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101.
Li‐Yang Xiong Ru‐Qiao Jiang Qing‐Hui Lu Bi‐Sheng Yang Fa‐Yuan Li Guo‐An Tang 《Transactions in GIS》2019,23(2):259-274
Depression filling is a critical step in distributed hydrological modeling using digital elevation models (DEMs). The traditional Priority‐Flood (PF) approach is widely used due to its relatively high efficiency when dealing with a small‐sized DEM. However, it seems inadequate and inefficient when dealing with large high‐resolution DEMs. In this work, we examined the relationship between the PF algorithm calculation process and the topographical characteristics of depressions, and found significant redundant calculations in the local micro‐relief areas in the conventional PF algorithm. As such calculations require more time when dealing with large DEMs, we thus propose a new variant of the PF algorithm, wherein redundant points and calculations are recognized and eliminated based on the local micro‐relief water‐flow characteristics of the depression‐filling process. In addition, depressions and flatlands were optimally processed by a quick queue to improve the efficiency of the process. The proposed method was applied and validated in eight case areas using the Shuttle Radar Topography Mission digital elevation model (SRTM‐DEM) with 1 arc‐second resolution. These selected areas have different data sizes. A comparative analysis among the proposed method, the Wang and Liu‐based PF, the improved Barnes‐based PF, the improved Zhou‐based PF, and the Planchon and Darboux (P&D) algorithms was conducted to evaluate the accuracy and efficiency of the proposed algorithm. The results showed that the proposed algorithm is 43.2% (maximum) faster than Wang and Liu's variant of the PF method, with an average of 31.8%. In addition, the proposed algorithm achieved similar performance to the improved Zhou‐based PF algorithm, though our algorithm has the advantage of being simpler. The optimal strategies using the proposed algorithm can be employed in various landforms with high efficiency. The proposed method can also achieve good depression filling, even with large amounts of DEM data. 相似文献
102.
The characteristics of seismic water level fluctuations of the two Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 on December 26,2004 and March 29, 2005 recorded at Jiaji well, Qionghai, Hainan were analyzed, the features of the infrequent "step" changes of well water level after the two earthquakes were also analyzed and the mechanism of the "step change" of well water level was discussed. Then the high-sample-rate digital observation data of seismically-induced water level fluctuations of the Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 recorded at Nanbin well, Sanya and Tanniu well, Wenchang were analyzed. The results suggest that the dominant period of the seismic well water level fluctuation in all three wells was comparatively accordant, the amplitudes of seismic water level fluctuation of the same earthquake in different wells were clearly different, the time duration of seismic water level fluctuations of different earthquakes at the same well was also clearly different. 相似文献
103.
104.
Stream channel erosion in a rapidly urbanizing region of the US–Mexico border: documenting the importance of channel hardpoints with Structure‐from‐Motion photogrammetry 下载免费PDF全文
Kristine T. Taniguchi Trent W. Biggs Eddy J. Langendoen Carlos Castillo Napoleon Gudino‐Elizondo Yongping Yuan Douglas Liden 《地球表面变化过程与地形》2018,43(7):1465-1477
Urbanization can lead to accelerated stream channel erosion, especially in areas experiencing rapid population growth, unregulated urban development on erodible soils, and variable enforcement of environmental regulations. A combination of field surveys and Structure‐from‐Motion (SfM) photogrammetry techniques was used to document spatial patterns in stream channel geometry in a rapidly urbanizing watershed, Los Laureles Canyon (LLCW), in Tijuana, Mexico. Ground‐based SfM photogrammetry was used to map channel dimensions with 1 to 2 cm vertical mean error for four stream reaches (100–300 m long) that were highly variable and difficult to survey with a differential GPS. Regional channel geometry curves for LLCW had statistically larger slopes and intercepts compared with regional curves developed for comparable, undisturbed reference channels. Cross‐sectional areas of channels downstream of hardpoints, such as concrete reaches or culverts, were up to 64 times greater than reference channels, with enlargement persisting, in some cases, up to 230 m downstream. Percentage impervious cover was not a good predictor of channel enlargement. Proximity to upstream hardpoint, and lack of riparian and bank vegetation paired with highly erodible bed and bank materials may account for the instability of the highly enlarged and unstable cross‐sections. Channel erosion due to urbanization accounts for approximately 25–40% of the total sediment budget for the watershed, and channel erosion downstream of hardpoints accounts for one‐third of all channel erosion. Channels downstream of hardpoints should be stabilized to prevent increased inputs of sediment to the Tijuana Estuary and local hazards near the structures, especially in areas with urban settlements near the stream channel. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
105.
