Document Type

Article

Journal/Book Title/Conference

Water Resources Research

Volume

55

Issue

2

Publisher

American Geophysical Union

Publication Date

2-25-2019

Keywords

watershed simulation model, reduced‐complexity modeling, nonpoint source sediment management, collaborative modeling

First Page

1544

Last Page

1564

Abstract

We developed a watershed sediment source and delivery model for use in evaluating conservation trade‐offs in southern Minnesota, where sediment loading has been identified as a priority and there is substantial public investment in cleaner water. The model was developed in a stakeholder process and links user‐specified management options to reductions in sediment loading at the outlet of a 2,880‐km2 intensively farmed watershed. The simulation model was formulated to allocate total sediment load among sources, which provides robustness to the model by constraining the relative magnitude of sediment loads and their reduction. A novel topographic filtering approach was used to develop spatially distributed maps of sediment delivery ratio, addressing the problem of storage between source and outlet. The dominant sediment source in the watershed is erosion of steep streamside bluffs in response to increases in river discharge. Rates of bluff erosion as a function of river discharge were determined from sediment loads measured at pairs of gages on individual streams. Using this analysis, upland water storage to reduce peak river flow was included as an option in the model. The model development process was designed to promote transparency and develop stakeholder trust through multiple meetings in which an underlying sediment budget was developed and refined. The model runs rapidly, providing real‐time response to user choice and supporting Monte Carlo simulation of the influence of uncertainty on the calculated sediment load. The stakeholder group used the model to identify a priority strategy for investing public funds to improve water quality.

Available for download on Sunday, August 25, 2019

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