Stat406 Term Project
Investigation on the Spatial Distribution of Subsurface Drainage
Volume Related to Soil Types and Land Cover
Abstract
Subsurface drainage systems make the swampy Iowa field into productive corn or
soybean farms. The drainage water volume depends on the weather conditions (rainfall,
temperature, evaporation), soil types, and land cover (crops, grass, bare soil). An
experimental farm with an area of 4 acres was divided into 75 plots which have been
drained by subsurface tile lines for 15 years in northwestern Iowa. The drainage volume
is measured by flow meter after every rainfall events, and the weather conditions are
recorded as well as the land cover. Soil distribution can be found in Iowa Soil Survey. In
this project, 3 topics will be investigated on the subsurface drainage under the same
weather condtions: 1) determine whether the annual drainage volume in each of the 75
plot is spatial independent via Moran’s I; 2) a spatial distribution model will be fitted to
the drainage volume (Gaussian, exponential, or spherical) and predict the drainage
volume by Kriging Method; 3) find the correlation between drainage volume and soil
types (How to do that? I am not quiet sure).