Collaborative Research: Changes in hyporheic exchange and nitrous oxide generation due to streambed alteration by macro-roughness elements

合作研究：宏观粗糙度元素改变河床引起的流水交换和一氧化二氮生成的变化

基本信息

批准号：
2100926
负责人：
William Reeder
金额：
$ 53.97万
依托单位：
Regents of the University of Idaho
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2100926&HistoricalAwards=false
关键词：
Collaborative Research Changes hyporheic exchange

项目摘要

Boulders and large cobbles are ubiquitous roughness elements in mountain rivers and their presence provides vital ecological and hydromorphological functions. They are routinely used in restoration projects to increase habitat quality for many aquatic species because they impact on stream morphology by inducing erosional and depositional areas, whose size and extent depend on the boulder/cobble density, sediment inputs, and flow conditions during sediment mobilizing flows. However, little is known about the role of roughness element induced-streambed changes in regulating hyporheic exchange, which is the process moving stream water into and out of stream bed sediments to form the subterraneous hyporheic zone. The hyporheic zone promotes important biochemical transformations, which affect stream and pore water chemistries with implications at both local and global scales because it is a primary driver of bioactivity in streams and a key source of the greenhouse gas nitrous oxide, N2O. Sustainable management of water resources including river restoration (a $1B/year industry in the US) would benefit from knowledge of hyporheic processes to predict the effects of regulated flows, climate, and land use on ecosystems, nutrient cycles, and solute transport at the local and watershed scales. The scientific goal for this project is to understand, quantify, and model the effects of boulder and cobble density and relative sediment supply during forming flows on hyporheic exchange, chemistry, and N2O production during low flow conditions. This will be addressed with flume and field experiments, supported by analytical and numerical modeling, and tested with hypotheses that boulder or cobble-induced changes in streambed morphology (1) have a primary role in regulating both the quantity and chemistry of hyporheic exchange at the reach scale, and (2) alter aerobic respiration, nitrification, and denitrification rates and increase the rates of apparent production and release of N2O.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

巨石和大鹅卵石是山河中无处不在的粗糙度元素，它们的存在提供了重要的生态和水分形态功能。它们通常用于恢复项目中，以提高许多水生物种的栖息地质量，因为它们通过诱导侵蚀和沉积区域对河流形态的影响，它们的大小和范围取决于巨石/卵石密度，沉积物输入和沉积物中的流动条件动员流动流动。然而，关于粗糙度元件引起的流膜变化在调节低音交换中的作用知之甚少，这是将流水移入和流出河流床沉积物以形成地下降压区的过程。低血压区促进了重要的生物化学转化，这些转化影响了局部和全球尺度的河水水化学，因为它是流中生物活性的主要驱动力，也是温室气氧化物N2O的关键来源。可持续的水资源管理（包括河流恢复（美国）$ 1B/年的行业）将受益于缺乏流行过程的知识，以预测受管制的流动，气候和土地利用对生态系统，营养周期以及当地和流域量表的溶液运输的影响。该项目的科学目标是了解，量化和建模在低流量条件下，在形成流动期间，在形成流动过程中，在形成流动过程中，巨石和卵石密度和相对沉积物供应的影响。 This will be addressed with flume and field experiments, supported by analytical and numerical modeling, and tested with hypotheses that boulder or cobble-induced changes in streambed morphology (1) have a primary role in regulating both the quantity and chemistry of hyporheic exchange at the reach scale, and (2) alter aerobic respiration, nitrification, and denitrification rates and increase the rates of apparent production and release of N2O。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响审查标准进行评估，被认为值得支持。