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[Display omitted] • A method for spatiotemporal coordination of multienergy systems is proposed. • Virtual energy storage gain is calculated based on spectral analysis. • The hydropower regulation ability affects the virtual energy storage gain. • The optimal coordination range between multiple energy sources is obtained. Utilizing the spatial heterogeneity and climate periodicity of various available renewable energy sources can enhance the multienergy complementarity, which will further reduce the energy storage demand and contributes to the "virtual energy storage gain." In this paper, we propose a spatiotemporal coordination method based on spectral analysis for a wind-PV-hydropower system that targets the maximum virtual energy storage gain. The complementary effect of hydropower on wind and PV power can be seen as changes in the regulation ability resulting from the hydropower construction development as well as a decreased variance in the total system production output. This method is used to determine the optimal coordination distance of multiple energy sources that are matched over different periods representing typical climate variation. A case study in the Yalong River basin in China obtains the best range of hydropower bundling surrounding wind power and PV power stations under different hydropower construction planning scenarios, and it reveals that increased regulation capacity of hydropower will reduce the optimal coordination distance but can achieve more energy balance if both actual storage and virtual storage is accounted for. This approach can realize energy delivery with the optimal coordination distance to meet intensive and efficient development needs, which can provide guidance and support for the planning and construction of wind-PV-hydropower storage systems. [ABSTRACT FROM AUTHOR]

As the global climate change and the rapid progress of urbanization, the frequent occurrence of flooding disasters and non-point source pollution seriously threaten the sustainable development of modern cities. To alleviate these problems, China started to pilot construction of the "Sponge City" (SPC). Over a decade, it has attracted public attention, supports, and participations. The paper presents a literature review of sponge city construction (SPCC) process (planning, design and construction) as well as the assessment of SPC, including: operation, maintenance, and effectiveness. Research gap and future works are also proposed. The paper offers some tactics for SPCC, including: 1) in the planning and construction stage of SPC, the goals and systematic plans should be formulated according to local water-environmental conditions. The drainage plan should cover the strategy to dispose runoff volumes at sources and the ultimately goal for flood mitigation. The drainage design involves the combination of various green and grey infrastructures; 2) It is important to identify monitoring methods and hydrological models which can be used to assess the performance of a SPC. With adequate field data, all models and methods should be calibrated for not only runoff quantity and quality control but also the alleviation of urban heat island effects, including the base flows and local groundwater table; 3) Based on the regional field data, it is necessary to standardize regional design parameters, construction material specifics, and maintenance scheme and schedule that would significantly affect the facility's infiltrating and filtering processes, therefore, a regular maintenance program should be initiated to monitor the operations of the as-built facilities according to local climate conditions. The paper evaluated several maintenance methods for ten typical facilities to provide a reference for the operation and maintenance of facilities in SPCC. • The sponge city construction (SPCC) and design methods were introduced in detail. • Scientific and reasonable assessment can better guide the SPCCs. • The sponge city (SPC) facilities can be a better way to control stormwater runoff. • Monitoring and simulation method are equally important for assessing SPC effect. • A maintenance program should be initiated to monitor the operations of SPC facility. [ABSTRACT FROM AUTHOR]