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Ponds constitute a pivotal component of aquatic ecosystems. The aquatic ecosystem of the Huai River Basin (HRB) in China was once damaged by severe pollution, and numerous ponds in the basin have not been secured. In this paper, Shenqiu County, a typical county in HRB with many ponds, is selected. Based on high-resolution images with ALOS in 2010, GF-2 in 2016, and GF-1 in 2022, we employed discriminant analysis (DA), classification and regression tree, support vector machine, and random forest to extract the ponds based on object-oriented and further analyzed the spatial-temporal variations of the ponds in this county. The results of the DA in these three years exhibited a higher kappa coefficient (>0.7), and overall accuracy (>75%), signifying superior performance when compared to the other three methods. There were 4625, 5315, and 4748 ponds in 2010, 2016, and 2022, with a total area of 12.87, 11.99, and 9.37 km2, respectively. The number of ponds had a trend of rising in the initial period (2010–2016) and falling later (2016–2022), while the total area revealed a continuous decline. Meanwhile, these ponds showed a clustering phenomenon with three main clustering areas, and the scope of the clustering areas also changed to a certain extent from 2010 to 2022. Our study offers valuable methodological support for the ecological monitoring and management of water environments in regions characterized by a dense concentration of ponds. The crucial data related to ponds in this study will help inform both environmental and social development initiatives within the area. [ABSTRACT FROM AUTHOR]

The developed karst caves may become the seepage channels of heavy metal to the soil and underground water in Southwest China. Therefore, it is necessary to apply effective seepage treatments to the base of heavy metal tailing reservoirs. This paper addressed the high-pressure rotary jet technology and slurry systems used in the seepage treatment of the deep tailing sand of the Shenxiandong tailing pond located in Southwest China. In this study, the factors of fluidity, initial and final setting times, compressive strength, and permeability coefficient of the slurry were conducted. The mechanism analysis was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and inductively coupled plasma-mass spectrometry (ICP-MS). Three different types of slurry systems were proposed, and the permeability coefficients of the solidification body following 28 days of curing were less than 1 × 10−7 cm/s. The concentrations of Pb and Zn in the slurry system containing bentonite were reduced by 26.2% and 45.7%, respectively. In the presence of slaked lime and fly ash, the concentrations of Pb and Zn could be reduced by 26.8% and 30%, respectively. A total of 2142 high-pressure rotary jet piles were completed by the high-pressure rotary jet method in the field trial. The diffusion radius of these piles was over 1 m. Following 28 days of curing, the solidification body's compressive strength was 7.45 MPa and the permeability coefficient was 6.27 × 10−8 cm/s. Both the laboratory and on-site trials showed that this method produced a good pollution barrier effect, which could prevent the diffusion of heavy metal into the adjacent underground water through the karst caves. It is also an effective way of engineering technology concerning heavy metal pollution control that occurs in tailing ponds. [ABSTRACT FROM AUTHOR]

Due to the frequent irrigation and excessive fertilization during the rice production in China, diffuse nitrogen (N) and phosphorus (P) pollution from paddy fields has become a serious environment problem and poses great challenges to national water and food security. Considering the regional heterogeneities of climate, cultivation types and cropping systems of rice planting, many water management strategies have been proposed and implemented to control diffuse N and P pollution. However, the water management optimization at different scales (the field scale, the watershed scale and national scale) is lack of comprehensive analyzed. Here, this paper summarized the characteristics of frequent-used water managements and recommended the optimal water managements after identifying the critical risk periods of diffuse N and P runoff losses at the field scale. The effects of water management optimization on diffuse N and P pollution control at the watershed and national scale were also synthetically reviewed. The results indicated that optimized field water management decreased irrigation water use (38.7–40.0%) and reduced diffuse pollution (25.5–38.8%) without significantly compromising rice yield security (−4.20 to 6.5%). The critical risk periods of diffuse pollution were pre-flooding in the Northeast Plain, pre-flooding, regreening stage for transplanting rice (the seeding-three leaf stage for direct seeding rice) and within 2 weeks after topdressing fertilization in the Yangtze River Basin and Southeast Coast in China. The corresponding water managements for these periods has been proposed after considering the climate, precipitation and fertilization characteristics. Ditches and ponds intercepted water and nutrients and mitigated 6.0–39.0% N and P runoff losses in paddy field watersheds. Furthermore, the extensive implementation of paddy water management optimization (paddy fields, ditches and ponds) combined with other advanced agricultural measures, for example, fertilization optimization, would decrease diffuse N and P pollution by 40.7–80.8% at the watershed scale and 44.7–88.1% at the national scale, respectively. This research provided great insights into the specific characteristics of paddy water managements from the fields, watershed and national scale, proposed optimal water management strategies for the realization of sustainable rice production in China, and also summarized the emerging development trends for future research directions. [Display omitted] • Optimal paddy water managements at field, watershed and national scales were analyzed. • Optimal water managements were proposed for critical risk periods at field scale. • Future emerging prospects of paddy water managements from different scales were proposed. [ABSTRACT FROM AUTHOR]

