USING LAND-COVER CHANGE AS A DYNAMIC VARIABLE IN SURFACE WATER AND WATER QUALITY MODELS

Land-cover data are typically used in surface water and water quality modeling to establish or describe land surface dynamics. This project is designed to demonstrate the use of land-cover change data in surface water and water quality models by incorporating land-cover as a variable condition as opposed to a static condition. Surface water and water quality are being analyzed using three different scenarios: 1) Agriculture in the Plains (the effects of land-cover change on water quality in the Illinois River Basin), 2) Loon habitat in New England (the effects of land-cover change on water quality in New Hampshire), and 3) forestry in the Ozarks (the effects of land-cover change on peak flow in northern Arkansas).

Agriculture in the Plains

The Illinois River flows across the Central Corn Belt Plains and Interior River Lowlands ecoregions before its confluence with the Mississippi River. Since the area of interest is supported by sample blocks from two ecoregions, the statistics must be re-sampled in order to create a new region covering the specific area of interest in the Illinois River basin. This revised assessment will be used to examine how land-cover change relates to recently assessed water quality and trends developed from baseline measurements of recharge and surface water.

Loon Habitat in New England

The Environmental Protection Agency’s (EPA) Atlantic Ecology Division is working in conjunction with the Loon Preservation Committee (LPC) to develop loon-specific demographic models that integrate the risk of mercury and human disturbance across a range of stressor levels. In order to test the potential contribution of historic land-cover change, the sample blocks from ecoregions in New Hampshire will be re-sampled and compared to water quality data. This research may augment the EPA’s data and enable researchers to back-calculate the impacts of human disturbance based on land-cover changes over time.

Forestry in the Ozarks

The timber industry has played a significant role in land-cover change in the Boston Mountains ecoregion. Generally, a land-cover class change from forest to mechanically-disturbed can be representative of forest cutting for development or timber harvesting. Forest cutting can have a significant effect on land-surface dynamics, including rates of runoff. Slope and land-cover multi-change data from 1973 to 1980 for a sample area in the ecoregion was organized in ArcGIS and compared to magnitudes of change in peak flows at streamgages. When all of the data were evaluated, we saw that an increasing-trend magnitude occurred at a down-slope streamgage in an area that converted from the forest to mechanically-disturbed land-cover class. Additionally, precipitation records from 1961 to 1980 do not indicate a significant deviance from normal rainfall in that area, confirming that the changes in the land-cover may have increased rates of runoff.

Acronym List

EPA Environmental Protection Agency

LPC Loon Preservation Committee