In this article, the 1961-2010 global reanalysis data was acquired from the National Centers for Environmental Prediction/National Centers for Atmospheric Research (NCEP/NCAR), which has a horizontal resolution of 2.5° Lon. ×2.5° Lat. The daily temperature data of 150 observatory stations in Northeast China was employed in the article too. A definition of extreme low-temperature event (ELTE) was given in the article, and the calendar of ELTE′ occurrence, peak value time and time-duration were investigated. It unveiled that: the occurrence of ELTE were mainly influenced by two major cold air tracks (i.e., north-west cold path ELTE and north-east cold path ELTE). Focusing on the tracks of ELTE events, it was found that during the period of 1961 to 2010, the north-west cold path was dominated compared with north-east cold track. Meanwhile, it should also be noted here that the maximum frequency was occurred in 1980′s, and after 1990′s it was declining significantly. However, it was clear that the north-east cold path ELTE was increasing obviously after 1990′s. Additionally, once the district of Baikal was dominated by low pressure trough, four days before ELTE occurrence (i.e., -4 d), north-west cold path ELTE was easy to take place. Moreover, while a blocking high in Baikal area and matched a low-pressure center in Okhotsk, a dipole of “+, -” wave train, north-east cold path ELTE was prone to take place.
An existing algorithm based on the statistical data was refined, and a Python implementation of the improved algorithm was programmed to extract the built-up areas of 656 cities in 1992, 2000, and 2010 based on DMSP_OLS nighttime light data. ArcGIS 10 and Visual FoxPro 6.0 were used to analyze the characteristics of the expansion of the cities. This study selected 2 indices, the compactness of urban external spatial morphology (CUESM) and the speed of urban spatial expansion (SUSE), to analyze the spatial expansion of county- and higher-level cities in China from 3 aspects: the sizes of cities (metropolises, large cities, medium-sized cities, and small cities), large regions (eastern, central, western, and northeastern China), and administrative divisions of China (provinces, autonomous regions, and municipalities). The results are as follows. First, during the same year, the values of CUESM were getting smaller with increasing city, and were larger in central and western China than those in the eastern and northeastern China. During the period of 1992-2010, the values of CUESM became slightly smaller in large cities, almost unchanged in small cities, and got larger in the cities of other sizes. The values of CUESM became smaller in the eastern and western China, but they got larger in the central and northeastern China from 1992 to 2010. Secondly, during the same period, SUSE increased with urban size. From 1992 to 2010, SUSE was high in the eastern China, low in the central and western China, and the lowest in the northeastern China. SUSE was high in Beijing, Chongqing, Shanghai, and Tianjin, low in Guangdong, Jiangsu, Shandong, Zhejiang, and Fujian, and the lowest in the rest of the provinces in China. From 1992 to 2010, SUSE accelerated in all sizes, regions and provinces.
As two major functional areas, job-housing spaces and the organizational patterns have great influence on urban development. At abroad,scholars mainly focus on the spatial organizational relationships between job-housing spaces, the influence of the mismatch between job-housing spaces to the traffic, the urban employment, the development mode of urban land use, and some other spatial mismatch issues. At home,scholars began this research from the late 1980s. Many researchers study this phenomenon from the commuting angle. However, the studies put particular emphasis on theory introducing and status research. The existing studies are incomplete and lack of characteristics and mechanism analysis. What's more, the research areas are mainly concentrated in the developed first-level cities,but rarely in the other big and medium-sized cities which are in rapid growth stage and also has the same problem. As one of the regional central cities in Changjiang River Delta region,Wuxi City develops very quickly in industrialization and urbanization since the reform and opening up. Meantime, the residential and employment spaces also started restructuring. Based on the fifth and sixth census data, this article explored the changes of job and housing spaces of Wuxi City in the past ten years, and tried to summarize the influencing factors. The results showed that the housing space of Wuxi City overall showed the pattern of descending distribution from the city center to the periphery, and the population growth of developed areas of industry was especially rapid. However, the employment space showed the extension pattern along northwest-southeast. From the angle of match analysis of job-housing spaces, the whole matching degree of job-housing spaces of Wuxi City has increased during the past ten years. The main function of old town is for living, while the main function of external zones is for employment. What's more, the matching degree of some districts is low. We analyzed quantitatively the influencing factors of relationship between job-housing spaces with Geographically Weighted Regression method. The results showed that development of regional economic and improvement of transport accessibility would intensify the job-housing separation, while industrial development and layout, urban spatial expansion and improvement of urban public services, would relieve the job-housing separation. Organizational patterns of job and housing spaces should be different in different stages of economic and social development.
