KGS--South-central KS--Geography

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Geography

Topography

Relief.--The region discussed in this report lies west of the Flint Hills and is included in the Great Bend Prairie physiographic province of Moore (1940). It is characterized by the extreme flatness of large areas and low topographic relief in parts of the area. The belt of sand dunes trending northwest-southeast along the northeast side of the Arkansas River valley, the scarps formed by Cretaceous sandstones in the northwestern and northeastern parts of the area, and the rough area underlain by Ninnescah shale along the Ninnescah River provide the only prominent relief to an otherwise nearly featureless plain.

The lowest points in the area, about 1,280 feet above sea level, occur along the Smoky Hill and Arkansas rivers where these streams flow out of the area. The highest points occur south of Sharps Creek about 3 miles north of Windom, McPherson County, and are about 1,700 feet above sea level.

The wide, flat, poorly drained valley plain of the Arkansas River, and the wide, flat to gently rolling surface of the ancient McPherson Valley comprise most of the area here discussed. Low terraces occur along the Arkansas and Smoky Hill rivers, but are not prominent topographic forms.

Drainage.--Most of the area covered by this report is drained by the Arkansas River and its tributaries. The northwestern part of the area is drained by the Smoky Hill River, a part of the Kansas River system, and the northeastern part is drained by the headwaters of Cottonwood River, a part of the Neosho River system. A few square miles southeast of Newton are drained by small tributaries of Walnut River, which joins the Arkansas River at Arkansas City. The central part of the area is drained by the Little Arkansas River which joins the Arkansas at Wichita. The southwestern part is drained by the north fork of the Ninnescah River which joins the Arkansas River near Oxford in Sumner County. The more important tributaries to the Little Arkansas River are Kisiwa, Emma, Turkey, and Black Kettle creeks; the tributaries to the Smoky Hill River are Sharps, Paint, Indian, and Gypsum creeks.

Climate

The climate of this part of central Kansas is characterized by moderate precipitation, a wide range of temperature variations, moderately high average wind velocity, and comparatively rapid evaporation. The summer days generally are hot, especially during July and August. The winters are moderately cold but generally are free from excessive snowfall. All climatic data presented in this report were compiled from records of the U.S. Weather Bureau.

The mean annual temperature is 56.0°F. at McPherson, and 57.9°F. at Wichita. The highest temperatures occur during the three summer months, the monthly mean at McPherson and Wichita, respectively, being 74.7°F. and 75.0°F. in June, 80.7°F. and 80.4°F. in July, 80.0°F. and 79.6°F. in August. The lowest temperatures occur in winter, the monthly mean at McPherson and Wichita, respectively, being 33.0°F. and 34.7°F. in December, 30.1°F. and 32.1°F. in January, and 33.6°F. and 35.1°F. in February. The highest recorded temperatures at these two stations are 117°F. at McPherson and 114°F. at Wichita. The lowest recorded temperatures are -27°F. at McPherson and -22°at Wichita. The year 1936 was one of unusual extremes, the highest and lowest temperatures having been 117°and -11°F. at McPherson and 114°and -8°F. at Wichita.

The average date of the last killing frost in the spring is April 9 at Wichita and April 22 at McPherson, but there have been killing frosts as late as May 15 at Wichita and May 27 at McPherson. The first killing frost in the fall has occurred as early as September 20 at McPherson and September 26 at Wichita, but the average date for this occurrence is October 16 at McPherson and October 22 at Wichita. The average length of the growing season is 177 days at McPherson and 196 days at Wichita.

Normal annual precipitation and other precipitation data are given in Table 1.

Table 1.--Precipitation data from six U.S. Weather Bureau stations.

Station	Length of record (years)	Normal annual precipitation (inches)	Greatest annual precipitation of record		Least annual precipitation of record
Station	Length of record (years)	Normal annual precipitation (inches)	Year	Precipitation (inches)	Year	Precipitation (inches)
Hutchinson	54	28.53	1944	46.97	1921	16.20
McPherson	56	28.91	1944	39.98	1921	15.57
Mt. Hope	51	28.29	1944	42.64	1910	16.38
Newton	48	31.25	1922	48.69	1936	18.67
Sedgwick	28	30.20	1927	42.85	1936	16.93
Wichita	56	30.37	1944	43.53	1936	15.58

The study of data collected at six U.S. Weather Bureau stations indicates that the least recorded annual precipitation in the area was 15.57 inches at McPherson in 1921 and the greatest recorded annual precipitation was 48.69 inches at Newton in 1922. Annual precipitation at each of the stations is shown graphically in Figures 2 to 7, inclusive. Normal annual precipitation in this region is about 29 inches; at Newton it is 31.25 inches, and at Hutchinson it is 28.53 inches. Deviations from the normal are frequent, however, as shown in Figures 2-7. Precipitation in this area seems to follow more or less irregular cycles in which periods of excessive moisture alternate with periods of deficient moisture or drought. A large proportion of the precipitation falls as torrential rains, followed by periods of scanty rainfall. Between 70 and 75 percent of the annual precipitation falls during the crop-growing season from April through September (Fig. 8). The normal rainfall during June, the wettest month, is about 4.5 inches; during January, the driest month, it is only about 0.7 inch.

Figure 2--Annual precipitation and cumulative departure from normal precipitation at Hutchinson.