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81.
Interpreting characteristic drainage timescale variability across Kilombero Valley,Tanzania 总被引:1,自引:0,他引:1
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Steve W. Lyon Alexander Koutsouris Friedemann Scheibler Jerker Jarsjö Rene Mbanguka Madaka Tumbo Keven K. Robert Asha N. Sharma Ype van der Velde 《水文研究》2015,29(8):1912-1924
We explore seasonal variability and spatiotemporal patterns in characteristic drainage timescale (K) estimated from river discharge records across the Kilombero Valley in central Tanzania. K values were determined using streamflow recession analysis with a Brutsaert–Nieber solution to the linearized Boussinesq equation. Estimated K values were variable, comparing between wet and dry seasons for the relatively small catchments draining upland positions. For the larger catchments draining through valley bottoms, K values were typically longer and more consistent across seasons. Variations in K were compared with long‐term averaged, Moderate‐resolution Imaging Spectroradiometer‐derived monthly evapotranspiration. Although the variations in K were potentially related to evapotranspiration, the influence of data quality and analysis procedure could not be discounted. As such, even though recession analysis offers a potential approach to explore aquifer release timescales and thereby gain insight to a region's hydrology to inform water resources management, care must be taken when interpreting spatiotemporal shifts in K in connection with process representation in regions like the Kilombero Valley. © 2014 The Authors. Hydrological Processes published by John Wiley & Sons Ltd. 相似文献
82.
Barry T. Hart Grant B. Douglas Ronald Beckett Annick Van Put Rene E. Van Grieken 《水文研究》1993,7(1):105-118
The composition and amount of colloidal and suspended participate matter transported during a small flood event in Magela Creek in tropical northern Australia was investigated. The flood studied constituted approximately 3 % of the total annual flow, most (90%) of which occurred between mid-January and mid-February of the study year. Three fractions were separated from water samples using a sequential method involving a continuous flow centrifuge to separate suspended particulate matter (SPM; nominally > 1 μm) followed by hollow fibre filtration, first using a 0.1 μm filter to separate course colloidal matter (CCM; nominal size 1–0.1 μm) and then a 0–015 μm filter to separate fine colloidal matter (FCM; nominal size 0.1–0.015 μm). The SPM was predominantly inorganic (organic matter 21 %), whereas the colloidal fractions were dominantly organic matter (CCM 60%; FCM 83%). Analysis of individual particles using electron microprobe and automated image analysis indicated that the mineral fractions in both the SPM and CCM were dominated by iron-enriched aluminosilicates (including kaolinite) (72–82%) and quartz (9–10%), indicative of a highly weathered and extensively laterized catchment. Surprisingly there was very little difference in the composition of the SPM or CCM fractions during the flood event studied, which may indicate either that sediment availability was restricted following the major run-off events in January and February, or that all the sediment sources within the catchment are geochemically similar. Approximately the same amounts of particulate (20 tonne), colloidal (21 tonne) and dissolved material (17 tonne) were transported during the 25 hour period of the main flood peak; over 90% of the colloidal matter was 0.1–1.0 μm in size. These data suggest that previous estimates of the amounts of particulate (and colloidal) matter transported by Magela Creek, which were based on suspended solids measurements, may have underestimated the particulate matter load by as much as 50%. It is possible that the relatively high proportion of colloidal matter is unique to Magela Creek because coagulation and aggregation of colloidal matter to particulate matter is slow due to the very low concentations of calcium and magnesium in these waters. However, if the result is more widespread, there are important implications for the global estimates of fluvially transported particulate and dissolved materials as many of the previous studies may have underestimated the particulate load and overestimated the dissolved load. 相似文献
83.
新技术应用——直接固体进样石墨炉分析 总被引:6,自引:1,他引:5
样品的消解问题在原子吸收光谱技术中普遍存在,从环境学研究、食品检查、材料分析到过程分析和医学应用,样品消解都是分析的最大可能误差来源,试剂污染、交叉干扰、原始样品的改变,所有这些问题都是分析工作者多年来一直努力探求解决的课题。直接固体进样石墨炉分析技术正是其中一种简单的解决方案。直接固体进样石墨炉分析的优点是:①直接分析原始样品;②无需样品消解和溶剂稀释;③降低污染的可能性;④高灵敏度,pg或fg级的检出水平,只有昂贵的ICP MS才能得到同样的检出限;⑤较少的样品量,10μg~50mg即可。随着商品仪器 相似文献