塔里木河下游河岸胡杨(Populus euphratica)林耗水过程模拟     

苏里坦  李玉生  艾尔肯·艾比布拉  赵天宇 《中国沙漠》2015,(2):380-384

选择塔里木河下游主要植物胡杨(Populus euphratica)林,以大气温度、太阳净辐射、大气相对湿度、冠层顶风速、地下水位和胡杨树茎横截面积为影响胡杨林耗水量的自变量,基于最小二乘法建立了多重线性回归模型、非线性回归模型和完全二次回归模型,并应用模型对塔里木河下游河岸胡杨林的耗水过程进行了日尺度上的模拟研究。结果表明:3个回归模型均表现出较好的模拟效果,其中完全二次回归模型的模拟精度最高,模型中大气温度、地下水位和胡杨树茎横截面积是影响胡杨耗水量的诸多环境因子中最敏感的因子;胡杨林的耗水量观测值与模拟值表现出较好的相关性,3个回归模型的模拟值与观测值的相关系数依次分别为0.6793、0.7299、0.7574,其相对误差分别为28.7%、26.1%、22.9%,其显著性水平均通过95%显著性检验;3个回归模型中完全二次回归模型具有使用简便、影响因子易测定、有一定精度等优点,能够更好刻画植被腾发量的复杂非线性特性,为干旱区自然植被耗水量估算、模拟和生态需水量计算提供了新的思路和方法。  相似文献   

Estimation of the Risk Management Index (RMI) using statistical analysis   总被引：1，自引：1，他引：0  

David A. Novelo-Casanova  Gerardo Suárez 《Natural Hazards》2015,77(3):1501-1514

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Modeling and Mapping High Water Table for a Coastal Region in Florida using Lidar DEM Data     

Caiyun Zhang  Hongbo Su  Tiantian Li  Weibo Liu  Diana Mitsova  Sudhagar Nagarajan  Ramesh Teegavarapu  Zhixiao Xie  Fred Bloetscher  Yan Yong 《Ground water》2021,59(2):190-198

Predicting and mapping high water table elevation in coastal landscapes is critical for both science application projects like inundation risk analysis and engineering projects like pond design and maintenance. Previous studies of water table mapping focused on the application of geostatistical methods, which cannot predict values beyond an observation spatial domain or generate an ideal pattern for regions with sparse measurements. In this study, we evaluated the multiple linear regression (MLR) and support vector machine (SVM) techniques for high water table prediction and mapping using fine spatial resolution lidar-derived Digital Elevation Model (DEM) data, and designed an application protocol of these two techniques for high water table mapping in a coastal landscape where groundwater, tide, and surface water are related. Testing results showed that SVM largely improved the high water table prediction with a mean absolute error (MAE) of 1.22 feet and root mean square error (RMSE) of 2.22 feet compared to the application of the ordinary Kriging method which could not generate a reasonable water table. MLR was also promising with a MAE of around 2 feet and RMSE of around 3 feet. The study suggests that both MLR and SVM are valuable alternatives to estimate high water table elevation in Florida. Fine resolution lidar DEMs are beneficial for high water table prediction and mapping.  相似文献   

2021年玛多MS7.4地震前玉树地震台井水温异常特征   总被引：1，自引：0，他引：1       下载免费PDF全文

苏维刚  刘磊 《地震学报》2021,43(3):392-396

2021年5月22日青海果洛州玛多县发生MS7.4地震,震中位于( 34.59°N, 98.34°E) ,其震源机制解显示该地震为高倾角走滑型(张喆,许立生, 2021).玛多地震的发震构造为昆仑山口—江错断裂,是东昆仑断裂的一条分支断裂(王未来等, 2021).玉树地震台位于甘孜—玉树断裂附近.玛多地震震中和玉树地震台均位于巴颜喀拉次级地块内,玉树地震台位于巴颜喀拉地块的南边界.此次地震震中处于玉树地震台的NE方向,距巴颜喀拉地块北边界85 km (图1).  相似文献   

