Analyzing the Impacts of Dams on Riparian Ecosystems: A Review of Research Strategies and Their Relevance to the Snake River Through Hells Canyon

Abstract

River damming provides a dominant human impact on river environments worldwide, and while local impacts of reservoir flooding are immediate, subsequent ecological impacts downstream can be extensive. In this article, we assess seven research strategies for analyzing the impacts of dams and river flow regulation on riparian ecosystems. These include spatial comparisons of (1) upstream versus downstream reaches, (2) progressive downstream patterns, or (3) the dammed river versus an adjacent free-flowing or differently regulated river(s). Temporal comparisons consider (4) pre-versus post-dam, or (5) sequential post-dam conditions. However, spatial comparisons are complicated by the fact that dams are not randomly located, and temporal comparisons are commonly limited by sparse historic information. As a result, comparative approaches are often correlative and vulnerable to confounding factors. To complement these analyses, (6) flow or sediment modifications can be implemented to test causal associations. Finally, (7) process-based modeling represents a predictive approach incorporating hydrogeomorphic processes and their biological consequences. In a case study of Hells Canyon, the upstream versus downstream comparison is confounded by a dramatic geomorphic transition. Comparison of the multiple reaches below the dams should be useful, and the comparison of Snake River with the adjacent free-flowing Salmon River may provide the strongest spatial comparison. A pre-versus post-dam comparison would provide the most direct study approach, but pre-dam information is limited to historic reports and archival photographs. We conclude that multiple study approaches are essential to provide confident interpretations of ecological impacts downstream from dams, and propose a comprehensive study for Hells Canyon that integrates multiple research strategies.

Experimental analysis of the impact of sluice regulation on water quality in the highly polluted Huai River Basin, China

“…(1) Analysis of aquatic organisms, water quality, water quantity, ecology, and other aspects of the water environment is conducted through field surveys (Muñoz et al 2005;Mallik and Richardson 2009;Zhao et al 2010); (2) exploration of the impacts of sluices and dams on river discharge, water quality, ecology, river structure, and other aspects of the water environment has been conducted through examination of historical data (Brandt 2000;Petts and Gurnell 2005;Gülbahar and Elhatip 2005;Kurunc et al 2006;William 2006;Braatne et al 2008); and (3) numerical simulation models, including mature hydrological models (such as the Solid and Water Assessment Tool (SWAT)) coupled with water quality models, mature water quality simulation models (such as the water quality analysis simulation program (WASP)), and other numerical simulation analyses have been used (Campbell et al 2001;Newham et al 2002;Chung et al 2008;Marcé et al 2010). Specifically, mature hydrological models, coupled with water quality models, have been used to analyze the impacts of discharged sewage on downstream water quality (Hayes et al 1998;Li and Zuo 2012;Zheng et al 2012;Zhang et al 2010Zhang et al , 2011Zhang et al , 2013; mature water quality simulation models have been used to calculate and analyze water quality and other aspects of the water environment (Di Toro et al 1983;Stow et al 2003;Jae 2010;Zheng et al 2010;Lai et al 2013); and (4) mechanism experiments have been carried out.…”

Diversité et structure des cordons ripicoles le long de la sirba (Nord-Est du Burkina Faso)

“…Les principaux facteurs de perturbation sont les cultures du tabac, de la pastèque, du haricot, les activités minières, l'exploitation anarchique du bois et la présence de barrage. Certains auteurs (Natta 2003 ;Braatne et al, 2007 ;Kokou et al, 2008) ont reconnu ces actions anthropiques comme étant les principales menaces de la végétation des berges.…”

“…C'est ainsi que, l'intensification de la mise en valeur des basfonds (zones de dépression environnantes des cours d'eau) s'est imposée (Lavigne Delville et al, 1996). Parmi les facteurs anthropiques, c'est la construction des barrages qui impacte encore de façon plus significative l'environnement des rivières (Braatne et al, 2007). Classées généralement comme écosystèmes menacés, particulièrement dans les pays sahéliens (Natta 2003) comme le Burkina Faso, les mesures de protection et de restauration de la biodiversité de ces écosystèmes doivent être entreprises.…”

Quantitative analysis on the environmental impact of large-scale water transfer project on water resource area in a changing environment

“…After 1980, with the uprising consciousness of environmental protection, people became cautious of the construction of water transfer projects and a series of reports came out concerning the negative ecological impacts of both construction and operation of these projects (Davies et al, 1992;Meador, 1992;Nardini et al, 1997). Since then, countries all over the world have begun to conduct environmental impact assessment of water transfer projects, and carried out thorough research on related environmental issues and ecological influence (Graf, 2006;Morais, 2008;Braatne et al, 2008;Kittinger et al, 2009;Baran and Myschowoda, 2009;Growns et al, 2009;Wu et al, 2010;Olden and Naiman, 2010). At the same time, laws and regulations in terms of the construction and operation of water transfer projects were published so as to mitigate and even prevent the ecological and environmental problems (Yang, 2003;Wang, 2009).…”