A storm event-based approach to TMDL development

Abstract

It is vitally important to define the critical condition for a receiving water body in the total maximum daily load (TMDL) development process. One of the major disadvantages of using a continuous simulation approach is that there is no guarantee that the most critical condition will be covered within the subjectively selected representative hydrologic period, which is usually several years depending on the availability of data. Another limitation of the continuous simulation approach, compared to a design storm approach, is the lack of an estimate of the risk involved. Because of the above limitations, a storm event-based critical flow-storm (CFS) approach was previously developed to explicitly address the critical condition as a combination of a prescribed stream flow and a storm event of certain magnitude, both having a certain frequency of occurrence and when combined, would create a critical condition. The CFS approach was tested successfully in a TMDL study for Muddy Creek in Virginia. The present paper reports results of a comparative study on the applicability of the CFS approach in Taiwan. The Dy-yu creek watershed in northern Taiwan differs significantly from Muddy Creek in terms of climate, hydrology, terrain, and other characteristics. Results show that the critical condition for different watersheds might be also different, and that the CFS approach could clearly define that critical condition and should be considered as an alternative method for TMDL development to a continuous simulation approach.

A combined catchment‐reservoir water quality model to guide catchment management for reservoir water quality control

“…The HSPF was developed by the USEPA and HydroComp Inc. and is capable of simulating the hydrological and water quality performance of catchments. Hsu et al (2010) used the HSPF to assess the water quality in the Feitsui Reservoir catchment under critical flow‐storm conditions. Tsai et al (2017) also applied the HSPF to the Feitsui Reservoir and obtained satisfactory results.…”

Phosphorus and thermotolerant coliforms’ loads in Brazilian watersheds with limited data: considerations on the integrated analysis of water quality and quantity

“…Hydrological services are also related to the "river absorption capacity" (WILK; ORLIŃSKA-WOŹNIAK; GĘBALA, 2018), which is the maximum pollutant load that a water body can assimilate or tolerate with no resulting changes that affect its self-depuration capacity or compliance with standards and guidelines (BRASIL, 2005). The evaluation of such capacity has been used as an alternative to the "total maximum daily load" (TMDL), which is widely reported in the international literature (e.g., USACE, 2006;HSU et al, 2010;CHUNG et al, 2011;CHEN et al, 2016;ABU-HMEIDAN;WILLIAMS;MILLER, 2018). Load duration and frequency curves can be useful to further integrate qualitative and quantitative datasets of water resources.…”

Combined inverse modeling approach and load duration curve method for variable nitrogen total maximum daily load development in an agricultural watershed

“…The total maximum daily load (TMDL) program, which incorporates the control of NPS into water quality management, has been widely applied in the USA (USACE 2006) and other countries (Kang et al 2006;Chen et al 2009;Hsu et al 2009). Due to the significant variability in TMDL magnitude with changing stream flows, TMDL development must be based on the designed water flows to assure that water quality is compliant with the target across a range of flow conditions (Bonta and Cleland 2003;Chen et al 2007a, b).…”