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Paddy surface water is the direct source of artificial drainage and surface runoff leading to N loss from rice paddy fields. Quantifying the N dynamics in paddy surface water on a large scale is challenging because of model deficiencies and the limitations of field measurements. This study analyzed the N dynamics and the influencing factors in paddy surface water in the three main Chinese rice-growing regions: Northeast Plain, Yangtze River Basin, and Southeast Coast. An improved first-order kinetic model was proposed to evaluate the total nitrogen (TN) dynamics at a countrywide scale by improving the calculation method of the initial TN concentration (C

Water-saving irrigation (WSI) is a promising management practice for sustainable rice production. Shallow-wet irrigation (SWI), controlled irrigation (CI), intermittent irrigation (II), and rain-gathering irrigation (RGI) are four common WSI regimes used in China. Their water saving, pollutant reducing, and yield increasing effects were analysed based on literature survey from multi-site field studies across China. An index system considering the applicability and effect of different WSI regimes was developed to identify their potential distributions across China. The potential overall effect of WSI practices at the country level was then estimated. Results showed that CI had the highest average water saving rate (WSR) of 35.12% and the highest average pollutant reducing rate (PRR) of 54.97%, followed by RGI, SWI, and II; while CI had the lowest average yield increasing rate (YIR) (0.79%), followed by II (5.40%), SWI (8.12%), and RGI (11.80%). Overall, the larger the WSR, the larger higher PRR; but the yield increasing effect will be diminished when the WSR is increased to a certain extent due to the resulting rice water stress. About 94.19% of the total paddy area in China are suitable for WSI practices and the unsuitable ones are mainly due to soil structure deterioration and low soil fertility. SWI is the most applicable WSI regime, suitable for 90.03% of paddy fields, followed by CI and II (23.33%), and RGI (4.16%). By full implementation of appropriate WSI regimes at the country level, the total WSR, PRR, and YIR are likely to reach 22.06–26.41%, 32.11–39.11%, and 5.39–6.87%, respectively. The application of WSI practices in China has noticeable potential to alleviate water shortage and non-point source pollution while ensuring high yield.

Non-point source (NPS) pollution has wide range of sources. Under rainfall conditions, NPS pollution occurs mainly by overland flow, resulting in difficult governance. In this study, based on the cooperative analysis of critical periods (CPs) and critical source areas (CSAs), a preferred hierarchical control strategy of NPS pollution, which was connected with management units, was proposed in the Danjiangkou Reservoir Basin (DRB) to improve the pertinence of NPS pollution control. The practicality of the grid-based CSA identification results was improved by point density analysis (PDA). CPs, sub-CPs, and non-CPs were identified on the temporal scale; CSAs, sub-CSAs and non-CSAs were identified on the spatial scale. The results showed that CPs (July, April, and September), sub-CPs (May, March, and August), and non-CPs contributed 62.8%, 31.1%, and 6.1% of the annual TP loads, respectively. Furthermore, we proposed a hierarchical NPS pollution control strategy: class Ⅰ (CSAs in CPs) → class II (sub-CSAs in CPs, CSAs in sub-CPs) → class III (non-CPs, non-CSAs, sub- and non-CSAs in sub-CPs). Class Ⅰ covered the periods and areas with the highest NPS pollution loads, contributing 26.2% of the annual load within 14.5% of the area and 25.0% of the time. This study provides a reference for the targeted control of NPS pollution at regional scale, especially in environmental protection with limited funds.

Spatiotemporal heterogeneity poses challenges on prevention and control of non-point source (NPS) pollution. Treating pollution sources sequentially by prioritizing the critical periods (CPs) and critical source areas (CSAs) is essential for effective control of regional NPS pollution. In this study, the gird-based dual-structure export empirical model (DSEEM) was used to simulate phosphorus losses in the Danjiangkou Reservoir Basin (DRB) on a monthly scale. Based on the co-analysis of CPs and CSAs coupled with the point density analysis (PDA), a preferred hierarchical control strategy, which was connected with regional management units, was proposed to improve the pertinence for phosphorus loss control. CPs, sub-CPs, and non-CPs were identified on the temporal scale; CSAs, sub-CSAs, and non-CSAs were identified on the spatial scale. The results showed that CPs (July, April, and September), sub-CPs (May, March, and August), and non-CPs contributed 62.8%, 31.1%, and 6.1% of the annual TP loads, respectively. Furthermore, we proposed a hierarchical control strategy for NPS pollution: class I (CSAs in CPs) → class II (sub-CSAs in CPs, CSAs in sub-CPs) → class III (non-CPs, non-CSAs, sub- and non-CSAs in sub-CPs). Class I covered the periods and areas with the highest loads, contributing 26.2% of the annual loads within 14.5% of the area and 25.0% of the time. This study provides a reference for the targeted control of NPS pollution at regional scale, especially in environmental protection with limited funds.

