浙江朱家尖岛东沙海滩对热带风暴“娜基莉”的响应及风暴后的恢复   总被引：1，自引：1，他引：0  

郭俊丽  时连强  童宵岭  郑禹君  徐岱璐 《海洋学报》2018,40(9):137-147

海滩对风暴的响应及风暴后海滩的恢复过程一直以来都是国内外海滩研究的热点。本文通过对浙江舟山市朱家尖岛东沙海滩地形地貌的现场调查，对比分析了热带风暴"娜基莉"影响下东沙海滩剖面的蚀积变化，探讨了海滩在热带风暴发生后的恢复情况。结果表明，在"娜基莉"影响期间，因风暴浪为向岸浪，东沙海滩几乎遭受全线侵蚀，12个剖面单宽侵蚀总量为73.46 m3/m，其中海滩直线段较两个遮蔽段侵蚀显著。由于海滩在风暴前进方向的左侧，且"娜基莉"距东沙较远，使得东沙海滩普遍侵蚀但强度较小。东沙海滩在热带风暴后的恢复过程中，不同部位的地貌调整和冲淤变化不同，下岬角遮蔽段基本趋于稳定，直线段和上岬角遮蔽段在恢复过程中因受海滩季节性调整的影响呈现持续侵蚀。  相似文献   

Hydrologic responses to land cover change: the case of Jedeb mesoscale catchment,Abay/Upper Blue Nile basin,Ethiopia          下载免费PDF全文

S. Tekleab  Y. Mohamed  S. Uhlenbrook  J. Wenninger 《水文研究》2014,28(20):5149-5161

The objective of this study was to quantify the impacts of land use/land cover (LULC) change on the hydrology of the Jedeb, an agricultural dominated mesoscale catchment, in the Abay/Upper Blue Nile basin, Ethiopia. Two methods have been used. First, the trends of certain daily flow variability parameters were evaluated to detect statistical significance of the change of the hydrologic response. Second, a conceptual monthly hydrological model was used to detect changes in the model parameters over different periods to infer LULC change. The results from the statistical analysis of the daily flows between 1973 and 2010 reveal a significant change in the response of the catchment. Peak flow is enhanced, i.e. response appears to be flashier. There is a significant increase in the rise and fall rates of the flow hydrograph, as well as the number of low‐flow pulses below a threshold level. The discharge pulses show a declining duration with time. The model result depicts a change in model parameters over different periods, which could be attributed to an LULC change. The model parameters representing soil moisture conditions indicated a gradual decreasing trend, implying limited storage capacity likely attributed to increasing agricultural farming practices in the catchment. This resulted in more surface runoff and less infiltration into the soil layers. The results of the monthly flow duration curve analysis indicated large changes of the flow regime. The high flow has increased by 45% between the 1990s and 2000s, whereas the reduction in low flows was larger: a 15% decrease between 1970s and 1980s, 39% between 1980s and 1990s and up to 71% between 1990s and 2000s. These results, could guide informed catchment management practices to reduce surface runoff and augment soil moisture level in the Jedeb catchment. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

A simple hypoplastic model with loading surface accounting for viscous and fabric effects of clays     

Merita Tafili  Theodoros Triantafyllidis 《国际地质力学数值与分析法杂志》2020,44(16):2189-2215

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中国陆相油页岩含油率与总有机碳的响应机理     

贾建亮  刘招君  孟庆涛  孙平昌  徐进军  柳蓉  白悦悦 《吉林大学学报(地球科学版)》2020,50(2):368-377

为了建立稳定可靠的利用油页岩总有机碳预测含油率的模型，揭示中国陆相不同成因类型油页岩含油率与总有机碳的内在关系极其重要。通过不同类型盆地油页岩钻井取心测试的关键参数，结合沉积学、有机地球化学、热模拟等学科技术，探讨油页岩含油率与总有机碳的响应机理。结果表明：不同盆地类型与沉积背景下发育的油页岩含油率与总有机碳质量分数均呈现良好的正相关性（R²=0.81~0.97）；中国陆相油页岩的成因类型进一步划分为5种类型，制约着含油率与总有机碳的内在关系；油页岩的升温加热模拟呈现3个失重阶段（温度<150、300~550、600~750℃），明确了含油率与总有机碳参数的物理意义；相同类型盆地与沉积背景下形成的油页岩具有相近的母质生源组合，从而具有大致相当的再生烃效率。中国陆相油页岩成因类型的细划、含油率与总有机碳物理意义的明确、油页岩再生烃能力的分析，有助于理解中国陆相油页岩含油率与总有机碳的内在响应关系。  相似文献   

Hydrodynamic performance of a T-shaped floating breakwater     

《Applied Ocean Research》2019

The comprehensive utilization of floating breakwaters, specially acting as a supporting structure for offshore marine renewable energy explorations, has received more and more attention recently. Based on linear water-wave theory, the hydrodynamic performance of a T-shaped floating breakwater is semi-analytically investigated through the matched eigenfunction expansion method (MEEM). Auxiliary functions, to speed up the convergence and improve the accuracy in the numerical computations, are introduced to represent the singular behavior of fluid field near the lower salient corners of the structure. The effects of the height and installation position of the vertical screen on the reflection and transmission coefficients, dynamic response and wave forces are examined. It is found that the presence of the screen shifts the resonance frequency of RAO for both surge and pitch modes to the low-frequency area, while has no effect on heave mode. The identical added masses, damping and transmission coefficients can be obtained in the cases where the screen holds the same distance away from the longitudinal central axis of the upper box-type structure. Moreover, a relatively small pitch response can be achieved in a wide wave–frequency range, when the breakwater is Γ-shaped.  相似文献   

