Spring Rain

Several days of alternating light, steady, and heavy rains have resulted in a soaked arboretum. It's the first of May, and we have yet to turn on the arboretum's irrigation system. For the coming week, there is even more rain in the forecast. Below are photos from today, May 4, 2019.

On the north side of the arboretum, rain water swiftly runs its established course over landscape rocks.

These large rocks, or mini-boulders, are not original to the grounds of the college; they were added to the landscape when the arboretum was founded. Fast-growing vines, such as our Virginia creeper, work to conceal these mini-boulders.

On the northeast side, a brick retaining wall encloses the arboretum. Water passes through this wall and into the arboretum at several points.

Hamilton Hall and Mickle Hall stand on the opposite side of the retaining wall. A series of drains collects water from around these massive buildings and redirects it into the arboretum. The upper pond receives much of this runoff.

When the arboretum was founded in 1984, the upper pond was designed as a permanent aquatic habitat. Over the years, due to environmental difficulties, adjustments were made to allow for more flow and less retention. Today, the upper pond serves as a floodplain. It's inundated during heavy rains and allows for the slow absorption of water over a wide area. It's rare to have standing water in the pond for more than a week.

Runoff from the west side of campus also drains into the arboretum. The well-defined drainage channels outside of the arboretum divert excess water away from buildings.

Once the runoff enters the arboretum, its flow is slowed by less-defined drainage channels and specific planting choices to allow for more absorption.

This is the west floodplain. On a day like today, with heavy rain, two inches of water can easily accumulate across a wide area. Tomorrow, the ground will assuredly be soggy but we do not expect to see much standing water.

This narrow, overgrown channel is where the water flow from the west meets the water flow from the north.

In the arboretum, we like to keep more vegetation surrounding the drainage channels. There are two main reasons for doing so. First, the extra vegetation slows and reduces runoff, which pleases our water loving trees. Second, the plant life keeps the soil in place, reducing erosion.

Of course, a great deal of runoff occurs despite the purposeful landscape features, i.e., ponds, floodplains, and overgrown channels. Excess water quickly drains out of the arboretum and off campus via this concrete floodway.