Local‐scale and watershed‐scale determinants of summertime urban stream temperatures          下载免费PDF全文

Derek B. Booth  Kristin A. Kraseski  C. Rhett Jackson 《水文研究》2014,28(4):2427-2438

The influence of urbanization on the temperature of small streams is widely recognized, but these effects are confounded by the great natural variety of their contributing watersheds. To evaluate the relative importance of local‐scale and watershed‐scale factors on summer temperatures in urban streams, hundreds of near‐instantaneous temperature measurements throughout the central Puget Lowland, western Washington State, were collected during a single 2‐h period in August in each of the years 1998–2001. Stream temperatures ranged from 8.9 to 27.5 °C, averaging 15.4 °C. Pairwise correlation coefficients between stream temperature and four watershed variables (total watershed area and the watershed percentages of urban development, upstream lakes, and permeable glacial outwash soils as an indicator of groundwater exchange) were uniformly very low. Akaike's information criterion was applied to determine the best‐supported sets of watershed‐scale predictor variables for explaining the variability of stream temperatures. For the full four‐year dataset, the only well‐supported model was the global model (using all watershed variables); for the most voluminous single‐year (1999) data, Akaike's information criterion showed greatest support for per cent outwash (Akaike weight of 0.44), followed closely by per cent urban development + per cent outwash, per cent lake area only, and the global model. Upstream lakes resulted in downstream warming of up to 3 °C; variability in riparian shading imposed a similar temperature range. Watershed urbanization itself is not the most important determining factor for summer temperatures in this region; even the long‐recognized effects of riparian shading can be no more influential than those imposed by other local‐scale and watershed‐scale factors. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Using Sentinel-1A DInSAR interferometry and Landsat 8 data for monitoring water level changes in two lakes in Crete,Greece     

D. D. Alexakis  E. G. Stavroulaki  I. K. Tsanis 《国际地球制图》2019,34(7):703-721

Differential Interferometric Synthetic Aperture Radar (DInSAR) methodology has been successfully employed to detect water level changes and produce corresponding water level variation maps. In this study, Agia and Kournas lakes, located in Western Crete, Greece, were used as pilot areas to monitor water level change with means of SAR interferometry and auxiliary Earth Observation (EO) data. The water level variation was monitored for the period 2015–2016, using Sentinel-1A imageries and corresponding stage water level data. Landsat 8 data were additionally used to study vegetation regime and surface water extent and how these parameters affect interferograms performance. The results highlighted the fact that the combination of SAR backscattering intensity and unwrapped phase can provide additional insight into hydrological studies. The overall analysis of both interferometric characteristics and backscattering mechanism denoted their potential in enhancing the reliability of the water-level retrieval scheme and optimizing the capture of hydrological patterns spatial distribution.  相似文献   

太行山山前断裂带倾斜潮汐因子动态组合分析     

张肖  佘雅文  齐玉妍  云萌 《大地测量与地球动力学》2019,39(10):1017-1021

利用Venedikov调和分析方法计算太行山山前断裂带地倾斜观测台站2002~2017年EW和NS分量的固体潮潮汐因子，获取潮汐因子异常与动态组合的3种特征量（扩容膨胀、剪切应变、介质的各向异性）时间序列，并分析其与太行山山前断裂带附近中等地震的关系。结果表明：1）断裂带上地倾斜潮汐因子受海潮负荷影响较小，潮汐因子并未因纬度的改变而表现出明显的规律性变化，其差异可能是因为受地壳横向不均匀变化的影响；2）地倾斜固体潮潮汐因子动态组合特征量与观测站点周边350 km范围内发生的ML4.0以上地震有较好的对应关系。  相似文献   

