Thomas Jefferson High School Student Water Action Team

2. It Rains, it Pours, it Floods!!! By Desirae Luera May 10, 2003

3. Lakes and Dams A dam is used to impound water by blocking its flow through a watershed Lakes impound water out of basins such as rivers, rain, and melting snow Many lakes are used as a municipal water resource Some lakes are used as water supplies for irrigation, electric power, recreation and more

4. Benefits of Lake Ecosystems Water provides for diversified vertebrate and invertebrate inhabitants Water provides habitat for land birds and water fowl Water released from a dam lets fish and other wildlife animals live in the stream below Aquatic plants provide food and habitat for diversified creatures Lakes provide a recreational area for human use

5. Types of dams Buttress Dams Roller Dams Embankment or Rock-fill Dams Concrete Dams Gravity Dams Arch Dams

6. Early History The earliest dams were built in North America providing water for gristmills and saw mills and other manufacturing productions Dams brought electric service to remote areas and water to arid regions Dams historically provided water for irrigation and human use and were sometimes located far from the city Dams were also used for recreation and the tourist industry Dams were used to abate flooding in rural and urban areas

7. Manufacturing Processes

8. Electric Power Some lakes are created as storage reservoirs for generating electric power Hydroelectric power plants make use of force of water to make it possible Stored water flows through hydraulic turbines for electric power,and water generation

9. Irrigation Uses

10. Recreation and Tourist Industry Benefits Motor boats and sail boats are used for recreation Increased water flow from dams to rivers below is used for tourist activities downstream Reservoirs generate millions of dollars in local recreational economy Hotels are built near to house visitors and tourist

11. Dams Used for Flood Control

12. Olmos Dam: San Antonio�s Guardian

13. Flood History of San Antonio Historical records showed that the floods of 1724, 1819, 1865, 1899, 1913, and 1921 were particularly destructive.� In 1865 the removal of in-channel dams and the enlargement bridges increased the potential of flood damage in the downtown area In 1911 a diversion channel was created to carry storm water away from the downtown horseshoe bend In 1920 an engineering study on flood prevention to the City of San Antonio was done

14. 1921 Flooding

16. Olmos Dam in 1926

18. Building of Olmos Dam

19. About Olmos Dam Owner - city of San Antonio Location - Olmos Creek Drained area - 32 sq. mi. Type - concrete Length - 1,941 ft. height - 60 ft. Top width - 12 ft. Roadway width - 24 ft.

20. Average Rainfall of the Two Floods in San Antonio During the 1921 Flood there was 6.83 inches of rain During the 1998 Flood, there was 11.26 inches of rain. Due to such flood control, there was less flood damage in the downtown area but the Olmos Park area was flooded.

21. Flood of �98

24. PROJECT BYDESARAE LUERASWAT 2003THOMAS JEFFERSON HIGHMrs. A. Aguirre, SponsorMay 10, 2003