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At the moment all the river sediment gets deposited onto the shoreline in an evensplit between the transects either side of the outlet channel. At time of high discharge this can create a localised bump and is quite unrealistic.

Need to differentiate beach from cliff on open coast

• River flow
• Sea level
• Hs
• Wave Dir

Also runup height?

Summarising the inputs would allow quick sensibility checking:

• River flow duration curve
• Wave rose
• Distribution of sea level
• Tidal constituents?

Need to handle:

• Outlet channel truncations to sea
• Outlet channel truncations to lagoon
• Lagoon end extension (truncation to cliffline)
• Breach?

Maybe transfer channel hydraulics (depth and velocity) to new variables the same size as lagoon/outlet bed elevation then transfer back after adjusting morphology and interpolate new/null values as necessary.

• position
• bed elevation
• width
• water level
• velocity
• bedload

Currently the netCDF file is getting quite large as it is being written to every morphological timestep.

Should be quite easy to fix with a new parameter in the config file.

This would make the model output animation comparable to the timelapse camera animation...

A pre-requisite to doing this is adding bdy condition data to the netCDF file (#44)

Need to resolve what happens when an outlet channel closes

Leave for now but likely important in some circumstances...

This could be an easy way to speed things up during stable periods.
Within Flood Modeller Pro timestep adjustment is triggered based on the number of iteration required to achieve convergence:
http://help.floodmodeller.com/floodmodeller/Technical_Reference/Simulation_Tab/Simulation_Tab.htm#advancedp

Develop test script to put the main mor code through a series of tests.
Needs to check:

• Truncation of seaward end of outlet
• Truncation of lagoon end of outlet
• Extension of lagoon via truncation of lagoon end of outlet to cliffline

Ideally checks should include some mass balance calcs!

• The outlet channel ends look very strange at the moment without their width being properly represented - improve plot to show width of channel ends
• adding arrows showing bedload (quiver plot similar to LST and CST) would be beneficial

Maybe put the linalg.solve_banded line into a try except statement and just warn + add noise if it returns this error?

So far none of my river hydraulics includes a momentum coefficient (β) (also termed Boussinesq coefficient) to correct for non-uniform velocity distribution. This should be fixed.

Barrier seepage needs to be incorporated in order to allow the possibility of long duration closure. It can be included by modifying the unsteady flow equations.

Need to deal with zero width outlet channel but different height inner and outer barrier (is the outer barrier always going to be lower?)

Similarish bug to #49 but different...

The barrier between the outlet channel and sea is not widening/raising due to overtopping/overwashing once the outlet migrates into transects beyond the end of the lagoon. E.g.

At the moment when the outlet channel re-elongates into a place it has already been it resets the channel position and width, even if this is making it narrower...

Probably fixed rate of erosion (or advance).

Currently breaching always results in a straight channel but this is not realistic in the case of transitory closure. Need to:

• preserve the location and size of the upstream end of the outlet channel during closure
• Differentiate between reopening of old (upstream connected) outlet channel vs breach where there is no, or disconnected outlet channel.

Needs to include:

• shoreline position
• lagoon and barrier backshore positions
• lagoon bed level
• barrier crest height
• outlet bed level
• lagoon WL
• lagoon velocity
• outlet WL
• outlet vel
• longshore transport rate

Should be able to hotstart by reading in from netCDF and model input parameters.

Test bench for unsteady solver to benchmark speed, accuracy and stability under different conditions. Should include tests for:

• supercritcal flow
• correct water surface profile through constriction
• reverse flow
• shallow flow (e.g. breach/overtopping)

Lagoon backshore and cliff position will be the same in the model, but where there is no lagoon I should track cliff line separately from shoreline. Currently I read in:

• Shoreline (polyline)
• Lagoon (polygon) - from which both edges of lagoon are read

I should change this to

• Shoreline (polyline)
• Barrier backshore (polyline) i.e. seaward edge of lagoon - only extends for length of lagoon
• Clifftoe (polyline) i.e. landward edge of lagoon but extending beyond lagoon as well to show setback of cliff from shoreline

When the downstream end of the outlet channel is widening the erosion could be weighted towards the outside of the bend rather than split 50/50 as it is currently. An extra input parameter specifying the weighting would be required. This could help replicate the preferential migration which occurs once the channel is offset?

• update centreline position when sed deposited on 1 bank due to LST or overwash
• update outlet channel end position when needed due to centreline moving (or shoreline/lagoon) or width changing.
• allow channel truncation

Possibly by relaxing part of the momentum equation at high froude numbers or by implementing an adaptive timestep?

Currently I track the outlet channel centreline as a free-form line in XY space defined by node (cross-section) locations along its length. This allows quite a bit of flexibility but it creates a number of headaches when trying to track the width of the channel and how this interacts with things (e.g. checking for truncations, working out which river-cross-section to deposit overwash sediment in, extending a approximately shore parallel outlet etc.)

As an alternative, I could track the outlet channel using the same shore profile lines as used for the shore position and lagoon width. There are a number of advantages and disadvantages:

Overall I think this change would resolve a number of issues I am facing with my original approach but I need to think it through fully as it is a bit of a change. In particular I need a plan for:

• how to migrate the channel ends in particular d/s end due to LST
• how to deal with a breached (straight) outlet channel
• how to deal with channel hydraulics as outlet changes in length (step-changes?)

• Quiet = don't print logging.info statements to console
• Verbose = print logging.debug statements to console and log file.

Using flags in argparse would be the best way to do this - although I need to make sure the main model code remains runable from python as well as commandline.

This would make it much easier for people to interpret animation and shouldn't be too difficult to do.

I need to export animations (or alternatively be able to create them by post processing).

Weird bug - not sure what is going on. Appears to be linked to high froude numbers (~1):

Reducing morphological timestep at times of high sediment flux would help stabilise model

Need to think about how it will interact with outlet channel and how volume changes will be calculated.

Create process to create new outlet channel when barrier is overtopped

Current shoreline position adjustment only accounts for volume below mean sea level (i.e. closure depth * Dx) but need to account for barrier height in calculation as well.

similar to the below but generated from real model data for a specified transect and without the dimension lines.

It probably makes sense to use some vertical exaggeration otherwise it will be very flat - could just let the plot auto-scale or could specify vertical exaggeration as an input parameter.

I shortened MorDt from 900 to 300s which shouldn;t have had much influence on the river hydraulics - but weirdly this happened:

Need to be able to see what time it is in the animation somehow.

Very strange bug!

Movement pulses with tide so likely to be linked to overtopping/overwashing?

They seem very small from what I'm seeing at the moment - Need to check against previous calcs for the Marine Geology paper. This could be a bug or maybe I just need a bigger K coefficient?

From Murray's Okarito report one approach is to apply the EurOtop (2007) “influence factor” to adjust for obliquely-approaching waves. I need to do some more reading...

EurOtop (2007) Wave overtopping of sea defences and related structures: Assessment manual. www.overtopping-manual.com, August 2007.