The construction of Trans-Bohai Strait Passageway will greatly improve traffic structure in the Bohai Region, it will surely exert a significant influence on the economic contacts between cities in Shandong Peninsula and East Liaoning Peninsula. This paper measures influence of the economic contacts between cities in Shandong Peninsula and East Liaoning Peninsula on the construction of Trans-Bohai Strait Passageway, through modifying regional economic contacts gravity model and selecting GDP, non-agricultural population in city proper, time cost distance between cities and Krugman index. Results show that the construction of Trans-Bohai Strait Passageway can greatly strengthen the economic contacts intensity and clearly change the spatial distribution of economic contacts between cities in Shandong Peninsula and East Liaoning Peninsula, hence its potential benefits are enormous. The measure information of economic contacts has a certain reference value for the influence of economic contacts between cities in Shandong Peninsula and East Liaoning Peninsula on the construction of Trans-Bohai Strait Passageway.
Based on ArcGIS9.3 and accessibility analysis technology, this article analyses the evolution of accessibility pattern of land use for different function quantitatively in Huai′an City and comes to the conclusions: The first, with the expansion of urban space, the range of accessibility time is also expand correspondingly, the level of accessibility changed a little in the core of city but changed significantly in the edge of city, and the increase of the level of accessibility in the core city will lead the city to development concentration further, and the increase of the level of accessibility in periphery of the city will lead the urban development elements to spread. The second, there are the close relationship between spatial distribution of urban land use and the level of accessibility. The land use for main function concentrated in lower-cost accessibility time; the evolution of accessibility spatial pattern of main function land shows different characteristics; industrial land migrate gradually from lower-cost accessibility time in urban core area to higher-cost accessibility time in urban periphery; the residential land is distributed in the different accessibility time uniformly; the small public facilities land distribute in lower-cost accessibility time in urban core area mainly, but the public facilities land migrate gradually to higher-cost accessibility time in urban periphery. The third, on the basis of the results mentioned above, we summarize five factors which impact on the evolution of accessibility pattern of land use for different function, such as natural conditions, economic development, transportation guide, population growth and government regulation. The increase of accessibility level can guide the urban development elements to concentrate development; city government should take the effective measures to improve the accessibility level by planning and building the road network in the connection zone of the two city subdivision, and to guide the urban transition zone to development rapidly. Only in this way can the city subdivision turn into one city and effective use the city public resources.
By using the methods such as CV,Gini and Theil and taking both domestic tourism income and foreign exchange earnings from tourism of three provinces in Northeast China from 2002 to 2013 as the analysis objects, the features of the spatial-temporal variation of the three provinces in tourism can be revealed economic differences to optimize the structure of the regional tourism economy and provide the basis for avoiding cutthroat competitions. The result shows that, 1）the absolute differences in tourism economy between the three provinces are not remarkable; the relative differences are gradually increasing, and the growing speed of foreign exchange earnings from tourism between the three provinces is more quickly than that of domestic tourism income differences. 2） There exists greater differences in the domestic tourism income differences and foreign exchange earnings of tourism differences in the cities of the three provinces, Heilongjiang tops the first, Jilin the second and Liaoning the third. Differences of domestic tourism income in Heilongjiang are increasing while in Liaoning and Jilin are decreasing. The foreign exchange earnings of tourism differences of Jilin remain about the same, Liaoning′s and Heilongjiang′s are reducing. 3）The differences of the tourism economy among the regions of the three provinces basically remain unchanged.
According to remote sensing images, relevant maps, social and economic data, water and sediment data, water quality monitoring data in typical years of the Dongting Lake, Based on ‘Pressure-State-Response’ mode, a health assessment indicator system of Dongting Lake was constructed, and the assessment indices, assessment criteria, indices weighted values and assessment grades were established. The principal component analysis was used to evaluate the spatial variation characteristics of ecosystem health in Dongting Lake. Fuzzy comprehensive evaluation was adopted to apprise the time serial change law of ecosystem health in Dongting Lake. The results showed that: 1) The typical years can be described as unhealthy except for the 1991 before impoundment and operation of TGP. However, the typical years after impoundment and operation of TGP can be described critically healthy. It demonstrated that TGP was benefit for the health of the Dongting Lake. The comprehensive health index of Dongting Lake is showing a slow upward trend. However, no one typical year of it is healthy,so the health status of Dongting Lakeis not optimistic.2) The South Dongting Lake has a relatively good health status, and then followed by the West Dongting Lake, the East Dongting Lake was the worst one. This is decided by the lake area, the benthic animal diversity, fishing capacity, ecological service function, the management level and the surrounding masses consciousness and other factors.3) From the health indexes of PSR, grade of pressure membership of Dongting Lake were not healthy, especially after impoundment and operation of TGP, its grades of state and response membership were keeping critically healthy state. It indicated that morphology was complete, structure was reasonable and ecological service value was stable, but it had signs of the disease. As a national nature reserve, this ecosystem was to be further improved in its health level.
