Ecological engineeing of surface water flow paths to improve ecosystem function
Local, regional, state, and federal organizations are looking to surface water conveyance improvments as a cost-effective means to meet sediment and nutrient reduction goals associated with MS4 permits and regional TMDL goals. Concerns with this approach include the potential for conflicting resource management values, uncertainty with how to credit sediment and nutrient reduction, and the nature of regulatory oversight
An EPA sponsored white paper (Schueler and Stack, 2013) evaluated types of surface water conveyance improvements for performance and has received final approval by the Chesapeake Bay Program’s water quality goal implementation team. Another study (Center for Watershed Protection, 2013) has documented the relative cost and benefits of many water quality practices, and improvements to surface water conveyance practices are often an order of magnitude less costly per unit of nutrient removed. This presentation will describe an integrated approach to surface water conveyance, which includes: 1) restoration of eroded ephemeral channels to hyporheic seepage flow dominated systems; 2) storage of pulsed runoff in sand-seepage systems to support the seepage hydrology of created wetlands in the riparian zone/floodplain as well as hyporheic flows to support stream base flow; and 3) base flow channel design, which has as a goal to reconnect the stream’s riparian zone/floodplain to yield a more sustainable channel form for runoff from precipitation events of stage increase. Photos of typical conditions for pre-restoration, typical construction phase, and representative post-restoration conditions will be included in the presentation. Monitoring results will be presented, including impacts of restoration on peak attenuation, increased time of concentration, temperature, and water quality benefits.