Migration of induced-infiltration stream water into nearby aquifer due to a transverse horizontal well in loess areas

Analysis of the migration paths of stream water introduced into a transverse horizontal well is important to better understand the interactions between streams and aquifers. This paper presents a method of using particle-tracking techniques to evaluate the transport of stream water that infiltrates through a transverse horizontal well that runs transverse to a stream and extends from the stream banks. By conceptualizing the horizontal well as a discrete pipe network, MODFLOW is coupled with the pipe flow equations that govern the movement of water in the horizontal well, and this coupled seepage-pipe flow model is used to calculate the transient groundwater flow field. MODPATH is then used to record the locations of each of the water particles from the interface between the stream and the aquifer. The path lines, travel times, influence zones and the production of infiltrated stream water are determined to depict the migration process. The results suggest that the infiltrated stream water that originates from different stream transects located upstream and downstream from the horizontal well has different migration characteristics, as does the infiltrated stream water coming from different locations on the same stream transect. Eventually, the pumpage of the horizontal well consists partly of the infiltrated stream water and groundwater inflow from the upstream model boundary. The groundwater enters the horizontal well through the two end segments of the horizontal well, and the infiltrated stream water enters the middle segment of the well. The pumped water is still a mixture of infiltrated stream water and groundwater, even if the pumping lasts for a long period. The hydrochemistry of the infiltrated stream water cannot be simply used to evaluate the hydrochemistry of the water pumped from a transverse horizontal well.     

南海东北部春季海表pCO_2分布及海-气CO_2通量

2013年南海东北部春季共享航次采用走航观测方式,现场测定了表层海水和大气的二氧化碳分压(pCO2)及相应参数。结合水文、化学等同步观测要素资料,对该海域pCO2的分布变化进行了探讨。结果表明,陆架区受珠江冲淡水、沿岸上升流及生物活动的影响,呈现CO2的强汇特征;吕宋海峡附近及吕宋岛西北附近海域受海表高温、黑潮分支"西伸"、吕宋岛西北海域上升流等因素影响,呈现强源特征。根据Wanninkhof的通量模式,春季整个南海东北部海域共向大气释放约4.25×104 t碳。     

陕西省降水量综合分析显示系统

利用V isualC 6.0编译系统开发了陕西省每天降水量的统计分析、显示和打印,实现了地理图形和表格2种显示方式,图形显示可以任意放大和缩小,并可以统计全省97个台站任意降水时段的降水量值和极值,在屏幕上用不同颜色显示出来。     

2010年1月24日山西河津-万荣Ms4.8地震特征

分析2010年1月24日山西河津-万荣Ms4.8地震序列特征,利用P波初动及振幅比和波形反演CAP两种方法计算震源机制解,结合本次地震的地质构造和历史地震活动背景、震源机制、余震分布、极震区长轴方向等分析,结果表明,隐伏的西辛封断裂为发震构造的可能性较大.     

Comprehensive evaluation of urban flood-bearing risks based on combined compound fuzzy matter-element and entropy weight model

The extreme precipitation events caused by climate change and the rapid development of urbanization have brought hidden flood risks to the cities. This paper comprehensively considered two major factors of vulnerability of urban flood-bearing and disaster prevention and mitigation (DPAM) capacity and built a comprehensive evaluation index system for urban flood-bearing risks. Secondly, a combined model consisted of composite fuzzy matter-element and entropy weight model was constructed to calculate the comprehensive risk indicator. Finally, the Zhengzhou City was taken as an example, the comprehensive indices of urban flood-bearing risk from 2006 to 2015 were evaluated. The results showed that the comprehensive risk of Zhengzhou City was generally on a slow upward trend, from II level (moderate-risk) in 2006 to III level (secondary high-risk) in 2015, which was mainly due to the mismatch between the rapid development of urbanization and the slow improvement of DPAM capabilities. This paper is expected to provide scientific reference and technical support for urban flood disaster prevention and sponge city construction.

