Accurate supply and demand matching of ecosystem services (ESs) is important for managing regional ecosystems. On the basis of remote-sensing, meteorological, and socio-economic data, we mapped the supply, demand, and matching status of four ESs (i.e., water production, carbon sequestration, food supply, and soil conservation) using biophysical models and the ArcGIS spatial analysis module within the Zhengzhou–Kaifeng–Luoyang (ZKL) urban agglomeration in 2018. Four-quadrant analysis was employed to identify the spatial matching types of supply-demand relationships within the study region. The results are as follows. The supply-demand ratios of different ESs in the cell scale exhibit different spatial characteristics because of major influencing factors, including the natural environment (e.g., precipitation and temperature) and social development (e.g., urbanization level). Analysis of the supply-demand imbalances of the four ESs indicates that water production is deficient across the entire research area, whereas the whole research area’s carbon sequestration, food supply, and soil conversation are in the surplus state. Regarding the spatial matching types for supply and demand of the four ecosystem services, water production is dominated by the “low–low (low supply and low demand)” type. Carbon sequestration is dominated by the “low–low” and “high–low (high supply and low demand)” types. The “low–low” type dominates food supply and soil conservation. Due to the severity of the deficit in water production, all districts and counties in the ZKL urban agglomeration are identified as areas requiring ecological conservation, ecological restoration, or ecological improvement. Development guidance strategies and planning suggestions are proposed in different ecological areas. These policies could also be applied in other similar urban agglomerations.

The Hongze Lake is the fourth largest freshwater lake in China and an important lake for the East Route of the South-to-North Water Diversion Project. The water quality of the lake affects social development and the lives of residents. To assess the impacts of environmental changes and human activities on the distribution of the total suspended matter (TSM) in the Hongze Lake, we developed an algorithm that utilizes the near-infrared (NIR) band to estimate TSM based on in situ measurements. The algorithm was applied to Landsat images to derive TSM distribution maps from 1984 to 2019, revealing significant inter-annual, seasonal, and spatial variability. The relationship between TSM, precipitation, and wind speed was analyzed, and we found that: (1) The estimation model of TSM concentration in the Hongze Lake constructed for TM and OLI has a high accuracy, and it can be used to jointly monitor TSM concentration in the Hongze Lake for long-term series; (2) From 1984 to 2019, the concentration of TSM in the Hongze Lake showed a trend of first rising and then falling, with the maximum value in 2010 at 100.18 mg/L mainly caused by sand mining activities. Precipitation and wind speed weakly influence the inter-annual variation of TSM concentration; (3) The concentration of TSM in the Hongze Lake in summer is easily affected by flooding in the Huai River, and the concentration of TSM in other seasons is significantly negatively correlated with precipitation; (4) TSM is highest in the Huaihe Bay, followed by the Lihe Bay and Chengzi Bay. The main reason for this is that the input of the Huaihe Bay flows directly into this lake area and is also the main navigation channel. The results of this study are of great significance for the protection and management of the water environment of the Hongze Lake.

The intensification of anthropogenic activities has led to the infiltration of enormous quantities of pollutants into rivers and lakes, resulting in significant deterioration in water quality and a more prominent occurrence of eutrophication. Poyang Lake, the largest freshwater lake in China, is facing a severe challenge related to eutrophication, which seriously threatens the delivery of the ecosystem service and the safety of drinking water. To address this challenge, Landsat-8 Operational Land Imager (OLI) data for the Poyang Lake Basin (PLB) from May 2013 to December 2020 were used. Since inland water bodies with complex optical characteristics, we developed a semi-analytical algorithm to assess the trophic state of the water based on two cruise field measurements in 2016 and 2019. Combining the semi-analytical trophic level index (TLI) with an atmospheric correction model is the most suitable model for OLI images of the PLB, this model was then applied to Landsat-8 time series observations. The trends of the trophic state of water bodies in PLB were revealed, and the annual, quarterly and monthly percentages of eutrophic water bodies were calculated. Natural and anthropogenic factors were then used to explain the changes in the trophic state of the PLB waters. The main findings are as follows: (1) From the 8-year observation results, it can be seen that the variation of trophic level of water in PLB showed obviously spatial and temporal variations, characterized by higher in the north than in the south and higher in winter than in summer. (2) Temperature promoted the growth of harmful algae and plays an essential role in affecting changes in the trophic level of the water. (3) Changes in the trophic level of water bodies in PLB were mainly affected by human activities. The results of spatial and temporal variation of the trophic level of water and the driving factors in PLB can extend our knowledge of water quality degradation and provide essential references for relevant policy-making institutions.

The landscape visual effect of a city, which is generated by its long-term development, is an important index in city planning. In this study, we build a quantitative evaluation and remote sensing estimation scheme of landscape visual effect. The study contains two main steps. First, utilizing the Elo rating system and in situ sampled panoramic pictures, the quantitative assessment of the city landscape visual effect was carried out. Then, the landscape visual effect estimation model was built and applied to Landsat remote sensing image to generate the spatial distribution of landscape visual effect in Zhengzhou city, 2017. At last, the effect of different combination of land use and elevation to the landscape visual effect was discussed. The results showed the following: (1) the Elo rating system is an effective method to quantitatively evaluate the city landscape visual effect; (2) the landscape visual effect remote sensing estimation model had a good performance, with the mean absolute percentage error (MAPE) and root mean square error (RMSE) of the model are less than 0.05 and 80, respectively; (3) the landscape visual effect score of Zhengzhou city, 2017, was high in the southwest and low in the northeast; (4) different land use situation and average surface elevation had a complex influence on the landscape visual effect.

The Yangtze River Delta region is the most economically active and open region in China. It is also the region with the most prominent contradictions between urban and rural development. Therefore, it is necessary to strengthen the resilience of the rural areas in this region so that they can develop further with resources and opportunities after sustaining shocks. This study used a weighted TOPSIS method to measure the rural resilience of 153 research units from 2000 to 2019 and then applied the ESDA method to measure the spatial agglomeration or heterogeneity characteristics. The results show that: (1) The rural resilience of this region is higher in the east and lower in the west; (2) rural resilience has obvious spatial agglomeration characteristics, which have undergone a process of shifting from strong to weak before becoming strong again; and (3) the hotspots of rural resilience gradually shifted from Jiangsu to Zhejiang, while the coldspots gradually shifted from Zhejiang to Anhui. Finally, the K-means clustering algorithm was applied to divide all research units into five types: natural capital-dominated areas, productive capital-dominated areas, human capital-dominated areas, social-financial capital-dominated areas and general development areas. Then, the strategies for resilience promotion were proposed accordingly.

Hyperspectral data are important for water color remote sensing. The inevitable noise will devalue its application. In this study, we developed a 1-D denoising method for water hyperspectral data, based on sparse representing. The denoising performance was compared with three commonly used methods in simulated and real datasets. The results indicate that: (1) sparse representing can successfully decompose the hyperspectral water-surface reflectance signal from random noises; (2) the proposed method exhibited better performance compared with the other three methods in different input signal-to-noise ratio (SNR) levels; (3) the proposed method effectively erased abnormal spectral vibrations of field-measured and remote-sensing hyperspectral data; (4) whilst the method is built in 1-D, it can still control the salt-and-pepper noise of PRISMA hyperspectral image. In conclusion, the proposed denoising method can improve the hyperspectral data of an optically complex water body and offer a better data source for the remote monitoring of water color.