波浪作用下单桩基础周围海床液化机制研究   总被引：1，自引：1，他引：0  

隋倜倜  张弛  高玉峰  郑金海 《海洋工程》2018,36(4):88-96

建立波浪作用下单桩周围三维海床动力响应模型,考虑自重影响下的海床长时间固结过程。采用已有物理模型试验数据对模型进行验证,证实其具有较好的适用性。模拟波浪作用下单桩周围三维海床液化区域,通过定量分析超孔隙水压力和土体初始有效应力的变化,讨论单桩插入深度对海床液化的影响机制。研究表明,单桩插入深度发生变化时,土体初始有效应力对海床液化的影响要大于超孔隙水压力,且影响程度随着插入深度的增加而逐渐增大。  相似文献   

Runoff response of a small agricultural basin in the argentine Pampas considering connectivity aspects     

María Guadalupe Ares  Marcelo Varni  Celio Chagas 《水文研究》2020,34(14):3102-3119

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A long‐term study of stable isotopes as tracers of processes governing water flow and quality in a lowland river basin: the upper Thames,UK          下载免费PDF全文

W. George Darling  Michael J. Bowes 《水文研究》2016,30(13):2178-2195

A long‐term study of O, H and C stable isotopes has been undertaken on river waters across the 7000‐km² upper Thames lowland river basin in the southern UK. During the period, flow conditions ranged from drought to flood. A 10‐year monthly record (2003–2012) of the main River Thames showed a maximum variation of 3‰ (δ¹⁸O) and 20‰ (δ²H), although interannual average values varied little around a mean of –6.5‰ (δ¹⁸O) and –44‰ (δ²H). A δ²H/δ¹⁸O slope of 5.3 suggested a degree of evaporative enrichment, consistent with derivation from local rainfall with a weighted mean of –7.2‰ (δ¹⁸O) and –48‰ (δ²H) for the period. A tendency towards isotopic depletion of the river with increasing flow rate was noted, but at very high flows (>100 m³/s), a reversion to the mean was interpreted as the displacement of bank storage by rising groundwater levels (corroborated by measurements of specific electrical conductivity). A shorter quarterly study (October 2011–April 2013) of isotope variations in 15 tributaries with varying geology revealed different responses to evaporation, with a well‐correlated inverse relationship between Δ¹⁸O and baseflow index for most of the rivers. A comparison with aquifer waters in the basin showed that even at low flow, rivers rarely consist solely of isotopically unmodified groundwater. Long‐term monitoring (2003–2007) of carbon stable isotopes in dissolved inorganic carbon (DIC) in the Thames revealed a complex interplay between respiration, photosynthesis and evasion, but with a mean interannual δ¹³C‐DIC value of –14.8 ± 0.5‰, exchange with atmospheric carbon could be ruled out. Quarterly monitoring of the tributaries (October 2011–April 2013) indicated that in addition to the aforementioned factors, river flow variations and catchment characteristics were likely to affect δ¹³C‐DIC. Comparison with basin groundwaters of different alkalinity and δ¹³C‐DIC values showed that the origin of river baseflow is usually obscured. The findings show that long‐term monitoring of environmental tracers can help to improve the understanding of how lowland river catchments function. Copyright © NERC 2015. Hydrological Processes © 2015 John Wiley & Sons, Ltd.  相似文献   

Prediction of river water temperature: a comparison between a new family of hybrid models and statistical approaches          下载免费PDF全文

Sebastiano Piccolroaz  Elisa Calamita  Bruno Majone  Aurélien Gallice  Annunziato Siviglia  Marco Toffolon 《水文研究》2016,30(21):3901-3917

River water temperature is a key physical variable controlling several chemical, biological and ecological processes. Its reliable prediction is a main issue in many environmental applications, which however is hampered by data scarcity, when using data‐demanding deterministic models, and modelling limitations, when using simpler statistical models. In this work we test a suite of models belonging to air2stream family, which are characterized by a hybrid formulation that combines a physical derivation of the key equation with a stochastic calibration of parameters. The air2stream models rely solely on air temperature and streamflow, and are of similar complexity as standard statistical models. The performances of the different versions of air2stream in predicting river water temperature are compared with those of the most common statistical models typically used in the literature. To this aim, a dataset of 38 Swiss rivers is used, which includes rivers classified into four different categories according to their hydrological characteristics: low‐land natural rivers, lake outlets, snow‐fed rivers and regulated rivers. The results of the analysis provide practical indications regarding the type of model that is most suitable to simulate river water temperature across different time scales (from daily to seasonal) and for different hydrological regimes. A model intercomparison exercise suggests that the family of air2stream hybrid models generally outperforms statistical models, while cross‐validation conducted over a 30‐year period indicates that they can be suitably adopted for long‐term analyses. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

鄂西岩溶槽谷区洼地的水位响应特征及产流阈值估算   总被引：1，自引：0，他引：1  

廖春来  罗明明  周宏 《中国岩溶》2020,39(6):802-809

以湖北省兴山县黄粮镇刘家坝和龙湾两处岩溶洼地作为研究对象，利用其降雨、水文和土壤水等监测数据，探讨灌入式补给条件下洼地汇流的水位响应特征和产流特点，并基于降雨量和洼地内明渠流量的关系，采用数学拟合方程，估算两处洼地的降雨产流阈值，进而分析了影响产流阈值的因素。结果表明:降雨强度增大，产流阈值减小；土壤前期含水率越大，越有利于坡面产流；落水洞和岩溶泉水位与降雨有较好的同步响应关系，水位变化曲线随雨强大小分别表现出“陡升陡降”和“缓升缓降”的特点；刘家坝和龙湾洼地的产流阈值分别为7.4 mm和10.6 mm。   相似文献