Integrated water system simulation by considering hydrological and biogeochemical processes: model development, with parameter sensitivity and autocalibration

Integrated water system modeling is a feasible approach to understanding severe water crises in the world and promoting the implementation of integrated river basin management. In this study, a classic hydrological model (the time variant gain model: TVGM) was extended to an integrated water system model by coupling multiple water-related processes in hydrology, biogeochemistry, water quality, and ecology, and considering the interference of human activities. A parameter analysis tool, which included sensitivity analysis, autocalibration and model performance evaluation, was developed to improve modeling efficiency. To demonstrate the model performances, the Shaying River catchment, which is the largest highly regulated and heavily polluted tributary of the Huai River basin in China, was selected as the case study area. The model performances were evaluated on the key water-related components including runoff, water quality, diffuse pollution load (or nonpoint sources) and crop yield. Results showed that our proposed model simulated most components reasonably well. The simulated daily runoff at most regulated and less-regulated stations matched well with the observations. The average correlation coefficient and Nash-Sutcliffe efficiency were 0.85 and 0.70, respectively. Both the simulated low and high flows at most stations were improved when the dam regulation was considered. The daily ammonium-nitrogen (NH4-N) concentration was also well captured with the average correlation coefficient of 0.67. Furthermore, the diffuse source load of NH4-N and the corn yield were reasonably simulated at the administrative region scale. This integrated water system model is expected to improve the simulation performances with extension to more model functionalities, and to provide a scientific basis for the implementation in integrated river basin managements

Temporal stability of soil moisture on two transects in a desert area of northwestern China

Temporal stability of soil moisture has important implications for optimal and effective field monitoring and has been observed for a range of soil and landscape conditions. However, relatively less is known about temporal stability of soil moisture in desert areas. In this study, two 5-km transects (TranA and TranB) with different soil properties in a desert area of northwestern China were chosen to assess the characteristics of the temporal variability and stability of soil moisture, to identify representative sampling locations (RSLs), and to evaluate the effect of sampling frequency on the determination of temporal stability. For each transect, moisture contents of the surface soil were measured using Theta Probes on 35 occasions at 51 locations from April to October 2012. The results showed that soil moisture for the finer-textured TranA was consistently higher and more variable than for the coarsertextured TranB. Both transects exhibited strong temporal stability during the monitoring period. Locations with higher sand contents tended to have more pronounced temporal stabilities. The RSL identified in each transect accurately represented the mean moisture contents of the transects over time, with coefficients of determination (R-2) higher than 0.95 and root mean square errors lower than 1 % vol/vol. Soil moisture has significantly higher degrees of temporal stability during dry periods than during wet periods. The effect of sampling frequency on temporal stability of soil moisture was not as evident, particularly for the coarser-textured soil. This study provides insights for designing strategies for the sampling and monitoring of soil moisture in the hydrological applications in desert areas

Understanding rural restructuring in China: The impact of changes in labor and capital productivity on domestic agricultural production and trade

In China, the provinces of Shandong and Henan are the leading provinces for grain production and also have the highest populations. In this study, we quantitatively analyze the impact of the two primary factors that indicate rural restructuring (namely, an increase in labor- and capital-augmenting technical change, represented by labor- and capital productivity) on wheat production in Shandong and Henan provinces, and the consequent effects on exported and imported wheat volumes in other provinces through to 2020. For the analysis, we use The Enormous Regional Model (TERM), an established multi region computable general equilibrium model. The results show that the magnitude of change generated by the increase in labor productivity is larger than that generated by the increase in capital productivity. Therefore, great importance should be attached not only to increasing capital technical change but also improving labor technical change. This study also reveals that regional competitive industry can easily shape absolute competition superiority, which consequently exerts a large impact on the homogeneity of products. Rural China is moving into a critical stage of restructuring, and therefore the government should provide rational top-down guidance. The central government should avoid adopting a "one size fits all" policy and simply supporting a single industry or particular development patterns. Rural China should form stable, sustainable, and specialized agricultural production arranged by geographic areas, which would not only guarantee China's food security, but also improve the nation's competitive capacity in the international market. (C) 2016 Elsevier Ltd. All rights reserved