This paper combines spatial poetics, landscape architecture theory and humanistic geographical ideology, analyzing Tang Dynasty Poet Bai Juyi’s . . . aesthetics of multi-layer landscape architecture on the waterscape of his Lü-dao Garden . . . This paper is divided into five parts. Part One discusses Bai Juyi's Lü-dao Garden as the typical “Dream Home;” the poet projected his subjective values and conducted multi-layer landscape architecture to shape his wooded garden, and waterscape is a crucial element in this project. Part Two discusses the aspect of the material environment in landscape architecture. Livi-dao Garden, with a pond in the center surrounded by meandering water paths, creates a focal point to showcase variations and can be appreciated from 360 degrees. It also offers a space allowing for wandering endlessly in loops. Thirdly, discuss the aspect of the artistic scene which Bai Juyi's created with the arrangement of surrounding waterscapes under the bed, producing the exclusive delight of “comer space” and symbolic imagery of lounging gestures above water. The reflection in the water is used to establish a microcosm, liberating conventional relationships when viewing the space. By re-organizing sceneries from South of the Yangzi River, he created a miniature homeland based on his memory; a transcendental angle is used as if lying on a boat to review the self's perspective. Part Four discusses landscaping actions involved in accordance with the ultimate spiritual principles. Bai Juyi applied a method of contemplative investigation in researching matters and efforts in meditative Zen practices to create a deep, distilled and lucid state for Lu-dao Garden as the ultimate spiritual principle, constructing a blissful condition of self-containment and perfection. Part Five is the conclusion. [ABSTRACT FROM AUTHOR]

A tile map in image format is one of the most important tools that people can use to acquire multiscale geographic information on the Internet. Traditional methods of typification in map generalization are used to handle traditional vector-based buildings and linear drainages such as rivers and ditches. In this paper, a new raster-tile-based method called artificial pond typification (APT) is developed for the typification of artificial water areas while maintaining the original distribution characteristics and reducing the number of water areas. First, combining the second-order neighborhoods of superpixels and median filtering, the water areas are grouped at different levels of detail. Then, three different types of superpixel generation algorithms, including simple linear iterative clustering (SLIC), linear spectral clustering (LSC) and superpixel extraction via energy-driven sampling (SEEDS), are applied to generate new typified positions. Finally, different strategies, such as maximum area and global feature strategies, are designed to reconstruct the shapes of water areas. To test the proposed APT method, the map tiles from the Baidu map in China are used as the raw experimental data. The experimental results show that the proposed APT method can be effectively used for the typification of artificial ponds at different levels of detail while gradually removing the details of boundaries as the scale changes. In addition, different typification strategies provide various cartographic alternatives in different cases. • A new method called APT is developed for typification of artificial water areas. • The proposed APT method can maintain the original distribution characteristics. • Different typification strategies provide various cartographic alternatives. [ABSTRACT FROM AUTHOR]

While tailings wastes have attracted public concern in China, the knowledge of their numbers, distribution, land occupation, perimeter, and altitude is incomplete. Based on statistics and geographic information system (GIS) method, the present study investigated 5189 of tailings ponds (TPs) in order to understand the present situation of tailings in China. Overall, this study revealed that the occupied land of TPs is about 1884.0 km2, average altitude is 699.4 m, and the strip between the tailings wastes and soil accumulated to 14,674.4 km. This is harmful to the security of closed biomes community. Besides, TPs are widely scattered, especially, the distribute density which ranges from 0.009 to 0.05/km2 are located in the northern Hebei Province, Liaodong Peninsula, Shandong Peninsula and western Henan province. In terms of watershed for TPs, the ascending order is Huaihe River, Heilongjiang River, Pearl River, Liaohe River, Yellow River, Yangtze River, Haihe River; and the land usage is Huaihe River < Pearl River < Liaohe River < Heilongjiang River < Yangtze River < Haihe River < Yellow River. In a nutshell, tailings wastes should be considered a huge environmental threat in China. • 5189 tailings ponds in China have been discussed in this paper. Especially, average altitude of tailings ponds is 699.4 m, the occupied land is 1884.0 km2, and the strip between the tailings wastes and soil are accumulated to 14674.4 km. • The tailings ponds were widely distributed throughout the country, especially, highest horizontal distribution density occurs in north Hebei province, with a mean density of >0.02/per km2. • The horizontal and vertical distribution of tailings ponds in the watershed was discussed. [ABSTRACT FROM AUTHOR]

Variation of pollutant removal index values for different monitoring units when compared to the system. • Evaluated representativeness of water quality monitoring units in distributed ditches and ponds buffer systems. • Partial monitoring units normally cannot represent the system's performance accurately. • Selection of monitoring units should refer to research objectives and certain evaluation indexes. • Target-oriented approaches are necessary for monitoring unit selection to well represent the buffer systems. Ditches and ponds in agricultural landscapes act as natural buffers for removing nutrients and pesticides lost from crop fields. The complex hydraulic condition of distributed ditch and pond systems (DDPSs), however, results in distinct pollutant removal capacities of single units. This poses a great challenge to the selection of representative monitoring units (MUs) of a DDPS. Based on a field investigation and theoretical analysis, this paper explored the representativeness of selected MUs in evaluating water quality functions of DDPSs in agricultural landscapes in southeastern China. The adopted evaluation indexes include the proportions of mass removal intensity, specific removal rate, and removal rate constant for designated pollutants. The results showed that the representativeness of a single MU varied with different evaluation indexes, and different combinations of MUs failed to represent the system accurately in the study area. The representativeness of a single MU may be expressed adequately with one evaluation index but poorly with another. This was caused by the size, hydraulic retention time and location of MUs, pollutant removal rate constant, as well as field drainage flow schemes. Strategies for selecting appropriate MUs to represent the whole system were recommended for using different evaluation indexes. Understanding the variations in MU selection may help improve water quality monitoring of DDPSs in agricultural landscapes. [ABSTRACT FROM AUTHOR]