西北干旱地区大气降水δ18O的特征及水汽来源 总被引:6,自引:1,他引:6
In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation (CHNIP). During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O. The established local meteoric water line δD=7.42 δ18O+1.38, based on the 95 ob-tained monthly composite samples, could be treated as isotopic input function across the region. The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions. The monthly δ18O values were characterized by a positive correlation with surface air temperature (δ18O (‰) =0.33 T (℃)-13.12). The amount effect visualized during summer period (δ18O (‰) = -0.04P (mm)-3.44) though not appeared at a whole yearly-scale. Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China. The quan-titative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops. Furthermore, the raindrop suffered a re-evaporation during falling processes, and the pre-cipitation vapor might have been mixed with a quantity of local recycled water vapor. Multiple linear regression equations and a δ18O-T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data. The estab-lished δ18O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate. 相似文献
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107.
栖霞牙山地区地处华北地台东部,对该区的似斑状花岗闪长岩体所作的岩石地球化学研究表明,该区岩石为钙碱性偏铝质岩石;微量元素MORB标准化蛛网图显示富集大离子亲石元素Ba、Sr,亏损高场强元素Nb、Ta、Hf、Y;K/Rb比值为295.34~388.88,Rb/Sr比值为0.21~0.29;稀土元素蛛网图表现为较平滑的具微弱负Eu异常向右陡倾的稀土元素配分模式曲线,∑LREE/∑HREE为9.14~12.22,显示轻重稀土元素分异较好。结合构造背景分析,认为牙山花岗闪长岩体为早白垩世太平洋板块向欧亚板块俯冲诱发的地幔柱活动,造成地幔底辟,引起地壳部分熔融,形成壳幔混合岩浆并进一步侵入形成。 相似文献
108.
提出了一种对灰色-马尔科夫链预测模型的状态区间取值修正方法.考虑实测值在状态区间中的位置分布情况作为先验知识,对状态区间的端点重新定权,修正预测值在状态区间中的取值,从而获得更高精度的预测结果.结合某建筑物的实测沉降数据,与原始GM(1,1)、残差修正G M(1,1)、灰色-马尔科夫链预测模型进行对比,结果表明:本文预... 相似文献
109.
为了对广西合浦盆地干热岩资源成热条件及其潜力进行评价,利用广西航磁勘查数据,采用Parker-Oldenburg法反演计算了居里面深度。在此基础上进行大地热流密度值和不同埋深地温计算,发现计算结果与现有测温资料吻合,合浦盆地内西场凹陷和常乐凹陷具有干热岩资源成生条件。结合合浦盆地内基础地质调查资料和油气钻孔资料,分析了合浦盆地干热岩资源的储层和盖层条件。初步圈出2个位于西场凹陷和常乐凹陷的干热岩勘查靶区C1和C2,面积分别为167.10和72.90 km2,干热岩资源量分别为182.48×1015、77.59×1015 J。按20%的采收率,合浦盆地干热岩资源量可开采量为52.01×1015 J,折合标准煤177.48×104 t,占2018年广西全区能源生产总量3 756.69×104 t标准煤的4.72%。在资源量评价基础上,可优先考虑位于合浦盆地西场凹陷的C1靶区开展进一步的勘探工作。 相似文献
110.
BTEX异常对海域油气藏指示作用的研究 总被引:2,自引:0,他引:2
常规的油气化探方法一般是应用烷烃类作为油气勘探的基本指标,但是烷烃类易受人类活动和生物活动的干扰,使常规的化探技术在油气勘探中一直受到限制。人们开始考虑采用直接的生物标记化合物来预测油气藏,如芳烃系列中的苯系化合物苯(benzene)、甲苯(toluene)、乙苯(ethylbenzene)、二甲苯(xylem),简称BTEX。国内外研究表明,BTEX基本不受人类活动和生物活动的干扰,对油气藏具有良好的指示作用。依据南海某区的实测资料,采用自主研发的油气化探可视化评价软件进行数据处理,剥离背景异常,圈出有效的BTEX异常,并与靶区地层剖面进行了对比,结果证实了BTEX对海域油气藏具有良好的指示作用。 相似文献