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INTEGRATING LANDSCAPE ASSESSMENT AND HYDROLOGIC MODELING FOR LAND COVER CHANGE ANALYSIS
Citation:
Miller, S. N., W G. Kepner, M H. Mehaffey, M. Hernandez, D. C. Goodrich, R. C. Miller, D T. Heggem, P. Miller, AND F. K. Devonald. INTEGRATING LANDSCAPE ASSESSMENT AND HYDROLOGIC MODELING FOR LAND COVER CHANGE ANALYSIS. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 38(4):915-929, (2002).
Impact/Purpose:
The primary objectives of this research are to:
Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;
Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;
Develop and validate multivariate models based on quantification studies;
Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;
Complete an initial draft (potentially web based) of a national landscape condition assessment.
This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.
Description:
This study is based on the assumption that land cover change and rainfall spatial variability affect the r-ainfall-runoff relationships on the watershed. Hydrologic response is an integrated indicator of watershed condition, and changes in land cover may affect the overall health and function of a watershed. This paper argon watershed response were quantified using describes a study wherein the effects of land coyer c* hydrologic simulation models in two distinctly different watersheds, one a semi-arid watershed in southeast Arizona, and the other a forested watershed in upstate New York- One of the models is event-based with a c)ne-minute time step (KINEROS), and the second is a continuous model with a daily time step (SWAT). Inputs to the models were derived from a geographic information system (GIS) based tool utilizing USGS digital elevation models, the State Soil Geographic Database (STATSGO) and Landsat-based North American Landscape Characterization (NALC) imagery in conjunction with available literature and look up ables. Continuous rainfall data from available National Weather Service rain gauges were used as input to SWAT, while design storms were created from historical data to provide rainfall input to KINEROS. Landscape composition and pattern metrics have been generated from digital land cover maps derived from the images and compared across a nearly 25-year period. Results about changes in land cover for the study period indicate that in the San Pedro study area, grasslands and desertscrub not only decreased in extent but also became more fragmented due to the encroachment of xerophytic mesquite woodland. In the Cannonsville watershed change has been subtle with shifts in composition resulting in a net 'increase in forest cover. These change have important implications for hydrology since alterations in land cover types can impact energy and water balance characteristics. Hydrologic simulations were carried out for both study areas over the periods of record covered by the interpreted satellite data, and simulation results underscore the role of land cover in determining runoff volume and rate as well as water quality.