Lakes Plenary

1. Walter Rast, Texas State University &
Vice-Chair, ILEC Scientific Committee
IWScience ConferenceIWScience Conference
Bangkok, Thailand, Sept. 24, 2012Bangkok, Thailand, Sept. 24, 2012
Lakes and Reservoirs:Lakes and Reservoirs:
Challenges and ConsiderationsChallenges and Considerations

2. Lakes in the WorldLakes in the World
• ~5.3 million lakes - >1 ha in size~5.3 million lakes - >1 ha in size
• Overall, lakes holdOverall, lakes hold ~~100,000 km100,000 km33
of freshwaterof freshwater

3.  >90% of liquid freshwater on Earth>90% of liquid freshwater on Earth
surface is in lakes/reservoirs;surface is in lakes/reservoirs;
 Lakes (lentic) used for wider range ofLakes (lentic) used for wider range of
ecosystem services than other typesecosystem services than other types
of water systemsof water systems  also greatestalso greatest
potential for water use conflictspotential for water use conflicts

4. Mirror LakeMirror Lake
44

6. 66

8.  ‘Sink” buffer function very important:
Lakes as ‘barometers’ of human
activities inside/outside basin;
 Often ‘trigger’ for initiation of
remedial actions

9. • Integrating Nature
(Everything comes together)
→ 1. Issues are mostly inseparable
• Long Retention Time
(Problems remain long, and
solving them also takes long time)
→ 2. Changes are gradual and mostly invisible
• Complex Response Dynamics
(Everything affects everything
else in waterbody)
→ 3. Often unpredictable and uncontrollable
UniqueUnique FeaturesFeatures of Lakesof Lakes

10. System won’t fully recover
(or Regime Shift may set
in)
Hysteresis

12. •12
Lake Taihu, ChinaLake Taihu, China

16. M. Nakamura, RCSE Shiga University, Chairman ILEC Scientific

19. 1919

20. ConsiderationsConsiderations
 Only 4 ‘lakes’ in GEF IW portfolio;Only 4 ‘lakes’ in GEF IW portfolio;
 No global-scale data bases for lakes;No global-scale data bases for lakes;
 Although within river basins, mostAlthough within river basins, most
river studies do not explicitlyriver studies do not explicitly
consider lakes; different spatial/consider lakes; different spatial/
temporal scalestemporal scales  managementmanagement
implications;implications;

21. ConsiderationsConsiderations
 Other hydrologic linkagesOther hydrologic linkages
(groundwater; LMEs) often ignored(groundwater; LMEs) often ignored
(management implications);(management implications);
 ‘‘Translating’ scientific results forTranslating’ scientific results for
decision-makers vs. decision-makersdecision-makers vs. decision-makers
communicating management needs;communicating management needs;
differing ‘languages’ & temporaldiffering ‘languages’ & temporal
scalesscales

22. ConsiderationsConsiderations
 Haven’t yet integrated science withHaven’t yet integrated science with
science (lakes, rivers, aquifers, etc)science (lakes, rivers, aquifers, etc)
or policy with policy (different wateror policy with policy (different water
Ministries with different mandates;Ministries with different mandates;
little coordination; fragmentation oflittle coordination; fragmentation of
authority and responsibility);authority and responsibility);

23. Resource Provision
Service
Regulating Service
Cultural Service
Supporting
Service
Ecosystem Services
We all want
this value
We tend to
forget
these
values

24. //
• …….Thanks for your kind attention..Thanks for your kind attention.