Food supply is a key problem in ecologically sensitive region .It determines the healthy development of ecologically sensitive region.The regional difference of per capita grain possession is very important for regional food security in the situation of limited arable land and rapid urbanization, especially in ecologically sensitive region。The county administrative is the basic unit of food production and consumption. Mechanism of per capita grain change is vital to the development of the ecological fragile areas. Taking 37 counties as sampling units in 2000-2011 in water source area of for the middle route of South-to-north Water Transfer Project, using the methods of ESDA and geographically weighted regression (GWR) model, the article presents spatial heterogeneity of per capita grain possession and driving factors according to difference in natural conditions and economic development types. The results showed that per capita grain possession shows a strong trend of spatial natural correlation. The similar areas cluster in space. As gross output of grain increases, per capita grain possession has limited room for growth. The county-level of internal per capita grain possession spatial disparities have been gradually narrowed. LISA cluster map demonstrated that counties with higher per capita grain possession gathered in Hanjiang Valley and intermountain Daba Mountains Basin, while counties with lower per capita grain possession gathered in the area of Funiu Mountain. The driving factors of different regions show localization characteristic of no-stationary intercourse. The effect of change of per unit area production to variation of per capita grain possession is the largest. The secondary factor is changes of cultivated land contributing to variation of per capita grain possession. These coefficient estimations are all positive. Factors of influence have obviously transitional characters from subtropical to warm temperate and plain area to mountain area. The coefficients estimation of change of per-capita GDP and weights changing of the second industry are negative. Influences of change of per unit area production, change of cultivated land and change of urbanization are declined from Ankang Basin to east and west sides. Effects of change of the second industry, population increasing and per-capita GDP have longitude zonal pattern. The influences are latitude zonal pattern of per unit area production, the proportion of secondary industry and per-capita GDP. According to present situation of per capita grain possession and effect mechanism of driving factors, effective measures should be adopted to ensure grain security and accelerate ecological construction in water source area for the middle route of South-to-north Water Transfer Project. Natural ecological environment is complex in ecologically sensitive region. When our decision-making, we must fully consider the characteristics of small-scale geographical unit in order to ensure the fragile ecological environment sustainable development.
This article uses GIS and RS technologies to study the dynamic changes and driving forces in land use of Fushun City in the two periods of 1986-2000 and 2000-2012. Its main findings are as follows: from 1986 to 2012 the main types of land use in Fushun City are woodland, farmland, water area and residential land, among which woodland gradually reduced, farmland and residential land gradually increased, and water area reduced first and then increased.The dynamic degree of the single land use in residential land is the highest, followed by water area and grassland, the last is woodland. It also finds out that the dynamic degree of the integrated land use from 1986 to 2000 in Fushun City is higher and spatial difference is little; while the dynamic degree of the integrated land use from 2000 to 2012 in Fushun City is lesser and spatial difference is obvious. This indicates that from 1986 to 2000 the whole city was being developed and its development degree was very high. But from 2000 to 2012 development activities of large-scale was only carried out in some local areas. There are three hot spots of dynamic changes in land use from 1986 to 2000 and they distribute in a larger range. While there is only one hot spot of dynamic changes in land use from 2000 to 2012 and it distributes in a smaller range. All of these four hot spots are located in the concentration area of Fushun residents. Natural factors are the essential conditions in change of land use. Contrary to natural factors, human activities have the decisive impact on the space and time change of land use. Human activities are also the main reasons for the rapid concentration change of land use in Fushun City. This article aims to put forward the best model for humans to use the land resources reasonably and provide a scientific basis for regional sustainable development.
