A NATIONAL PLAN FOB AMERICAN FORESTRY 405 



northeastern New Mexico agriculture is dependent upon the flow of 

 mountain streams included in these drainages. 



In the central or plains portion of the two drainages floods, water 

 supply, and erosion are all important locally. On the upper part of 

 the Cimarron, a tributary of the Arkansas, the Folsom flood of 

 August 1908 cost many lives and almost totally destroyed the town 

 of Folsom. The State of New Mexico plans to construct three flood- 

 control reservoirs on the head of the Cimarron. To impound about 

 50,000 acre-feet of water the Oklahoma State Commission of Drain- 

 age, Irrigation, and Reclamation has developed plans for 18 flood- 

 control reservoirs in the Cimarron Basin which would have a storage 

 capacity of nearly 1,750,000 acre-feet. The value of these reservoirs 

 would depend largely upon controlling soil erosion and thus preventing 

 sedimentation. 



TOPOGRAPHY 



Topographically, the Arkansas and Red River drainages are most 

 varied. In the extreme west the Rockies rise to elevations of 14,000 

 feet, some of the high peaks bearing perpetual snow. Steep slopes 

 and rugged topography prevail in the Rockies. The foothills, below 

 6,000 feet, are much less broken. Largely because of the roughness 

 of the topography, most of the Rocky Mountain forest area is classed 

 as having a major watershed-protective influence. 



The plains region, which constitutes something like 60 percent of 

 the two drainages, is largely a gently rolling area. The "Breaks " are 

 a badly dissected area in the Red Plains of western Oklahoma and 

 northeastern Texas where the streams flow in cuts from 300 to 500 

 feet below the plains level. This area is characterized by steep 

 escarpments or sometimes almost perpendicular cliffs with steps and 

 terraces down to the streams. 



Western Arkansas, eastern Oklahoma, southeastern Kansas, and 

 southern Missouri are composed largely of highlands. Elevations in 

 excess of 2,600 feet exist, although most of the hills are below 2,200 

 feet. The topography is much broken and slopes are steep; partly 

 for this reason, the forests that occur on these highlands are classed 

 principally as protection forests. 



Rolling hills, seldom exceeding 500 feet in elevation, occur in 

 southern Arkansas, eastern Texas, and northern Louisiana. 



The alluvial valley at the eastern end of these drainages is prac- 

 tically a level floor less than 200 feet above sea level. Flood waters 

 drain from this valley slowly. The bottomland forests are classed 

 as having little or no watershed protective influence. 



PRECIPITATION 



Great differences exist between different parts of the Arkansas and 

 Red River drainages as to quantity, intensity, and seasonal distribu- 

 tion of rainfall. In the east the average annual precipitation is 

 around 50 inches, but annual precipitation as high as 109 inches has 

 been recorded. Toward the west the precipitation gradually be- 

 comes less, reaching a minimum of about 12 inches in the plains. It 

 rises again to 30 or 35 inches in the Rocky Mountains, where a con- 

 siderable portion of the precipitation occurs as snow. 



