floodplains. The Pledger series dominates further inland on high-level flood- 

 plains with calcareous, reddish, stratified clayey and silty sediments (USDA, 

 1973). 



Climatology . The climate of the area is subtropical with short mild 

 winters and long hot summers. High humidity and abundant evenly distributed 

 rainfall are characteristic throughout the year. Extended periods of sub- 

 freezing temperatures are rare, as are significant amounts of snowfall. 



Summer conditions extend from about May to September, with highest 

 temperatures normally occurring during July and August. There is little 

 variation in day-to-day weather patterns, except for an occasional tropical 

 storm that may affect the area. The coastal circulation is influenced by sea 

 breezes during the afternoon and evening. 



Winter conditions extend from December through February, although little 

 cold weather is experienced before mid-December. Intrusions of cool (and dry) 

 polar air masses are generally short-lived and alternate with days of warmer 

 weather. Fall (October and November) and spring (March and April) conditions 

 are short-lived and are characterized by mild, pleasant weather. 



The annual mean temperature is 21. PC (69.9°F). The highest average 

 daily maximum temperature, 30.8°C (87.5°F), occurs during August, while the 

 lowest average daily minimum temperature, 9.6°C (49.3°F), occurs during 

 January (USDC, 1971). 



Monthly average rainfall ranges from a maximum of 16.8 cm (6.6 inches) in 

 September to a minimum of 6.9 cm (2.7 inches) in March. The annual average 

 precipitation is 116 cm (45.5 inches). Monthly precipitation extremes at 

 Galveston vary from zero to over 66 cm (26 inches USDC, 1971). 



The prevailing wind directions at Galveston are south and southeast. The 

 annual average wind speed is 5.1 m/sec (11.5 mph) (USDC, 1973). 



Thunderstorms occur most frequently during the summer season. Thunderstorm 

 damage may result from hail, high winds, flooding, or an infrequent tornado. 

 Tropical cyclones, including hurricanes, represent another category of serious 

 weather disturbance. These storms lose strength rapidly as they move inland, 

 and the greatest concern is potential damage from high winds and excessive rain- 

 fall. The close proximity of the refuges to the coast exposes both locations 

 to the additional hazards of hurricane tides (waves and swells). The hurricane 

 season extends from June to October, with storms most frequent during August 

 and September. 



Hydrology . Geologic formations containing fresh to slightly saline water 

 in Brazoria County range in age from Pliocene to Holocene. These units are 



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