Approaches of climate factors affecting the spatial variation of annual gross primary productivity among terrestrial ecosystems in China

Analyzing the approaches that climatic factors affect the spatial variation of annual gross primary productivity (GPP(yr)) would improve our understanding on its spatial pattern. Based on network eddy covariance measurements and published data in literature, we separated GPP(yr) into radiation use efficiency (RUE) and annual absorbed photosynthesis active radiation (APAR(yr)), where APAR(yr) can be regarded as the product of the fraction of absorbed annual photosynthesis active radiation (FPAR(yr)) and annual PAR (PAR(yr)). Given that PAR(yr) affects the spatial variation of GPP(yr) directly through itself, we investigated factors affecting the spatial variations of RUE and FPAR(yr), to reveal how climatic factors affect the spatial variation of GPP(yr). Results suggest that the spatial variation of RUE was directly affected by annual mean air temperature (MAT) and annual mean CO2 mass concentration (rho(cyr)). The increasing MAT and rho(cyr), directly enhanced RUE. The increasing annual precipitation (MAP) directly prompted FPAR(yr). Therefore, MAT and rho(cyr) affected the spatial variation of GPP(yr) through altering RUE while the effect of MAP was achieved through altering FPAR(yr). Our study could also provide an alternative way for regional GPP(yr) assessment. (C) 2015 Elsevier Ltd. All rights reserved

Heavy metal deposition through rainfall in Chinese natural terrestrial ecosystems: Evidences from national-scale network monitoring

Industrialization and urbanization have led to increasingly serious levels of atmospheric heavy metal pollution, which is one of the main sources of heavy metals to terrestrial ecosystems. Therefore, it is essential to quantify atmospheric fluxes and explore their potential effects on natural ecosystems and human welfare. We monitored water-soluble heavy metals (lead (Pb), cadmium (Cd), and chromium (Cr)) in rainfalls on a monthly basis in 2013 and 2014, at 31 field stations located in typical natural Chinese ecosystems. The average soluble Pb, Cd, and Cr deposition was 1.90 1.54, 0.28 0.25, and 0.96 +/- 0.48 mg m(-2) yr(-1), respectively, with a large variation among the different sites. Generally, the atmospheric deposition of soluble Pb, Cd, and Cr was higher in the southwest, central, south, and north China than in the northwest and northeast China, Inner Mongolia, and Qinghai-Tibet. As expected, the atmospheric heavy soluble metal deposition fluxes were significantly correlated with the number of vehicles (Ps < 0.1). The wet deposition of soluble Pb and Cr was positively correlated with oil and coal consumption, unlike Cd deposition. Moreover, soluble Pb and Cd in atmospheric wet deposition were positively correlated with the contents of Pb and Cd in soil at different regions. In this study, atmospheric heavy metal deposition through rainfall in typical natural ecosystems in China is assessed at the national scale, alerting potential ecological hazards resulting from an increasing atmospheric heavy metal deposition and providing a basis for future studies. (C) 2016 Elsevier Ltd. All rights reserved

Interactions between warming and soil moisture increase overlap in reproductive phenology among species in an alpine meadow

Climate warming strongly influences reproductive phenology of plants in alpine and Arctic ecosystems. Here, we focus on phenological shifts caused by experimental warming in a typical alpine meadow on the Tibetan Plateau. Under soil water stress caused by warming, most plants in the alpine meadow advanced or delayed their reproductive events to be aligned with the timing of peak rainfall. As a result, warming significantly increased the temporal overlap among reproductive stages of early- and late-flowering species. In addition, we found that some species, for example the late-flowering species, were unable to produce flowers and fruits under warming with failed monsoon rains. The potentially warmer- and drier-growing seasons under climate change may similarly shift the phenological patterns and change species composition of these alpine systems

