GIS in Water Resources      

Homework #3


1.   Search the internet and find a web site that has interesting GIS or water resources observation data available.  Make a short description of this data source, covering what kinds of data are available, and giving a picture of a typical data set that can be obtained from this source.  Give the web site location.


2.  Consider the one degree box surrounded by parallels 42oN and 43oN and meridians 111oW and 112oW.  Approximate the earth as a sphere with radius 6370 km. 


(i)            Calculate the length (km) from north to south of this box.

(ii)          Calculate the length (km) from east to west of the north and south ends of this box.

(iii)         Calculate the area of this box (km2).

(iv)        Sketch this box as it would be shown in ArcGIS (1) using geographic coordinates and (2) in an equal area projection.  Your sketch does not have to be exact, but should be sufficiently precise to show the difference in shape between (1) and (2).


3.  Here are the spatial reference properties of the coordinate system for the San Marcos basin.


(i)  What horizontal earth datum is used?

(ii)  What map projection is used?  Why is this particular projection used for this exercise?

(iii)  What are the geographic coordinates of the origin (fo, lo)?  Express these coordinates both in decimal degrees and in degrees, minutes and seconds notation.

(iv)  What are the projected coordinates of the origin (Xo, Yo)?

(v)  At what latitudes does the projection cone cut through the earth's surface?  Express these latitudes both in decimal degrees and in degrees, minutes and seconds notation.