Evaluating watershed-based optimized decision support framework for conservation practice placement in Plum Creek Minnesota

Targeting field-scale implementation of conservation practices (CPs) in agricultural watersheds is critical to meeting sustainable resource management goals. This not only needs accurate and extensive field-scale assessment, but also incorporation of willingness of the farmers to adopt the suite of practices. Many useful watershed models have not only lacked in accurate siting of field-scale practices based on rigorous physiographic/terrain criteria and hydro-conditioned digital elevation models (DEMs), but also limited in mathematically incorporating farmer's uncertain, diverse and conflicting viewpoints into the model, which is pivotal to TMDL scenario assessment. This study develops an integrated decision support framework (DSF) to site CP opportunities at the field-scale using high-resolution Light Detection and Ranging (LiDAR)-hydro-conditioned DEM and other secondary data. Using python coding, DSF integrates three robust models namely Prioritize, Target and Measure Application (PTMApp), Agricultural Conservation Planning Framework (ACPF) and Hydrological Simulation Program FORTRAN-Scenario Application Manager (HSPF-SAM). The novel nature of this framework is its ability to facilitate precision planning at field-scale by siting the optimized conservation practices to achieve TMDL's based on (i) rigorous terrain derivatives and siting criteria; (ii) simulation of accurate stream flow network (extensive hydro-conditioning and D infinity approach for flow accumulation); and (iii) incorporating diverse, conflicting and uncertain preferences of farmers using fuzzy logic. The framework offers a simplified interface to the locals to simultaneously address agronomical (siting practices to improve soil health and crop productivity), hydrological (improving water quality, TMDL's), ecological (delineation of sites for riparian buffers) and socio-economic (farmer preferences and cost-analysis) objectives with moderate technical expertise. Besides field-scale practice siting, one of the superior features of the model is its flexibility to filter out even technically feasible cost-effective practices if they are not preferred by farmers, and thus giving a realistic assessment of TMDL's. The model is applicable to any Hydrologic Unit Code (HUC-12) sub-watershed and has been demonstrated for Plum Creek watershed in Minnesota. Results showed 537 cost-effective practices including bioreactors, grassed waterways, nutrient removal wetlands, water and sediment control basins and riparian buffers yielded an 8.5% reduction in total nitrogen constrained with a budget of $250,000. Field-scale maps generated through this DSF empowers practitioners and farmers to work together to make implementation decisions based on sound agronomic, water quality, and economic considerations.