concept design san antonio river improvements project

HISTORICAL MISSION (SOUTHERN) REACH
A goal in the Master Plan process was to test the application of fluvial geomorphology principles and determine its
appropriateness for the San Antonio River. This investigation began with the testing of three conceptual
approaches to a segment of the Historical Mission (Southern) Reach. These alternative approaches included:
26 SAN ANTONIO RIVER DESIGN GUIDELINES
ALTERNATIVE A – RIVER IMPROVEMENTS WITHIN THE EXISTING RIVER CHANNEL
This approach included minor river channel realignment but limited to the area within the existing
flood channel right-of-way.
Component Pro
Con
Flooding Potential None
Some out-of-bank flow during 100-year
storm (existing).
Design could raise 100-year water surface
elevation where channel has capacity.
Pilot Channel None
Size limited to base flow (10 cfs).
Bankfull event not accommodated.
River Meanders Pilot channel can be curved for aesthetic
purposes.
Riffles and Pools Can be created.
Plant and Animal Habitat Allows vegetation and habitat
improvement but minimizes trees.
Sinuosity does not meet fluvial
geomorphologic principals and is limited to
area between flood control banks.
Channel Stability None
Low stability- required maintenance not
reduced. Much armoring required.
Aesthetics Somewhat improved. “Decorated” trapezoidal channel.
Canoeing Can be accommodated.
Water Quality Not improved significantly.
Land Acquisition None required.
Other program elements Simplest pilot channel trail crossings.
Budget $100M overall budget can be
accommodated.
None
None
May require some portaging.
None
None
None