Review of stochastic and other approaches in water resources planning: summary
Published 6 June 2025
Applies to England
© Crown copyright 2025
This publication is licensed under the terms of the Open 바카라 사이트 Licence v3.0 except where otherwise stated. To view this licence, visit or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gov.uk.
Where we have identified any third party copyright information you will need to obtain permission from the copyright holders concerned.
This publication is available at /government/publications/review-of-stochastic-and-other-approaches-in-water-resources-planning/review-of-stochastic-and-other-approaches-in-water-resources-planning-summary
1. Chief Scientist바카라 사이트™s Group report summary
This project reviewed the use of stochastic and other approaches in water resources planning, including their current use and limitations, potential developments and alternative options.
1.1 Background
Stochastic simulation methods, where realistic rainfall totals are drawn at random from a probability distribution, have become an established way for water companies to create a large set of rainfall inputs for hydrological models, extending beyond the observed record. But there has been little to no assessment of their use in practice, or appropriateness when considering future climate. This project aimed to review the science behind stochastic methods and the performance of existing products, whilst clarifying their strengths, weaknesses and appropriate uses, alongside an equivalent appraisal of alternative approaches.
1.2 Approach
The project consisted of a review of the stochastic methods currently used by water companies, and the potential alternatives. This was primarily literature-based, including both academic and grey (e.g. water company documents) and the findings summarised in topic focused reviews (e.g. climate change). This was then complimented with semi structured interviews with both users and creators of stochastic datasets.
1.3 Results
The review has drawn together the current body of knowledge on stochastic methods and other approaches to water resource planning. It concludes that there is not one single approach or dataset that meets all the needs of water resources planning and that there are trade-offs when deciding which approach to use. It has also identified gaps in our knowledge and made recommendations, including the need for improved consideration of the:
- Effects of non-stationarity and long-term variability
- Incorporation of climate change
- Biases in stochastic model, especially when applied to future climate
- Interpolation and generation of extremes that are not present in observed data.
The outputs include a summary report and a collection of individual topic reviews in a separate annex report.
1.4 Conclusion
The improved understanding of stochastic methods, and alternative options, is important for both the Environment Agency and those we regulate (water companies). It will help promote discussion on their appropriate use and help shape the future direction of water resources planning. The identification of knowledge gaps also provides a basis for future research.
1.5 Publication details
This summary relates to information from project SC220039 reported in detail in the following outputs:
- Report: SC220039/R1
- Title: Review of stochastic and other approaches in water resources planning
- Report: SC220039/R2
- Title: Annex to the review of stochastic and other approaches in water resources planning
- Project manager: Stuart Allen, Chief Scientist바카라 사이트™s Group
This project was commissioned by the Environment Agency바카라 사이트™s Chief Scientist바카라 사이트™s Group, which provides scientific knowledge, tools and techniques to enable us to protect and manage the environment as effectively as possible.
Enquiries: research@environment-agency.gov.uk.
© Environment Agency