Paper No. JAWRA-11-0136-P of the Journal of the American Water Resources Association (JAWRA). Discussions are open until six months from print publication.
TMDL Balance: A Model for Coastal Water Pollutant Loadings†
Article first published online: 21 MAR 2013
© 2013 American Water Resources Association
JAWRA Journal of the American Water Resources Association
Volume 49, Issue 4, pages 838–850, August 2013
How to Cite
2013. TMDL Balance: A Model for Coastal Water Pollutant Loadings. Journal of the American Water Resources Association (JAWRA) 49(4): 838–850. DOI: 10.1111/jawr.12044, , and ,
- Issue published online: 1 AUG 2013
- Article first published online: 21 MAR 2013
- computational methods;
- geographic information systems (GIS);
- total maximum daily loads;
Bacterial contamination accounts for more than 60% of the impairments included on the 2008 Texas 303(d) List. Many of these bacterial impairments are along the Texas Gulf Coast because coastal waters often are regulated for oyster harvesting, which have strict water quality standards. Under the Clean Water Act, each one of these impaired waterbodies requires a total maximum daily load (TMDL) study to be performed. A recent, statewide study recommended the development and application of simple modeling approaches to address the majority of Texas's bacteria TMDLs, including “… simple load duration curve, GIS [geographic information systems], and/or mass balance models.” We developed the TMDL Balance model in response to this recommendation. TMDL Balance is a steady state, mass balance, GIS-based model for simulating pollutant loads and concentrations in coastal systems. The model uses plug-flow reactor and continuously-stirred tank reactor equations to route spatially distributed point and nonpoint source loads through a watershed via overland flow, non-tidal flow, and tidal flow, decaying the loads via first-order kinetics. In this paper, we explain the development of the watershed loading portion of the TMDL Balance model, demonstrating the methodology through a case study: computing bacterial loads in the Copano Bay watershed of southeast Texas. The application highlights an example of distributing bacterial sources spatially based on land use data.