Collaborative Research: on the causes of recent trends in precipitation over La Plata basin and their impact on the basin's hydrology

合作研究：拉普拉塔盆地近期降水趋势的原因及其对该盆地水文的影响

• 批准号: 0450209
• 负责人: Dennis Lettenmaier
• 金额: --
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0450209&HistoricalAwards=false
• 关键词: Collaborative; Research; causes; recent; trends

Berbery/Lettenmaier0450089/0450209La Plata is the second largest river in South America and its tributaries are the life blood of the southern part of the continent. La Plata has an annual-mean discharge at its mouth near Buenos Aires larger than that of the Mississippi. The installed hydropower generating capacity (mostly in the Parana, a major subbasin) exceeds 20,000 MW, almost double that of the Columbia River basin, which by far has the largest hydropower production among U.S. rivers. On the other hand, the region is vulnerable to large scale floods with losses of life and damages to property.Precipitation and other land surface water cycle variables have undergone very large decadal scale changes over the last century in much of the southern part of South America, and within La Plata Basin in particular. In the last thirty years, precipitation increased up to 30-40% over the central La Plata basin, and important scientific questions have emerged: what are the reasons for these changes, and how are variations in precipitation linked to streamflow changes? Up to now, no certain evidence has been offered to explain the reasons for such changes.A team of North and South American hydrologists and atmospheric scientists has been assembled to address this crucial and unique aspect of the basin's regional water cycle. The overarching scientific question to be addressed by this research is: "What is the importance of local effects in the observed interannual-to-decadal scale changes in La Plata Basin precipitation and streamflow?" Specifically, it will be sought to: (a) Assess the degree to which regional climate simulations capture the precipitation changes in the 1970's over La Plata Basin; (b) Estimate the effects of local forcings (e.g., soil moisture, vegetation) on the precipitation and surface hydrology of La Plata Basin; (c) Identify the role of local effects and large scale precipitation variability in the basin.The research strategy outlined in this proposal is based on diagnosis analysis and numerical experiments with the atmospheric regional mesoscale Eta model and the VIC hydrologic model, in coupled and uncoupled mode. The Eta model, coupled with VIC and a river routing scheme, will be employed to describe the pathways from remote and/or local forcings to the changes in river discharge. Experiments are designed to understand the impacts of land use changes on the longer term climate and the feedbacks between land use/land cover and precipitation and river discharge. Experiments will also focus on the mechanisms by which large scale variability affects the regional precipitation.The relevance of this research is not only due to the yet unanswered scientific questions it will address, but also because it is a defined application for water resources of a region of the developing world. The approach aims at having the atmospheric and hydrologic problems treated in a consistent manner. The proposal has a strong educational component. Students will be directly involved in the research; scientists from Universities of South America will participate adding regional expertise but also enhancing the educational component. Plans are in place for exchanges with students of South America, and one or two related courses at the University of Buenos Aires are planned (at no cost to this project).This proposal takes advantage of available infrastructure both at the University of Maryland and the University of Washington. Computer systems are already in place and needed upgrades will be ready by the time this project starts.

拉普拉塔河是南美洲第二大河流，它的支流是南美洲南部地区的生命之源。拉普拉塔河靠近布宜诺斯艾利斯的河口的年平均流量比密西西比河还要大。水力发电装机容量（主要在巴拉那河，一个主要的子流域）超过2万兆瓦，几乎是哥伦比亚河流域的两倍，哥伦比亚河是迄今为止美国河流中水力发电量最大的。另一方面，该地区容易遭受大规模洪水的袭击，造成人员伤亡和财产损失。在上个世纪，南美洲南部大部分地区，特别是拉普拉塔盆地，降水和其他陆地地表水循环变量经历了非常大的年代际变化。在过去的30年里，拉普拉塔盆地中部的降水增加了30-40%，重要的科学问题出现了：这些变化的原因是什么，降水的变化如何与河流的变化联系在一起？到目前为止，还没有确凿的证据来解释这种变化的原因。一个由北美和南美的水文学家和大气科学家组成的团队已经聚集在一起，研究这个盆地区域水循环的关键和独特方面。这项研究要解决的首要科学问题是：“在观测到的拉普拉塔盆地降水和流量的年际到十年尺度变化中，局部影响的重要性是什么？”具体而言，将力求：(a)评估区域气候模拟在多大程度上捕捉到1970年代拉普拉塔盆地上空降水的变化；(b)估计当地强迫（例如土壤湿度、植被）对拉普拉塔盆地降水和地表水文的影响；(c)查明流域的局部影响和大尺度降水变化的作用。本文提出的研究策略是基于大气区域中尺度Eta模式和VIC水文模式在耦合和非耦合模式下的诊断分析和数值试验。Eta模型与VIC和河流路线方案相结合，将用于描述从远程和/或本地强迫到河流流量变化的路径。实验旨在了解土地利用变化对长期气候的影响，以及土地利用/土地覆盖与降水和河流流量之间的反馈关系。实验还将侧重于大尺度变率影响区域降水的机制。这项研究的相关性不仅是因为它将解决尚未解决的科学问题，而且还因为它是发展中国家一个地区水资源的明确应用。该方法的目的是以一致的方式处理大气和水文问题。这个提议有很强的教育成分。学生将直接参与研究；来自南美洲大学的科学家将参与，增加区域专业知识，同时也加强教育部分。已制定与南美学生交流的计划，并计划在布宜诺斯艾利斯大学开设一到两门相关课程（该项目无需支付费用）。该提案利用了马里兰大学和华盛顿大学的现有基础设施。计算机系统已经到位，需要的升级将在这个项目开始时准备好。