Urban development has positive and negative effects on the evolution of enclosed lake water quality. This study aims to quantitatively analyze the water quality evolution of a typical urban lake, the Sha Lake, in the process of urban development. The land use degree comprehensive index (I) was calculated to reveal the level of urban development; water quality index (Smid) and eutrophication index (Tmid) were used to evaluate the water quality changes by fuzzy comprehensive-quantifying assessment (FCQA) method. The urban construction process and the water quality changes in 2000–2018 in the Sha Lake Basin were divided into three stages: (1) in 2000–2006, with the slow urban development, water quality remained stable and the degree of eutrophication improved slightly; (2) in 2007–2009, I increased rapidly to reach 300, Smid and Tmid increased from 90.62 to 92.83 and 75.06 to 87.52, respectively. Water quality deteriorated because of the failure to implement environmental protection measures in time; (3) in 2010–2018, although urban development reached a high level (I > 300), the water network connection project, dredging project, exogenous pollutant control, and sewage pipe network renovation since 2009 were critical measures to improve water quality for a long time. Due to the lag effect on improving water quality, the implementation of environmental protection measures should be synchronized with or even before urban construction. The research results can provide a scientific basis for the urban lake water environment protection in the process of urban development.

Real-time monitoring of non-point source (NPS) pollution is challenging owing to the minute-scale change in runoff flow and concentration under rainfall condition. In this study, we proposed a real-time measurement method for total nitrogen (TN) by combining the timeliness of sensor detection and the accuracy of intelligent algorithms, based on the physical and chemical relationships between TN and sensor-measured indexes. Extra tree regression was selected as the TN inversion algorithm, which has high precision, high computational efficiency, and better ability in over-fitting control. The results show that: (1) the real-time inversion algorithm of TN can achieve the monitoring frequency at the minute scale (5 min); (2) the method performs well (R

In its 25 years of existence, the Journal of Transport Geography (JTRG) has emerged as the key outlet for cutting-edge transport geography research. However, in practice the journal is part of a much broader publication landscape of research on the geographical dimensions of transport, travel and mobility. In this paper, we therefore analyse the position of JTRG in the different research agendas at the intersection of the geographical and transport sciences. To this end, we present a bibliometric analysis of relevant research covered in the (Social) Science(s) Citation Index ((S)SCI) bibliographic databases. Our analyses include breakdowns of the major journals; key contributing regions and institutions; and variations in topics as revealed by keyword analysis. Throughout the paper, the main focus is on comparing (evolutions in) the research covered in JTRG with (evolutions in) the research at the intersection of the geographical and transport sciences published in other journals. Results are used to reflect on the position of the journal in the field as well as on relative blind spots in terms of authorship and the nature of the research covered, and can thus inform deliberations about possible directions for the journal.

In the process of software evolution, a lot of evolution history information will be stored in software repository. Because some open source repositories (such as GitHub) only record the version of every source file, it is difficult for people to comprehend and manage the evolution of software component and software architecture. In the paper, we propose the concept of software evolutionary binary tree to present the evolution history of software architecture and its components, propose a method to recover them by software architecture recovery technology as well. The experimental results of four open source software (Cassandra, Hbase, Hive and Openjpa) demonstrate that the method is effective.

Critical periods (CPs) and critical source areas (CSAs) refer to the high-risk periods and areas of nonpoint source (NPS) pollution in a watershed, respectively, and they play a significant role in NPS pollution control. The upstream Daning River Basin is a typical watershed in the Three Gorges Reservoir area. In this study, a Hydrological Simulation Program-Fortran (HSPF) model was used to simulate phosphorus loss in the upstream Daning River Basin. Co-analysis of critical periods and critical source areas (CACC) is a quantitative collaborative analysis method for the identification of CSAs in CPs, and it was used to classify the periods and areas of NPS pollution as CPs, sub-CPs, non-CPs, CSAs, and non-CSAs. The CPs occurred in months 5–7 and accounted for 53.7% of the total phosphorus (TP) loads, and the sub-CPs occurred in months 1, 3, 4, and 8 and accounted for 29.2% of the TP loads. In CSAs, 49.4% of the TP loads occurred in 26.8% of the basin. Furthermore, we proposed the following multilevel priority control measure for NPS pollution in the upstream Daning River Basin: CSAs in CPs (with load-area rate of 1.4), CSAs in sub-CPs (0.7), CSAs in non-CPs (0.4), non-CSAs in CPs (0.3), non-CSAs in sub-CPs (0.2), and non-CSAs in non-CPs (0.1). CSAs in CPs accounted for 25.8% of the TP loads from 19.0% of the areas in only 3 months while 49.4% of the TP loads from similar areas over an entire year. These findings indicated that the CSAs in CPs located in farmland along the Daning, Dongxi, and Houxi Rivers should be prioritized for pollution management measures.