基于无人机可见光影像的高原丘陵盆地区山药植株识别   总被引：1，自引：0，他引：1  

黄登红  周忠发  吴跃  朱孟  尹林江  崔亮 《热带地理》2019,39(4):571-582

采用四旋翼无人机采集特色作物山药种植区影像，针对山药种植时间和管护水平差异导致的植株生长差异化特征，通过筛选红绿比值指数（RGRI）、过绿指数（ExG）和过绿减过红指数（ExG-ExR）等颜色指数获取山药植株最优颜色指数计算方法；以高斯高通滤波（GHPF）增强和保留山药植株高频信息，抑制杂草、玉米植株的噪声；结合田间测量山药植株数据，通过人机交互解译方法对图像滤波增强后的影像进行灰度分割和提取山药植株信息。结果表明：1）样区总体提取精度为91.14%，样区A、B、C的提取精度分别为90.94%、91.96%、90.81%，精度验证完整性为93.16%；2）随着山药植株多株连体生长复杂程度的增强，过绿指数具有的土壤与植被的分离性仍优于红绿比值指数和过绿减过红指数；3）使用高斯高通滤波能够有效消除杂草、玉米植株的影响，减小山药植株多株连接生长所产生的干扰；4）高斯高通滤波卷积核大小79×79适用于不同时相和不同生长情况的山药植株影像处理，针对不同的山药植株生长情况和不同时相的可见光影像，需调整灰度分割的阈值参数t，单株山药植株面积S由田间测量确定。该方法以快速灵活、低成本的方式识别和计算不同生长状态的山药植株数目，适用于喀斯特山区的精准农业监测研究和现代农业生产活动。  相似文献   

Characteristics of δ13CDIC in lakes on the Tibetan Plateau and its implications for the carbon cycle     

Yanbin Lei  Tandong Yao  Yongwei Sheng  Enlou Zhang  Weicai Wang  Junli Li 《水文研究》2012,26(4):535-543

Dissolved inorganic carbon isotope (δ¹³C_DIC) is an important tool to reveal the carbon cycle in lake systems. However, there are only few studies focusing on the spatial variation of δ¹³C_DIC of closed lakes. Here we analyze the characteristics of δ¹³C_DIC of 24 sampled lakes (mainly closed lakes) across the Qiangtang Plateau (QTP) and identify the driving factors for its spatial variation. The δ¹³C_DIC value of these observed lakes varies in the range of ? 15·0 to 3·2‰, with an average value of ? 1·2‰. The δ¹³C_DIC value of closed lakes is close to the atmospheric isotopic equilibrium value, much higher than that in rivers and freshwater lakes reported before. The high δ¹³C_DIC value of closed lakes is mainly attributed to the significant contribution of carbonate weathering in the catchment and the evasion of dissolved CO₂ induced by the strong evaporation of lake water. The δ¹³C_DIC value of closed lakes has a logarithmic correlation with water chemistry (TDS, DIC and pCO₂), also suggesting that the evapo‐concentration of lake water can influence the δ¹³C_DIC value. The δ¹³C_DIC value shows two opposite logarithmic correlations with lake size depending on the δ¹³C_DIC range. This study suggests that the δ¹³C in carbonates in lacustrine sediments can be taken as an indicator of lake volume variation in closed lakes on QTP. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Influences of watershed landscape composition and configuration on lake‐water quality in the Yangtze River basin of China     

Wenzhi Liu  Quanfa Zhang  Guihua Liu 《水文研究》2012,26(4):570-578

Lake‐water quality is highly dependent on the landscape characteristics in its respective watershed. In this study, we investigated the relationships between lake‐water quality and landscape composition and configuration within the watershed in the Yangtze River basin of China. Water quality variables, including pH, electrical conductivity (EC), dissolved oxygen (DO), Secchi depth (SD), NO₂^?, NO₃^?, NH₄⁺, TN, TP, chemical oxygen demand (COD_Mn), chlorophyll‐a (Chl‐a), and trophic state index (TSI), were collected from 16 lakes during the period of 2001–2003. Landscape composition (i.e. the percentage of vegetation, agriculture, water, urban, and bare land) and landscape configuration metrics, including number of patches (NP), patch density (PD), largest patch index (LPI), edge density (ED), mean patch area (MPA), mean shape index (MSI), contagion (CONTAG), patch cohesion index (COHESION), Shannon's diversity index (SHDI), and aggregation index (AI), were calculated for each lake's watershed. Results revealed that the percentage of agriculture was negatively related to NO₂^?, TN, TP, Chl‐a concentrations, and TSI, while the percentage of urban was significantly correlated with EC, NH₄⁺, and COD_Mn concentrations. Among landscape‐level configuration metrics, only ED showed significant relationships with TN, TP concentrations, and TSI. However, at the class level, the PD, LPI, ED, and AI of agriculture and urban land uses were significantly correlated with two or more water quality variables. This study suggests that, for a given total area, large and clustered agricultural or urban patches in the watershed may have a greater impact on lake‐water quality than small and scattered ones. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

