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User Forum

All Topics | Topic "Unexpected Flow Behaviour"
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Author Message
Mr. Michael Mutz

Subject: Unexpected Flow Behaviour   
Posted: 3/20/2018 Viewed: 86 times
I have a problem with the WEAP model that I am setting up. As mentioned in a forum post earlier, I model different pathways that water can take, possibly from the same source to the same destination. These intermediate nodes have the sum of the fractional demands of all its destinations as demand. The intermediate nodes have the same priority and a higher priority than the destination nodes, the intermediate nodes' consumption is 0.

For example, two villages could get 70% of their water via tankers. That means that the tanker node would have 0.7*(demand(village1) + demand(village2)) as requirement.

Another source of water is a dam that is conceptually modeled as a simple reservoir. The maximum outflow that can be provided by this source is set in the transmission link. The water is supplied to a pumphouse that has the sum of the respective demands of the destination nodes as demand. The pumphouse also receives water from the groundwater node, but only in case if the reservoir water is not sufficient to cover the pumphouse's demand.

Are these approaches for modeling this equivalent?

1. actual_reservoir_supply = min(reservoir_maximum_supply, actual_pumphouse_demand) in the reservoir -> pumphouse link, supply priority 1

maximum_flow = If(actual_pumphouse_demand > reservoir_maximum_supply, actual_pumphouse_demand - reservoir_maximum_supply, 0) in groundwater-> pumphouse link, supply priority 1

2. actual_reservoir_supply = min(reservoir_maximum_supply, actual_pumphouse_demand) in the reservoir -> pumphouse link, supply priority 1

supply priority 2 at groundwater-> pumphouse link


All this worked as expected, however, when I added another village (NKT Domestic) that receives water through three other, separate intermediate nodes, the transmission link groundwater -> pumphouse disappears in the table results. When I deactivate any of the three new intermediate nodes, the groundwater -> pumphouse link is shown as expected. Also, the same amount of 204.93 million litres is supplied from the pumphouse in both cases although the reservoir can and does only provide 198.89 million litres.

Do you have any suggestions on why this might happen? There is no restriction in groundwater availability and the priorities should also be the same.

Here are some pictures:
general overview:
https://flic.kr/p/24gBLfQ

All transmission links connected:
overview
https://flic.kr/p/22AjwMQ
flow table (no flow to KK Groundwater!)
https://flic.kr/p/24gBKtj

Link from GW to NKT private tanker disabled:
overview
https://flic.kr/p/Hdt2RE
table
https://flic.kr/p/23ZfbnZ









Mr. Michael Mutz

Subject: Re: Unexpected Flow Behaviour   
Posted: 4/16/2018 Viewed: 82 times
The issue seems to have not been the actual flow behaviour, instead, the transmission link flow view is not correct if it is set to "all", since it does not display all transmission links, as in this example. If "selected links" is activated, I could manually select all actually present and used transmission links.
Topic "Unexpected Flow Behaviour"