Hydrologic and biogeophysical parameter estimation for simulating watershed-scale conservation to reduce nutrient losses to surface waters using SWAT
Abstract
The croplands of the Midwestern United States are critically important for the economy and play a vital role in feeding the country and the world. At the same time, agricultural activities are a major source of nutrient pollution to aquatic systems in the form of excess dissolved nitrogen (N), phosphorus (P) and sediments. Along with affecting the local rivers and lakes, the runoff from the agricultural fields in the Midwest has significantly impaired water quality of downstream water bodies such as the Great Lakes, the Mississippi River system, and the Gulf of Mexico. Winter cover crops have been identified as an effective conservation practice for reducing nutrient runoff from fields into adjacent waterways. Cover crops are planted in the fall and are terminated before planting of the cash crop the following spring, keeping the biological cover on what would typically be bare ground, which protects fields from soil and nutrient loss, especially during winter snowmelt and spring storms. Over the past four years, watershed-scale cover crops have been implemented at varying levels of cover crop saturation in the Shatto Ditch Watershed (SDW) and Kirkpatrick Ditch Watershed (KDW) in northern Indiana, and high-frequency water quality data will be used to calibrate high-resolution baseline SWAT models in both SDW and KDW for streamflow and water quality. Using these initial small-scale modeling studies, we will estimate hydrologic and biogeophysical model parameters needed to develop SWAT models at larger spatial scales that can accurately forecast the potential benefits of cover crop implementation in larger river basins, under both historical and projected future climate. We will also test the ability to transfer these model parameters to nearby watersheds (and across scales) by comparing the independent calibrations in SDW and KDW, and also by implementing and calibrating SWAT models in the Paw Paw River watershed in southern Michigan where cover crops are planned for future implementation. The approach presented determines how observed field data can be used to test parameter transfer schemes among watersheds and scales and informs scaling of SWAT results to larger watersheds.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H43C2395E
- Keywords:
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- 1632 Land cover change;
- GLOBAL CHANGEDE: 1834 Human impacts;
- HYDROLOGYDE: 1847 Modeling;
- HYDROLOGYDE: 1879 Watershed;
- HYDROLOGY