A Modified Certainty Coefficient Method（M-CF） for Debris Flow Susceptibility Assessment：A Case Study for the Wenchuan Earthquake Meizoseismal Areas

In the meizoseismal areas hit by the China Wenchuan earthquake on May 12, 2008, the disasterprone environment has changed dramatically, making the susceptibility assessment of debris flow more complex and uncertain. After the earthquake, debris flow hazards occurred frequently and effective susceptibility assessment of debris flow has become extremely important. Shenxi gully in Du Jiangyan city, located in the meizoseismal areas, was selected as the study area. Based on the research of disaster-prone environment and the main factors controlling debris flow, the susceptibility zonations of debris flow were mapped using factor weight method（FW）, certainty coefficient method（CF） and geomorphic information entropy method（GI）. Through comparative analysis, the study showed that these three methods underestimated susceptible degree of debris flow when used in the meizoseismal areas of Wenchuan earthquake. In order to solve this problem, this paper developed a modified certainty coefficient method（M-CF） to reflect the impact of rich loose materials on the susceptible degree of debris flow. In the modified method, the distribution and area of loose materials were obtained by field investigations and postearthquake remote sensing image, and four data sets, namely, lithology, elevation, slop and aspect, wereused to calculate the CF values. The result of M-CF method is in agreement with field investigations and the accuracy of the method is satisfied. The method has a wide application to the susceptibility assessment of debris flow in the earthquake stricken areas.     

Investigation and Assessment of Landslides and Debris Flows in Sichuan Province of China by Remote Sensing Technique

Taking TM images, ETM images, SPOT images, aerial photos and other remote sensing data as fundamental sources, this research makes a thorough investigation on landslides and debris flows in Sichuan Province, China, using the method of manual interpretation and taking topography maps as references after the processes of terrain correction, spectral matching, and image mosaic. And then, the spatial characteristics of landslides and debris flows in the year of 2005 are assessed and made into figures. The environmental factors which induce landslides and debris flows such as slope, vegetation coverage, lithology, rainfall and so on are obtained by GIS spatial analysis method. Finally, the relationships of landslides or debris flows with some environmental factors are analyzed based on the grade of each environmental factor. The results indicate： 1） The landslides and debris flows are mainly in the eastern and southern area of Sichuan Province, however, there are few landslides and debris flows in the western particularly the northwestern Sichuan. 2） The landslides and debris flows of Sichuan Province are mostly located in the regions with small slope degree. The occurring rate of debris flow reduces with the increase of the vegetation coverage degree, but the vegetation coverage degree has little to do with the occurrence of landslide. The more rainfall a place has, the easier the landslides and debris flows take place.     

Alpine Ecosystems of Northwest Yunnan, China： an Initial Assessment for Conservation

Implementing conservation actions on-the-ground is not a straightforward process,especially when faced with high scientific uncertainty due to limited available information. This is especially acute in regions of the world that harbor many unique species that have not been well studied,such as the alpine zone of the Hengduan Mountains of Northwest Yunnan (NWY),a global biodiversity hotspot and site of The Nature Conservancy’s Yunnan Great Rivers Project. We conducted a quantitative,but rapid regional-level assessment of the alpine flora across NWY to provide a broad-based understanding of local and regional patterns of the alpine flora,the first large-scale analysis of alpine biodiversity patterns in this region. Multivariate analyses were used to classify the major plant community types and link community patterns to habitat variables. Our analysis indicated that most species had small distributions and/or small population sizes. Strong patterns emerged with higher diversity in the more northern mountains,but beta diversity was high,averaging only 10% among sites. The ordinations indicated that elevation and geographic location were the dominant environ-mental gradients underlying the differences in the species composition among communities. The high beta diversity across the alpine of these mountains implies that conservation strategies ultimately will require the protection of large numbers of species over a large geographical area. However,prioritiza-tion should be given to areas where potential payoffs are greatest. Sites with high species richness also have a greater number of endemic species,and,by focusing efforts on these sites,conservation investments would be maximized by protecting the greatest number of unique species.     

Food Security of Shifting Cultivation Systems： Case Studies from Luang Prabang and Oudomxay Provinces, Lao PDR

Introduction The shifting cultivation system is one of the most important agricultural systems in Luang Prabang and Oudomxay provinces, where many production systems are found in the uplands. The factors, determining the systems, include ethnicity,Journal…     

A Case Study for a Digital Seabed Database： Bohai Sea Engineering Geology Database

This paper discusses the designing plan of ORACLE-based Bohai Sea engineering geology database structure from requisition analysis, conceptual structure analysis, logical structure analysis, physical structure analysis and security designing. In the study, we used the object-oriented Unified Modeling Language （UML） to model the conceptual structure of the database and used the powerful function of data management which the object-oriented and relational database ORACLE provides to organize and manage the storage space and improve its security performance. By this means, the database can provide rapid and highly effective performance in data storage, maintenance and query to satisfy the application requisition of the Bohai Sea Oilfield Paradigm Area Information System.     

Field Modeling Method for Identifying Urban Sphere of Influence： A Case Study on Central China

With rapid development of urbanization and regional interaction and interdependence, regional urban agglomeration planning becomes more and more important in China, in order to promote integrated development of various cities with close interrelationship. However, it is still arguable academically on how to define the boundary or which cities to be included for the urban agglomeration of a region. This paper aims to shed lights on how to identify urban spheres of influence scientifically by introducing field modeling method and by practicing a case study on 168 cities in Central China. In our field modeling method, the influence intensities of cities were measured by a comprehensive index and urban spheres of influence were represented spatially by field intensity. Then, their classification and spatial distribution characteristics of study area in 2007 were identified and explored by using GIS and statistical methods. The result showed that: 1) Wuhan is the absolute dominant city in Central China; 2) the provincial capital cities dominate their own provinces and there are no other lower grade agglomeration centers; and 3) the basic types of organization form of urban sphere of influence are single-polar type, agglomeration type, close-related group type and loose-related group type.     

