摘要
选择Na Cl作为保守性示踪剂、NH4Cl和KH2PO4为添加营养盐,在巢湖流域的二十埠河某一农田源头溪流段,采用恒定连续投加示踪剂的方式,开展野外示踪实验。通过对不同情景下暂态存储参数和营养螺旋指标模拟结果的比较,解析丁坝型挡板对于溪流暂态存储和氮磷滞留能力的调控效果。结果表明:丁坝型挡板使溪流交换系数α显著增大,其中间距为2.5 m的α值较无挡板情景高出132.36%,1.5 m和3.0 m间距则分别高出825.37%和641.29%;相对于无挡板情景,设置挡板的溪流交换长度Ls明显下降,水力持留因子Rh、行进时间中值F200med及过水断面面积和暂态存储区断面面积的比值As/A等出现不同程度的增大;设置挡板的氮磷吸收长度Sw较无挡板情景显著下降,吸收速度Vf则有不同程度的提高。丁坝型挡板对于农田溪流暂态存储和氮磷滞留能力具有很好的调控效果。
To quantitatively exhibit the variations of transient storage and retention efficiency of in-channel ammonium and phosphorus in agricultural headwater stream, five constant-rate injection experiments were performed with nitrogen （NH4C1）, phosphorus （KH2PO4）, and a conservative tracer （NaC1） in a first-order stream of the Ershibu River, located in Chaohu Lake basin. Regulation of the impacts on transient storage and nutrient retention efficiency from spur dikes, which were made of plastic baffles, were analyzed and in- vestigated by the comparison of transient storage and nutrient spiraling metrics among different scenarios. The results show that values of the stream-storage exchange coefficient a with spur dikes are higher than that of no spur dike. Specifically, the a value of 2.5 m distance is 132.36 % higher than that of no spur dike, and the values for 1.5 m and 3.0 m are even 825.37 % and 641.29 % larger, respectively. Relative to no spur dike, the average length L~ is descended markedly, but the storage zone residence time Rh, the per- cent of median travel time down a 200 m reach length Fmed/200 and the area of storage zone normalized to ar- ea of the channel As/A are all ascended in different degrees. Moreover, the uptake length Sw declines obvi- ously, however, the uptake velocity Vf goes up in different levels for the spur dike scenarios. From the changes of transient storage and nutrient spiraling metrics pre- and post- spur dike experiments, a conclu- sion could be drawn that spur dikes, staggered in the stream, enhance the regulation of transient storage and nutrient retention efficiency for agricultural headwater stream.
出处
《水利学报》
EI
CSCD
北大核心
2015年第1期25-33,共9页
Journal of Hydraulic Engineering
基金
国家自然科学基金资助项目(51179042)
关键词
源头溪流
暂态存储
氮磷滞留
实验操纵
丁坝
headwater stream
transient storage
nitrogen and phosphorus retention
experimental manipula-tion
spur dike
