Growing concerns about the adverse environmental effects of agriculture have led to the establishment of various government-led or partnership programs to incentivize farmers to implement agricultural conservation practices or beneficial management practices (BMPs) such as conservation tillage, nutrient management, and riparian and wetland restoration for improving water quality and other benefits. In this presentation I introduce the development of a GIS-based fully distributed hydrologic model, namely Integrated Modelling for Watershed Evaluation of BMPs (IMWEBs), for evaluating the water quality benefits (sediment and nutrient reductions) at site, field, farm, watershed, and river basin scales. The IMWEBs characterizes climate, runoff, sediment, plant growth, and nutrient processes from overland to streams to the watershed out. In addition, the IMWEBs characterizes crop management (e.g., crop rotation and tillage), manure and nutrient management (e.g., manure setback and catch basin), riparian and surface water management (e.g., riparian buffer and wetland restoration), wintering site management (e.g, alternating wintering site annually), pasture management (e.g., rotational grazing) and marginal cropland management (e.g., conversion to tame and native perennials). The IMWEBs utilizes climate, topography, soil, landuse, land management and other data for setup and uses flow and water quality monitoring data for calibration and validation. The calibrated IMWEBs can be then used to estimate location-specific watershed quality benefits for various BMP scenarios. The IMWEBs has been applied to quantify water quality benefits of existing and future agricultural conservation practices for evaluating agri-environmental program performance and planning further investments on these programs in provinces of Alberta, Manitoba and Ontario in Canada.