福建九龙江河口第四纪沉积物特征及沉积环境演变          下载免费PDF全文

陈慧娴  骆美美  王建华  苏志华  金刚雄  瓦西拉里  杨小强  曹玲珑 《古地理学报》2014,16(2):263-273

根据福建九龙江河口ZK1孔及ZK7孔沉积物AMS(Accelerator Mass Spectrometry,加速器质谱测年技术) ¹⁴C测年、古地磁和剖面特征分析,进行该地区的第四纪地层划分,依据粒度特征,结合磁化率、微体古生物和Sr/Ba等环境代用指标进行沉积相分析,重建了该区晚第四纪的古环境演变历史。结果表明:(1)九龙江河口第四纪沉积时代为晚更新世中期至全新世晚期。(2)上更新统沉积可划分为下部龙海组洪冲积相和上部东山组河漫滩相沉积,中间有10 ka的沉积间断,末次冰期又再遭受风化剥蚀作用,推测有5～6 ka的风化剥蚀期。(3)全新统最早沉积年代约为14 ka BP,依次出现河口湾相、河口砂坝—分汊河道相、潮滩相沉积。(4)根据年代学数据和沉积相变化,重塑了该区晚第四纪沉积环境变化过程,为该区的第四纪研究和工程地质工作提供了参考依据。  相似文献   

甘肃张掖地区白垩系风成砂岩沉积序列! 祁连山白垩纪隆升的沉积学响应   总被引：2，自引：1，他引：1       下载免费PDF全文

梅冥相  苏德辰 《古地理学报》2014,16(2):143-156

白垩纪祁连山隆升过程及其沉积学响应的研究,对认识青藏高原的形成及其环境效应具有重要意义。受控于祁连山隆升过程的甘肃张掖地区下白垩统,包括赤金堡组、下沟组和中沟组,其基本特征是：（1）分布局限而且厚度上千米的赤金堡组,主要由旋回性发育的“冲积扇（或洪积扇—辫状河—滨湖相风成沙丘”序列所组成,形成一种反映了“雨影效应”的粗碎屑岩序列;（2）下沟组总体为一套红层沉积,在盆地边缘发育更多的风成沙丘,可能代表了与祁连山更加快速隆升相对应的更加强烈的“雨影效应”时期的产物;（3）中沟组,从冲积体系演变为一个分布广泛的湖泊沉积体系,总体上属于潮湿气候背景下未受到“雨影效应”影响的产物,与祁连山均衡抬升存在成因联系;（4）研究区上白垩统总体缺失,可能与祁连山的卸载过程产生的山前地壳均衡反弹存在关联。因此,从赤金堡组到下沟组的风成砂岩序列、特殊的沉积相构成及其演化序列,不但成为窥视早白垩世祁连山隆升过程的物质记录,而且为早白垩世东亚大气环流格局的重建提供了另外一个重要的物质记录。  相似文献   

澳大利亚芒特艾萨地区遥感地质特征与找矿模型——以沉积变质型铜多金属矿为例   总被引：1，自引：0，他引：1  

黄智才  徐文斌  郐开富  李素  陈刚 《地质通报》2014,(Z1):247-254

利用遥感技术对澳大利亚芒特艾萨地区铜多金属矿的遥感地质特征进行研究。根据ETM遥感影像数据,对芒特艾萨地区的遥感地质矿产解译,总结和分析该区区域地层、构造和岩浆岩的影像特征。在解剖芒特艾萨铜矿等3处典型铜多金属矿床的基础上,分析各控矿要素的遥感影像特征,初步建立了该类型铜多金属矿的遥感地质找矿模型。根据找矿模型圈定1处遥感地质特征相符的找矿远景区。通过遥感影像数据研究,划分和进一步缩少找矿靶区,对减少境外矿产投资的盲目性具有一定的指导意义。  相似文献   

Structure equation model-based approach for determining lake nutrient standards in Yungui Plateau ecoregion and Eastern Plain ecoregion lakes,China     

Danfeng Ji  Beidou Xi  Jing Su  Shouliang Huo  Ji Wang  Fangfang Gong  Mingxiao Li  Xuan Jia  Daichun Wei 《Environmental Earth Sciences》2014,72(8):3067-3077

