Modeling sediment loading and riverine water quality in intensively managed landscapes
Advisor: Ximing Cai (CEE)
Co-advisor: Gregory F. McIsaac (NRES)
Abstract
Nutrient runoff from intensively managed agricultural landscapes owing to management practices (such as fertilizers, manures, and tillage) and augmented by tile drains and changes in climate have markedly altered stream water quality that has led to eutrophication and hypoxia in inland and coastal waters. Agricultural intensification has also accelerated soil erosion leading to reservoir sedimentation and loss of reservoir storage, ending with water stress for human livelihood. These severe water resources issues are likely to worsen with increasing hydroclimatic variability associated with climate change and human interventions. More frequent extreme events have the potential to deliver a larger proportion of the total annual nutrient and sediment loads in a shorter timeframe that can further degrade riverine water quality. Moreover, anticipated changes in seasonality with increase in spring precipitation, especially in the Midwestern United States, could potentially decrease agricultural yield and increase nutrient loads to the water bodies enhancing the possibility of a larger extent of hypoxia and dead zones. As a result, human adaptations—such as changing agricultural management operations/schedules and adding subsurface drainage infrastructures—to enhance agricultural production, could exacerbate the water quality issues in the Midwest United States. This dissertation models sediment loading and riverine water quality (nitrate and total Phosphorus) in intensively managed landscapes and understands the impact of human activities and policies on the sustainability of an intensively managed agricultural watershed located in the Midwestern United States. This thesis addresses the data issue and reliability of a watershed model, assesses the effectiveness of the various best management practices, and explore adaptive solutions to resolve climate change effect on riverine water quality of Midwestern watersheds.
