Sponge city is an important Low Impact Development (LID) pattern, and also is a key to solve the urban water issues in China. In this study, we focus on the three core tasks including urban flood control and drainage, non-point source pollution control and urban rainfall-flood utilization, and explore the key technology and methodology to support the implementation of sponge city from the perspective of virtuous-water-cycle (e.g., the numerical simulation and LID optimization techniques), and finally develop an urban rainfall-flood model (HIMS-URBAN). This model is applied in Changde City, which is one of the first batch of sponge city. The results demonstrate that: 1) runoff coefficient in Changde City ranges from 0.33 to 0.81 in current state, with an average of 0.64. 2) Based on the objective of controlling total annual runoff, several LID measures (e.g., infiltration, storage and retention), are employed to consume the runoff from each block. By optimization, the controlling objective can be achieved in 90% of urban blocks. The areas of sunken green space, permeable pavement and green roof are 496.75, 1 338.15 and 613.21 hm², respectively, and the total area of LID measures accounts for from 3.9% to 31.4% of each block’s area. The reduction rate of pollution load SS is between 45.0% and 47.7%, with an average of 46.1%. By adopting the LID measures, the outputs of storm runoff and the pollution load in Changde urban area are remarkably reduced, and the control objective is almost achieved. This study provides great valuable results for construction of sponge city in Changde City, and also gives a good reference of theory and technology for urban planning and design.

Promoting energy cooperation is the core and the strategic breakthrough of constructing Silk Road Economic Belt. Since it lacks of systematic analysis of the reserves, production, consumption and trade of oil resources in the Silk Road Economic Belt, this paper adopts boxplot analysis method to discuss the ranks of the main oil-producing countries in the economic belt in the world oil supply and their changes. Combining with their changing statues in oil supply-demand balance, this paper makes suggestions regarding China’s oil cooperation with main oil-producing countries in the belt. Results suggest that: 1) As to either the proven reserves, productions, R/P or exports, the economic belt is on top of the world, and is the primary sources of world’s oil supply growth; even in the diversified trend of world’s proven oil reserves and R/P, the status of the economic belt is still strong and outstanding, and in further polarized trend of world’s oil production and export, the leading superiority of Saudi Arabia and Russia is more prominent. 2) Most oil supply countries in the belt are large and medium sized countries, and are highly clustered, forming a core area along Persian Gulf and the Golden Triangle of “Russia-Kazakhstan-Azerbaijan” surrounding Caspian Sea, especially the region surrounding Caspian Sea where the strong growth has narrowed the its gap with the Persian Gulf region; the cluster of oil super supplies plays regional advantages for oil exporting countries to share regional energy infrastructures, and for oil importing countries to have more cooperation choices. 3) There are obvious fluctuations of oil production and exports, which are mainly affected by the changes of regional situation, OPEC production regulation and the fluctuations of domestic demands in oil supplying countries. 4) In the future, China should continue to take Persian Gulf countries as the major partners, and diversify the origins of oil; region surrounding Caspian Sea is another big strategic cooperator of China, where the emphasis should be focused on the cooperative construction of oil transport infrastructure; China should gradually construct a Golden Cooperation Triangle consisting of Russia, Kazakhstan and Azerbaijan to hedge the risk in cooperation. 5) The cooperation between China and India also needs to be strengthened in order to enhance the regional power in barging, and improve the regional oil transportation safety.