Introduction to Lakes and Reservoirs - Hydro-Environmental Analysis: Freshwater Environments - page 285

Lake

Reservoir

Especially abundant in glaciated areas; orogenic
areas are characterized by deep, ancient lakes;
riverine and coastal plains are characterized by
shallow lakes and lagoons

Located worldwide in most landscapes, including
tropical forests, tundra and arid plains; often
abundant in areas with a scarcity of natural lakes

Generally circular water basin Elongated and dendritic water basin

Drainage: Surface area ratio usually <10:1 Drainage: Surface area ratio usually >10:1

Stable shoreline (except for shallow, lakes in
semiarid zones)

Shoreline can change because of ability
to artificially regulate water level

Water level fluctuation generally small
(except for shallow lakes in semiarid zones)

Water level fluctuation can be great

Long water flushing time in deeper lakes Water flushing time often short for their depth

Rate of sediment deposition in water basin is
usually slow under natural conditions

Rate of sediment deposition often rapid

Variable nutrient loading Usually large nutrient loading their depth

Slow ecosystem succession Ecosystem succession often rapid

Stable flora and fauna (often includes endemic
species under undisturbed conditions)

Variable flora and fauna

Water outlet is at surface Water outlet is variable, but often at some depth

in water column

Water inflow typically from multiple,
small tributaries

Water inflow typically from one or more large
rivers

FIGURE 9.14 General characteristics of lakes and reservoirs. (Modiied from Loucks and van Beek, Water
Resources Systems Planning and Management, Appendix A: Natural system processes and interactions,
United Nations Educational, Scientiic and Cultural Organization, Delft, 2005. With permission.)

28,383

30,000

25,000

20,000

13,528

15,000

12,507

7,967

10,000

7,132

5,095

3,400

5,000

2,210

1,963

847

418 426 258

0

FIGURE 9.15 Project purposes of dams in the U.S. Army Corps of Engineers National Inventory of Dams
2009 database (the y -axis is the number of dams in the database).