我国资源环境承载约束地域分异及类型划分

开展资源环境承载约束地域类型研究是推进我国工业化和城镇化发展的重要基础工作之一。文章以人均可利用土地资源潜力、人均可利用水资源潜力、环境胁迫度、生态制约度为关键指标,通过构建分步式或集成式测算方法,按县级单元分别对我国水、土、环境和生态等资源环境要素的承载约束进行了测算、空间差异分析和地域类型划分。结果表明:(1)我国有近90%的国土已处于资源环境的强约束状态,其中近半受到双要素的强约束,且主要分布在贺兰山—龙门山线以东的人口产业密集区。(2)我国东、中部人口密集地区以及青藏高原已处于土地资源缺乏的强约束状态;华北、西北、东北、四川盆地以及南方城市地区已处于水资源缺乏的强约束状态;华北平原、长三角及苏北、川渝黔桂省区、东北平原、黄土高原地区北部等地已达到环境胁迫强约束程度;生态强约束区域主要集中在天山—大别山线的西南部,该线东北部的黄土高原、阿拉善盟、东北周边及苏北沿海也有成片分布。(3)资源环境承载约束的要素交叉类型多样,多要素约束类型空间分布相对集中,除青藏高原为土地-生态约束类型外,其他交叉约束类型主要集中在贺兰山—龙门山线以东地区。(4)针对我国资源环境承载约束面大地广、类型复杂多样且与人口产业密集区高度重叠等特点,十三五期间国家宜在国情基础数据挖掘整理、资源环境承载力监测预警、承载力评价基础理论方法以及国土空间管控制度完善等方面加大工作力度

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<正>党的十八届五中全会提出创新、协调、绿色、开放、共享五大发展理念,将绿色发展作为十三五乃至更长时期我国经济社会发展的重要理念,预示着十三五时期将成为绿色发展理念指导下的产业绿色转型关键期。旅游业是典型的资源环境依赖型产业,改革开放以来在我国发展迅速,取得了良好的经济、社会和生态效益,成为支撑建设美丽中国的重要载体,但也存在一些对目的地

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橡胶生产关乎国计民生,特别是天然橡胶,其与钢铁、石油、煤炭并称四大工业原料,为重要的战略物资。本文基于FAO橡胶数据库,从全球、区域、国家等层次定量分析了1961-2013年全球橡胶生产的时空格局及其演变特征,探讨了影响橡胶产量的主要因素。结果表明:1从时间格局上看,1961年以来全球橡胶总产增速较快,总体呈上升趋势;橡胶主要生产国(主产国)产量占全球的90%以上,并存在明显的阶段性增长特征。2就空间格局而言,橡胶生产具有明显的地域集中性,主产国集中分布在亚洲特别是东南亚,其中以泰国、马来西亚和印尼最为集中,但其产量差异显著并有进一步扩大趋势。3种植面积是主产国橡胶产量的主要影响因子;少部分国家(如中国、泰国)受橡胶单产水平的影响明显。4全球橡胶生产由传统三巨头(泰国、马来西亚和印尼)向双核(泰国和印尼)集聚,东南亚主产国橡胶林由海岛国家向中南半岛扩展,且中南半岛发展势头强劲,已成为全球橡胶主产区中的优势产区

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纵观全球,社会经济发展迅速,人类活动对生态环境可持续发展的影响不断增加。足迹理论可将这种影响定量化,为解决生态环境问题奠定基础,主要包括生态足迹、水足迹、碳足迹以及能源足迹等。论文基于文献计量分析方法,研究了我国四大足迹理论2000—2015年间的主要研究进展。研究表明:1)在我国,生态足迹理论在2000年首先出现,研究论文年均162篇,并促进水足迹和碳足迹的产生,现三者都已发展较成熟;能源足迹逐渐成为寻求经济发展与生态环境平衡的新突破口。2)各类足迹研究内容包括理论概念、方法、评估以及应用等;其中,生态足迹、碳足迹的应用指数整体高于理论指数,表明两者理论研究整体水平低于其方法技术应用水平;而水足迹、能源足迹相反。3)四类足迹具有相通性,未来应重点发展综合足迹理论,全面评估可持续发展