Contrasting signatures of distinct human water uses in regulated flow regimes

Abstract

In the last century, about 50,000 dams have been constructed all around the world, and regulated rivers are now pervasive throughout the Earthʼs landscapes. Damming has produced global-scale alterations of the hydrologic cycle, inducing severe consequences on the ecological and morphological equilibrium of streams. However, a recognizable link between specific uses of reservoirs and their impact on flow regimes has not been disclosed yet. Here, extensive hydrological data are integrated with a physically-based model to investigate hydrological alterations downstream of 47 isolated dams in the Central Eastern U.S. Our results reveal a strong connection between the anthropogenic use and the hydrological impact of dams. Flood control reduces the temporal variability and spatial heterogeneity of river flows proportionally to the specific capacity allocated to mitigate floods (i.e., capacity scaled to the average inflow). Conversely, water supply increases the relative variability and regional heterogeneity of streamflows proportionally to the relative amount of withdrawn inflow. Accordingly, downstream of our multipurpose reservoirs the impact of regulation on streamflow variability is smoothed due to the compensating effect of flood control and water supply. Nevertheless, reservoirs with high storage capacity and overlapping uses produce regulated hydrographs that increase their unpredictability for larger aggregation periods and, thus, resemble an autocorrelated red noise. These findings suggest that the increase of freshwater demand could redefine the cumulative effects of dams at regional scale, reshaping the trajectories of eco-morphological alteration of dammed rivers.

Sensitivity of Regulated Streamflow Regimes to Interannual Climate Variability

“…In particular, the analysis of the first two moments of unregulated and regulated discharges (i.e., and CV Q ) indicates that reservoirs for flood control and hydropower production decrease the long‐term hydrological variability, in line with previous findings (Destouni et al, ; Graf, ; Poff et al, ). Instead, structures only operated to supply freshwater reduce the average downstream discharge and, thus, increase the relative variability of streamflows (Ferrazzi & Botter, ; see Tables S1 and S2).…”

Assessment of geomorphic effectiveness of controlled floods in a braided river using a reduced-complexity numerical model

“…A more detailed analysis of the impact of regulation on river regimes has been presented by Botter et al (2010), who applied 165 a physically-based modelling approach to assess the alterations of the streamflow regime observed in various cross sections of the drainage network downstream of dams and weirs. The authors have applied an analytical stochastic model (Botter et al, 2007) to characterize the streamflow probability density function (pdf) by means of climate, soil and vegetation parameters. After a preliminary model application to smaller, unregulated sub-catchments (that allowed to properly verify the capability of the model to reproduce locally the natural streamflow regime) the authors have applied the model also in 170 several regulated sections of the Piave River, including Soverzene (about 5 km upstream of Ponte nelle Alpi, Fig.…”

“…Several works (Darby and Van De Wiel, 2003;Hoey et al, 2003;Wilcock and Iverson, 2003) emphasized the challenge of a proper calibration of process-based models in fluvial geomorphology due to the increase of uncertainty proportionally with the complexity of the modeled processes and the number of parameters to be estimated (Formann et al, 2007;Papanicolaou 240 et al, 2008). Despite this intrinsic complexity, it is crucial to understand limitations and performance of RCMs (Aronica et al, 2002;Hall et al, 2005;Lane, 2006), adopting methods that (i) are able to include all the limitations inherent in calibration of this type of model and (ii) are mainly based on field and remote sensing data (Nicholas, 2010).…”

“…Human activities in riverine areas (i.e., river damming, river engineering, gravel mining, land-use change in the drainage basin) have historically led to notable changes in the flow regime (Gore and Petts, 1989;Poff et al, 1997;Magilligan and 25 Nislow, 2005;Poff et al, 2007;Zolezzi et al, 2011;Magilligan et al, 2013;Ferrazzi and Botter, 2019), along with ecological (Collier, 2002;Céréghino et al, 2004;Paetzold et al, 2008;McDonald et al, 2010;Overeem et al, 2013;Espa et al, 2015) and geomorphic functioning of river systems (Hicks et al, 2003;Petts and Gurnell, 2005;Melis, 2011;Ziliani and Surian, 2012;Magilligan et al, 2013;Mueller et al, 2014;Lobera et al, 2016). Nowadays, dam construction is considered a viable strategy to support the increasing energy and water demands due to climate change and population growth (World https://doi.org/10.5194/hess-2019-424 Preprint.…”

Characterization of contrasting flow and thermal regimes in two adjacent subarctic alpine headwaters in Northwest Canada

“…be the result of natural changes, anthropogenic perturbations, or their combinations (Caissie, 2006). The main anthropogenic perturbations include deforestation (e.g., Bourque & Pomeroy, 2001), flow modifications (e.g., construction of water reservoirs and canalization, Ferrazzi & Botter, 2019;De Gaay & Blokland, 1970;Liu, Yang, Ye, & Berezovskaya, 2005), urban water inputs and withdrawals (e.g., Kinouchi, Yagi, & Miyamoto, 2007), and climate change (e.g., Ficklin et al, 2013;Isaak, Wollrab, Horan, & Chandler, 2012).…”