Precipitation water storage capacity in a temperate mixed oak–beech canopy     

Frédéric André  Mathieu Jonard  Quentin Ponette 《水文研究》2008,22(20):4130-4141

The storage capacity of a temperate mixed oak–beech stand was investigated as a function of stand density and species composition. Measurements were performed in selected zones delimited by three neighbouring trees. Three independent approaches were compared: (i) a spraying laboratory experiment to estimate the water storage on foliage before and after dripping; (ii) a mechanistic model describing rainfall partitioning within the forest canopy and providing estimates of foliage storage capacities; and (iii) linear regression analyses to evaluate the canopy (foliage + branches) storage capacity using the relationship between throughfall and rainfall. Good agreement was generally observed between the laboratory experiment and the mechanistic model estimates, while estimations from the regression method tended to exceed those from the other approaches. Storage capacity estimates ranged from 0·22 mm to 0·80 mm for pure oak zones, from 0·24 mm to 1·12 mm for mixed zones and from 0·53 mm to 1·17 mm for pure beech zones. The increase of storage capacity with increasing proportion of beech in the canopy resulted from higher beech LAI compared with oak. Similarly, for mixed and pure beech canopies, storage capacity was higher for high density zones than for low density zones as a result of the increase in LAI with increasing local basal area; in contrast, for pure oak, the storage capacity was not related to basal area because of the lower shade‐tolerance of this species compared with beech. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

冷却物冷藏间内湿空气热物理参数的计算     

殷少有 《广东海洋大学学报》1999,(2)

推导了冷却物冷藏间内湿空气热物理参数计算方程，并编制了湿空气热物理参数计算程序。该程序能快速、精确地计算冷却物冷藏间内不同气流速度、不同气压的湿气热物理参数  相似文献   

降雨量、土壤蓄水量对流动沙地土壤水分深层渗漏的影响     

吴丽丽  刘丹一  杨文斌  王涛  李卫  冯金超  冯伟 《中国沙漠》2020,40(3):210-218

土壤水分深层渗漏是陆地近地层水分循环的重要环节。利用土壤水分深层渗漏记录仪对毛乌素沙地典型流动沙丘不同深度土层的土壤渗漏水量连续进行两年定点监测。结果表明：（1）2016年生长季（4月1日至10月31日）降水量为2017年的1.93倍，但50、100、200 cm沙层的渗漏水量分别是2017年同期的4.53、5.53，5.22倍。同时，渗漏水量与降雨量及土壤蓄水量的波峰较一致。（2）强降雨对深层渗漏水量的影响较大，土壤蓄水量的变化也与深层渗漏水量密切相关；降雨量较小时，土壤蓄水量与深层渗漏水量之间的关系更为密切。在连续降雨过程中，越往深处，渗漏的产生通常是多次降雨过程累积的结果，将土壤蓄水量作为中间变量，能更好地分析土壤深层渗漏过程。（3）当天蓄水量与次日渗漏水量的相关系数较高，土层越深，深层渗漏水量与土壤蓄水量的相关系数增加，二者之间的线性拟合的R²也相应增加。  相似文献   

Assessment of intermediate fine sediment storage in a braided river reach (southern French Prealps)     

O. Navratil  C. Legout  D. Gateuille  M. Esteves  F. Liebault 《水文研究》2010,24(10):1318-1332

This paper presents a field investigation on river channel storage of fine sediments in an unglaciated braided river, the Bès River, located in a mountainous region in the southern French Prealps. Braided rivers transport a very large quantity of bedload and suspended sediment load because they are generally located in the vicinity of highly erosive hillslopes. Consequently, these rivers play an important role because they supply and control the sediment load of the entire downstream fluvial network. Field measurements and aerial photograph analyses were considered together to evaluate the variability of fine sediment quantity stored in a 2·5‐km‐long river reach. This study found very large quantities of fine sediment stored in this reach: 1100 t per unit depth (1 dm). Given that this reach accounts for 17% of the braided channel surface area of the river basin, the quantities of fine sediment stored in the river network were found to be approximately 80% of the mean annual suspended sediment yields (SSYs) (66 200 t year^?1), comparable to the SSYs at the flood event scale: from 1000 t to 12 000 t depending on the flood event magnitude. These results could explain the clockwise hysteretic relationships between suspended sediment concentrations and discharges for 80% of floods. This pattern is associated with the rapid availability of the fine sediments stored in the river channel. This study shows the need to focus on not only the mechanisms of fine sediment production from hillslope erosion but also the spatiotemporal dynamics of fine sediment transfer in braided rivers. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

冷冻牡蛎贮存过程中脂溶性有毒物质的变化研究     

张宁  林洪  隋涛  钟响  张艺兵  刘峰 《中国海洋大学学报(自然科学版)》2010,40(1)

牡蛎是我国出口量较大的水产品之一,由于产品本身的特殊性,在生长过程中易产生腹泻性贝毒(DSP).本实验中原料牡蛎DSP生物法检测结果为阴性,冷冻贮存4个月后检测结果即为阳性.本研究以分析这一变化原因为目的,采用LC-MS法对DSP生物检测的阳性样品进行确认,结果表明,生物法DSP检测的结果为假阳性,造成生物法DSP检测中小白鼠死亡的是牡蛎在贮藏过程中产生的脂溶性有毒物质.进一步分析确定该有毒物质为牡蛎脂肪水解物--游离脂肪酸.同时本研究对牡蛎在不同贮存温度和贮存时间下产生的游离脂肪酸含量进行了测定,在-10 ℃贮存温度下,贮存0,2,4,6,8,10个月,游离脂肪酸的变化范围为5.2～788.6 mg/kg;在-10 ℃,-18 ℃,-25 ℃贮存温度下,贮存4个月,游离脂肪酸的变化范围为92.5～389 mg/kg.  相似文献   