     

Assessment of macrobenthic community function and ecological quality after reclamation in the Changjiang (Yangtze) River Estuary wetland

An ecological optimization project (semi-closed reclamation project) was implemented to control the invasion of Spartina alterniflora, and optimize the habitat of the Chongming Dongtan wetland, in the Changjiang (Yangtze) River Estuary. After project implementation, a macrobenthic ecological survey was conducted in a natural tidal flat and a semi-closed reclamation restoration area within the Chongming Dongtan wetland from 2019 to 2020. Compared with historical data before reclamation, findings showed that the groups, numbers, and species diversity of the macrobenthos increased significantly, and the ecological optimization project resulted in good ecological benefits. In addition, compared to the natural tidal flat, the number of collected macrobenthic phyla, and the macrobenthic density and biomass were significantly lower in the restoration area. Furthermore, the biodiversity index and functional redundancy of natural tidal flats were generally higher, indicating that the community composition and function of natural tidal flats were relatively more stable. Even though the species composition differed between a number of restoration areas and natural tidal flats, there was no difference in functional diversity, indicating that the effect of restoring ecological functions in restoration areas was optimal. Among them, the biodiversity and functional redundancy of Site S2 were significantly reduced, and the ecosystem function was extremely unstable. Habitat heterogeneity, vegetation community and decreasing salinity were the main factors that affected the ecological functions of macrobenthos. The ecological quality was also evaluated; the Transects N3 and N4 showed good quality. The overall ecological quality of the restoration area was generally high, but that of Site S2 was poor and that of Site S2E was merely good, which was mainly due to modifications of the ecological function of macrobenthos. It is suggested that reeds mowing and freshwater species release should be adopted in restoration areas to improve the community function and the environmental disturbance resistance of the macrobenthos.     

攀枝花太阳能资源评价

为了有效地开发和利用攀枝花太阳能资源,本文在广泛搜集国内相关地区太阳辐射资料的基础上,整理了攀枝花几十年的太阳能相关气象数据,通过天文辐射量、日照百分率、经纬度、水汽压等因子建立相关辐射量计算模式,系统地分析和研究了攀枝花地区太阳能辐射量的主要分布特征和优势,对大力开发利用攀枝花太阳能资源提供了科学依据,并就如何发展特色农业和旅游业等综合开发利用方面提出了具体可行的对策建议。     

An analysis of drag force on wind of shrubs simulated in a wind tunnel

Shrubs that exert drag force on the wind significantly affect the air–surface interaction in arid and semiarid regions, and some coastal regions where aeolian processes are active. An understanding of the drag force on wind of shrubs provides important information on the dynamics of shrubs in reducing wind erosion, and their geomorphological significances. Thus, we analyzed the drag force and drag coefficient for model shrubs using wind measurements obtained by particle image velocimetry in a scaled wind tunnel simulation. The drag force was found to be a function of wind velocity and shrub density. Both drag force and drag coefficient revealed a critical shrub density of around 0.08. The vertical drag force changed direction when the shrub density became greater or less than the critical density. The drag coefficient increased rapidly with shrub density when the density was below 0.08, but it increased very gently when the density was increased beyond the critical value. The results have an important theoretical significance for our understanding of the dynamics of vegetated dunes and the windbreak mechanism of shrubs.     

Model Test and Theoretical Analysis of New and Old Embankments Differential Settlement Considering Lateral Deformation

Geotechnical and Geological Engineering - In the embankment widening project, the new embankment will produce large deformation due to the low degree of consolidation, which will affect the...     

井水位前驱波普遍性问题的探讨

以山西、河北、内蒙等地5口映震能力较强的地下水位观测井为研究对象,对井水位前驱波普遍性问题进行了探讨.结果表明,强震井水位前驱波现象较为普遍,其比例可达65.1％(41/63);相同地震不同观测井前驱波特征各不相同,同一观测井在不同地震前的特征也各异,这可能与不同观测井具有不同的井-含水层结构以及不同地震前有着不同的震源参数有关;与单井水震波相比,震前有前驱波记录的次数略低于水震波,其比例在39.7％～50.7％之间;震前有前驱波记录的观测井占研究区观测井总数的比例可达66.7％.