Question on Lake Representation

[Saba Shaghaghi]

Hello,

I am modeling a watershed in Florida with many lakes and would like guidance on how to correctly represent them.

1. If I define lakes as reservoirs/ponds using a shapefile, should I still keep them as WATR in the land use map, or could this cause double-counting?
2. For lakes classified as RES = 1, is it necessary to define a decision table for release rules when no operational data are available?
3. For lakes classified as RES = 2, do they require a decision table, and must they be connected to the stream network?
4. Is there a recommended approach or threshold for deciding which lakes should be explicitly modeled versus left as WATR?

My goal is to avoid errors in flow and water quality (mainly nitrogen and phosphorus) simulation and ensure reliable calibration.

Thank you for your guidance.

Best regards,
Saba Shaghaghi

[Chris George]

1. Landuse is ignored for lakes defined in shapefiles.
2. I don't think you need data.
3. No data is needed; they do need to connect to the channel network
(and so do reservoirs)
4. Shapefiles are better because they define the area precisely.

Just my opinions: I am not an expert apart from point 1.
Chris

On 4/23/2026 2:34 PM, Saba Shaghaghi wrote:
> Hello, I am modeling a watershed in Florida with many lakes and would
> like guidance on how to correctly represent them. If I define lakes as
> reservoirs/ponds using a shapefile, should I still keep them as WATR in
> the land use map, or could this

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>
> Hello,
>
> I am modeling a watershed in Florida with many lakes and would like
> guidance on how to correctly represent them.
>

> 1. If I define lakes as reservoirs/ponds using a shapefile, should I

> still keep them as WATR in the land use map, or could this cause
> double-counting?

> 2. For lakes classified as RES = 1, is it necessary to define a

> decision table for release rules when no operational data are available?

> 3. For lakes classified as RES = 2, do they require a decision table,

> and must they be connected to the stream network?

> 4. Is there a recommended approach or threshold for deciding which

> lakes should be explicitly modeled versus left as WATR?
>
> My goal is to avoid errors in flow and water quality (mainly nitrogen
> and phosphorus) simulation and ensure reliable calibration.
>
> Thank you for your guidance.
>
> Best regards,
> Saba Shaghaghi
>

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