Evaluation of the Blackberry Creek Daylighting Project, Berkeley

Evaluation of the Blackberry Creek daylighting project, Berkeley

Imanishi, J. 2000. Evaluation of the Blackberry Creek daylighting project, Berkeley. UCB Water Resources Center Archives MS 96/2 83. pp.1-31. 2000.12.

Abstract

I reviewed Blackberry Creek Daylighting Project as a five-year post-evaluation from the perspectives of vegetation, channel form and capacity, and design. In terms of vegetation, Salix lasiolepis (arroyo willow) and Cornus stolonifera (red-osier dogwood) were well established. Species were becoming more diverse. The channel form was stable after a ten-year return interval precipitation. The channel capacity was enough to contain discharge from upstream culvert. In terms of design, Koch et al (1999) and others showed high level of uses and stewardship in the park where the daylighted portion of Blackberry Creek is located. These implied success of this project. On the other hand, lack of visibility due to overgrown plants was diminishing safety and attractiveness. Some of intended species, Aesculus californica (California buckeye) and Aquilegia formosa (western columbine), disappeared. Exotic species were increasing. The channel capacity was insufficient to correspond to possible future enhancement of storm drain. And inadequate circulation design was causing surface abrasions and erosions on the slopes.
From these results, I propose five recommendations for a future daylighting project. The recommendations are 1) to secure visibility relating to safety and attractiveness of a creek, 2) to use fast-growing or shade-tolerant species if we use live stakes and/or cuttings of Salix spp. (willows) together, 3) to provide a program of removing exotic species in advance, 4) to decide channel capacity in the long term, and 5) to analyze circulation and implement adequate design that avoids surface erosion.