Quantitative Assessment of Impacts of Regional Climate and Human Activities on Saline-alkali Land Changes： A Case Study of Qian＇an County, Jilin Province

Interdecadal and interannual variations of saline-alkali land area in Qian’an County, Jilin Province, China were comprehensively analyzed in this paper by means of satellite remote sensing interpretation, field flux observations and regional climate diagnosis. The results show that on the interannual scale, the impact of climate factors accounts for 71.6% of the total variation of the saline-alkali land area, and that of human activities accounts for 28.4%. Therefore the impact of climate factors is obviously greater than that of human activities. On the interdecadal scale, the impact of climate factors on the increase of the saline-alkali land area accounts for 43.2%, and that of human activities accounts for 56.8%. The impact of human activities on the variation of saline-alkali land area is very clear on the interdecadal scale, and the negative impact of human activities on the environment should not be negligible. Besides, changes in the area of heavy saline-alkali land have some indication for development of saline-alkali land in Qian’an County.     

Evaluation for Use Efficiency of Agricultural Resources in Grain Production： A Case Study of Changshu, Taihe and Ansai in China

This paper aims to establish an index system for evaluation of agricultural resources use efficiency (ARUE) in grain production and discuss the causes of low efficiency and high consumption of agricultural resources in Changshu of Jiangsu Province, Taihe of Jiangxi Province and Ausai of Shaanxi Province in China by analyzing the data about meteorology, soil, water consumption and grain production. Agro-ecological Zone (AEZ) method was adopted to calculate the potential productivity, and synthetically multivariate equation was used to evaluate the ARUE of study areas. This paper can be concluded as: 1) the agricultural resources in grain production can be classified into five categories, i.e., climatic resources, water resources, land resources, biological resources and assistant resources, and 15 indexes were selected to evaluate their use efficiency in grain production; 2) the values of ARUE in grain production are 0.5868, 0.6368 and 0.5390 respectively in Changshu, Taihe and Ansai; and 3) Changshu ranks the highest among the three study areas in terms of the use efficiency of climatic resources and biological resources (evaluation values are 0.0277 and 0.1530), but Taihe tops the three in terms of the use efficiency of water resources, land resources and assistant resources (evaluation values are 0.0502, 0.2945 and 0.1379 respectively). However, the ARUE remains always low in Ansai for all the resources. The inefficiencies are caused by poor grain revenue in Changshu, deficient agriculture investments in Taihe and unfavorable natural conditions in Ansai.     

Temporal Change of Runoff and Sediment Load and their Differential Response to Human Activities：A Case Study for a Well-vegetated Mountain Watershed of Southern China

This study examined the temporal trends of runoff and sediment load and their differential response to human activities in the Lishui river,a tributary of the Yangtze river in southern China.The long-term observation data at four gauging stations,generally involving two periods from 1954 to 1985 and from 2007 to 2011,were used.We detected no significant temporal trend for both the annual runoff volume（Q） and the annual suspended Sediment Load（SL） over more than 30 years before 1985.The flow duration curves and the Suspended Sediment Concentration（SSC） also hold constant before 1985.Compared with the period before 1985,SL has decreased by about 80% though Q remains unchanged for the period after 2007.Detailed examination shows that the flow duration curves after 2007 have changed with a significant decrease in the high-flow component,which acts as a major cause for the decreasing SL.In addition,SSC has decreased by several times,which also contributes to the decrease in SL after 2007.Both decreases in high-flow discharges and in SSC can be linked with recent human activities,mainly including vegetation establishment and dam constructions.The constant Q and the decreasing SL are also reported for the main stream of the Yangtze River and other major rivers in southern China,although they are orders of magnitude larger than our study area in drainage area size.The present study highlights the importance of high-flow discharges on SL and suggests that the use of SL is more appropriate to reflect environmental change than Q.     

Developing a risk assessment model for typhoon-triggered debris flows

A methodology is developed for interactive risk assessment of physical infrastructure and spatially distributed response systems subjected to debris flows.The proposed framework is composed of three components,namely geotechnical engineering,geographical information systems and disaster management.With the integration of slope stability analysis,hazard scenario and susceptibility,geological conditions are considered as temporary static data,while meteorological conditions are treated as dynamic data with a focus on typhoons.In this research,the relevant parameters required for database building are defined,and the procedures for building the geological database and meteorological data sets are explained.Based on the concepts and data sets,Nantou and Hualien in Taiwan are used as the areas for case studies.     

Geomorphic characteristics of hillslope and channelized debris flows: A case study in the Shitou area of central Taiwan

The data on the hillslope and channelized debris flows in the Shitou area of central Taiwan occurred during Typhoons Toraji and Nali in 2001 were applied in this paper. The geomorphic parameters, including the flow length, gully gradient, drainage area and form factor of the debris flows were determined by spatial analysis using a Geographic Information System （GIS） based on the data derived from field investigation, aerial photographs, and topographical maps. According to such determined geomorphic parameters, the threshold conditions and empirical equations, such as the relationship between the gully gradient and drainage area and that between gully length and drainage area and topographic parameter, are presented and used to distinguish the geomorphic characteristics between the channelized and hillslope debris flows.