Project Maker

riverarchitect.projectmaker - the Project Maker tab.

The last step of the chain, and the only one that produces a number a funding body recognises: what the works cost, what they buy in habitat, and the ratio between them.

The two halves

Cost is a bill of quantities. Every task in riverarchitect.projectmaker.COST_ITEMS carries a unit rate; the quantity comes from what the earlier modules mapped:

Quantity	Comes from
per-feature areas - plantings, streamwood, boulders, fine sediment	Lifespans (Max Lifespan)
excavation volume and the area cleared	Morphology (Terraforming) (Terraforming)
terrain acquisition	the project area
everything else - culverts, roads, bridges, groin cavities	entered directly

Benefit is the difference in SHArea between two conditions - the existing state and the state with the project built - for one species and lifestage. Both come from riverarchitect.sharc.SHArC.run(), so the comparison is like for like.

Their ratio, cost per unit of habitat gained, is what lets two designs be compared when one is cheap and small and the other expensive and large.

from riverarchitect.maxlifespan import MaxLifespan
from riverarchitect.projectmaker import ProjectMaker
from riverarchitect.sharc import SHArC

maker = ProjectMaker("my_project", unit="us")
maker.quantities_from_lifespan(
    MaxLifespan("Output/MaxLifespan/2100_sample").run(),
    terraforming=terraforming_result,
    project_area=336000.0)

before = SHArC("2100_existing").run("Chinook salmon", "spawning")
after = SHArC("2100_with_project").run("Chinook salmon", "spawning")

result = maker.run(before=before, after=after)
print(result["costs"]["total"], result["cost_per_area"])

The rates

The unit rates are the original’s Project_assessment_vii.xlsx, unchanged, but held as Python rather than a workbook so a change to a rate shows up in review. Several were Excel formulas averaging a range; those are recorded as the average, with the range in the item’s note.

They are grouped as the workbook grouped them: Terraforming, Stabilising bioengineering, Vegetation plantings, Other bioengineering, Maintenance and Civil engineering. Four percentage rates then apply to the construction subtotal, compounding in order:

Rate
Site (de-)mobilization	10%
Unexpected	10%
Markups (overhead, profit, insurance)	16.5%
Permitting	35%

Each is a fraction of the running total, not of the construction subtotal, so they multiply rather than add - on the sample reach they roughly double the figure.

Quantities that cannot be derived are not invented

A rate priced per area follows from a feature map directly. A rate priced per log or piece follows only through an assumption - the original’s workbook divided the area by a log_length of 25, taking one log to occupy that squared - and log_length is a parameter here for exactly that reason.

A rate priced per yard of bank, per culvert or per bridge does not follow from an area at all. Those are left empty and reported in the log rather than filled with a number that looks authoritative and is not. Enter them yourself.

Reading the result

run() returns the bill, the group subtotals, the applied rates, the habitat gain and the ratio, and writes a CSV bill of quantities listing only the lines that carry a quantity.

A project that does not increase habitat area has no cost-benefit ratio; cost_per_area is None and the log says so, rather than reporting a negative number that reads like a bargain.

Comparing a condition that has no flow duration curve raises rather than returning a half-comparison: build one first with Get Started ▸ analyze flows (Get started, terminology and signposts).

In this section

• Project Maker
• Introduction to the Project Maker module
• Quick GUIde to a project assessment
• Cost quantity assessment and the cost master workbook
• Mapping of construction elements
• Ecological benefit asessment (Calculate SHArea)

See also

riverarchitect.projectmaker in the API reference.