Applicability of Models to Predict Phosphorus Losses in Drained Fields: A Review

Abstract

Most phosphorus (P) modeling studies of water quality have focused on surface runoff loses. However, a growing number of experimental studies have shown that P losses can occur in drainage water from artificially drained fields. In this review, we assess the applicability of nine models to predict this type of P loss. A model of P movement in artificially drained systems will likely need to account for the partitioning of water and P into runoff, macropore flow, and matrix flow. Within the soil profile, sorption and desorption of dissolved P and filtering of particulate P will be important. Eight models are reviewed (ADAPT, APEX, DRAINMOD, HSPF, HYDRUS, ICECREAMDB, PLEASE, and SWAT) along with P Indexes. Few of the models are designed to address P loss in drainage waters. Although the SWAT model has been used extensively for modeling P loss in runoff and includes tile drain flow, P losses are not simulated in tile drain flow. ADAPT, HSPF, and most P Indexes do not simulate flow to tiles or drains. DRAINMOD simulates drains but does not simulate P. The ICECREAMDB model from Sweden is an exception in that it is designed specifically for P losses in drainage water. This model seems to be a promising, parsimonious approach in simulating critical processes, but it needs to be tested. Field experiments using a nested, paired research design are needed to improve P models for artificially drained fields. Regardless of the model used, it is imperative that uncertainty in model predictions be assessed.

Evaluating Hydrologic Response in Tile‐Drained Landscapes: Implications for Phosphorus Transport

“…Understanding the factors that affect surface–tile connectivity may help identify regions and/or conditions that promote P losses via tile drainage, as there is substantial evidence that runoff is rapidly routed from the surface into tile drains through macropores (King et al, 2015b; Kleinman et al, 2015b; Williams et al, 2016). Further, a comprehensive understanding of site‐specific or climate factors that influence rapid surface–tile connectivity may improve modeling efforts, which currently do not capture such processes effectively (Radcliffe et al, 2015). The present study relied on time lags between the activation of tile and surface flow, as well as tile‐flow thresholds for surface‐flow activation, to infer runoff‐generation mechanisms.…”

Phosphorus and the Chesapeake Bay: Lingering Issues and Emerging Concerns for Agriculture

“…Historically, there has been relatively limited monitoring of the Delmarva's riverine systems. In addition, only recently has there been widespread recognition that computational models have poorly predicted P fate and transport in flat landscapes with extensive artificial drainage—a problem not restricted to the Chesapeake Bay but also common to the watersheds of Lake Erie, the Mississippi River basin, the Baltic Sea, and other water bodies affected by P (King et al, 2015; Kleinman et al, 2015a; Radcliffe et al, 2015). …”

The Latitudes, Attitudes, and Platitudes of Watershed Phosphorus Management in North America

“…Artificial drainage introduces quickflow, which reduces residence time and interactions between flow with soil P sorption–desorption controls. Indeed, for the transport of P, tile drainage is often considered to carry the concentration–discharge signature of surface runoff (Radcliffe et al, 2015; Smith et al, 2015a). Where open ditches are the principal conveyance, P leaching processes are a concern and P sorption saturation a controlling factor, as documented in the coastal plain of the Chesapeake and Lake Okeechobee watersheds.…”