Five parcels of land have been chosen for a land use investigation. 21, 27, 31, 33, 35, 39 and 41 Loomis Street were mapped. Within the five parcels the total footprint is approximately 25,280 squared feet. The resolution of this image is in such poor quality that the distinction between the grass areas and areas of compact ground could not be decerned. The paved areas have been interpreted from the 2018 satellite image and from the use of Google Earth as well as my interpretation from this satellite image. There are no outstanding differences in the two satellite images that can be seen.
With the higher resolution image from 2018 I was able to determine the different parts of each parcel. Within the five parcels there are areas of grass, pavement, building, and compact dirt. The area occupied by the buildings is around 13,295 squared feet. The grass area is around 5,228 square ft. The paved area is around 5,712 squared feet. The compact ground is around 1,045 squared feet. The majority of the parcels land consists of buildings, upwards of 52%.
Over the past 19 years land use of the five selected parcels, shown above, have not changed notably. The land use on the five properties consists of buildings (houses), grassy areas, compact surfaces, and paved surfaces. Since 1999 there has been no visual changes of the buildings in the past 19 years. The majority of the the totaled parcels consist of theses buildings, just over 52%. The paved area is around 22% while the grassy area makes up only around 20% in 2018. Due to the large majority of the properties being impermeable surfaces, around 75% of precipitation is runoff. During a 2 year return, 1 hour storm from the 2018 map, there would have been .8456 inches of runoff from an inch of rainfall. That is 84.56% runoff because of the limited permeable surfaces. For a 100 year return, 1 hour storm from 2.2 inches of rainfall, 1.86 inches are runoff.
When the data from the past 19 years is compared to a pre-European settlement time around 1600 CE, the results are completely reversed. During the per-settlement of Vermont the land was almost 100% vegetated with forests. The permeability of the forest is much higher than that of a modern structure. During a 2 year return, 1 hour storm the runoff of a 1 inch rainfall results in a 30% runoff. This is substantially lower than the runoff from the 1999, and 2018 runoff percentages. For the 100 year return, 1 hour storm, the runoff from a 2.2 inch rainfall is only .66 inches. The percentage of runoff from a forested area is 30%, much less than that of the impermeable surfaces of present Vermont landscapes. With this information we can really see the effects that we have had on our landscape just in terms of changing the water cycle. We have changed an excellent permeable Vermont into an urban paved and developed landscape where the runoff is a potential pollutant to Lake Champlain.
Landscapes near UVM have a large effect on the runoff that is produced when there are rainstorms. The neighborhoods, and the campus itself have been paved over reducing the amount of permeable surfaces. When you walk or drive around the neighborhoods next to the campus, it is very clear that the majority of the properties are made up of buildings, sidewalks, driveways, and other impermeable surfaces with little grassy and shrubby areas. The effect that this has on the water quality of Lake Champlain must be extensive. To have so many areas that are not absorbing the water when there is precipitation means that everything used on peoples lawns, and anything that leaks from cars is going downhill into the lake. This means there is oil, gasoline, coolant, fertilizer, and many other chemicals that are getting into the lake because of the impermeable surfaces. These chemicals that are entering the lake are effecting the organisms that live there and the quality of the water. If there is any solution to fix this problem it is clearly to improve the permeability of Burlington's surfaces.
Calculations for the average rainfall for 1600 CE, 1999 and 2018