A Quantitative geomorphological study of public drainage ditches in south central Minnesota

The development of artificial drainage ditches has become extensive in South Central Minnesota in the last 120 years. This study examines the effects of artificial drainage on surface water hydrology using quantitative geomorphic analysis. Eighteen quantitative geomorphic parameters and seven descriptors for 269 artificial drainage ditches were determined. The parameters include: drainage area, drainage density, length of overland flow, length of open ditch, length of closed ditch, length of main stream, longest basin length, longest basin width, ditch gradient, ditchshed gradient, texture ratio, channel maintenance, form f, shape 1, shape 2, circularity ratio, elongation ratio and lemniscates ratio. The descriptors include: geomorphic types, soil types, origin, termination point, repairs, improvements and decade of ditch establishment. A statistical analysis using SPSS a computer language was developed to show interrelationships between the parameters, parameters versus descriptors, frequency distributions, scatter diagrams and crossbreaks were determined. The most significant findings were in the relationships of the descriptors "origin" and "termination point" to the geomorphic parameters and to themselves.