06/08/13
Abstract Central - Abstract Proof PopUp
Proof
CONTROL ID: 1801037 TITLE: Adaptive Flow Management in Regulated Rivers: Successes and Challenges ABSTRACT BODY: Experimental high flows are becoming common management actions in rivers affected by large dams. When implemented under clear objectives and goals, experimental flows provide opportunities for long-term ecological successes but also impose various ecological challenges as systems shift under environmental change or from human-related actions. We present case studies from long-term adaptive flow management programs on the River Spöl, Switzerland and the Colorado River, USA, both of which are regulated by high dams and flow through National Parks. The management goals in each system differ thus reflecting the different high flow practices implemented over time. Regulated flows in the Spöl reflect a compromise between hydropower needs and ecology (native brown trout fishery), whereas Glen Canyon Dam flows have mainly been directed towards maintenance of river beaches in Grand Canyon National Park with co-management of both nonnative rainbow trout in the tailwater immediately below the dam and downstream endangered native fish of Grand Canyon also an objective. Some 24 experimental floods have occurred on the Spöl over the last 13 years, resulting in a positive effect on the trout fishery and a zoobenthic assemblage having a more typical alpine stream composition. The system has experienced various shifts in assemblage composition over time with the last shift occurring 7 years after the initial floods. A major challenge occurred in spring 2013 with an accidental release of fine sediments from the reservoir behind Punt dal Gall Dam, causing high fish mortality and smothering of the river bottom. Results showed that the effect was pronounced near the dam and gradually lessened downriver to the lower reservoir. Zoobenthic assemblages displayed relatively high resistance to the event and some fish found refugia in the lower reservoir and larger side tributaries, thus projecting a faster recovery than initially thought. Below Glen Canyon dam, benefits to sandbars have been marginal since experimental constrained hydropower releases began in 1991 and controlled floods began in 1996 (7 have been released through 2012), while native fish populations have increased, although apparently not in response to flows. However, nonnative rainbow trout have been shown to increase in abundance repeatedly below Glen Canyon Dam in response to both controlled floods and more stable flows, both of which were originally proposed to benefit Grand Canyon beaches. Survival of trout fry following the 2008 spring flood was apparently tied to increased abundance of benthic invertebrates in the tailwater. Expansion of nonnative trout in response to high flows pose a potential threat to native fish downstream through competition for limited food and habitat, and through predation of juvenile native fish. Challenges are presented for each system in terms of flow implementation under hydropower needs (Spöl) and environmental change (Colorado). We close with perspectives on improving adaptive flow management actions in regulated rivers as learning-based, long-term ecological experiments. CURRENT SECTION/FOCUS GROUP: Hydrology (H) CURRENT SESSION: H044. Hydrological change and water systems: feedbacks, prediction, and experimental management INDEX TERMS: 1808 HYDROLOGY Dams, 1821 HYDROLOGY Floods, 1856 HYDROLOGY River channels. AUTHORS/INSTITUTIONS: C.T. Robinson, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, SWITZERLAND; T.S. Melis, T. Kennedy, USGS, Flagstaff, Arizona, UNITED STATES; J. Korman, Ecometric, Vancouver, British Columbia, CANADA; agu-fm13.abstractcentral.com/viewer?TAG_ACTION=VIEW_PROOF&ABSTRACT_ID=1801037&SHOW_COMMENT=FALSE&NEXT_PAGE=PROOF_POP…
1/2
06/08/13
Abstract Central - Abstract Proof PopUp
J. Ortlepp, Hydra, Constance, GERMANY; CONTACT (E-MAIL ONLY):
[email protected] TITLE OF TEAM: (No Image Selected) (No Table Selected) PRESENTATION TYPE: Assigned by Committee (Oral or Poster) [Invited]
ScholarOne Abstracts® (patent #7,257,767 and #7,263,655). © ScholarOne, Inc., 2013. All Rights Reserved. ScholarOne Abstracts and ScholarOne are registered trademarks of ScholarOne, Inc. Follow ScholarOne on Twitter Terms and Conditions of Use Product version number 4.2.0 (Build 45) Build date Aug 05, 2013 14:55:26. Server tss1be0015
agu-fm13.abstractcentral.com/viewer?TAG_ACTION=VIEW_PROOF&ABSTRACT_ID=1801037&SHOW_COMMENT=FALSE&NEXT_PAGE=PROOF_POP…
2/2
