CIVE 633 - ENVIRONMENTAL HYDROLOGY
LARGE RIVER-FLOODPLAIN ECOSYSTEMS
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- Natural functions of river-floodplain systems have disappeared.
- River modifications have tended to prevent regular flooding.
- Limnology usually presumes static water levels.
- Use of rivers for bulk transportation, waste disposal and hydroelectricity has affected natural uses.
- Productivity of natural resources have decreased due to drainage of wetlands.
- Many countries are following the practices of developed countries to harness and modify rivers.
- Dynamic interaction between water and land produces and maintains flood plains, and affects the biological adaptations
that have evolved therein.
- The flood pulse concept was developed to summarize these effects on the biota.
- The flood pulse is not a disturbance; prevention of floods is a disturbance.
- The flood pulse enhances biological productivity and maintains biodiversity.
- In large systems like the Amazon, conditions are more lentic and lotic because the pulse has one seasonal recurrence.
- The moving littoral during flooding provides excellent nursery grounds for fish and nearly optimal for invertebrates.
- Fish need to grow quickly through the flood period to reach sufficient size to reduce predation losses when the water volume
subsequently reduces to its minimum.
- In the Upper Mississippi, the flood pulse now tends to occurs earlier and more briefly that it did last century.
- The benefit of maintaining genetic and species diversity are self evident.
- The concept of flood pulse implies that biological production is enhanced through a variety of processes during the flood cycle.
- There is a optimal rate of increase in water levels.
- Flood pulse may increase biological productivity per unit water area compared to a lotic system.
- All available data indicates that yields are higher in river-floodplain systems.
- A restoration process requires a return to natural flooding conditions, and regular access of water and biota to previously isolated
flood plains.
- Physical alterations result in a highly unpredictable flood pulse and denial of access to water to much of the floodplain.
- Tangible economic and recreational benefits are expected from restoration attempts.
- Other benefits are increased biodiversity and decreased probability of catastrophic flooding.
- Research must account for the effect of scale.
- Studies should focus on large spatial and temporal scales.
- Experiments should be designed paying attention to hydrology and geomorphology.
- Landscaping of the floodplain requires accurate prediction of the dynamics of water and sediment transport,
and on the effect of those dynamics on vascular plant colonization, and viceversa.
- Understanding of these processes is necessary before landscaping is undertaken.
- River restoration needs to begin with an experimental approach in which different hydrological alternatives
are evaluated with respect to natural responses on the landscape and flora.
- Detailed fisheries studies should be postponed until the vegetation has been stabilized.
- There are some economic advantages from river restoration, including increased biodiversity and stability.
- Cultural development has adversely affected river-floodpalin ecosystems, and has destroyed our ability to study them
in their pristine state.
- Restoration of the natural hydrological regime is necessary to gain useful information about river-floodplain ecosystems.
- Experimental restoration and evaluation should be preferred to conventional ecological research.
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