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

林冠通过截留、储存和蒸发树叶和树皮表面的水滴，可以减少到达地面的降水量达50%。这一过程被称为“截留损失”，影响径流、补给、洪水暴发、侵蚀等，和雨水管理的成本。 目前还不清楚冠层结构如何影响截留损失，特别是在城市森林中。 这项研究解决了这一问题，通过监测拦截损失变量为一个共同的美国东南部树种（火炬松）在森林结构的自然到城市的梯度。监测的截留损失变量包括储存在树冠中并从树冠蒸发的雨水，穿过树冠（穿透雨），以及在降雨期间和之后的空气温度，湿度，风速/风向，压力和入射太阳辐射。这些测量将与新的、高分辨率的、非破坏性的激光扫描（LiDAR）技术相关，以解决2个问题：1）从自然条件到常见的城市条件的林分结构变化如何影响截留损失过程;激光雷达测量的冠层结构和截留损失过程是否会改善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，由于树木的条件影响分支和叶结构，截留损失及其基本变量将根据风暴条件而变化。将这些响应纳入通用模型将对暴雨条件变化方面的水资源管理具有预测价值。这是一个RUI（本科院校研究）项目，将培养本科生在尖端水文科学，并纳入教育推广工作达到数千名K-12学生，本科生，高中教师和社区成员。 格鲁吉亚南方大学（GSU）有大量的非洲裔美国学生（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。 项目数据将用于开发GSU校园的管理实践。森林林冠截留损失（I）对径流、补给、洪水暴发、侵蚀和雨水管理基础设施的成本产生重大影响。然而，目前还不清楚森林冠层结构如何控制I（存储，S和蒸发，E）的组成部分，特别是在城市森林。 现有的研究没有：1）比较S和E行为沿着不同林冠结构的自然-城市森林连续体或2）将陆地LiDAR（TLiDAR）测量的林冠结构和这些结构与S和E动态的相互作用纳入常见的I模型。这项研究将这样做沿着自然城市森林结构梯度的格鲁吉亚南方大学（GSU）校园使用区域优势种（火炬松，火炬松）。该研究将现有的生物监测方法（气象，茎流和穿透雨测量）与新的陆地激光雷达技术（LaserBark和L-Architect）相结合，以比较城市森林中的S和E与直接，非破坏性测量的冠层结构指标。这涉及两个问题：1）对于2个城市森林结构，S和E的跨风暴和风暴内动态如何变化，以及与天然树木林分相比如何，以及2）在多大程度上可以将直接测量的冠层结构纳入城市林分中，从而改变I输出，参数，甚至是最常用模型的参数化（即，Gash和Rutter类型）？ 这些发现将推进几乎所有的水文模型，模拟或包括森林拦截过程。由该提案支持的六名本科生将获得跨越研究活动（包括现场仪器培训，安装和维护;数据收集和处理;建模和模型评估;手稿准备;和在国家会议上的演讲）的广度的大量研究经验，在水资源管理的及时和关键的子领域。数据还将用于改进：（1）L-Architect模型，该模型正被纳入Computree，这是国家森林办公室（法国）用于国家改进森林清单的工具;（2）GSU校园目前采用的可持续灌溉做法。

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.