三维地理信息在辅助冬奥会规划设计决策中的应用 ——以2022年冬奥会延庆赛区为例     

吕扬  周庆  侯庆明  李兵 《测绘通报》2019,(10):133-137

冬季奥林匹克运动会的雪上项目建在高差悬殊、地形复杂、山高林密的区域，为了因地制宜，减少挖填方，控制资金，场馆设计需要精细准确的现状数据。本文以2022年冬奥会延庆赛区为例，利用无人机遥感、LiDAR技术获取现状数据，制作高分辨率数字正射影像及高精度数字高程模型，搭建实景三维场景，将规划设计方案制作三维模型，导入实景三维场景，进而开展辅助冬奥会规划决策的相关应用。本文成果不仅为冬奥组委会、业主和相关管理部门信息共享提供了切实的技术支撑，也为三维地理信息技术在山区大型工程中的应用提供了有效的方法借鉴，为山区冰雪项目的设计提供了参考。  相似文献   

How did the suspended sediment load change in the North Caucasus during the Anthropocene?     

Anatoly Tsyplenkov  Valentin Golosov  Pelagiya Belyakova 《水文研究》2021,35(10):e14403

Quantifying and understanding catchment sediment fluxes is crucial both from a scientific and environmental management perspective. To deepen the understanding of landuse impacts and climate change on sediment load, we explore factors controlling the suspended sediment load formation in the Northern Caucasus during the Anthropocene. We examine how sediment flux of various river basins with different land-use/landcover and glacier cover changes during the 1925–2018 period. Our analysis is based on observed mean annual suspended sediment discharges (SSD, kg s⁻¹) and annual fluxes (SSL, t year⁻¹) from 33 gauging stations of The Federal Service for Hydrometeorology and Environmental Monitoring (Russia). SSL series have been analysed to detect statistically significant changes during the 1925–2018 period. The occurrence of abrupt change points in SSD was investigated using cumulative sum (CUSUM) charts. We found that SSL has decreased by −1.17% per year on average at most gauges. However, the decline was not linear. Several transition years are expected in the region increasing trends from the 1950s and decreasing trends from 1988 to 1994. Correlation analyses showed that variation in SSL trend values is mainly explained by gauging station altitude, differences in landuse (i.e. the fraction of cropland), and catchment area. Nonetheless, more accurate quantifications of SSL trend values and more refined characterizations of the catchments regarding (historical) landuse, soil types/lithology, weather conditions, and topography may reveal other tendencies.  相似文献   

Transpiration Rates of Carex Meyeriana in Relation to Micrometerological Factors in a Mountain Valley Wetland     

XU Huifeng  JIN Yanming  DENG Wei  XU Kezhang  WANG Zhen College of Agriculture  Jilin Agricultural University  Changchun    P.R. China 《山地科学学报》2009,(3)

In order to reveal transpiration rates of wetland plants and its relationships to micro-meterological factors in a mountain valley wetland, relative humidity, air temperature, leaf temperature, soil temperature, photo flux density and transpiration rates were measured once two hours in a Carex meyeriana wetland of the Changbai Mountain valley in dry (July) and wet (September) of 2003, respectively. Results showed that the tendency of "decreasing after increasing" was obvious in wet season. However, a relati...  相似文献   

青海大风山天青石矿床地质特征及成因分析   总被引：3，自引：0，他引：3  

马顺清  李善平  谢智勇  潘彤  白宗海  陈静  任华 《西北地质》2012,(3):130-140

大风山天青石矿床位于柴达木盆地西北部,由Ⅰ、Ⅱ、Ⅲ、Ⅳ四个矿区组成,赋矿地层为第三系上新统狮子沟组,含矿层位不稳定,矿体多呈薄层状、扁豆状或透镜状产于含碳钙质泥岩中,矿石主要为天青石、菱Sr矿等;矿区内东西、北东东向次级断裂及舒缓短轴复式背斜构造严格控制着天青石矿体的产出形态;成矿物源具有多源性,一方面周边山系含Sr水为主要补给源,其次为富Sr的油田水。另外,深部含Sr卤水的补给也具有重要作用;矿床成因具有陆相湖泊化学沉积-热水沉积叠加改造型矿床特征。  相似文献