Western Lake Erie Basin: Soft-data-constrained, NHDPlus resolution watershed modeling and exploration of applicable conservation scenarios

Abstract

Complex watershed simulation models are powerful tools that can help scientists and policy-makers address challenging topics, such as land use management and water security. In the Western Lake Erie Basin (WLEB), complex hydrological models have been applied at various scales to help describe relationships between land use and water, nutrient, and sediment dynamics. This manuscript evaluated the capacity of the current Soil and Water Assessment Tool (SWAT) to predict hydrological and water quality processes within WLEB at the finest resolution watershed boundary unit (NHDPlus) along with the current conditions and conservation scenarios. The process based SWAT model was capable of the fine-scale computation and complex routing used in this project, as indicated by measured data at five gaging stations. The level of detail required for fine-scale spatial simulation made the use of both hard and soft data necessary in model calibration, alongside other model adaptations. Limitations to the model's predictive capacity were due to a paucity of data in the region at the NHDPlus scale rather than due to SWAT functionality. Results of treatment scenarios demonstrate variable effects of structural practices and nutrient management on sediment and nutrient loss dynamics. Targeting treatment to acres with critical outstanding conservation needs provides the largest return on investment in terms of nutrient loss reduction per dollar spent, relative to treating acres with lower inherent nutrient loss vulnerabilities. Importantly, this research raises considerations about use of models to guide land management decisions at very fine spatial scales. Decision makers using these results should be aware of data limitations that hinder fine-scale model interpretation.

Assessment of Optional Sediment Transport Functions via the Complex Watershed Simulation Model SWAT

“…The semi-distributed watershed simulation model, Soil and Water Assessment Tool (SWAT) [1] has been applied worldwide to identify critical source areas of water quality impairments and evaluate potential solutions through land use change and water resource planning and management [2][3][4][5][6][7][8][9]. Various SWAT applications have been conducted to explore sediment loading from watersheds [10][11][12][13].…”

IPEAT+: A Built-In Optimization and Automatic Calibration Tool of SWAT+

“…As shown in Figure 2, users shall define many simulation details here. The first part of the control file is to define variables in conducting optimization algorithm: (i) Perturbation Factor (PF): The default value of PF is 0.2, which has been validated in literature and users do not need to adjust this value to find better solutions [31]; (ii) Total Number of Model Evaluation (TotalRuns): The maximum simulation runs defined before conducting calibration routines; (iii) Initial Para Index (InitialParaIndex): Users can start automatic calibration from randomly selected initial parameter set (InitialParaIndex = 0), or, it is also supported to begin with designated one (InitialParaIndex = 1); and, (iv) Restart Mechanism…”

“…As shown in Figure 2, users shall define many simulation details here. The first part of the control file is to define variables in conducting optimization algorithm: (i) Perturbation Factor (PF): The default value of PF is 0.2, which has been validated in literature and users do not need to adjust this value to find better solutions [31];…”

Assessing the Impact of Site-Specific BMPs Using a Spatially Explicit, Field-Scale SWAT Model with Edge-of-Field and Tile Hydrology and Water-Quality Data in the Eagle Creek Watershed, Ohio

“…Calibration was first performed at the EOF and tile sites. Parameters from Daggupati et al [43] and Yen et al [55] were used as a starting point for calibration and adjusted or modified to suit the simulated conditions in the study watershed. Detailed management data, as implemented by the producer from 2012 to 2016, were available and used for management in subbasins 38 and 39.…”