Understanding the factors that affect residents’ waste separation behaviors helps in constructing effective environmental campaigns for a community. Using the theory of planned behavior (TPB), this study examines factors associated with waste separation behaviors by analyzing responses to questionnaires distributed in Guangzhou, China. Data drawn from 208 of 1000-field questionnaires were used to assess socio-demographic factors and the TPB constructs (i.e., attitudes, subjective norms, perceived behavioral control, intentions, and situational factors). The questionnaire data revealed that attitudes, subjective norms, perceived behavioral control, intentions, and situational factors significantly predicted household waste behaviors in Guangzhou, China. Through a structural equation modeling analysis, we concluded that campaigns targeting moral obligations may be particularly effective for increasing the participation rate in waste separation behaviors.

Satellite-based remote sensing is important for monitoring the spatial distribution of water resources. The water index is currently one of the most widely used water body extraction methods. Based on Sentinel-2 remote sensing image, this study combines area-to-point regression kriging interpolation, bilinear interpolation, and the Gram–Schmidt (GS) pan-sharpening method with the water indices MNDWI, AWEI_sh and WI₂₀₁₅ to compare different water body extraction methods. The experimental results showed that all water indices have satisfactory extraction ability, with the kappa coefficient as an accuracy threshold above 0.8. Moreover, the GS downscaling method combined with the WI₂₀₁₅ yielded the best performance. This research demonstrates the efficacy of the WI₂₀₁₅ method to extract water bodies in urban areas and its ability to comprehensively describe river water bodies. The findings indicate that high-resolution band information is particularly important for improving low-resolution band downscaling results and can significantly minimize erroneous water body extraction.

The expansion of urban areas has resulted in a substantial increase in demand for water ecosystem services. To address this issue, this study aims to investigate how the interaction between urbanization and water ecosystem services changed in response to different levels of urbanization in the Dongjiang River Basin from 1985 to 2020. The research examines four water ecosystem services (water yield, soil retention, and water purifications of N and P) and three types of urbanizations (population urbanization, economic urbanization, and land urbanization) to identify spatial heterogeneities among developed urban areas, developing urban areas, and rural regions, as well as their dynamic interactions. The findings indicate that water ecosystem services and urbanizations tend to be spatially polarized, with high values downstream and low values upstream. Although they have become more closely aligned, there is a local mismatch under basin-level homogeneity. Urbanization has migrated and centralized in a southward direction, while water ecosystem services have moved westward. This difference of migration results in an increasing trade-off in the west band of Dongjiang River. In particular, the developing urban area has been strengthening the function of the transition zone between the developed urban area and rural area, resulting in a dramatic decrease in synergy. The synergy of the rural area dominates the increasing synergy of the entire basin, but the developed urban area tends to lower the water ecosystem services that lag behind urbanization. The study recommends that policymakers consider different urban levels when developing urbanization plans and water resource management strategies, and implement measures to maintain the synergy in the rural area and mitigate the trade-off in the developing area.

Urban color represents the visual skin of a city, embodying regional culture, historical memory, and the contemporary spirit. However, while the existing studies focus on pedestrian-level facade colors, the “fifth facade” from a bird’s-eye view has been largely overlooked. Moreover, color distortions in traditional remote sensing imagery hinder precise analysis. This study targeted 56 Chinese coastal cities, decoding the spatiotemporal patterns of their fifth facade color (FFC). Through developing an innovative natural color optimization algorithm, the oversaturation and color bias of Sentinel-2 imageries were addressed. Several color indicators, including dominant colors, hue–saturation–value, color richness, and color harmony, were developed to analyze the spatial variations of FFC. Results revealed that FFC in Chinese coastal cities is dominated by gray, black, and brown, reflecting the commonality of cement jungles. Among them, northern warm grays exude solidity, as in Weifang, while southern cool grays convey modern elegance, as in Shenzhen. Blue PVC rooftops (e.g., Tianjin) and red-brick villages (e.g., Quanzhou) serve as symbols of industrial function and cultural heritage. Economically advanced cities (e.g., Shanghai) lead in color richness, linking vitality to visual diversity, while high-harmony cities (e.g., Lianyungang) foster livability through coordinated colors. The study also warns of color pollution risks. Cities like Qingdao exposed planning imbalances through color clashes. This research pioneers a systematic and large-scale decoding of urban fifth facade color from a remote sensing perspective, quantitatively revealing the dilemma of “identical cities” in modernization development. The findings inject color rationality into urban planning and create readable and warm city images.