Truly Integrated Catchment Modelling

March 29, 2018 Categories: Articles

Truly Integrated Catchment Modelling!

Environmental modelling has come a long way from the early attempts to represent water company assets and their interactions with the natural world.  But are these tools fit for purpose now when there is focus on integrated asset management and catchment management solutions?  WRc’s innovative integrated catchment model, SIMPOL ICM is being used now to address these concerns.

The water cycle

The basic water cycle that is taught to all school aged children appears to be straight forward; water evaporates from the earth’s water bodies – seas and lakes, rises into the skies and forms clouds then drops back to earth as rain (or other forms of precipitation) flowing over the land to form rivers which return to the sea. But put human kind into the picture and things get more complicated.  In fact the human water cycle is a complex system with many interrelationships and knock-on effects that are not well understood.


Managing water assets in a changing world

Water companies are tasked with delivering clean, wholesome water to their customers and dealing with the wastewater generated from its use. This requires abstraction of water from rivers or groundwater and treatment of that water to a suitable standard before distribution to homes and businesses.  Once used, the wastewater is collected and treated to an acceptable standard before being returned to the rivers or seas.  Many factors can affect this cycle and water companies are faced with many questions when trying to manage their assets in this changing environment.

  • How clean is the water to begin with – is it contaminated with chemicals arising from agriculture or from run-off from the urban environment?
  • How can water companies continue to provide enough water to meet ever increasing demand?
  • What sort of treatment is required to clean the water to drinking water standards? How much will this cost? Is it better to protect the water source from contamination in the first place through catchment management solutions? 
  • What sort of wastewater treatment is required to allow the water to be returned to the environment? How much will it cost? Is it better to treat the wastewater locally or to centralise at a large wastewater treatment works?
  • How will the river environment change over time whether that be short term seasonal variations, during periods of extremes: high rainfall or drought, or through future decades due to the effects of climate change?


The role of computer models

The water industry uses computer models to predict how its physical assets such as treatment works and pipe systems interact with the natural world.  The introduction of the Urban Pollution Management (UPM) Procedure in the 1990s saw the integration of wastewater network systems and river modelling tools to understand their impact on the receiving water.  Likewise the drinking water supply side of the industry has its own set of tools for assessing resources, distribution, treatment and supply. But there is little or no integration between the two to provide a comprehensive view across the whole water cycle.

The current modelling tools are not ideal for this joined up view of the whole water cycle due to their detailed nature leading to high data input requirements and long run times. So a different approach is required which is why WRc has developed SIMPOL ICM, a rationalised model which can:

  • represent all aspects of the human water cycle from the customer demand for potable water and its supply and treatment through to the environmental impact of wastewater discharges.
  • be calibrated to the more detailed wastewater and water supply models already routinely used
  • be run over long periods of time to understand the key interactions and their impacts – working out what’s important and what isn’t.
  • identify a range of potential catchment wide solutions quickly and help eliminate less favourable options.

So how does this bring benefits to the water industry?

  • Water companies can understand their resilience to changes in the human water cycle, when
    • their resources become compromised such as when demand > supply
    • environmental targets may be exceeded
    • assets need upgrading
  • Water companies and regulators can have more confidence in Business Plans
  • Water companies can achieve regulatory standards at lowest cost to customer
  • Water companies can use the tools and modelling outputs to communicate to their stakeholders

Karen Light, Head of Catchment Management & Dr Karen Murrell, Senior Environmental Modeller, WRc


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