中国南方调整水稻种植格局——一种水稻生产预先适应气候变化的选择(英文)

Rice planted in southern China accounts for 94% of the total in sown acreage and 88% of the total in production, which matters a lot to Chinese food security. However, due to the prolonged conflict between water availability and rice growth in spatial/temporal distribu-tion, rice production suffers from seasonal drought at acreage of 16%-22%, which compro-mises food production capacity and food security. Focusing on the spatial distribution of seasonal drought with rice and the practices to adapt to it, and based on an analysis of bal-anced water supply for and demand by rice at a growing season scale during 1981-2030, this paper assesses the changing seasonal drought in the process of rice production under the changing climate in the future, and identifies general rice re-cultivation options for climate change adaptation. Some conclusions can be drawn as follows. (1) Rice suggests a decline in seasonal drought, with early season rice (early rice hereafter) by 12,500 km2, middle season rice (middle rice) by 80,000 km2, and in particular late season rice (late rice) by 25,000 km2, which accounts for almost 20% of its cultivated acreage. It is indicated that due to climate change, seasonal drought in major rice producing areas tends to alleviate in general, late season rice in particular. (2) Future climate change brings about a significant impact on the spatial/temporal distribution of water resources in rice producing areas in China. Based on ’pre-designed’ adaptation actions for rice-re-cultivation, the rice cultivation pattern undergoes a significant alteration between 1981-2000 and 2001-2030. In eastern Guizhou and western Hunan, the pattern of single early plus single dry farming is changed into double cropping. In eastern Hunan, the pattern of dry cropping is changed into single early plus single dry farming. In northern Anhui, the pattern of dry farming cropping is changed into middle rice. All this is aimed at a potential adequate availability of water for rice production in the future. (3) Rice re-cultivation patterns developed in this paper help re-balance water demand and supply for rice growth using the spatial analysis tool to adapt rice growth to the changing water avail-ability from spatial perspective, and come up with rice producer-friendly re-cultivation options in response to climate change.     

A Voronoi neighborhood-based search heuristic for distance/capacity constrained very large vehicle routing problems

Local search heuristics for very large-scale vehicle routing problems (VRPs) have made remarkable advances in recent years. However, few local search heuristics have focused on the use of the spatial neighborhood in Voronoi diagrams to improve local searches. Based on the concept of a k-ring shaped Voronoi neighbor, we propose a Voronoi spatial neighborhood-based search heuristic and algorithm to solve very large-scale VRPs. In this algorithm, k-ring Voronoi neighbors of a customer are limited to building and updating local routings, and rearranging local routings with improper links. This algorithm was evaluated using four sets of benchmark tests for 200–8683 customers. Solutions were compared with specific examples in the literature, such as the one-depot VRP. This algorithm produced better solutions than some of the best-known benchmark VRP solutions and requires less computational time. The algorithm outperformed previous methods used to solve very large-scale, real-world distance constrained capacitated VRP.     

Tendances et ruptures au niveau des pluies journalières extrêmes en Côte d'Ivoire (Afrique de l'Ouest)

Résumé

Le changement climatique est une réalité qui affecte plusieurs variables climatiques dont les précipitations. Néanmoins, son impact sur les évènements extrêmes et en particulier sur les pluies journalières extrêmes n'est pas encore certain car peu de travaux y ont été consacrés en Afrique de l'Ouest. Dans ce contexte, il a été proposé de détecter d'éventuels tendances et ruptures dans les propriétés statistiques (moyenne, variance) des pluies journalières extrêmes à l'aide de tests statistiques locaux et régionaux. Pour détecter ces changements, les indices caractérisant la pluie maximale journalière annuelle (PJmaxan), le nombre annuel de jours de pluie dépassant 50 mm (NJsup50) et la contribution des pluies dépassant 50 mm dans les cumuls annuels (R(PJsup50/Pan)) ont été définis. L'analyse de 44 postes pluviométriques en Côte d'Ivoire sur la période 1942–2002 ne montre pas de changement généralisé ni en moyenne, ni en variance. Toutefois, en subdivisant la Côte d'Ivoire en régions climatiques homogènes, des tendances à la baisse ont été observées dans les régions IV (au Nord) et II (au Sud-Est).

Editeur Z.W. Kundzewicz; Assistant editeur G. Mahé

Citation Goula, A.B.T., Gneneyougo Soro, E., Kouassi, W. et Srohourou, B., 2012. Tendances et ruptures au niveau des pluies journalières extrêmes en Côte d'Ivoire (Afrique de l'Ouest). Hydrological Sciences Journal, 57 (6), 1067–1080.     

