EVALUATING ENVIRONMENTAL FACTORS OF WETLAND RESILIENCE TO CLIMATE CHANGE WITH REMOTE SENSING TECHNIQUES

Wetlands provide valuable ecosystem services, habitats for many plant and animal species, and are of high economic value. With the current trend of a warming climate, however, these important ecosystems are at risk. Recent research has shown that the Prairie Pothole Region (PPR), a large area of glacially sculpted terrain in the Midwestern U.S. and Southern Canada, has lost more than half of its surface water area since 1997. The abundance of wetlands in this area is in decline, but certain environmental variables may allow for some wetlands to be more resilient to a warmer climate than others.

A remote sensing-based study of Kidder County, ND was conducted to evaluate the effect of varying climate inputs and subsurface geology on surface water persistence. Kidder County, ND, was selected as the study area due to its unique climate extremes and varied geological and hydrological characteristics. Climate data was interpreted by evaluating the historical Palmer Drought Severity Index (PDSI) for the region including Kidder County. Geological and hydrogeological data for Kidder County was obtained from the North Dakota GIS hub. Areas of varying aquifer yield and subsurface type (e.g. cross-bedded sand, till, outwash) were mapped. 17 scenes of Landsat TM data in 2 sets (spring and fall), covering the time period between 1991 and 2009, were processed using the Modified Normalized Difference Water Index. Surface water areas were identified using a supervised parallelepiped classification method and areas were calculated.

In general, surface water area within Kidder County has increased over the time of the study. There is an intra-annual decrease in surface water from spring to fall. Since 1991, surface water areas overlying an aquifer complex and a cross-bedded sand deposit were the most sensitive to changes in the climate. These changes in surface water area show a correlation with PDSI averaged over the previous two years, suggesting that there is a significant period of inertia before the wetlands become impacted. The response of these wetlands to climate drivers, and the higher sensitivity of the wetlands overlying sand aquifer complexes will need to be taken into account when assessing future conservation efforts in prairie pothole wetlands, specifically in relationship with predicted climate change in the region.