The Lay of the Land: Clues to Foil a Flood

Water can be a threat to a country cabin. Rushing in a torrent or trickling down a slope, rolling in ocean waves or rising from a flooded river, it can damage or destroy the sturdiest structure. To some extent you can meet the danger by using a special method of construction—building a cabin on a set of high poles, for example, may raise the structure above flood levels—but the real key to protecting a cabin from floods is the right choice of a building site.

Sometimes the choice is fairly obvious: anyone can see that the closer a beach cabin is to the ocean, the more likely it's to be swamped by exceptionally high tides or storm-driven waves. Elsewhere, the problems of correct siting are relatively subtle, and locations that seem ideal at first glance may turn out to be the most vulnerable. A site next to a peaceful stream at the bottom of a ravine or valley, for example, may look safe, especially if you set your cabin well above the water level. Actually, it's a site to be avoided: during or after a heavy rain, the stream is likely to rise rapidly and flow with great force, destroying any property in its path. Other danger spots are shown in the drawings opposite.

Surveyors and landscape architects can identify potential flood problems for you, but you can do a good deal of preliminary detective work yourself before you go to the expense of hiring an expert. To begin with, ask the people of the locality and the area office of the Soil Conservation Service about the history of flooding at or near the site you are considering. Then study the site itself during a rainstorm. As the water runs off, you will see it flowing or collecting in natural drain age paths—areas that should not be blocked by any structure you build.

Vegetation and topographic features give additional clues to potential problems. Plants growing in a generally arid plot of ground indicate a spot that may become a short-lived pond or waterway during a heavy rain. Smooth, rounded boulders were probably shaped by water flowing over them repeatedly in the past, level ground, near creeks and streams, is a likely sign of periodic flooding.

If you plan to build at the beach, consult a coastline survey map, available from local building officials. These maps indicate many of the high-hazard areas where wind and waves are likely to cause significant damage to nearby buildings.

A steep ravine or valley. The cabin in the background is sited much too close to a stream running along the bottom of a narrow ravine. In a storm, the volume and velocity of the stream will increase and water will rise up the sides of the steep slope. The cabin at left, situated on a gradual slope well away from the stream, is safe from such flash floods.

95a An upland meadow. The cabin at left is located in a depressed area that collects rain water, and the driveway that links it to a main road cuts across the natural drainage path around the building site; in a storm, this roadway would channel water directly into the dish-like meadow The cabin at right is built on a higher site, which drains quickly; its driveway follows the contour of the land, and underground culverts protect the driveway from a washout,

95b Near a river. The cabin in the foreground is built in the oxbow of a river, at the heart of a flood plain; in a heavy rain, the river might widen, completely submerging the site. The cabin in the distance, on a gentle slope well above the flood plain, lies clear of the probable flood pattern.

An ocean beach. The cabin at left, close to the ocean shoreline, is vulnerable to high waves and shifting sands. Even a location farther from the water, on the ocean side of the sand dunes in the middle distance, would be unwise, because it could disturb the natural shifting of sand that forms the protective barrier of dunes. The cabin to the right is located correctly—well behind the first row of dunes and vegetation that form a natural barrier to the waves.