Table 1. Census information for the 10 largest U.S. cities, 1990 and 2000.
1990 Population
Rank
2000 Population
Rank
% Increase
City
(thousands)
(1990)
(thousands)
(2000)
19902000
New York, New York
7,323
1
8,008
1
9.4
Los Angeles, California
3,485
2
3,694
2
6
Chicago, Illinois
2,784
3
2,896
3
4
Houston, Texas
1,631
4
1,953
4
19.8
Philadelphia, Pennsylvania
1,586
5
1,517
5
4.3
San Diego, California
1,111
6
1,223
7
10.2
Detroit, Michigan
1,028
7
951
10
7.5
Dallas, Texas
1,007
8
1,189
8
18
Phoenix, Arizona
983
9
1,321
6
34.3
San Antonio, Texas
936
10
1,145
9
22.3
Table 2. Census information for largest increases in population growth for U.S. cities over 50,000 (not due
to county consolidation).
2000
1990
Change in
Percentage Change
Rank
Municipality
Population
Population
Population
in Population
1
Gilbert, Arizona
109,697
29,188
80,509
276%
2
Flower Mound, Texas
50,702
15,527
35,175
227%
3
Vancouver, Washington
143,560
46,380
97,180
210%
4
Henderson, Nevada
175,381
64,942
110,439
170%
5
Sugar Land, Texas
63,328
24,529
38,799
158%
6
McKinney, Texas
54,369
21,283
33,086
156%
7
Bend, Oregon
52,029
20,469
31,560
154%
8
North Las Vegas, Nevada
115,488
47,707
67,781
142%
9
Chino Hills, California
66,787
27,608
39,179
142%
10 Jacksonville, North Carolina
66,715
30,013
36,702
122%
Consideration of urban flood problems that are characteristic of the arid and semi-arid west is critical. The Urban Flood
Demonstration Program (UFDP), developed through collaboration between the Corps' Engineer Research and Development
Center (ERDC) and the Desert Research Institute (DRI), is exploring urban flooding in arid and semi-arid regions. Research
topics are similar to those pursued in TOWNS, and include hydrology, hydraulics, sediment transport, channel stability and
restoration, and ecological aspects of flooding in arid and semi-arid regions. One important aspect of hydrology and
hydraulics is the estimation of the rainfallrunoff relationship for flash floods, particularly those occurring during the summer
months. Anecdotal evidence suggests that there are seasonal effects on the rainfallrunoff relationship; however, this has not
been studied in depth. This technical note addresses a knowledge gap: the combined effects of soil and temperature on infil-
tration rate.
Background
The hydrographic response of watersheds to precipitation is determined by their morphologies and their abilities to
abstract rainfall. The abstraction ability of a soil is determined by its infiltration rate, which in turn is a function of its
hydraulic properties and antecedent water content. Loss rate parameters in runoff models are typically determined by the
type, condition, and cover for the hydrographic unit being considered. Seasonal effects are rarely, if ever considered. Recent
research by scientists at ERDC and DRI has found that temperature can have a strong influence on loss rates. Modeling
studies funded by the UFDP in the Las Vegas Valley indicate that temperature also can have a strong effect on infiltration.
Further, these studies indicate that the nature of the temperature effect is strongly affected by the soil. Accordingly, modeling
of hydrographic response may be improved by including temperature effects, but only if the temperaturesoil interaction is
included explicitly.
2
ERDC/CRREL TN-04-6
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