The development of long-term mean annual total nitrogen and total phosphorus load models for Mississippi, U.S., using RSPARROW

Water
By: , and 

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Abstract

Water-quality degradation from nutrient pollution remains a major challenge for resource managers. Developing effective strategies requires tools to characterize nutrient sources and transport. This study used the RSPARROW framework to develop and assess new, smaller-scale models for Total Nitrogen (TN) and Total Phosphorus (TP) transport across Mississippi (MS). These state-level models were built using 15 years (2005–2020) of observation data and considered variables including multiple nutrient sources, land characteristics, and attenuation processes. The MS models demonstrated comparable accuracy to larger regional SPARROW models, validating the use of smaller-scale models for local management. Results showed agricultural sources are the major contributors to TN, dominated by fertilizer in northern MS and livestock manure in the south. Urban land cover also significantly influenced TN and was the second most significant source of TP, following geologic material (background P). Fertilizer and manure were also important TP sources. This study provides valuable, spatially explicit data on nutrient distribution in MS streams, supporting the state’s nutrient reduction planning. It concludes by highlighting the need for future model improvements via updated source data and mean annual flow estimates.

Suggested Citation

Roland, V.L., Gain, E., and Hicks, M.B., 2026, The development of long-term mean annual total nitrogen and total phosphorus load models for Mississippi, U.S., using RSPARROW: Water, v. 18, no. 3, 292, 31 p., https://doi.org/10.3390/w18030292.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The development of long-term mean annual total nitrogen and total phosphorus load models for Mississippi, U.S., using RSPARROW
Series title Water
DOI 10.3390/w18030292
Volume 18
Issue 3
Publication Date January 23, 2026
Year Published 2026
Language English
Publisher MDPI
Contributing office(s) Lower Mississippi-Gulf Water Science Center
Description 292, 31 p.
Country United States
State Alabama, Georgia, Louisiana, Mississippi, North Carolina, Tennessee
Additional publication details