Todini Index Calculation for the Net6 network - Values outside the range [0,1] about wntr

[kbonney]

I was able to reproduce this with the following snippet:

import wntr

inp_file = 'Net6.inp'
wn = wntr.network.WaterNetworkModel(inp_file)
wn.options.time.duration = 96*3600
sim = wntr.sim.WNTRSimulator(wn)
results = sim.run_sim()

head = results.node["head"]
pressure = results.node["pressure"]
demand = results.node["demand"]
flowrate = results.link["flowrate"] 
todini = wntr.metrics.hydraulic.todini_index(head, pressure, demand, flowrate, wn, 21.09)
todini.plot()

Not sure why we are seeing those unexpected values, though. Will continue to look into this.

[amsinhaubc]

I was able to reproduce this with the following snippet:

import wntr

inp_file = 'Net6.inp'
wn = wntr.network.WaterNetworkModel(inp_file)
wn.options.time.duration = 96*3600
sim = wntr.sim.WNTRSimulator(wn)
results = sim.run_sim()

head = results.node["head"]
pressure = results.node["pressure"]
demand = results.node["demand"]
flowrate = results.link["flowrate"] 
todini = wntr.metrics.hydraulic.todini_index(head, pressure, demand, flowrate, wn, 21.09)
todini.plot()

Not sure why we are seeing those unexpected values, though. Will continue to look into this.

Thanks for looking into this.

[kaklise]

The Todini index generally results in values between 0 and 1, but values below 0 and above 1 are possible. The paper by Jayaram includes an explanation and suggests a modified resilience index (MRI), which is also included in WNTR.

WNTR function for MRI: https://usepa.github.io/WNTR/apidoc/wntr.metrics.hydraulic.modified_resilience_index.html#wntr.metrics.hydraulic.modified_resilience_index

Jayaram, N., & Srinivasan, K. (2008). Performance‐based optimal design and rehabilitation of water distribution networks using life cycle costing. Water resources research, 44(1).

[amsinhaubc]

The Todini index generally results in values between 0 and 1, but values below 0 and above 1 are possible. The paper by Jayaram includes an explanation and suggests a modified resilience index (MRI), which is also included in WNTR.

WNTR function for MRI: https://usepa.github.io/WNTR/apidoc/wntr.metrics.hydraulic.modified_resilience_index.html#wntr.metrics.hydraulic.modified_resilience_index

Jayaram, N., & Srinivasan, K. (2008). Performance‐based optimal design and rehabilitation of water distribution networks using life cycle costing. Water resources research, 44(1).

Thanks @kaklise for your reply and the link to the paper. Please correct me if I am wrong, the highest Todini Index attainable is one, while MRI can theoretically range till infinity.