利用外部DEM辅助山区SAR立体像对匹配及地形制图

SAR立体像对的匹配是利用雷达摄影测量技术提取地形高程信息的关键,匹配精度将直接影响结果 DEM的高程精度。针对山区SAR立体像对匹配过程中同名点选取困难的问题,引入外部粗分辨率DEM作为辅助数据,将该DEM高程转换为视差,为匹配提供初值,同时采用金字塔匹配策略,不仅可以缩小搜索范围,提高搜索效率,而且能够减少粗差的产生。试验结果表明,采用外部DEM辅助之后,匹配粗差点数量相对于传统的雷达摄影测量处理结果明显减少,从而有效地提高了高程信息提取重建的精度。     

A mechanism for formation of the western North Pacific monsoon trough: nonlinear upscale cascade

Linear and nonlinear barotropic vorticity model frameworks are constructed to understand the formation of the monsoon trough in boreal summer over the western North Pacific. The governing equation is written with respect to specified zonal background flows, and a wave perturbation is prescribed in the eastern boundary. Whereas a uniform background mean flow leads no scale contraction, a confluent background zonal flow causes the contraction of zonal wavelength. Under linear dynamics, the wave contraction leads to the development of smaller scale vorticity perturbations. As a result, there is no upscale cascade. Under nonlinear dynamics, cyclonic (anticyclonic) wave disturbances shift northward (southward) away from the central latitude due to the vorticity segregation process. The merging of small-scale cyclonic and anticyclonic perturbations finally leads to the generation of a pair of large-scale cyclonic and anti-cyclonic vorticity gyres, straddling across the central latitude. The large-scale cyclonic circulation due to nonlinear upscale cascade can be further strengthened through a positive convection-circulation feedback.

     

沙三中亚期东营三角洲前缘滑塌浊积岩定量预测

东营凹陷沙三中亚段广泛发育三角洲-浊积体系沉积。根据砂层组沉积的垂向变化特征,将沙三中亚段沉积时期东营三角洲自上而下划分为1～9期次,自东向西向湖盆中心进积。与三角洲有关的前缘浊积体包括滑动浊积岩、滑塌浊积岩及远源浊积岩3种类型,其中滑塌浊积岩发育的规模、数目最为稳定,是前缘浊积体定量研究的重要类型。笔者采用控制变量的方法对单因素关系进行探讨,进而分析多因素综合关系,对沙三段中亚段沉积时期东营三角洲前缘浊积体进行定量研究,从而探讨三角洲沉积结构与前缘滑塌浊积体发育的定量关系。研究发现,三角洲沉积结构特征(三角洲前缘地层厚度H、砂岩百分含量x等)、浊积岩滑移距离s以及三角洲前缘斜坡坡角的大小α,可以定量地确定,并且三角洲前缘滑塌浊积体发育的厚度h与前缘厚度H、前缘砂岩百分含量x成正相关,与浊积体滑移距离s呈负相关,并且得到预测三角洲前缘浊积体厚度h的数学模型。     

楼面地价在容积率改变补缴土地出让价款评估中的应用

出让土地改变容积率是一个普遍的问题,国土资源部要求用楼面地价核定应当补缴的土地出让价款,但没有具体的实施方案。该文结合德州市基准地价体系研究了楼面地价与容积率的关系,对如何评估楼面地价及如何用楼面地价核定应当补缴的土地出让价款进行了探讨。     

爆心距对爆破震动信号频谱的影响分析

结合临沂某一隧洞工程,利用matlab分析软件分析了不同爆心距下的爆破震动信号的频谱变化情况。得出：在爆破中近区,震动信号的主频在垂直方向的分量较水平方向大,随着爆心距的增加地面震动峰值速度的主震方向会由水平方向向垂直方向转化,总体呈衰减趋势,震动主频趋向于低频;在爆破参数和爆区特征类似于本工程的工程爆破现场其中低频震动信号在水平方向上的分量所占能量比例高于垂直分量的能量比例,在距爆源较远的位置也不能忽略爆破震动对建筑结构的影响,尤其是要加强水平方向的抗震设防。     

Seasonal variation of suspended-sediment transport through the southern Bohai Strait

Based on field observations made in winter 2006 and summer 2007 and on multiscene MODerate resolution Imaging Spectrometer (MODIS) imagery, the seasonal variation of suspended-sediment transport in the southern Bohai Strait and its possible mechanisms are examined. The field observations in two different seasons allow an exponential empirical model to be used to retrieve suspended-sediment concentration (SSC) from MODIS imagery. Both the field-survey data and the MODIS-derived SSC show that the sediment transport in the southern Bohai Strait has a significant seasonal variation due to the seasonally varying thermohaline structure of the water column and the hydrodynamics resulting from the seasonally alternating monsoons. The SSC in winter is approximately 3–10 times higher than in summer. Considering the seasonal variation of water flux (WF) and SSC, the annual sediment flux (SSF) through the southern Bohai Strait is estimated to be approximately 40.0 Mt yr⁻¹, about 4–8 times previous estimates, which did not take into account seasonal variation. Although the Huanghe (Yellow River) discharges a large amount of sediment in the summer, the SSF through the southern Bohai Strait in the winter (∼32.0 Mt) is about 4 times greater than it is in the summer. The strong seasonal variability of SSF through the southern Bohai Strait indicates that strong resuspension along the coast of the Huanghe delta in winter and enhanced longshore transport by coastal currents due to winter monsoon activity might be the major mechanisms of cross-strait transport of sediment in winter.     

全球变化背景下北方泥炭地释放溶解有机碳的驱动机制

泥炭地（peatland）是一类储碳效率很高的特殊陆地生态系统,其碳储量约占全球土壤碳库的近1／3,对全球碳循环有着举足轻重的作用。有证据表明在过去20余年,北半球大范围的天然水体中溶解有机碳的浓度呈显著增升趋势。普遍认为与全球变化背景下北方泥炭地大规模释放溶解有机碳有关,但其驱动机制尚不十分清楚。已经提出的具有代表性...