Atlantis Press Journal style Editor’s Introduction for Volume 5, Issue 4 The changing world always is uncertain so that various risks exist everywhere, endless crises always happen. JRACR, launched by SRA-China in 2011, is becoming an important journal in risk analysis and management, although it hasn’t been indexed by SCI. This issue contains 6 papers. Among them, 2 are written in English and 4 in Chinese with English abstracts. In the paper “Analysis of a Risky Two Unit System under Marked Process Incorporating Two Repairmen with Vacations ” by Tiwari and Singh, the supplementary variable technique, Laplace transformation and copula are used to obtain various transition state probabilities, reliability, availability, cost analysis and the steady state behaviour of the system. To make a comparison between the measures obtained using two families of copulas Gumbel-Hougaard family and Bivariate Clayton, the model has been solved with the help of Gumbel-Hougaard family of copula and Bivariate Clayton copula both in two different cases. The paper “Sweden’s Capacity to Prepare and Respond to a Terrorist Attack on Rail-Bound Traffic” by Veronica Strandh, takes an interest in evolving collaborative practices in crises caused by terrorism targeting rail-bound traffic. Sweden provides the empirical focus, by examining current preparedness processes, this article offers an important perspective on inter-organizational collaboration; that is, the perspective of the involved actors themselves. This study relies on 20 interviews with key actors in the response system and rail bound traffic actors. There are two papers in risk assessment. In the first paper “Research on Urban Waterlogging Disaster Risk Assessment Based on ARCGIS and MIKE FLOOD” by Zhang, et al., Chunyang Zhang, an urban drainage system model of Shijiazhuang city was built based on the MIKE21, MIKE URBAN and MIKE 11 modules in MIKE FLOOD platform in order to provide a storm sewer drainage capacity and waterlogging risk evaluation. The results show that, in Shijiazhuang, 64.5% of storm sewer drainage criteria is less than 1-year return period storm, and only 28.9% of storm sewer can meet the drainage criteria of 2-year return period storm. The second paper “Regional Risk Assessment of Earthquake-triggered Landslides” by Tian, et al., presents a review on the methods for risk assessment include the evidence-weight model, information value model and certainty factor method, logistic regression model, artificial neural networks, support vector machine method, Newmark displacement model, analytic hierarchy process, and so on, and puts forward some ideas about the research trend of seismic landslide hazard evaluation. The paper “Research on Construction of Major Drainage System for urban area of Shijiazhuang” by Zhang, et al., introduces the relationship between major and minor drainage systems, as well as the significance of major drainage system construction based on the comprehensive plan of drainage and waterlogging Prevention of Shijiazhuang. According to the current problems of urban drainage systems of Shijiazhuang, two-dimensional surface flow modelling tools was applied, with the consideration of urban master planning, major drainage system was established. In “The variable characteristics and response to climatic factors of the runoff in the downstream areas of the Yellow River Under the background of Global Change”, Hong, et al. calculated and analyzed the runoff of Huayuankou and Lijin Hydrologic Stations of the areas from 1951 to 2012, and obtained four important conclusions. Many thanks to the referees for their strong support and kind help. And also thank the authors very much for all their submissions. Editor-in-Chief: Prof. Chongfu Huang Email: rim_007@163.com Email: hchongfu@126.com Publication Chair of SRA-China: Prof. Mu Zhang Director of Editorial Department: Prof. Junxiang Zhang Email: jracr_srachina@126.com Journal of Risk Analysis and Crisis Response, Vol. 5, No. 4 (December 2015), 199 Published by Atlantis Press Copyright: the authors 199