Impact/Purpose:

The QUAL2E model has provided water-quality modelers and managers with a useful tool for simulating the transport and fate of conventional pollutants that is, nutrients, phytoplankton and dissolved oxygen in rivers.

However, it has two major deficiencies that detract from its use to support current nutrient TMDLs:

u Outdated kinetics. It currently has the following major deficiencies:

u No attached plants. It presently simulates floating plants (phytoplankton) and does not model attached plants such as periphyton and macrophytes.

u Sediment-water interactions are not explicitly modeled. QUAL2E prescribes rather than calculating fluxes of nutrients and oxygen (SOD) at the sediment-water interface.

u No equilibrium water chemistry. Thus, water quality variables such as pH is not calculated. This omission can have a detrimental impact on evaluation problems such as ammonia toxicity.

u One form of organic carbon, carbonaceous BOD is modeled. Although this is adequate when evaluating large point sources, it is lacking for river basins where slowly decomposing organic carbon can be significant.

u Denitrification is not included. This important sink of nitrogen must be modeled in order to accurately represent the available nutrients that lead to profuse plant growth.

u Anoxia is modeled incorrectly. The oxidation reactions (carbon oxidation and nitrification) do not shut down when oxygen approaches zero.

Consequently QUAL2E overestimates the river,s assimilative capacity under such conditions.

u Outmoded User Interface. The model can either be run from DOS or via a graphical user interface. The former forces the user to adopt a "batch Fortran" mentality and hence is cumbersome and inefficient. The latter was a step in the right direction, but unfortunately was not developed to accommodate hardware and software upgrades. Hence, although it can be implemented on Windows 95 and 98, it cannot be used on Windows NT or 2000

Description:

Recently, a revised version of QUAL2E has been developed to recify the aforementioned deviciencies. Call QUAL2K, it is designed to facilite defensible TMDL evaluations of rivers. We propose to apply QUAL2K to the Sugar River in New Hampshire. Specific tasks will be to calibrate the model to data collected during the late summer of 2001. Provide guidance on future data collection to improve the model predictions. Deliverables:

• The calibrated model software
• Model users manual
• Study report describing the results, and including recommendations for future data collection to improve model reliability.

Record Details: