Mud, models, and managers: Reaching consensus on a watershed strategy for sediment load reduction
Abstract
Agricultural nonpoint source sediment pollution is a leading cause of impairment of U.S. waters. Sediment sources are often on private land, such that solutions require not only considerable investment, but broad acceptance among landowners. We present the story of a participatory modeling exercise whose goal was to develop a consensus strategy for reducing sediment loading from the Greater Blue Earth River Basin, a large (9,200 km2) watershed in southern Minnesota dominated by row crop agriculture. The Collaborative for Sediment Source Reduction was a stakeholder group of farmers, industry representatives, conservation groups, and regulatory agencies. We used a participatory modeling approach to promote understanding of the problem, to define the scope of solutions acceptable to farmers, to develop confidence in a watershed model, and to reach consensus on a watershed strategy. We found that no existing watershed model could provide a reliable estimate of sediment response to management actions and developed a purpose-built model that could provide reliable, transparent, and fast answers. Because increased stream flow was identified as an important driver of sediment loading, the model and solutions included both hydrologic and sediment transport components. The model was based on an annual sediment budget with management actions serving to proportionally reduce both sediment sources and sediment delivery. Importantly, the model was developed in collaboration with stakeholders, such that a shared understanding emerged regarding of the modeling challenges and the reliability of information used to strongly constrain model output. The simplicity of the modeling approach supported stakeholder engagement and understanding, thereby lowering the social barrier between expert modeler and concerned stakeholder. The consensus strategy focused on water storage higher in the watershed in order to reduce river discharge and the large supply of sediment from near-channel sources. Because water storage must occur largely on private farmland, this strategy was initially opposed by some stakeholders, such that model simplicity and transparency was essential in reaching a consensus strategy.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.H54A..07W
- Keywords:
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- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY;
- 1880 Water management;
- HYDROLOGY