Resources-orientated cities has contributed a lot to our country's economic and social development,with declining resources and accumulation of contradictions increasingly exposed, now, in the process of regional development, such cities have become areas full of contradictory problems from every angle,and facing serious challenge of sustainable development.How to choose the development direction and path of superseded industries is the forefront of current research and hot spot.Pingxiang City, located in Jiangxi province, is a typical industrial and mining city whose leading industry is based on traditional resource exploitation. In 2008, State Council made it fixed that Pingxiang is one of the 12 resources depletion cities and districts in our country.There are many problems of its industrial development at present.it has a single industrial structure,give priority to the second industry,its main resource(coal)is shrinking ,the ecological environment problem is becoming more and more serious,and many coal workers are hardly to find a job or again employed. This article analyzed its industrials by qualitative and quantitative study through the model of PCDL,which is a consolidation analysis stage of industrialization, competitiveness of industry, drive for industrial development, and locus analysis, using the analysis results of four angles to make a final decision.By comparing the per capita of GDP dollars, value structure of three industries, proportion of employment in primary industry, four indicators of urbanization rate in Pingxiang with phasing standard put forward by scholars, we can conclude that Pingxiang generally at the middle stage of industrialization, but there has appears a obvious features that it is making the transition to late stage of industrialization; based on the statistical data of Pingxiang in 2010 and by adopting principal component analysis to do data processing, it can be inferred that with the continuous depletion of coal resources, the status of extractive industry, especially coal mining and washing industry, is declining;competitive industries are mainly manufacturing of intermediate goods; industrial development have gradually diverted to manufacturing of intermediate goods and deep processing, the adjustment of industrial structure has not made much significant contributions to the whole growth, Pingxiang has to strengthen its adjusting force of industrial structure; the thrust of industrial development is not strong enough and industrial development has progressively turned from exploitation of coal to other resources and relevant processing industries. Therefore, Pingxiang should focus on manufacturing, regard manufacturing of intermediate goods and deep processing manufacturing as current successive industries, and help Pingxiang achieve the adjustment of its resources-orientated economic structure to a manufacturing-orientated one.
PATMOS-x is a project to derive atmospheric and surface climate records from NOAA's Advanced Very High Resolution Radiometer (AVHRR).The longest global remotely sensed cloud imagery record is from AVHRR, located on the National Oceanic and Atmospheric Administration(NOAA) polar-orbiting satellites. The PATMOS-x provides multiple products (cloud, aerosol, surface and radiometric) on the same grid using a common processing path. The International Satellite Cloud Climatology Project (ISCCP) was established in 1982 as part of the World Climate Research Program (WCRP) to collect weather satellite radiance measurements and to analyze them to infer the global distribution of clouds, their properties, and their diurnal, seasonal and interannual variations. This study focused on the comparison of cloud amount from PATMOS-x and ISCCP with ground observation over China. The spatial and temporal differences of low cloud amount and total cloud amount are investigated using PATMOS-x data, ISCCP data and ground observation in 1984-2006. The quantitative analysis results show that the distribution of total cloud amount from PATMOS-x and ISCCP are better than that of low cloud amount according to that of ground observation. And it is the same as grid-based correlation with ground observation. The distribution of low cloud amount from PATMOS-x is more similar with ground observation than that of ISCCP. The low cloud amount from PATMOS-x and from ground observation over China both show obviously linear increasing trend.
Reasons of serious drought in eight cities and provinces of Northern China in 1942 were analyzed. Results indicated that there is an extreme arid event occurred in 1942 and centering on Henan Province, which occurred under a relatively warm background. The arid event was the most serious during the summer and winter. The warm sea temperature of Pacific Ocean during 1942 was the most important sea background of this extreme arid event was, while the negative phase of South Oscillation during 1940-1942 was the most outstanding circulation environment of this extreme arid event. In addition, the El Nino event with the intensity of 1 level, the weaker East Asian summer monsoon, and the less landing typhoon than the other years possibly could be the main reasons inducing to this extreme arid event in 1942 over the north China. Because Henan Province is the climatic change sensitive area and the ecological environment frail area, the earlier period dry waterlogging disaster frequency sends, in addition the multi-disasters were in the past concurrent, caused Henan Province's drought to be most serious in 1942.
