GIS Shapefile - Analysis of potential stewardship in support of BES research, block group

Potential stewardship for Baltimore City summarized by block group. PRIZM 5, 15, and 62 classes are also present. PRIZM is the Potential Rating Index by Zip code Markets produced by the Claritas corportation - (http://www.clusterbigip1.claritas.com/claritas/Default.jsp). Potential stewardship is that land within a parcels not occupied by buildings, that is land that could potentially undergo "greening." Not Realized Potential Stewardship is the land not occupied by buildings or existing vegetation, and is thus the land that is potentially available for "greening" initiatives. This dataset provides several summarizations at the block group level: 1) total potential stewardship area, 2) not realized potential stewardship, 3) normalized potential stewardship (potential stewardship area / block group area), 4) normalized not realized potential stewardship (not realized potential stewardship area / block group area), and 5) tree potential stewardship area. The potential stewardship was calculated using parcel data, building footprints, and GDT census block groups. Building footprints were erased from the parcel area, resulting in a layer indicating the potential stewardship for each parcel. The potential stewardship layer was then unioned MD DNR's SUFA vegetation layer. All polygons corresponding to water features were deleted since water features cannot undergo "greening." All polygons that did fall in the potential stewardship area were deleted. This resulted in a layer in which the polygons represented the potential stewardship land along with the potential stewardship land occupied by either grass or trees. This layer was then intersected with the census block group layer resulting in a layer that had the potential stewardship land, potential stewardship vegetation, and block group IDs. All attributes were then summarized at the block group level. Total Potential Stewardship (Tot_PotStew) is the area of parcel land in a block group that is not occupied by buildings or water. Not Realized Potential Stewardship (NotReal_PotStew) is the area of parcel land in a block group that is not occupied by buildings, water, or vegetation, and is thus the land that is actually available for greening. Normalized Potential Stewardship (Norm_PotStew) is the Potential Stewardship area � Block Group area. Normalized Not Realized Potential Stewardship (Norm_NotReal_PotStew) is the Not Realized Potential Stewardship area � Block Group area. Summations of grass (Grass), tree (Trees), and vegetation (Tot_Veg) area within the potential steward zone are also presented. Tree potential stewardship (Tree_PotStew) was calculated by identifying the land that is available for plating trees, i.e. not building, water, or existing trees. Normalized tree potential stewardship (Norm_Tree_Pot_Stew) was calculated by dividing by the area of the block group. Standardized tree potential stewardship (Std_Tree_PotStew) was calculated from the normalized tree potential stewardship: ((value - min) / range) * 100. A cursory analysis of the parcel data indicated that parcel data was outdated for the following block groups: 245102503031, 245102503032, and 245102503033. Note: transportation networks are not part of the parcel data, and thus were appropriately not part of this analysis.

本数据集以街区组（block group）为统计汇总单元，展示巴尔的摩市的潜在管护潜力，同时包含PRIZM 5、15与62类别的相关数据。PRIZM（邮政编码市场潜在评级指数，Potential Rating Index by Zip code Markets）由克拉里塔斯公司（Claritas Corporation）推出，其官方网址为http://www.clusterbigip1.claritas.com/claritas/Default.jsp。所谓潜在管护潜力，指地块中未被建筑物占用的土地，即具备“绿化”实施潜力的用地；未实现潜在管护潜力则指未被建筑物或现有植被占用的地块，也就是实际可用于“绿化”项目的可用土地。本数据集提供了以下5项街区组级别的汇总统计指标：1）总潜在管护面积；2）未实现潜在管护面积；3）标准化潜在管护面积（潜在管护面积 / 街区组总面积）；4）标准化未实现潜在管护面积（未实现潜在管护面积 / 街区组总面积）；5）树木潜在管护面积。潜在管护潜力的计算基于地块数据、建筑基底轮廓（building footprint）以及GDT人口普查街区组数据实现：首先从地块总面积中剔除建筑基底轮廓，得到表征单块地块潜在管护潜力的矢量图层；随后将该图层与马里兰州自然资源部（MD DNR, Maryland Department of Natural Resources）的SUFA植被图层进行空间融合；删除所有对应水体要素的多边形，因水体无法开展绿化作业；进一步删除所有属于潜在管护范围的多边形，最终得到同时涵盖潜在管护用地及被草本或树木覆盖的潜在管护用地的图层；将该图层与人口普查街区组图层进行空间相交处理，得到包含潜在管护用地、潜在管护植被及街区组ID的整合图层；最后对所有属性字段按街区组进行汇总统计。各指标的具体定义如下：总潜在管护面积（Tot_PotStew）指街区组内未被建筑物或水体占用的地块用地总面积；未实现潜在管护面积（NotReal_PotStew）指街区组内未被建筑物、水体或现有植被占用的地块用地面积，即实际可用于绿化的可用土地；标准化潜在管护面积（Norm_PotStew）为潜在管护面积与对应街区组总面积的比值；标准化未实现潜在管护面积（Norm_NotReal_PotStew）为未实现潜在管护面积与对应街区组总面积的比值；本数据集同时提供了潜在管护范围内的草本（Grass）、树木（Trees）及总植被（Tot_Veg）面积的汇总统计结果；树木潜在管护面积（Tree_PotStew）指可用于种植树木的用地，即未被建筑物、水体或现有树木占用的土地；标准化树木潜在管护面积（Norm_Tree_Pot_Stew）为树木潜在管护面积与对应街区组总面积的比值；标准化得分树木潜在管护面积（Std_Tree_PotStew）通过对标准化树木潜在管护面积进行标准化处理得到，计算公式为：((数值 - 最小值) / 极差) * 100。通过对地块数据的初步审查发现，以下街区组的地块数据已过时：245102503031、245102503032及245102503033。注：交通路网未纳入地块数据范畴，因此未被纳入本次分析。