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Chapter 3: Hydrological Processes in Riparian Areas
Floods and Droughts
- Floods and droughts are common in Arizona. Arizona has had major floods and drought periods (Table 3.1).
Figure 3.11. Arizona streams may have perennial (right) or ephemeral flow (right).
- Although floods can have destructive effects by eroding and reshaping channels, they also provide critical overbank deposits in riparian areas that replenish nutrient supplies. Historically, flooding in Arizona has occurred between September and March.
- Droughts can also have severe consequences, especially if they are persistent. Long-term drought consequences include: soil moisture deficit, reduced surface flow and drops in ground water levels. All these can severely impact riparian vegetation.
Table 3.1. Chronology of major and other memorable floods and droughts in Arizona, 1862-1988.
Flood or Drought |
Date |
Area Affected |
Recurrence Interval (years) |
Remarks |
|---|---|---|---|---|
Flood |
Jan. 19-23, 1862 |
Gila and Colorado Rivers |
Unknown |
Severe at Yuma. Wet year in Verde and Bright Angel basins, but not in upper Salt. |
Flood |
Feb. 18- 26, 1891 |
Central Highlands |
25 to 100 |
Phoenix and Yuma flooded. In Clifton, deaths, 18; damage, $1 million. |
Flood |
Nov. 27- 30, 1905 |
San Francisco to Verde Rivers |
5 to 10 |
Several moderate to severe floods, particularly at Phoenix and along the lower Gila River. |
Flood |
Jan. 19- 22, 1916 |
Central Highlands |
10 to 0 |
Intense rain on melting snow produced large flows in central Arizona. Deaths, 4; damage, $300,000. |
Flood |
Aug. 21, 1921 |
Phoenix (Cave Creek) |
Unknown |
Six inches of rain in two days flooded 4,000 acres and the State capitol building. Damage, $240,000. |
Flood |
Sept. 27- 29, 1926 |
San Pedro River and Mexico |
>100 |
Tropical storm. Peak flow 2 - 3 times larger than any other in 70 years. Damage, $450,000. |
Drought |
1932- 36 |
Statewide |
10 to 20 |
Effects differed among basins. |
Flood |
Mar. 14- 15, 1941 |
Central Arizona |
5 to 40 |
One of several storms that caused general runoff and filled reservoirs. |
Drought |
1942- 64 |
Statewide |
>100 |
Second most severe in 350 years, on the basis of tree-growth records. |
Flood |
Sept. 26- 28, 1962 |
Brawley and Santa Rosa Washes |
>100 |
Deaths, 1; damage, $3 million, mostly to agriculture near Casa Grande. |
Flood |
Dec. 22, 1965 to Jan. 2, 1966 |
Verde, Salt, and Gila Rivers and Rillito Creek |
10 to 50 |
First large flow through Phoenix since reservoirs were built on Verde River (1939). Damage, $10 million. |
Flood |
Dec. 5- 7, 1966 |
Grand Canyon to southwestern Utah |
>100 |
Mudflows and channel erosion damaged Indian ruins that had been undisturbed for 800 years. |
Flood |
Sept. 5- 7, 1970 |
Tonto Creek to Hassayampa River |
40 to 100 |
Labor Day weekend floods in recreation areas. Reservoirs stored most runoff. Deaths, 23; damage, $8 million. |
Flood |
Oct. 17- 21, 1972 |
Upper Gila River |
10 to 40 |
Tropical storm. Deaths, 8; damage, $10 million. |
Drought |
1973- 77 |
Statewide |
15 to 35 |
Most severe in eastern Arizona. |
Flood |
July 17, 1974 |
Safford (Holyoke Wash) |
>100 |
Thunderstorm produced flow of 1,740 cubic feet per second from 0.85 square mile. |
Flood |
Oct. 1977 to Feb. 1980 |
Central and southeastern Arizona |
5 to 100 |
Seven regional floods. Phoenix declared a disaster area three times. Deaths, 18; damage, $310 million. |
Flood |
July 26, 1981 |
Tucson (Tanque Verde Falls) |
less than 2 |
Flash flood at recreation area on Sunday; deaths, 8. Two larger peak discharges in the same week were not noticed. |
Flood |
June 20 to Aug. 17, 1983 |
Colorado River |
20 to 40 |
Upper basin rain and snowmelt. First reservoir spill since Hoover Dam was built (1935). Damage, $80 million. |
Flood |
Oct. 1- 3, 1983 |
Santa Cruz to San Francisco Rivers |
10 to >100 |
Record floods on 18 streams; two peak discharges doubled 65-year-old records. Deaths, 8; damage, $226 million. |
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