Sub Surface Drainage at www.japanese-home-gardens.com

Drainage Basins.—The area that a river system drains is called a drainage basin. The boundary of a drainage basin is called the drainage dhide, and is the line separating water flowing into different drainage systems (Fig. 1). The rim of high country which forms the divide of the Mississippi Basin includes the Appalachian and Rocky mountains on the east and west respectively, and lesser highlands in the north.

Poor sub surface drainagesurface drainage causes water to gather in the soil in excessive amounts and drive out air. When this occurs an environment unfavorable to grass and encouraging to moss develops. If your mossy lawn lies wet at its surface for considerable periods in spring or after rain suspect that the under-drainage is unsatisfactory. Such a state of affairs is particularly likely to occur in low-lying areas but is not necessarily confined to such.

Where current revenues do not provide sufficient funds for urgently needed road improvements, borrowing is justified. It is generally held that highway debt should be repaid within the life of the improvements made. Highway surfaces wear out and must be replaced, but grading has permanent value and drainage structures last for a long time. When a surface is worn out, it still has value as a base for a new surface. One third or more of the cost of a new highway may be for improvements that will be of value for many years after the original surface is replaced.