Forests and Flooding
by Martin Hollingham
Co-ordinator, MSc Water
Resources, University of Wales Bangor.
A search for Forests
and Flooding will lead to disappointingly few sites dedicated to
this topic. The webpages youll find are typically a single page
describing the link between forests and reduction in runoff and are usually
part of a larger web site concerned with catchment management or environmental
protection. Most of these are watershed groups in the US
The Whyfiles, University
is typical of these and explores the links between land use change and
flooding, and also links to the US forest roads guidance document which details the best methods of road
construction to prevent runoff. Some of the others are: the NBC4 page
There are also numerous single
page articles detailing current or summarizing past research, such as
this summary of a hydrological experiment at the USFS Fernow Experimental Forest in north-central West Virginia (http://wvhc.drw.net/VoiceAug01/Floods&Forests_DG_Aug01Voice.htm#Table%201).
All the units are American but at least this webpage includes some results.
An example of a more general
paper is Forests and Water from The Overstory web page (http://www.agroforester.com/overstory/overstory80.html).
Details of how the effects of operations can
have impacts on drinking water quality through increased runoff, are
given in the U.S. Department of Agriculture, Forest Service, Southern
Research Stations pdf document, Drinking water from forests
and grasslands (http://www.srs.fs.fed.us/pubs/viewpub.jsp?index=1866).
A more useful reference though
is the UN press Forests Climate and Hydrology (http://www.unu.edu/unupress/unupbooks/80635e/80635E00.htm)
publication which although not out of print, is difficult to obtain, but
gives useful summaries of research exploring the links between forests,
hydrology and climate, Chapter 5 is particularly relevant with respect
While the above pages
are interesting in themselves the are no websites specifically dedicated
to Forests and Flooding and articles have to be retrieved from the search
engines of relevant research agencies such as CEH (http://www.ceh.ac.uk),
DFID (http://www.dfid.gov.uk), USEPA. (http://www.epa.gov)
websites. Very little seems available from the Forestry Commission website
, however reference to flooding is made in this pdf document on a management
plan for the Glen Urquhart forest. http://www.forestry.gov.uk/website/pdf.nsf/pdf/urquhart.pdf/$FILE/urquhart.pdf.
The nearest subject area
to Forests and Flooding is Catchment/Watershed Management or Land Use
and Hydrology/Water Resources. Some of the more famous Catchment experiments
are online, the Coweeta hydrological laboratory, run by the US Forest
Service can be found at http://sparc.ecology.uga.edu/webdocs/1/index.htm,
while a brief summary of research at the UK equivalent at Plynlimon
can be found at http://www.wetlands.demon.co.uk/PlynRes.htm.
The FAO Land-water linkages
site ( http://www.fao.org/ag/agl/watershed
) is a useful site for those wishing to apply catchment management
principles. Here you can find: to what extent different land use systems
and practices affect hydrological regime and water quality; and methods
to value the resulting benefits and costs. There are also links to some
FAO publications which deal with soils, irrigation and catchment management,
which are available free online unlike their hardcopy counterparts.
Other sites containing relevant
reports are: the Land Use and Water Resources Research Journal, which
is available free online, while it is a relatively young journal there
are some articles on flooding. (http://www.luwrr.com/welcome.html);
the Centre for Land use and water resources research (http://www.cluwrr.ncl.ac.uk/about/search.html);
and The Forest Conservation Portal (http://forests.org).
There are numerous pages that point to the
benefits of forests on water resources, the methods of quantifying these,
and the need for participatory catchment management projects. Such a site
as the European Tropical Forest Research Network which has a page on how to
value forests for their hydrological services; hydropower in Costa
Rica is used as an example (http://www.etfrn.org/etfrn/newsletter/news35/index.html).
Also for more detail on how to include the benefits of reduced flooding
in your annual report, look at the Forest Trends Developing markets
for water services from forests (http://www.forest-trends.org/resources/pdf/Developing_Markets_for_Water_Services.pdf).
While not overly concerned with flooding this pdf document details methods
of assessing the benefits of forests on water resources, such as watershed
protection, biodiversity conservation, and carbon storage.
With all this talk of forests
influencing hydrology its easy to forget that forests can also be affected
by hydrology and can suffer from flood damage. The north eastern US Forestry
Service web pages contains webpage on the effects of flooding on trees.
Some forests may also need seasonal flooding.
The Barmah- Millewa forest is such is affected by changes in the river
regime caused by the Hume Dam in the Murray Darling watershed. The Hume
Dam is used for irrigation and this has the effect of prolonging summer
flows in the forest. The water management plan is detailed in http://www.mdbc.gov.au/naturalresources/policies_strategies/projectscreens/pdf/bmf_strategy2.pdf
If after all that surfing you feel that you
now know enough about forests, flooding and watersheds, why not get a
certificate! Join the US EPA watershed academy, which runs an online course
in watershed management. As well as watershed ecology and pollution there
is a section on forestry and methods of watershed management including
community participation (http://www.epa.gov/watertrain).