Statistical Analysis of Streamflow Hydrographs and the Relation of Hydrograph Characteristics to Geological and Ecological Landscape Units

Abstract

Dependence of river runoff on climatic, topographic, geologic and vegetation factors is an axiom in our days. It represents great interest to reveal major factors influencing runoff within not only individual basins but for large areas such as Minnesota. For this scale it is convenient to conduct studying using a concept of natural complexes as a research objects. Investigated complexes were based on ecological and quaternary geology landscape subdivisions. Hydrological characteristics were derived from flow data for watersheds, sorted by criteria of 100 to 1,300 mi2 for area and periods of observation not less than 20 years, for 69 Minnesota watersheds. Unit runoff and monthly modules (discharge per unit area) were calculated and used as a set of random samples for statistical analysis. Statistical tools such as hypothesis testing allowed regionalization of hydrology on the base of changing quaternary and ecological conditions. Hydrological response based on ecological units was a reflection of climate patterns; hydrologic response based on quaternary geology was associated largely with topographic expression and sediment type.