Hydrology BC ENV 3025
Dams
- large dams all over the world (Fig)
-
a summary of issues related to dams is given in the talk given by Marc
Reisner at the State of the World conference at CU in 1999 (The
age of dams and its legacy, Earth Matters, winter 99/00)
-
take notes of the presentation
-
present the key points in a structured outline in
a fomat similar to the lecture notes on this web site
- Dams have a whole range of positive and negative effects
- positive:
- reduced risk of floods
- more reliable water
supply
- hydro power generation, by region (table), by country (table)
- fishing
- tourism
- negative effects
-
changes in channel morphology
-
reduced beaches
-
debris jams in tributaries
-
lower temperature of the downstream water
-
lower sediment load -> clearer water
-
increased sediment storage
-
altered riparian vegetation,
- displacement of people
- Three gorges:
- location (fig)
- statistics (fig)
-
changes in fish population
- declining numbers and quality of spawning grounds for native fish
- NW US: loss of most of the salmon fishery in the regional ocean waters & within
the river itself, due to obstruction of fish spawning migration by dams,
as well as other perturbations. (Fisheries is 7% now from what it was)
- mercury contamination of fish in the new reservoirs (James Bay)
- large production of methane gas from the flooded forest areas (addition
source of greenhouse gas)
-
dam construction rates
have gone down in the US dramatically, because the best sites have been
built up and also because of increasing opposition
-
a particularly big problem is the sediment load of certain rivers and the
'silting up' of dams
-
examples:
Resources
