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751.
黄冈市水资源分析与利用   总被引:3,自引:1,他引:3  
南阳春  李国华 《气象》2004,30(7):47-51
通过计算黄冈市各县市及不同水系降水、径流、蒸发等要素的时空分布、不同保证率工农业生产、人民生活对水资源的需求,分析了黄冈市水资源的分布规律,总结了平水、偏旱、干旱三种典型年全市水资源的盈亏特征。指出,黄冈市水资源总量丰富,开发利用潜力很大,但因时空分布不均,导致水旱灾害频繁,需要采取综合措施,努力提高人均占有量和资源利用率。  相似文献   
752.
小型蒸发器对E-601B蒸发器的折算系数   总被引:12,自引:1,他引:12       下载免费PDF全文
为了便于将过去40多年的小型蒸发器观测资料与E-601B蒸发器观测资料衔接使用,对全国618个基准和基本站直径20 cm小型蒸发器与E-601B蒸发器3年平行对比观测结果进行了统计,按省(市)给出了这两种仪器的月、年平均折算系数值及年折算系数的全国分布图,并给出了相应的标准差和相对标准差。  相似文献   
753.
In this paper it is proposed to quantify the importance of some physical parameters responsible for stone decay on monuments. The most common decay process is the crystallisation of salt near the surface of the rocks or inside their porous network. Therefore, the water balance in rocks submitted to these special saturation and position conditions has been studied specifically, using the general concepts of water transfer in unsaturated porous media, and using the capillary imbibition kinetics of different rocks. Different parameters have been taken into account for the calculation of the salt crystallisation position: on one hand, several external parameters such as relative humidity, air convection and the presence of solute in solution, and on the other hand, the intrinsic water transfer properties of the rocks. Their relative importance is discussed, considering the potential values that each parameter can reach in nature.  相似文献   
754.
根据土壤基本水分物理常数,将土壤水分蒸发划分为三个阶段,土壤水分累积蒸发量Q与蒸发历时T具有:Q=aT ̄b关系。不同土壤的蒸发能力不同,主要与土壤质地、结构等因素有关,同时不同土壤的抗旱力也有很大差异,土壤抗旱力由强至弱依次为:普通薄层土、变性燥红土、普通燥红土、表蚀干热的半干润变性土、表蚀燥红土。  相似文献   
755.
Salt evaporation basins in south-eastern Australia, in contrast with natural saline lakes in this region, were not highly saline and exhibited little seasonal pattern in water depth and salinity over a 2-year sampling period. Lack of seasonality arose from either constant inflow (from continuous groundwater pumping) or erratic inflow (from unpredictable irrigation demands). Differences in zooplankton species composition between the salt evaporation basins and natural saline lakes might reflect the differences in temporal salinity patterns. Some typical saline lake zooplankton were not found in the evaporation basins. Salt evaporation basins therefore may represent additions to the inland water habitats of semi-arid Australia.  相似文献   
756.
本文前半部介绍我国清乾隆年间戴源所记方测雨器、方蒸发器的构造和作用,并对比介绍欧美方测雨器及方蒸发器的沿革。后半部主要探讨这些仪器外形方圆变化的原因。并对戴源仪器本身及《测圆图解》进行分析,进而证明这种仪器并非我国自创,却系耶稣会传教士由巴黎传入中国。但在我国气象仪器史中有着重要意义。  相似文献   
757.
张军  张宝全 《盐湖研究》1993,1(4):45-51
本文在察尔汗盐湖氯化镁饱和不同浓缩阶段卤水比蒸发实验的基础上,处理了在氯化镁析出阶段卤水的比蒸发实验数据,完成了比蒸发系数二元参数的拟合,给出了该卤水的蒸发模型。并与石盐析出阶段和光卤石析出阶段比蒸发系数的数学模型相衔接,对氧化镁饱和前后不同蒸发机理进行了探讨。  相似文献   
758.
云下雨滴蒸发是雨滴下降过程中重要的物理过程,特别是当云下相对湿度较低时更为明显。本文建立了考虑雨滴蒸发的云下雨水酸化的物理化学模式,用以研究云下雨滴蒸发作用对各种大小雨滴及雨水酸化的影响,并估算了由于小雨滴的完全蒸发进入到大气中的硫酸盐气溶胶的生成速率。计算结果表明:这种小雨滴的完全蒸发使雨滴内化学反应生成的硫酸盐结晶进入大气,在降水初期云下相对湿度较小时,形成硫酸盐气溶胶的速率可达1% h-1,与气粒转化速率相当。  相似文献   
759.
Mangrove swamps and hypersaline saltflats fringe many estuaries in dry tropical climates, especially in Northern Australia. For most of the year these estuaries receive zero riverine freshwater input and thus, after the wet season, a steady increase in salinity occurs. In some locations the estuary becomes fully inverse, i.e. the salinity increases monotonically from the mouth to the head. In other locations, a salinity maximum zone separates the sea from low salinity water that persists at the head of the estuary throughout the dry season. Field data from five estuaries indicate that in short estuaries where a large area of saltflats and mangroves extends over the whole length of the estuary, the estuary becomes completely inverse with salinity rising to 55 within a couple of months. The evaporation and evapotranspiration over the saltflats and mangroves cause this rapid increase in salinity. Longer estuaries where a large area of salt flat exists only close to the mouth do not become completely hypersaline for the whole length of the estuary by the end of the dry season. A salinity-maximum is generated close to the river mouth but salinities of less than 10 persist in the upper reaches of the estuary until the end of the dry season, even though the estuary does not receive any further freshwater input. A simple analytical expression is presented that reproduces the changes in salinities in the estuaries studied. This model can be used to predict the formation of hypersaline conditions in other mangrove and saltflat fringed estuaries where freshwater flow is negligible.  相似文献   
760.
The relative contributions to total actual evapotranspiration (AET) from pond and riparian areas in a pond‐wetland complex in the Western Boreal Plain (WBP) of northern Alberta are measured using the Bowen ratio energy balance technique. Measurements show that a pond typical of the WBP evaporates at a rate more than twice that of the adjacent riparian peatland. Relating the actual to potential evapotranspiration over both surfaces yields Priestley–Taylor α coefficients of 0·69 and 1·11 for the peatland and pond respectively. Further results demonstrate that the sheltering and turbulent influences of the adjacent forested areas must be considered in the processes governing the permanence of WBP ponds. That is, forestry practices may inadvertently enhance the evaporative losses from the ponds, over and above the controls exerted by the regional climate. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
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