卫星遥感接收数据的管理与软件开发          下载免费PDF全文

李军  宋海英  李海滨  郭思海 《海洋测绘》2009,29(4):70-73

卫星遥感接收数据是遥感影像应用的重要数据来源，因此对特殊格式的海量接收数据的存储和管理成为卫星遥感应用的重要环节。采用多层存储模式对数据分类、分级存储，建立空间数据库管理空间数据和属性数据。基于ArcEngine开发技术建立卫星接收数据管理平台，实现空间数据的快速查询和属性数据的自动入库等高效管理功能。  相似文献   

Design and elementary realization of the Vision Earth System     

Yunliang YU  Shixiang LIU  Narenna WU  Xudong ZHANG 《世界地质(英文版)》2007,10(1)

The Vision Earth System is a interactive system by employing B/S model. The system has the function of query display and mutuaUy displays relevant geologic information, integrating image information of one outcrop and realizing 3D geologic visualization. In this system, the basis is effective store, transmitting, display and quick query of enormous images and their properties data. From Java technology, this essay researches the elementary realization of Vision Earth System by adopting store formality of enormous images database,quick display image of website and quick image storage method.  相似文献   

Lateral flow thresholds for aspen forested hillslopes on the Western Boreal Plain,Alberta, Canada     

T. E. Redding  K. J. Devito 《水文研究》2008,22(21):4287-4300

To predict the long‐term sustainability of water resources on the Boreal Plain region of northern Alberta, it is critical to understand when hillslopes generate runoff and connect with surface waters. The sub‐humid climate (P ≤ ET) and deep glacial sediments of this region result in large available soil storage capacity relative to moisture surpluses or deficits, leading to threshold‐dependent rainfall‐runoff relationships. Rainfall simulation experiments were conducted using large magnitude and high intensity applications to examine the thresholds in precipitation and soil moisture that are necessary to generate lateral flow from hillslope runoff plots representative of Luvisolic soils and an aspen canopy. Two adjacent plots (areas of 2·95 and 3·4 m²) of contrasting antecedent moisture conditions were examined; one had tree root uptake excluded for two months to increase soil moisture content, while the second plot allowed tree uptake over the growing season resulting in drier soils. Vertical flow as drainage and soil moisture storage dominated the water balances of both plots. Greater lateral flow occurred from the plot with higher antecedent moisture content. Results indicate that a minimum of 15–20 mm of rainfall is required to generate lateral flow, and only after the soils have been wetted to a depth of 0·75 m (C‐horizon). The depth and intensity of rainfall events that generated runoff > 1 mm have return periods of 25 years or greater and, when combined with the need for wet antecendent conditions, indicate that lateral flow generation on these hillslopes will occur infrequently. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

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兰小机  任金铜 《大地测量与地球动力学》2009,29(6):139-143

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Impact of dynamic feedbacks between sedimentation,sea-level rise,and biomass production on near-surface marsh stratigraphy and carbon accumulation     

Simon M. Mudd  Susan M. Howell  James T. Morris 《Estuarine, Coastal and Shelf Science》2009

Salt marshes accrete both organic and inorganic sediments. Here we present analytical and numerical models of salt marsh sedimentation that, in addition to capturing inorganic processes, explicitly account for above- and belowground organic processes including root growth and decay of organic carbon. The analytical model is used to examine the bias introduced by organic processes into proxy records of sedimentation, namely ¹³⁷Cs and ²¹⁰Pb. We find that accretion rates estimated using ²¹⁰Pb will be less than accretion rates estimated using the ¹³⁷Cs peak in steadily accreting marshes if (1) carbon decay is significant and (2) data for ²¹⁰Pb extend below the ¹³⁷Cs peak. The numerical model expands upon the analytical model by including belowground processes such as compaction and root growth, and by explicitly tracking the evolution of aboveground biomass and its effect on sedimentation rates. Using the numerical model we explore how marsh stratigraphy responds to sediment supply and the rate of sea-level rise. It is calibrated and tested using an extensive data set of both marsh stratigraphy and measurements of vegetation dynamics in a Spartina alterniflora marsh in South Carolina, USA. We find that carbon accumulation in marshes is nonlinearly related to both the supply of inorganic sediment and the rate of sea-level rise; carbon accumulation increases with sea-level rise until sea-level rise reaches a critical rate that drowns the marsh vegetation and halts carbon accumulation. The model predicts that changes in carbon storage resulting from changing sediment supply or sea-level rise are strongly dependent on the background sediment supply: if inorganic sediment supply is reduced in an already sediment poor marsh the storage of organic carbon will increase to a far greater extent than in a sediment-rich marsh, provided that the rate of sea-level rise does not exceed a threshold. These results imply that altering sediment supply to estuaries (e.g., by damming upstream rivers or altering littoral sediment transport) could lead to significant changes in the carbon budgets of coastal salt marshes.  相似文献