Updating and expanding the impoundment model

[connorb5]

Before AGU, I put together a model of 20 impoundments rather haphazardly; before I had access to the command line interface, I was forced to build pond and channels within themselves. Currently, the network is confusing and it is difficult to track drainage areas and flows. We need to create pond objects for each impoundment and then find a way to deal with irregular/branching channel structures. A couple of instances to keep in mind are as follows:

1. Ponds that have no upstream channel
2. Ponds that are fed directly by multiple impounded upstream channels
3. Ponds that are fed by upstream branching channels such that it is difficult to find just one representative length

After we complete the sensitivity analysis on outlets and maybe geometry, we will get a better sense of how to choose new impoundments to model and how to update the network.

[rburghol]

My thoughts on these:

0. once we finish the sensitivity analysis of outlet structure we can use that to prioritize which ponds to use -- if it's dimensions don't suggest potential for significant flow alteration, then not much reason to include it.
1. Ponds with no upstream channel -- these are prime candidates for removal, unless we feel they represent stormwater retention ponds and want to see what cumulative effect of those are.
2. Multiple impounded upstream channels - outlet structure SA will guide us here. If it's significant we should model it, if not we may choose to lump it or ignore it.
3. Ponds that are fed by upstream branching channels -- my sense is that these can be generalized into a single channel using the average length. If we are looking at floodplain dynamics (per Tyler's stuff) then yes, we want to model individually, but if we just want to get peak flows the average length should work. Again, a sensitivity analysis will tell us the implications of whatever "lumping" decisions we might make, and we could copy one of the multi-channel objects that you've already created as a a good test-bed that will be easy to run.

On Sun, Feb 11, 2018 at 8:28 AM, connorb5 notifications@github.com wrote:

Before AGU, I put together a model of 20 impoundments rather haphazardly; before I had access to the command line interface, I was forced to build pond and channels within themselves. Currently, the network is confusing and it is difficult to track drainage areas and flows. We need to create pond objects for each impoundment and then find a way to deal with irregular/branching channel structures. A couple of instances to keep in mind are as follows:

1. Ponds that have no upstream channel
2. Ponds that are fed directly by multiple impounded upstream channels
3. Ponds that are fed by upstream branching channels such that it is difficult to find just one representative length

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[rburghol]

Note that the channel settings "Watershed Drainage Area" and "Local Drainage Area" should be identical if a segment is a headwater. In other words "Watershed Drainage Area" only applies to the watershed "up till that point". This controls channel dimensions, and honestly, it's probably of negligible impact, but just to be sure we should make sure that we are consistent. For example, Pond 2 which is a trib to Piney Branch has the full drainage of Piney Branch in the Watershed Drainage Area field:

[rburghol]

Piney Run updated:

[connorb5]

I have eliminated the embedded impoundments and secondary channels within all of the impoundment objects (not sure what to call the overall holding container, but I use "impoundment object" to refer to those elements that have the element IDs like 339991). I reverted drainage area and channel lengths to reflect this network simplification. Something happened to Lake Thoreau and it currently has no subcomponents. This will need to be recopied and set up. Pond two is in the wrong position within the network (it is not a child to Piney Run and needs to be moved to be a child of Difficult Run). However, every time I try to create new pond objects in command line it ends up creating several hundred/thousand that I then have to delete one-by-one (a very painful process). Is this the correct command to copy element ID 340100 to be a child of element ID 339991? w_copy_element 104 339991 340100

[connorb5]

Additionally, many of the impoundments are not functioning right now. Oddly, pond 22 works fine. All of the impoundments have the same subcomponents, but the others are reading as "Bad record ID" and I have not been able to figure out why (for instnace Lake Fairfax)

[rburghol]

Ahh -- copy_element is backwards :) -- this command: w_copy_element 104 339991 340100 is creating a copy of Difficult Run and all it's triburaties into a tributary of Difficult Run itself (340100). In general, the w_* functions will tell you their usage if you run them with no parameters, like: w_copy_element

Created a new version of Thoreau. Pond 22 has been one of the ones that I spruced up to test -- so I think it should be OK -- or at least it should run. The key when deleting sub-comps is to check your broadcast variables, especially "Send to Parent", for variables that are no longer present and then break the select list for the local -- see below for the settings that are recommended:

[rburghol]

I think w should use Pond 22 as our template for copying. Thus, we can do this to create a new copy for Lake Thoreau: w_copy_element 104 340136 340098 (which says copy element 340136 as a child of element 340098)

[connorb5]

Okay sounds good! I will go back and start updating everything tonight so I can begin running some stuff by tomorrow! I don't know how I got those IDs mixed up, but it will be nice to not accidentally create 1000+ copies of our ponds

[rburghol]

elementid: 340268 imp_lat: 38.935259 imp_lon: -77.253643 New Object created "Difficult Run (standalone)" to be the single unit - 1 channel representing the whole watershed (for run comparison no. 2). DA: 58.3 Local area: 58.3 Local Channel length: 77,502.3 ft