Based on the diagnostic analysis of a wide range of cold vortex rainstorm and heavy rainstorm process from 27 to 29 July,2010 in Jilin Province, the conceptual model of such heavy weather was established："two ridge and one trough" type was consisted, upper-level jet was divergent and located in Jilin Province, the central maximum of jet wind speed was≥60 m/s at 200 hPa; the strong development of northeast cold vortex and the stable maintenance of Okhotsk blocking high at 500 hPa was an important weather system of the strong precipitation, the jet zone with ≥20 m/s west wind speed crossed over the central section of Jilin Province; the three jets with ≥12 m/s wind speed at 850 hPa intersected in the middle-eastern area of Jilin Province and formed the cyclonic vorticity column of low-level convergence and upper-level divergence, the strong vertical-rising gas column had been extended upward to near 500 hPa,these were very beneficial to the maintain of convection and the development of strong precipitation. By the calculation of the correlative vector field between the whole layer of water vapor flux and 6-hour average precipitation in Jilin Province, results showed that: collection of the three water vapor channels of west, south and north in the middle-southern part of Jilin Province was an important condition for the rainstorm;the rainstorm area was highly correlated to the confluence area of vertically integrated water vapor flux; the dominant direction of water vapor transport was meridional (South and North).The rainstorm was benefited from suitable dynamic, thermal and energy conditions, especially the wet Convective Available Potential Energy(CAPE) was obviously strong and the heavy precipitation occurred when the CAPE value began to fall from the maximum. Dry intrusion was one of the dynamic conditions that stimulated the occurrence and development of cold vortex; the tongue of high potential vorticity of ≥1PVU (Potential Vorticity Unit) shifted downward vertically and moved southward at the same time, corresponding to the move of heavy precipitation area from north to south in the central region.
Shandong region is located in eastern coastal of China. Due to the combined effects of marine and Continental, monsoon climate significantly, rainfall mainly concentrate in the summer and heavy rain often appears. It is easy to form flood disaster. Because of less rain in the other seasons, especially spring, it is easy to form the drought. Due to unequal distribution of rainfall during the year, the drought and flood disasters occurred frequently in the region. Studying the characteristics of summer precipitation from regional scale in Shandong region, not only has the vital significance to the evaluation of regional precipitation and the water resources situation, also provides the scientific basis for the prediction of precipitation in the future and the change trend of water environment and water resources. Based on the monthly precipitation data of 16 weather stations in Shandong region in 1961-2012 and atmospheric circulation index included The East Asian summer monsoon (EASM) index, Southern Oscillation (SO)Index and Arctic Oscillation (AO) Index. The non-parametric Mann-Kendall Test, Accumulated Difference Curve, Order Cluster Analysis and Mann-Whitney-Pettitt (MWP) methods were used in this paper to reveal the temporal-spatial variation and influential factors of summer precipitation and summer precipitation accounted for the proportion of annual precipitation in Shandong region during the last 50 years. Results obtained showed a number of observations: The summer precipitation showed a decreasing trend on the whole during the last 50 years. But the change process had obvious stages. The coast is less than the inland in the changes amplitude of summer precipitation. The coast is earlier than the inland in the stages transformation and mutation of the summer precipitation, mountains earlier than plains in the inland. The summer precipitation accounted for the proportion of annual precipitation showed an increasing trend on the whole in the coast. But the change process had no obvious stages and mutation phenomenon. However, the summer precipitation accounted for the proportion of annual precipitation showed a decreasing trend on the whole in the inland. But the change process had stages and mutation phenomenon, which are different in the mountains and the plains. According to the analysis, the summer precipitation changes in Shandong region has a significant response relationship with the East Asian summer monsoon, Southern Oscillation and the Arctic Oscillation change on the same period. The differences between coastal and inland, mountains and plains are notable.
