Exploring landscape and geologic controls on spatial patterning of streambank groundwater discharge in a mixed land use watershed

Preferential groundwater discharge features along stream corridors are ecologically important at local and stream network scales, yet we lack quantification of the multiscale controls on the spatial patterning of groundwater discharge. Here we identify physical attributes that best explain variation in the presence and lateral extent of preferential groundwater discharges along two 5th order streams, the Housatonic and Farmington Rivers, and 32 1st to 4th order reaches across the Farmington River network. We mapped locations of preferential groundwater discharge exposed along streambanks using handheld thermal infrared cameras paired with high-resolution topographic and land use land cover datasets, surficial soil characteristic maps, and depth-to-bedrock geophysical measurements. The unconfined Housatonic River, MA, USA (12 km) had fewer discharge locations and less lateral extent (41 discharge locations with 38 m of active discharge/km of river) compared to the partially confined Farmington River, CT, USA (26 km; 169 discharge locations with 129 m of active discharge/km of river). Using a moving window analysis, we found along both rivers that discharge was more likely to occur where bank slopes were steeper, floodplain extent was narrower, and degree of confinement was higher. Along the Farmington River, groundwater discharge was more likely to occur where saturated hydraulic conductivity was higher and depth-to-bedrock was shallower. Among the 32 stream reaches surveyed (33.2 km of total stream length) within the Farmington River watershed, preferential discharge was observed in all but two stream reaches, varied from 0 to 25% of lateral extent along stream banks (mean = 6%), and was more likely to occur where stream reach slopes were steep, saturated hydraulic conductivity was high, and watershed urbanization was low. Our results show that, though both surface (e.g., topographic, land use land cover) and subsurface (e.g., soil characteristics, bedrock depth) factors control the prevalence of streambank preferential groundwater discharge, the dominant controls vary across valley settings and stream sizes.     

Differential subsidence driving the formation of mounded stratigraphy in deep-water sediments; Palaeocene, central North Sea

Deep-water Palaeocene strata of the East Central Graben, UK North Sea, are characterised by elongate depressions and elevations parallel with the palaeotransport direction and with underlying structural lineaments. Palaeozoic and mesozoic faults underlying the basin were briefly re-activated during the Palaeocene, affecting the seabed topography in the form of gentle folding, faulting and slope instability. Two types of mounded features formed in response to the tectonically induced seabed structuration: (i) deformational mounded morphology, a product of syndepositional faulting and mass wasting, (ii) non-deformational mounded morphology, interpreted to result from changing flow dynamics as flows travelled over the deformed sea floor, accentuating the structural topography by means of localised erosion and deposition. This study shows how differential subsidence acted as the ultimate control behind a range of processes leading to mounded stratigraphy. The models of the origin of the mounded morphologies are novel in the context of the North-Sea Palaeocene and have implications for the prediction of lithology in mounded basinal deposits, in the North Sea and elsewhere.     

国内外CTD校准实验室及校准技术研究的现状和展望

本文在叙述ＣＴＤ剖面仪和传感器校准方法的基础上,介绍了当前国内外ＣＴＤ校准技术研究和校准设备的现状。提出了我国应加强ＣＴＤ传感器动态校准的研究,同时,应研制精度慢温盐水盐力罐,用于在实验室内研究建立ＣＴＤ传感器数学模型的方法。     

含氮污水净化的数学模型及其实例模拟

含水层中氮污染已经是相当普遍的问题。本文分析了含水层中水流运动、对流－弥散作用、物理化学吸附和生物化学反应等对污染物运移的影响，特别是阐述了含水层中NO3^-、NO2^-、NH4^ 三种形式之间的转化关系，在此基础上，探讨了这些物理、化学和生物作用导致的物质转化过程定量描述的数学模式。     

