has been affected by river course transfer. The reaches have experienced upriver scouring in early days of river course transfer and it has exhibited upriver siltation as the extension of river mouth in mid-and late periods of transfer. During the survival time of Shenxiangou course, the water level variation under the same flow at hydrological stations has descended mainly with the characteristic of erosion in the reaches.
To estimate the alteration of downstream sediment flux affected by dam construction is an international scientific problem. In this paper, we estimate the water and sediment supplies from "ungauged area" next to the main river that the gauging stations of tributaries failed to cover. In combination of the estimated data with the geodesic datum collected at Cuntan, Yichang, Hankou and Datong stations and the tributaries gauge stations between Cuntan and Datong, we build a suspended sediment budget to quantify the influence of water impoundment phases I and II of the Three Gorges Reservoir on downstream (to estuary) suspended sediment flux. The results indicated: (1) During the Three Gorges Reservoir phases I (2003-2005) and II (2006-2007) impoundment period, the settlement rates of SSC in the Three Gorges Reservoir was 64% and 83% respectively. (2) Due to the dam downstream river bed erosion and sediments from tributaries, water impoundment phases I and II of Three Gorges Reach induces the suspend sediment of Yichang station decreased by 62% and 82%, Hankou station decreased by 37% and 54%, Datong station decreased by 28% and 40%. (3) Compared with the former five years (1998-2002), the five years (2003-2007) after The Three Gorges Dam put into operation, the suspended sediment load of three stations mentioned above was decreased by 354, 172 and 163×109 kg/a respectively. The decrease rates attributed to water impoundment of the Three Gorges Reservoir were 41%, 55% and 45%, respectively.
