Understanding how ecological quality and human activity co-evolve in densely populated watersheds is essential for sustainable land management, yet spatially explicit long-term evidence remains limited. This study investigated the spatiotemporal dynamics and coupling coordination between ecological quality and multi-dimensional human activity intensity in the Huai River Basin (approximately 269,000 km²) from 2012 to 2024. An Improved Remote Sensing Ecological Index (IRSEI) was constructed by integrating EVI, wetness, dryness, land surface temperature, and a salinity index through annual principal component analysis. A composite Human Activity Intensity (HAI) index combining nighttime light, built-up intensity, and population density was derived with objectively determined weights. The coupling coordination degree (CCD) model and a pixel-level four-quadrant classification were then applied to characterize the human–environment interaction. Results showed that the basin-wide mean IRSEI declined from 0.564 in 2012 to 0.516 in 2020, before recovering to 0.566 in 2024, while HAI increased moderately by 16.9%. CCD improved slightly from 0.451 to 0.480, indicating limited but positive coordination gains. Four-quadrant transitions revealed that high-ecology, low-activity areas expanded, low-ecology, low-activity areas contracted, whereas low-ecology, high-activity zones persisted as stable pressure cores. These findings demonstrate that ecological recovery and human activity intensification can coexist spatially, but persistent high-pressure areas require targeted management interventions.

Public altruistic protective behavior is pivotal in public health emergencies, yet integrated evidence on how multidimensional risk communication shapes it is limited. Grounded in the protective action decision model (PADM) and risk communication theory, this study aims to construct a multidimensional communication strategy impact model encompassing information sources, communication content, narrative style, and communication media, with risk perception introduced as a mediating variable and trust in authoritative information sources as a moderating variable, to systematically examine how these factors affect public altruistic protective behavior. Taking the pandemic as a typical public health emergency scenario, a questionnaire survey of 1,417 respondents across 11 Chinese provinces revealed that (1) all dimensions of risk communication exert significant positive association with altruistic protective behavior, (2) risk perception mediates the relationship between risk communication and altruistic behavior, and (3) trust in authoritative sources negatively moderates the path from information sources to risk perception, displaying a “high-trust attenuation effect.” This study provides theoretical support for more precise governmental messaging and altruistic mobilization.