**7. Drainage patterns**

temperatures are 25 and 26°C (77 and 79°F) at these locations. As expected, June–August are the warmest months. The growing season generally has 210-plus frost-free days. The soils are frozen only at the surface and only for brief periods of time. The rainfall is reasonably well distributed, with the total annual precipitation averaging 1.14 m at Cape Girardeau and 1.27 m at Kennett. The remnants of tropical storms from the Gulf of Mexico may provide more

We define wetlands as soilscapes transitional between terrestrial and aquatic systems that support hydrophytes and possess an undrained substratum having anoxic conditions, typically having a water table for some portion of the time when the soil temperature is above biologic zero. In our study area, a large-scale drainage management system has been implemented to produce agriculture lands; however, the ancestral wetlands would have been classified as southern deepwater swamps and riparian forested wetlands [4]. Hydric soils are defined as "soil that is saturated, flooded or ponded long enough during the growing season to develop anaerobic conditions in the upper part" [5]. Prolonged anaerobic conditions promote selected biogeochemical soil processes that modify the soil morphology, such as (i) organic matter accumulation, (ii) iron and manganese oxyhydroxide transformations/depletions/accumulations, (iii) sulfate-sulfide transitions, nitrogen transformations, and (iv) biogeochemical nutrient cycle alterations. These indicators are used to delineate hydric soils; however, in the USA the indicator criteria may vary among the major land resource areas. Wetland delineation in the USA is based on the presence of hydric soils, the local hydrology, and wetland indicator plants.

Much of the natural vegetation has been removed and replaced with agricultural enterprises. Depressional areas consisting of backswamp deposits typically supported bald cypress (*Taxodium distichum* L.), water tupelo (*Nyssa sylvatica*), sweetgum (*Liquidambar styraciflua* L.), and multiple species of canes, rushes, and grasses, whereas recent meander belt deposits have willows (Salicaceae sp.), eastern cottonwoods (*Populus deltoides* Marsh.), American elm (*Ulmus americana* L.), yellow poplar (*Liriodendron tulipifera* L.), and boxelder (*Acer negundo* L.). Mixed forest species existed on well-drained to moderately well drained soils residing on variably textured alluvium and natural levees. Mixed forest species included: southern red oak (*Quercus falcata* L.), willow oak (*Quercus phellos*), white oak (*Quercus alba* L.), swamp white

The Southeast Lowlands Groundwater Province (SLGP) is bounded on the north and west by the Ozark Plateau, with the transition from the SLGP to the Ozark Plateau called the Ozark escarpment. The eastern boundary is the modern Mississippi River and the southern boundary is the Missouri-Arkansas state border. The western boundary of Dunklin Co. is

oak (*Quercus bicolor* Willd.), and shagbark hickory (*Carya ovata* Mill.).

than 0.25 m of rainfall during a rainfall event [3].

156 Wetlands Management - Assessing Risk and Sustainable Solutions

**6. Landforms and vegetation**

the St. Francois River (**Figure 1**).

**5. Wetlands and hydric soils in the study area**

The study area is bordered on the west by the St. Francois River and on the east by the Mississippi River. Each of these southerly flowing river systems may alternately supply floodwaters or provide surface drainage. A series of dendritic streams and rivers drain the Black River Ozark, the Inner Ozark, and the Outer Ozark Border regions, providing surface waters to the Advance Lowlands and the Morehouse Lowlands. These rivers include: the Black River, White River, Castor River, and the St. Francois River. In addition, small streams provide drainage from the Benton Hills and Crowley's Ridge, providing water to the Advance and Morehouse Lowlands [8].
