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Resilience of a dammed tropical river.

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Resilience of a dammed tropical river. Zambezi river...Kariba Dam. DAFNE project

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Resilience of a dammed tropical river.

  1. 1. Resilience scales of a dammed tropical river References Elisa Calamita 1, Martin Schmid 2, Bernhard Wehrli 1,2 ETH Zürich, Environmental Systems Sciences - Aquatic Chemistry; elisa.calamita@usys.ethz.ch 1 2 ...the reversible/irreversible classification is not straightforward because of the complexity of the river systems. • artificial river impoundments disrupt the seasonality and dynamics of thermal, chemical, morphological and ecological regimes in river systems ‘river continuum’ discontinuity element downstream ecosystem motivation resilience scales multisystem modelling Physical runoff (Q) temperature (T) sediment supply (sed) light Chemical oxygen (O2) CO2 and CH4 pH nitrogen (N) organic matter (OM) phosphorus (P) total suspended solids (TSS) Biological plankton (PP) benthos (ben) fish reversible or irreversible? Impoundment alterations on downstream river systems: Zambezi River…Kariba Dam • biogeochemical model for Lake Kariba by using GLM • water quality survey • assessment of released water quality • quantification of seasonal water quality alterations • spatio-temporal river water quality modelling time [month] opened in 1959 for hydropower production total capacity: 180 km3 second largest artificial lake in Africa preliminary results The water temperature resilience is shown already 40 km downstream the reservoir, the seasonality starts to be recovered… …at the same location the discharge doesn’t show any seasonal variability. The resilience scale is a measure of the disruption of the continuum river system… ..it is a measure of the longitudinal extent of the physicochemical alterations. [Wikipedia] [Wikipedia] • river systems resilience downstream the dam has never been quantified [Wikipedia] maximum water depth: 97 m Ward and Stanfard, 1983. The Serial Discontinuity Concept of lotic ecosystems. In: Fontaine, TD, Bartell, SM (Eds), Dynamics of lotic ecosystems Ann Arbor Science, Ann Arbor, Michigan: 29-42. Straskraba, Tundisi and Duncan, 1993. State-of-the-art of reservoir limnology and water quality management. Comparative reservoir limnology and water quality management: 213-288. Oliver, Dahlgren and Deas, 2014. The upside-down river: reservoirs, algal blooms, and tributaries affect temporal and spatial patterns in nitrogen and phosphorus in the Klamath River, USA. Journal of hydrology 519: 164-176. Piccolroaz, Calamita, Majone, Gallice, Siviglia and Toffolon, 2016. Prediction of river water temperature: a comparison between a new family of hybrid models and statistical approaches. Hydrological processes 30: 3901—3917 Teodoru, Nyoni, Borges, Darchambeau, Nyambe and Bouillon, 2015. Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget. Biogeosciences 12: 2431-2453. DAFNE project • the Zambezi River is one of the most dammed river of Africa, with further dams already planned to be installed • little is known about the longitudinal distance that rivers need to partially restore their physical, chemical and biological integrity The reversibility of some characteristics is intimately linked to the equilibrium between the river and surrounding environment (atmosphere, streambed,..) EU project supported by Horizon 2020 Research and Innovation Action: Decision-Analytic Framework to explore the water-energy-food Nexus in complex and transboundary water resources systems of fast growing developing countries. DAFNE How are dams changing water quality in tropical African rivers? time [day] depth 35 16 T[°C] water temperature coordination WEF drivers analysis and modelling socio-economy trade-off results impact communication WP1 WP2 WP3 WP4 WP5 WP6 WP7 www.dafne.ethz.ch Temperature[°C]Discharge[m3/s]

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