RUI: Measurement and modeling of rainfall interception loss from Georgia Southern University's urban forest.

森林树冠可以通过截留、储存和蒸发树叶和树皮表面的水滴，将到达地面的降雨量减少高达50%。这一过程被称为“截流损失”，影响径流、补给、洪水暴发、侵蚀等，以及雨水管理的成本。树冠结构如何影响截留损失，特别是在城市森林中，目前还不是很清楚。这项研究通过监测美国东南部一种常见树种(火炬松)在森林结构从自然到城市的梯度上的截留损失变量来解决这一问题。监测的截留损失变量包括储存在树冠和从树冠蒸发的雨水、穿过树冠的雨水(穿透雨量)、从树干向下排出的雨水(树干流量)以及在降雨期间和之后的气温、湿度、风速/方向、压力和传入的太阳辐射。这些测量将与新的高分辨率非破坏性激光扫描(LiDAR)技术有关，以解决两个问题：1)从自然条件到普通城市条件的林分结构变化如何影响拦截损失过程；以及2)LiDAR测量的树冠结构和拦截损失过程是否会改善对水文过程的估计和预测，从而改善水资源管理和规划？假设是，由于林分条件影响树枝和树叶结构，截留损失及其潜在变量将随着风暴条件的变化而变化。将这些响应纳入通用模型将对有关风暴条件变化的水管理具有预测价值。这是一个RUI(本科院校研究)项目，将培训本科生在尖端水文科学方面的知识，并纳入教育推广工作，覆盖数千名K-12学生、本科生、高中教师和社区成员。佐治亚南方大学(GSU)拥有相当多的非洲裔美国学生(2012年和2013年分别占本科生的25.7%和26.4%)，因此该项目将为代表性不足的群体提供研究经验。项目数据将用于发展格拉斯哥州立大学校园的管理实践。森林冠层降雨截留损失(I)对雨水管理基础设施的径流、补给、洪泛、侵蚀和费用有重要影响。然而，森林冠层结构如何控制I的成分(储存，S和蒸发，E)还不是很清楚，特别是在城市森林中。现有的研究还没有：1)比较S和E在不同冠层结构的自然-城市森林连续体上的行为；2)将陆地激光雷达测量的冠层结构以及这些结构与S和E动态的相互作用纳入公共I模型。这项研究将沿着佐治亚州南部大学(GSU)校园内从自然到城市的森林结构梯度，使用区域优势物种(火炬松、火炬松)进行这项研究。这项研究将把现有的生物气象监测方法(气象、树干径流和穿透雨测量)与新的陆地激光雷达技术(激光树皮和L建筑师)结合起来，将S和E在城市森林中与直接、非破坏性测量的树冠结构指标进行比较。这解决了两个问题：1)S和E的两个城市森林结构的跨风暴和风暴内的动态如何变化，以及这与自然林分相比如何；2)在城市林分中包含直接测量的冠层结构在多大程度上可以改变最常用的模型(即Gash和Rutter类型)的I输出、参数甚至参数化？这些发现将推进几乎所有模拟或包括森林拦截过程的水文模型。在这项建议的支持下，6名本科生将在水资源管理的一个及时和关键的分领域获得广泛的研究经验(包括实地仪器培训、安装和维护；数据收集和处理；建模和模型评估；手稿准备；以及在全国会议上的陈述)。数据还将用于改进：1)L-建筑师模型，该模型正被纳入法国国家森林资源研究所用于改善全国森林清单的工具计算机树；以及2)格拉斯哥州立大学校园目前采用的可持续灌溉方法。

Forest canopy can reduce precipitation reaching the ground by up to 50% through interception, storage, and evaporation of droplets from leaf and bark surfaces. This process, called "interception loss," impacts run-off, recharge, flood flashiness, erosion, etc., and cost of stormwater management. It is not well understood how canopy structure affects interception loss, particularly in urban forests. This research addresses this by monitoring interception loss variables for a common SE US tree species (the loblolly pine) across a natural-to-urban gradient in forest structure. Interception loss variables monitored include rainwater stored in and evaporated from the canopy, passing through the canopy (throughfall), and draining down the stem (stemflow) as well as air temperature, humidity, wind speed/direction, pressure, and incoming solar radiation during and after rainfall. These measurements will be related to new, high-resolution, non-destructive laser-scanning (LiDAR) techniques to address 2 questions: 1) how do stand structural changes ranging from natural conditions to common urban conditions affect interception loss processes; and 2) Will LiDAR-measured canopy structures and interception loss processes improve estimation and prediction of hydrologic processes and, thereby, improve water management and planning? The hypothesis is that, because tree stand conditions affect branching and leaf structures, interception loss and its underlying variables will vary in response to storm conditions. Inclusion of these responses in common models will have predictive value for water management concerning shifts in storm conditions . This is an RUI (Research at Undergraduate Institutions) project that will train undergraduate students in cutting-edge hydrologic science and be incorporated into educational outreach efforts reaching thousands of K-12 students, undergraduate students, high school teachers, and community members. Georgia Southern University (GSU) has a substantial African American student population (25.7% and 26.4% of undergraduates in 2012 and 2013), so the project will provide research experiences to underrepresented groups. Project data will be used to develop management practices on the GSU campus. Forest canopy rainfall interception loss (I) is documented to exert significant influence on run-off, recharge, flood flashiness, erosion and the cost of stormwater management infrastructure. However, it is not well understood how the forest canopy structure controls the components of I (storage, S, and evaporation, E), particularly in urban forests. No existing study has: 1) compared S and E behavior along a natural-urban forest continuum of differing canopy architecture or 2) incorporated terrestrial LiDAR (TLiDAR) measured canopy structures and the interaction of these structures with S and E dynamics into common I models. This study will do this along a natural-to-urban forest structure gradient on the Georgia Southern University (GSU) campus using a regionally dominant species (Pinus taeda, loblolly pine). The study will couple existing biometeorological monitoring methods (meteorological, stemflow, and throughfall measurements) with novel terrestrial LiDAR techniques (LaserBark and L-Architect) to compare S and E in urban forests with directly, non-destructively measured canopy structural metrics. This addresses two questions: 1) how do across- and within-storm dynamics of S and E vary for 2 urban forest structures, and how does this compare to natural tree stands, and 2) to what extent can inclusion of directly-measured canopy structures in urban stands alter I outputs, parameters, and even parameterizations for the most commonly used models (i.e., the Gash- and Rutter-type)? These findings will advance nearly all hydrologic models that simulate or include forest interception processes. Six undergraduates supported by this proposal will receive substantial research experiences spanning the breadth of research activities (including field instrument training, installation, and maintenance; data collection and processing; modeling and model evaluation; manuscript preparation; and presentation at national meetings) in a timely and critical subfield of water resource management. Data will also be used to improve: 1) the L-Architect model, which is being incorporated into Computree, a tool used by the Office National des Forêts (France) for national improvement of forest inventories; and 2) the sustainable irrigation practices currently employed on the GSU campus.