Significance: This research provides a global-scale evaluation of the impact of dam construction by using a variety of global spatial databases. In particular, it provides insight into the impacts on economy, population, and greenness of 631 recently built hydropower dams by region and dam size. We discovered that 631 recently built hydropower dams were associated with reduced local economy, population, and greenness in areas within 50 km of the dam sites, particularly in the Global South. This is contrary to claims that dams improve the livelihoods of people as well as ecosystem services. The research highlights that policy interventions are needed to address impacts on populations and urban land near small and medium dams.

The consequences of dams show the complex impacts of human activities on the environment. While they provide benefits, dams also negatively affect hydrological systems, which in turn influence geomorphology, ecosystems, and society. Remote sensing offers unique spatiotemporal insights, filling gaps in understanding of the environmental consequences of dams by covering areas without in-situ measurements and providing data that conventional approaches cannot capture. As a result, remote sensing has been widely employed to disentangle the complexity in the consequences of dams. This study reviewed 73 relevant research papers to characterize the remote sensing approach in quantifying spatiotemporal environmental consequences of dams, focusing on hydrology, geomorphology, ecosystems, and society. The review examined the consequences of dams as measured by remote sensing data, the methods employed, and the techniques used to separate dam-related impacts from climatic influences. Based on this review, we discussed the limitations of current remote sensing-based dam studies and proposed future research agendas aimed at better understanding the effects of dams on hydrology, geomorphology, ecosystems, and society.

Water resources in lakes of the Korean Peninsula play a significant role in society and ecosystems in both South and North Korea. This study characterized spatiotemporal changes in the lake area during the dry season (March–May) in the Korean Peninsula over the last 40 years. The satellite images (Landsat 5–9) were used to derive annual areas of 975 lakes during the dry season from 1984 to 2023. Our analysis indicated that the MNDWI is the optimal remote sensing-based index for delineating lake areas in the Korean Peninsula, with an overall accuracy of 92.3%. Based on the selected index, the total lake areas of the dry seasons have increased from 1070.7 km² in 1984 to 1659.3 km² in 2023, mainly due to newly constructed dam reservoirs. While the detailed changes in lake area vary, we found divergent results based on their sizes. The large lakes (> 10 km²) showed their area increased by 0.0473 km² (0.1%) every year and have more influences from climate change. On the contrary, the small lakes (≤ 10 km²) have area decreases by 0.0006–0.006 km² (0.15–0.5%) every year and have less influence from climate change. This study shows that the spatiotemporal lake area changes are determined by either climate change or human activity.

Many hydro-dams have been built for beneficial gains, but they are causing numerous unintended negative effects on the environment. The complexity of dam impacts and the insufficient knowledge of developing countries result in many uncertainties in managing land systems and environmental impact assessments (EIAs). Also, considering the consequences beyond the dam sites proved challenging in EIAs. In this context, this paper aims to determine the spatial pattern of the environmental consequences of dams, quantify the distance of impacts, and identify different patterns in both upstream and downstream areas. We considered the hydrological linkage of dams with wetlands in watersheds and the spatial relationship between watersheds to explicate the spatial pattern. Two hundred and ninety wetlands in the Mekong, Salween, and Irrawaddy Basins were categorized into those linked with dams and those without dams, and the hydrological characteristics were statistically compared for two periods (before and after the dam booms) using the Mann–Whitney U test. The watersheds having significant differences were found, and their spatial relationship in terms of location (i.e., upstream and downstream) and distance was determined by utilizing the HydroBASINS’ Pfafstetter coding system. The results indicate that the impacts of dams on downstream areas extend significantly farther than their effects on upstream regions in HydroBASINS level-7 representation. The quantitatively determined spatial patterns on upstream and downstream areas can provide accurate spatial baseline information in land system management and EIA.