Subject: Modelling a demand site as water treatment plant. Posted: 5/22/2025 Viewed: 1793 times
Hello everyone, i'm here to ask about the possibility of using a demand site to model a water treatment plant since the software doesn't have one. If possible, how do i go about it ? Assuming my treatment plant capacity is 25.5 million gallons per day, where do i add that to ? The annual activity level ? or the water use rate ? Or would you recommend me using a wastewater treatment node ?
Mr. Doug Chalmers
Subject: Re: Modelling a demand site as water treatment plant. Posted: 5/23/2025 Viewed: 1747 times
Muritala,
I would recommend using a WWTP object to represent a water treatment plant. Are you looking to divert water from a river, treat it in a water treatment plant, then send it to a demand site? If so, you could make a "dummy" demand node that diverts water out of the river- set its expression to the same demand and priority as your real demand node, but with consumption of 0. Send the dummy return flow to the WWTP, then connect a transmission link from the WWTP to the real demand node.
Alternatively, you could set the the BOD/DO/other water quality parameter Concentration within a demand node to set its outflow concentration from the demand site. To limit the amount flowing to a demand site, set the Maximum Flow Volume on a transmission link.
Hope this helps!
-Doug
Mr. Muritala Kadiri
Subject: Re: Modelling a demand site as water treatment plant. Posted: 5/23/2025 Viewed: 1706 times
Alright, thank you very much for this tip. I'll try it out immediately and give you a feedback.
Mr. Muritala Kadiri
Subject: Re: Modelling a demand site as water treatment plant. Posted: 5/26/2025 Viewed: 1623 times
Hello Mr Doug. After following your recommendation, the supply to my main demand sites still seems to be zero. All that has changed is that the demand has doubled. could you tell me where the problem could possibly come from ? and if this doesn't work, is there a way i could make it work? i've tried reducing the capacity of the transmission links to fit the capacity of the treatment plants supplying water but the coverage drops to zero after the second year.
Thanks in anticipation.
Mr. Doug Chalmers
Subject: Re: Modelling a demand site as water treatment plant. Posted: 5/27/2025 Viewed: 1593 times
Muritala,
I would check the flow results for each object to see where the inflow stops. Make sure that your consumption on your first demand node is 0% and that you've entered a daily capacity for your WWTP.
-Doug
Mr. Muritala Kadiri
Subject: Re: Modelling a demand site as water treatment plant. Posted: 5/27/2025 Viewed: 1572 times
Thank you very much. I checked my inflows and discovered that the supply didn't change because there was no reservoir inflow data in my model. So I'll fix that and see how that turns out. Though I'd like to ask though, I've got 4 reservoirs in my study area. Would using one catchment to simulate the Hydrology do the job for all via the soil moisture method ? Or do I have to create catchments for each reservoir I'm working on ?
Thank you.
Mr. Doug Chalmers
Subject: Re: Modelling a demand site as water treatment plant. Posted: 5/27/2025 Viewed: 1555 times
Assuming the intake points for the 4 reservoirs are in different places, I'd recommend at least 4 different catchments. Generally, you want to create a new catchment upstream for each location you need to have accurate flow modeled in the model.
Mr. Muritala Kadiri
Subject: Re: Modelling a demand site as water treatment plant. Posted: 6/16/2025 Viewed: 595 times
Hello mr doug. Thank you for your responses i really appreciate them. I'm here once again to ask for your invaluable insight on my model. Before you go on, i'd like to apologize for my extremely long write-up here. I felt the need to write this so you could a good idea of the model.
To break it down, I'm modelling the historical water demand and supply for my study area (1999-2024) and model some allocation scenarios after (2025-2050) . I have three demand sites and dummy sites as you recommended earlier. For these demand sites, i also have three reservoirs that supply these demand sites. However, these reservoirs and demand sites have a peculiar relationship; let's call these sites east,west and south.
1. The reservoir 1 = 43 million cubic meters(supplies all sites) and is the sole supplier of the west site.
2. Reservoir 2 = 1.344 million cubic meters supplies the south site along with the reservoir 1.
3. Reservoir 3 = 1 million cubic meters supplies the east demand site along with the reservoir 1.
After creating this model, I see errors with how the supply and unmet demand are presented. For example; the supply not being constrained after hitting the WTP capacities limit making the unmet demands much smaller than they should actually be.
From my reaserch, I've seen that it's either an allocation order issue or a capacity constraint issue but i'm still yet to solve it. So i'd like to ask for your insight and recommendations on how to go about this.
Thank you for your assitance.
Mr. Doug Chalmers
Subject: Re: Modelling a demand site as water treatment plant. Posted: 6/17/2025 Viewed: 565 times
Muritala,
Two things come to mind. One is that the priority of any downstream demand node or reservoir must be a higher priority than the filling priority of the upstream reservoir. If the downstream priority is not higher, then the upstream reservoir will only release water when totally full.
The other is that the WWTP capacity isn't the limit of the water able to flow through it or be sent through it. Rather, it is the limit of the amount of water able to be treated. More water than this limit can flow through the WWTP- it simply will just not be treated.
Generally, I encourage you to look at the results for flow through transmission links, demand site supplied delivered, and river streamflow to see how the water is moving through the system. I might especially suggest using the Map results feature to visualize this. From here, you can identify the particular object where the flow results begin to look different than what you expected.
Hope this helps!
-Doug
Topic "Modelling a demand site as water treatment plant."
