Good day
My name is Essy, am currently working on a project, and I want to determine the current and future Water demand and supply for Tugela catchment in South Africa. However am experiencing problems, The catchment has more than 1 gauge station, and when I am trying to calibrate the stream flows I am experiencing problems because while adjusting the hydrological parameters for one gauge station, the other one statistics parameters are also changing. I need help with calibrating more than one gauge station.

Another problem is there are mines and bulk industries around the catchment but I cannot determine the annual activity level, annual activity rate and consumption because there is little to no data available. This problem is also experienced with livestock data

Another problem is, there is a transfer out within the catchment how do I put that into Weap.

How do I project future Water demand and supply, using Weap?

Thank you

Essy,

The challenges of calibration and lack of detailed data are extremely common for water models, but unfortunately lack easy solutions. But, I'll try and help here.

There is often a balance, as you say, in calibrating for multiple stations. The general approach is to first calibrate the most upstream and unimpaired (lack of human development impacts) gauge station first. Then, work your way downstream. If the more downstream gauge is not calibrated well using the parameters from the upstream gauge, first explore if you have represented any major human operations well enough. If you have, then you may need to adjust your calibrations for both upstream and downstream gauges. Often, you can achieve the same results for a single gauge using a different combination of parameters- you may need to adjust the combination you are using so that it works for both gauges at once. It is difficult to give much specific advice on this topic, but I recommend to see the Calibration chapter of our tutorial (www.weap21.org/tutorial) or our YouTube channel which describes the use of the Model Inspector calibration tool: https://www.youtube.com/watch?v=Notx1vfeRCk&lc=UgzcXOePTuvAWINNIjx4AaABAg.

Your challenge in lacking specific demand data is also common. While there are tools to estimate the agriculture use, mining, industry, and livestock are more unique. A big part of the task of building the water model is collecting this data, so consider this a part of your process. My best advice would be to search for academic literature and public government information on this topic, plus to reach out to local experts involved in the industry in the area who may be able to help.

A transfer out of the watershed could be modeled with a demand node. If you want to continue to model the water after it is transferred, you could set your demand node to have 0% consumption and to have a return link into a different river or diversion object.

Future water demand and supply can be modeled using either time-series data going into the future (set your Years and Time steps accordingly in WEAP), or by using the functions contained within Expression Builder. But, to know what your future demand will be, you will have to find this data or create estimates based on local knowledge as mentioned above. If you are interested in modeling future climate impacts on hydrology and agriculture demand, WEAP contains future climate data within the Catchment Delineation Mode- this future climate can be used to modify the future agriculture demand and catchment hydrology.

Hope this helps!
-Doug