Name NRS 409 Exam I. 1. (24 Points) Consider the following questions concerning standard data for GIS systems.

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1 Read every question carefully. You may use a calculator if you wish. Conversion tables are provided at the end of the exam. If you have any questions, raise your hand. Be sure to show your work on computational questions. Pace yourself, you have 75 minutes to complete this test. 1. (24 Points) Consider the following questions concerning standard data for GIS systems. A. What is the NLCD dataset and what would you use it for? National Land Cover Data, USGS, national land use and land cover. Many viable applications. 30m, raster. B. If you were modeling risk of inundation from sea level rise for a small area in downtown Providence, what would be your best source of downloadable elevation data from USGS? Be sure to tell me what resolution you would use. 1/9 arc second (3 m) 3DEP/NED, USGS, raster C. If you were modeling landslide risk zones (based on steep slopes) for Portugal, what would be your best source of downloadable elevation data from USGS? Be sure to tell me what resolution these data would be in. SRTM, 90 m pixel, USGS (or NASA), raster D. What resolution of census data would you use if you wanted to make a very detailed map of the spatial pattern of where senior citizens live in downtown Providence? Block level TIGER polygon data from Census Dept., vector, 1:24K Page 1 Points Total Points this Page = 16

2 E. What dataset would you use to determine the exact location of 12 specific streams in Rhode Island for which you had water quality and pollution data from EPA for the same 12 stream segments (reaches). NHD, 1:24,000, USGS, vector F. You need to map soil drainage classes for your town (in RI) in order to determine where septic systems might fail. USDA NRCS SSURGO, 1:15,840, vector 2. (16 Points). An early choice you must make in performing a GIS analysis is choosing the proper format of the spatial data you intend to use. Please answer the following questions concerning raster and vector GIS data. A. Name two common geospatial datasets that come from federal sources that originate in raster format. For each, provide the name of the dataset, the agency that distributes it, and the pixel size of the dataset. NLCD, 30 m, USGS 3DEP/NED, varies from 30-3 m, USGS SRTM, 90 m, USGS DRG, 1:24K, USGS B. Describe a situation where a raster GIS data model would be the most appropriate data model for a GIS application. When you start with a raster dataset for example NLCD, or you have a lot of modeling to do. Many answers possible. C. Describe a situation where a vector GIS data model would be the most appropriate. Atlas quality mapping, need topology, many answers possible. Page 2 Total Points Points this Page = 20

3 D. Describe a situation where either a raster or a vector GIS data model would be equally appropriate. Some analytical procedures, when you can convert from one to another, when you need atlas quality maps but your pixel sizes are very small. Many answers possible 3. (14 Points). A GIS is much more than computer software and data files. A. What are the five elements of a complete, integrated GIS system? What element do you think is the cheapest? What element do you think is the most expensive? People, methods, hardware, software, data. People most expensive, data might be cheapest now. B. How about geospatial data -- what are four unique properties of this kind of information? Briefly define or describe each one of these essential components of geospatial data. Graphic Element -- points, lines, polygons, pixels Attribute/Database Element -- database defining features Geographic Parameters -- NAD, coordinate system, projection Topology -- adjacency, connectedness Metadata -- data about data Page 3 Total Points Points this Page = 18

4 6. (14 Points) Consider the map below. What is the scale of the map? The asterix (in the north) is RI State Plane (feet) coordinate , The dot is RI State Plane , Gd= =111,000 =1,332,000 Md=1.5 S=1,332,000 /1.5 = 888,000 1:888,000 Using this scale, what is the distance in kilometers from the cross to the star? Md=1.5 S=1:888,000 Gd=1.5*888000=1,332,000 = 33.8 km Page 4 Total Points Points this Page = 14

5 5. (16 Points) Short Answer. Provide a brief description or definition for the following terms. Aerial photo versus orthophoto Air photo has distortion from tilt, optics, and terrain. Ortho have these error removed. Web Map Service Access to geospatial data via the Internet. Only graphic images of the feature are streamed to your mapping application, not the data themselves. You can not control symbology and do not have access to the original data. Topology Spatial relationships, connectedness, embededness, adjacency 289,000 by 4,593,000 UTM Coordinates NAVD88 Vertical datum mean seal level at a tide gage in Quebec Canada. ESI Environmental sensitivity index, NOAA dataset on coastal features used in emergency response. Geoid Shape of the earth based if it were covered with water. Variation in elevation due to differences in gravitational pull Meades Ranch, Kansas Datum for NAD27 more or less the center of the country Page 5 Total Points Points this Page = 16

6 6. (16 Points). Map Accuracy. A. Usually, large scale maps are more accurate than small scale maps. You have two sources of stream locations in your GIS database (and both meet National Map Accuracy Standards). One was mapped at 1:24,000 scale and the other was mapped at 1:15,000 scale. Which one has the best spatial accuracy? Is this an example of large scale maps being more accurate than small scale maps? Why or why not? S= 24,000 S=15,000 Md=0.02 Md= Gd= 480 Gd=500 More accurate Less accurate Difference due to 1:20,000 threshold in NMAS tolerance from 1/50 th to 1/30 th B. What is the potential positional error in a 1:1,200 scale map that meets National Map Accuracy Standards. Express your answer in map units (in inches). NMAS for 1:1,200 scale map. 90% features shall be within 1/30 th inch (0.033 ) Page 6 Points Total Points this Page = 16