Geohydrology

A:

Based on this graph, it appears that the orographic effect on precipitation is present in the data. Average precipitation increases as elevation increases.

2. Average annual precipitation in Vermont is 42.15 in.

3. To calculate the average precipitation of the Winooski River Basin (in./yr), I first found the average elevation of the 5 towns of the dataset that are in the watershed. These towns were determined by looking at several different maps of the watershed; the town lines that intersected the watershed boundary was consistent across my findings. Out of the 5 towns (Burlington, Huntington Center, Montpelier, Mansfield, and Waterbury), the average elevation was 1,376 ft. Then, I calculated the average precipitation in across these towns using the equation of the graph shown above: y = 76.632x - 2326.1

I plugged in the calculated elevation (1,376 ft) for y and determined x (average precipitation) to be 48.36 in./yr

Conversion: 48.36 in. -> 122.8344 cm/yr

4. The area of the Winooski River Drainage Basin is 1680.155 km^2 (1044 mi^2). To calculate the volume of precipitation in the basin, I multiplied this value (1680.155 km^2) by the average precipitation I calculated in the previous question (converted to km -> 0.001228344 km) to get:

2.064 km^3 precipitation in the drainage basin

5. Based on the Channels lab from 2 weeks ago, I knew that the discharge (Q) of the Winooski at this particular point is 1817.36 cfs. This converts to 1.6047 km^3/yr. This means that 77% of precipitation in the drainage basin becomes runoff (average discharge [1.6047km^3/yr]/average precipitation [2.06km^3/yr]) and 23% is "lost" via evapotranspiration and human-use.

TDS:

81.75 mg/1L -> 81.75 kg/km^3 * 1.6047 = 131.18 kg/km^3 -> 0.1312 Mg/km^3

SS:

81 mg/1L -> 81,000 g/km^3 -> 81 kg/km^3 * 1.6047 = 0.1299 Mg/km^3

B:

As stated above, about 77% of incoming precipitation into the Winooski River Drainage Basin ends up as runoff. This means that roughly 23% of this precipitation ends up elsewhere; these alternative pathways and destinations include evapotranspiration and human attainment. As precipitation falls, it can be intercepted by buildings and trees, or land directly on the ground. Here, it can simply evaporate over time (how long depends on the temperature/sunlight) and return to the atmosphere. Alternatively, this precipitation can be taken up by vegetation to be used for photosynthetic processes before transpiring back into the atmosphere. A smaller but significant portion of this precipitation ends up being captured by humans for consumption. Thus, it makes sense for the annual discharge value for the basin to be less than the annual precipitation value for the basin.

C:

The dissolved and suspended loads in the Winooski were similar to each other (~0.13Mg/km^3 respectively). The GSA Water Chemistry study in Cuba (https://www.geosociety.org/gsatoday/science/G419A/GSATG419A.pdf) showed rivers there having much more dissolved material in their flow. The study found a range of 117-780 mg/L of dissolved material, which is significantly more than what was found in the Winooski River (81.75 mg/L). The paper explains how this is likely due to the differing substrates between the two study areas; due to more tectonic activity occurring in Cuba, there is more young, exposed sedimentary rock that is easily eroded by streams. These rocks release various elements that are part of their composition into the stream as dissolved materials.

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