黄河口高流速区近50年演变过程

根据黄河口外大量的现场历史观测资料分析发现,其附近海域流场存在着明显的高流速区。这些高流速区在大时间尺度上随着入海流路的改变以及黄河三角洲的演变也发生着此消彼长的变化。利用ChinaTide潮汐预报软件模拟海域潮汐,并利用不同历史年代的海图资料构建海域地形,通过建立黄河口数学模型分析了黄河口流场特性;利用2015年营口港的潮位资料以及实测流速值对数学模型进行了率定和验证;然后分别利用数学模型,对不同代表年的流场进行模拟复演。计算结果表明：①自1962年,黄河口沿岸就已经存在高流速区,分别位于甜水沟和神仙沟口外;②1976年,从神仙沟到清水沟一线沿岸存在着多个小型的高流速区群;③1996年至今,该阶段内存在3个高流速区,分别位于湾湾沟、神仙沟以及清8口门3个沙嘴处;④高流速区的演变与海岸形态的变化存在着密不可分的联系,岸线凸出的沙嘴处往往容易形成平面高流速区。     

Spatio-temporal variability of bedload transport rate: analysis and 2D modelling approach

Field measurements to calibrate numerical bedload formulae are largely missing. Measurements using a Large Helley-Smith sampler were performed over a period of five years in the large Alpine Drau River, Austria. Our results reveal the high spatio-temporal variability of bedload transport rates. Commonly used bedload predictors poorly describe measured transport rates. Temporal and localised cross-sectional variation in bedload transport rates are observed in short time frames. To obtain significant mean values, the measurement period has to be extended to cover the existing bedload transport periodicity. The discrepancy between bedload transport measurements and simulation is partially explained by local hydraulic variations. The results can be improved, particularly for verticals where most of the bedload occurs, by relating measured transport rates to local hydraulic parameters. The incorporation of local cross-sectional parameters demonstrates the utility of 2D bedload models and their greater predictive power over similar 1D models.     

泉州市县域经济差距研究

区域经济差异的研究历来是区域经济研究的主线。通过运用加权变异系数、锡尔系数和基尼系数等数学方法对泉州市县域经济进行研究,探讨了三次产业以及地区（沿海与内陆）内、地区间对泉州市县域经济发展差距的影响。得出如下结论：（1）泉州市县域经济发展总体差距缩小;（2）第三产业对泉州市县域经济发展差距的贡献率最大,第二产业次之,第一产业最小;（3）地区间的差距对总体差距的贡献呈先上升后下降,而地区内差距特别是沿海内部差距对泉州市县域经济发展差距的的贡献总体呈现上升趋势。     

Exploring the fringe belt concept in Auckland: An urban morphological idea and planning practice

The idea of urban fringe belts has been recognised as a powerful means of understanding the physical form of urban areas and the process of urban outward growth and internal change. Surrounding Auckland's city core, an inner fringe belt can be recognised. Farther out there are middle and outer fringe belts. Fluctuations in socio-economic development, the adoption of new transport modes, land reclamation and topography are major factors influencing the formation of these fringe belts. The examination of changes to fringe belts highlights important issues of urban transformation, which are pertinent to planning and design policies for urban landscape management.     

天山北坡绿洲城市空间形态时空特征分析

借助GIS 软件支持, 综合遥感影像、地形图和其它空间数据, 提取天山北坡8 个绿洲城市 1990 年和2000 年建设用地图形信息, 计算1990 年和2000 年天山北坡8 个绿洲城市的平面轮 廓形状的分维数、紧凑度以及城市用地扩展类型, 讨论紧凑度与分维数的关系。研究结果表明, 天 山北坡绿洲城市形态总体特征表现为形状规则, 结构紧凑。1990~2000 年, 城市扩展类型主要为 外延型, 城市形态分维数增加, 紧凑度降低, 城市外部形态趋于复杂化和不规则化, 而内部结构趋 于松散化, 与同时期我国大部分城市的用地扩展方式有所不同。同时, 天山北坡绿洲城市形态特 征描述参数间存在着明显的幂函数关系, 并且是一种线性负相关关系, 即随着分维数的增加, 紧 凑度呈递减的趋势。     

模糊数学方法在旅游景区环境质量评价中的应用研究——以广东丹霞山为例

在实地调查和专家访谈的基础上,设计调查问卷,运用多层次模糊综合评价方法建立旅游环境质量评价模型,对丹霞山旅游风景名胜区的环境质量进行综合评价。评价结果表明:丹霞山旅游环境质量总体上是比较好的,在资源特色、自然生态和基础设施方面均有较大的优势。但存在一些制约旅游可持续发展的环境因素,植被发育和森林覆盖率不够理想,达不到游客满意的程度,从业人员素质和居民文化素养有待提高,医疗救护设施的完备性方面仍需要进一步加强。