Yosemite National Park - Flood Plain - Open Data

These datasets shows various modeled likely extents of ordinary high water and flood events in Yosemite National Park. Several endeavors over the years have developed these datasets for different areas and in different geometries. This dataset includes models from three different studies that cover eastern Yosemite Valley, Glen Aulin High Sierra Camp, Tuolumne Meadows Lodge, and Tuolumne Meadows areas. Contractors Cella-Barr and Associates modeled the likely extent of a 2-year, 10-year, 25-year, and 100-year flood event in eastern Yosemite Valley. Data provided in 1998. The polylines represent the boundaries of that modeled flood extent. There is one polygon representing the boundaries of an update to the 2-year flood extent in this dataset that was done by the Denver Service Center in 2006 after finding a shift. In a 2006 study, 100-year floodplains and ordinary high water marks were determined for 3 locations: the Tuolumne Meadows Lodge Area, Tuolumne Meadows Campground to Visitor Center, and Glen Aulin High Sierra Camp. Ordinary high water marks were determined in order to map the jurisdictional waters of the US that are associated with the Tuolumne River, including the Dana and Lyell Forks in Tuolumne Meadows. By observing spring flooding and using many indicators recommended by the US Army Corps of Engineers (see study)- including types of vegetation, changes in soil, and presence of litter and debris- the researchers defined the ordinary high water marks of these locations. The magnitude of the 100-year flood was calculated using equations developed by the US Geological Survey for ungaged river basins in the Sierra Nevada. The floodplains were determined using the US Army Corps of Engineers Hydraulic Engineering Center River Analysis System, a 1-dimensional hydraulic flow model. There are three polygons from the U.S. Corps of Engineers modeled floodplain for Yosemite Valley. Date unknown. They are likely the modeled or projected 100 year flood line boundary. IRMA Data Store Reference本数据集涵盖约塞米蒂国家公园内各类模拟得到的常规高水位（ordinary high water）与洪水事件潜在影响范围。多年来，相关团队针对不同区域、以不同几何形态构建了多套此类数据集。 本数据集包含三项不同研究生成的模型，覆盖区域包括约塞米蒂山谷东部、格伦奥林高山营地（Glen Aulin High Sierra Camp）、图奥勒米草甸小屋（Tuolumne Meadows Lodge）以及图奥勒米草甸区域。 承包商塞拉-巴尔联合事务所（Cella-Barr and Associates）于1998年完成约塞米蒂山谷东部2年一遇、10年一遇、25年一遇及100年一遇洪水事件的潜在波及范围模拟，相关数据于1998年提交。多段折线用于表征该模拟洪水范围的边界。 本数据集还包含一个多边形，用于表征丹佛服务中心（Denver Service Center）于2006年修正后的2年一遇洪水范围边界——该修正源于此前发现的偏移问题。 在2006年的一项研究中，研究人员为三处区域划定了100年一遇漫滩与常规高水位标记（ordinary high water marks）：图奥勒米草甸小屋区域、图奥勒米草甸营地至游客中心区域，以及格伦奥林高山营地。 划定常规高水位标记的目的是绘制与图奥勒米河相关的美国管辖水域范围，其中包括图奥勒米草甸内的达纳支流（Dana Fork）与莱尔支流（Lyell Fork）。 研究人员通过春季洪水观测，并采用美国陆军工程兵团（US Army Corps of Engineers）推荐的多项指标——包括植被类型、土壤变化以及碎屑与垃圾的分布——划定了上述区域的常规高水位标记。 100年一遇洪水的洪量采用美国地质调查局（US Geological Survey）为内华达山脉无实测水文数据流域开发的公式进行计算。 漫滩范围则通过美国陆军工程兵团水力工程中心河流分析系统（US Army Corps of Engineers Hydraulic Engineering Center River Analysis System，一维水力学流动模型）确定。 另有三份来自美国陆军工程兵团的约塞米蒂山谷洪水漫滩模拟多边形数据，具体生成日期不详，其大概率为模拟或预测得到的100年一遇洪水线边界。 IRMA数据存储引用