Predictive nutrient criteria method, combined with expert elicitation and structural equation model (SEM), was proposed in this study for establishing lake nutrient standard in Chinese lakes (Yungui Plateau ecoregion and Eastern Plain ecoregion). Expert elicitation was involved to quantify the probability of attainment of the designated-use (drinking water source) based on monitoring data. The experts scoring results were introduced to SEM to assess predictive relationships between candidate standard variables and the designated-use attainment. In Yungui ecoregion, the standardized effects of chlorophyll-a (Chl-a), chemical oxygen demand and total phosphorus (TP) on designated-use attainment were ?0.41, ?0.14, and ?0.43, respectively. These result demonstrated that the two most predictive indicators for designated-use attainment were TP and Chl-a. In Eastern ecoregion, the standardized effects of TP, total nitrogen (TN), dissolved oxygen and water temperature (T) on designated-use attainment were 0.77, ?0.12, 0.13 and ?0.02, respectively. The most predictive indicator was TP. The model was further used for estimating the designated-use attainment associated with various levels of candidate standards. TP, TN, Chl-a and Secchi depth (SD) were selected as standard indicators in Yungui ecoregion. TP, TN, and Chl-a were selected in Eastern ecoregion. In order to achieve the 85 % designated-use attainment, standard values of TP, TN, Chl-a and SD in Yungui ecoregion would be 0.02 mg/L, 0.2 mg/L, 1.4 μg/L, and 0.581 m; and standards of TP, TN, and Chl-a in Eastern ecoregion would be 0.039 mg/L, 0.95 mg/L, and 1.75 μg/L, respectively. Finally, the differences between standards in these two ecoregions were also analyzed.  相似文献   

Low permeability Neogene lithofacies in Northern Croatia as potential unconventional hydrocarbon reservoirs     

Tomislav Malvić  Antonija Sučić  Marko Cvetković  Filip Resanović  Josipa Velić 《Central European Journal of Geosciences》2014,6(2):182-194

We present two examples of describing low permeability Neogene clastic lithofacies to outline unconventional hydrocarbon lithofacies. Both examples were selected from the Drava Depression, the largest macrostructure of the Pannonian Basin System located in Croatia. The first example is the Beni?anci Field, the largest Croatian hydrocarbon reservoir discovered in Badenian coarse-grained clastics that consists mostly of breccia. The definition of low permeability lithofacies is related to the margins of the existing reservoir, where the reservoir lithology changed into a transitional one, which is mainly depicted by the marlitic sandstones. However, calculation of the POS (probability of success of new hydrocarbons) shows critical geological categories where probabilities are lower than those in the viable reservoir with proven reserves. Potential new hydrocarbon volumes are located in the structural margins, along the oil-water contact, with a POS of 9.375%. These potential reserves in those areas can be classified as probable. A second example was the Cremu?ina Structure, where a hydrocarbon reservoir was not proven, but where the entire structure has been transferred onto regional migration pathways. The Lower Pontian lithology is described from well logs as fine-grained sandstones with large sections of silty or marly clastics. As a result, the average porosity is low for conventional reservoir classification (10.57%). However, it is still an interesting case for consideration as a potentially unconventional reservoir, such as the ”tight” sandstones.  相似文献   

新疆七角井德哲塔勒德上石炭统奥尔吐组沉积相特征及意义     

郭丽娜  李勇  苏春乾  肖良  周建仁 《新疆地质》2014,(1):48-52

新疆巴里坤县七角井镇德哲塔勒德地区上石炭统奥尔吐组沉积相类型为扇三角洲相和滨海碎屑岩相。扇三角洲平原泥炭沼泽沉积和平原分流河道粗碎屑沉积组成扇三角洲平原亚相;水下分流河道和水下分流河道间沉积组成扇三角洲前缘亚相。主体是由碎屑岩组成不同规模的韵律层,发育平行层理、交错层理、较大型的楔状交错层理、水平层理。其中水平层理一般发育在静水地带,平行层理、交错层理则分别主要出现在以高流态、高水动力为特征的条件下,二者交互出现,反映地层沉积于海水进退较频繁的滨浅海地带。本组地层基本层序内部为由下至上粒度变细的特征,显示为海进过程。同时发现了大量化石,包括头足化石:尖形卡拉温菊石(Cravenoceras acutum Liang);腕足化石:网格长身贝(Dictyoclostus sp.),在含碳细砂岩中发现了桶箍芦木化石(Calamites cf.schützeiformis Kidst.et Jongm)碎片,结合该组沉积岩成分成熟度和结构成熟度均较低的特征,岩石为近岸源区快速剥蚀、搬运、堆积形成的,所含植物化石碎片是沿途生长的植物异地埋藏形成的,说明本组沉积岩是在滨海区沉积形成的。  相似文献