Just a few thoughts in response to both Tony and = Nigel…

There is some interest here at the District to add = sediment diagenesis also. WASP has a version of

DiToro’s sediment diagenesis model. I had asked Tim = Wool for the code and documentation at the

summer WASP workshop in Atlanta and have not yet received = it, but I suspect that it being a dynamic

model might make it more readily adaptable to HSPF. =

If sediment diagenesis is added, then macrophyte uptake = could depend on bed nutrient levels, not

just an assumed infinite source, at least as an = option.

Regarding sediment transport, is it possible to allow = some localized scour and deposition to increase

low-flow suspended concentration that is not subject to = normal advection? I’m imagining something

parallel to the specialized phytoplankton advection = routine, though of course the details would differ.

If detailed parameterization of pools and riffles is = beyond the scope of what is plausible in a zero-D

model like RCHRES (though there is some in the new = multispecies benthic algae routines), something

simple and empirical might suffice, though parameters = might be difficult to justify based solely on

suspended sediment measurements.

I assume that the multiple plant canopy layers are driven = by a desire to represent the aboveground storages of

nutrients in plants in more detail, with differential = litterfall and return rates, not just the effect of shading

on differential growth rates. Nigel – does = the CropGro model address this too?

Would it make sense to define a fraction of coverage for = the interception by (the one or more layers of)

canopy, so that some rainfall reaches the soil surface immediately before the entire unit area CEPSC is

filled? I think this makes sense physically, but I = have not thought seriously about how numerically important

it is to represent.

Tom Jobes

St Johns River Water Management District

tjobes@sjrwmd.com

W: 386-328-4463

C: 386-937-6341

From: Nigel Pickering [mailto:npickering@crwa.org]
Sent: Wednesday, November 28, 2007 8:53 AM
To: Private list for BASINS users
Subject: RE:[basinsinfo] basinsinfo digest: November 27, = 2007

Tony

If you are planning some updates to HSPF, here two = deficiencies that, if added, would be very useful for phosphorus and algae dominated streams:

1) no sediment diagenesis – easy to add QUAL2K’s formulation, an abbreviated form of Di Toro’s work

2) no macrophyte simulation – modify new 4 benthic = algae compartments to decouple photosythesis & DO from water-column = nutrient uptake by assuming sediment have infinite nutrients (like = AquatTox)—could have different options for each of the 4 benthic algae = components

On the improved plant canopy idea, my first question = would be why? If you have to do this, then don’t use layers, rather = use the sunlit / shaded leaf approach.

Boote, K.J. and N.B. = Pickering, 1994. Modeling photosynthesis of row crop canopies. = HortScience: 29:13-24.

This work on canopy photosynthesis and ET is suitable for = row (or hedge) crops and is useful for climate change responses to changes = in CO2 and temp. Talk to Ken Boote—he took the approach and = furthered it for the CropGro model (Ken Boote at UF Agronomy Dept, kjb@gnv.ifas.ufl.edu).

Nigel

Senior Engineer / Watershed Modeler

Charles River Watershed Association

From: Private list for BASINS users digest [mailto:basinsinfo@lists.epa.gov] =
Sent: Tuesday, November 27, 2007 11:00 PM
To: basinsinfo digest recipients
Subject: basinsinfo digest: November 27, 2007

To All BASINS/HSPF = Model Users -

As part of a current modeling research effort, AQUA TERRA Consultants is investigating selected enhancements to HSPF process algorithms related = to:

1. an improved plant canopy compartment (e.g. = multi-layer canopy and plant growth),

2. upgrades to the sediment erosion and instream scour/deposition algorithms (e.g. bed/bank erosion), and

3. procedures to represent impacts of prescribed = burning and wildfires.

There has recently been = a number of postings related to issues/problems with the sediment erosion and = instream transport capabilities, indicating that the HSPF User community might be = a valuable source of suggestions on algorithm problems, weaknesses, = limitations, and possible enhancements that should be considered as we embark on this research effort.

Consequently, AQUA TERRA would like to solicit any and all input from = HSPF model users related to these processes and their representation within = HSPF, along with suggestions, potential solutions, alternative formulations = (e.g. from other models), or just identification of problem areas that should = be considered for investigation.

Any emails in response to this request can be addressed either to the = BASINS listserver, or directly to me, Tony Donigian, at AQUA TERRA (email:donigian@aquaterra.com).&n= bsp; Any reports, journal articles, model surveys, etc. in support of the = suggestions, would be welcome, and should be directed to the AQUA TERRA email = address.

Thank you for your time,

Tony Donigian

~~~~~~~~~~~~~~~~~~~~~~~~~= ~~~~~~

Tony Donigian, P.E., = D.WRE

AQUA TERRA = Consultants

2685 Marine Way, Suite = 1314

Mountain View, CA = 94043-1115

650-962-1864; fax = 650-962-0706

www.aquaterra.com

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