The Tailan River Watershed, a branch of the Aksu River Basin, is a glacier-melt runoff river and has a drainage area of 1 324 km2. So far, there is still no detailed assessment of changes of the characteristics of the glaciers. Therefore, timely and correct assessment of glacier changes in the Tailan River to fill gaps in this region is urgent, and it has an extremely important significance for the Tailan River Watershed′s economic development and people's livelihood. 1∶50 000 topographic map data, Landsat ETM+ remote sensing images and digital elevation model data were used in this research. Through integrated computer automatic interpretation and visual interpretation methods, the object-oriented image feature extraction method is applied to extract glacier information. And the images overlying digital elevation model was used to extract the debris- covered glacier terminal in this region. At last, the expert guidance was referenced to revise the glacier outline again. Glacier change data in 1972-2011 were derived from this research, and analyses the glacier variation characteristics and its response to climate change in the past nearly 40 a. The results show that: between 1972 and 2011, the Tailan River watershed′s glaciers had an evident retreat trend, the total area of ??glaciers was from 435.44 km2 to 385.38 km2; shrinking at a rate of 11.50%, with the average annual decrease was approximately 1.25 km2 and the average single glacier area decrease was 0.31 km2. Glacier total number decreased from 113 to 109, 10 glaciers were disappeared and three glaciers separated into nine remaining. Other 100 glaciers were presenting decreasing trend. In 2011, according to the results of object-oriented image feature extraction method of glacier distribution and temporal variation, glaciers in this basin are mainly distributed in an elevation of 3 900-4 200 m range, and aspect of the glacier terminal toward the east occupy the vast majority in this basin. By analyzing Aksu and Baicheng weather stations′ annual average temperature and precipitation data from 1960 to 2010, the mean annual temperature increased significantly and the annual precipitation also showed an increasing trend. The study concluded that glacier shrinkage is closely related with temperature rising and glacier melting caused by rising temperatures offsets the supply by increased precipitation to some extent.
In the palaeoclimatic reconstruction research, the characteristics of proxy data are limited in number, which has a great deal to do with the influence of research. The optimal regional averaging method is a far more effective approach to slove this problem. The optimal regional averaging method is a method that can obtain the average temperature of target area by means of optimal weights using limited temperature data in target areas. In the application of this method, first optimal weighting mechanism based on minimum mean squqre error and Lagrange multiplier method are applied to get optimal weight, and then Optimal weights and temperature data are joined together to obtained regional average temperature. This existing optimal regional averaging method has weakness in the regional average temperature calculation of large target area. To overcome the weakness and make this method can calculate the average temperature of the large region, such as the Northern Hemisphere (NH) average temperature, the optimal regional averaging method is improved in this article. 1) Haar wavelet function and matrix operator are used to replace mesh summation method in process of solving covariance pattern. 2) Optimal weights are got through applying all principal component gauss elimination method to solve the linear algebraic equations. The result shows that the covariance pattern solved is more accurate because of the application of Haar wavelet function and matrix operator in the calculation. The temperature data used in the calculation derived from Climatic Research Unit (CRU), which is considered among the most authoritative sources on reconstruction research. After adopting the above mentioned improvement, taking calculation of the Northern Hemisphere (NH) average temperature in 1961-1990 as an example, it is found that the correlation coefficient between the NH temperature series obtained by the improved optimal regional averaging method and the published result from CRU is higher than the result obtained by this method before the above improvement. Thus the improved the optimal regional averaging method provides a reasonable approach for palaeoclimatic reconstruction in case that proxy data are limited and scarce in spatial distribution.
Under the influences of human activities, the successive water and sediment disasters posed threats on people′s production and life. Based on the series data of annual runoff and sediment of representative hydrometric stations in Dongting Lake Basin, P-III distribution curve is applied to fit the marginal distribution of annual runoff and sediment of 3 inlets (Songzikou, Taipingkou, Ouchikou), four rivers (Xiangjiang River, Zijiang River, Yuanjiang River and Lishui River) (entering the lake) and Chenglingji (coming out of the lake). The application of popular Copula-constructed two-dimensional joint distribution of runoff and sediment was illustrated, and the joint distribution was used to calculate the encounter probability of rich-poor runoff and sediment in Dongting Lake Basin. Result shows that 1) Synchronous frequency of the runoff and sediment in 3 inlets is far more than asynchronous frequency, and the frequencies of rich water-rich sediment, poor water-poor sediment and normal water-normal sediment are equal basically. 2) Synchronous frequency of the runoff and sediment in four rivers and Chenglingji approximately equals asynchronous frequency, and the frequency of rich water-rich sediment is the highest in synchronous frequency, the frequency of poor water-poor sediment ranks the second, and the frequency of normal water-normal sediment is the lowest. 3) The frequency of the encounter of opposite status of runoff and sediment (the frequency of rich water-poor sediment and the frequency of poor water-rich sediment) is the lowest of the asynchronous frequencies of rich-poor runoff and sediment encounters in Chenglingji, 3 inlets and 4 rivers. The research results show that the model posses good evaluating performance and reveals a close contact with the basic characteristics of the runoff and sediment in Dongting Lake. With the analysis of the rich-poor runoff and sediment encounter probability, the frequency of water-sediment disasters can be understanding quantitatively, so the study can provide a technical guidance for the flood prevention and disaster reduction in Dongting Lake Basin.
