Report No FR0108

THE DEVELOPMENT OF A DYNAMIC RIVER WATER
QUALITY MODEL (SPRAT) FINAL REPORT

FR0108

June 1990

SUMMARY

I OBJECTIVES

To document the development and operation of the dynamic river water quality model known as SPRAT (Spill Pollution Response Assessment Technique).

II REASONS

Intermittent discharges from combined sewer overflows can have a significant impact on river water quality. A dynamic river water quality model is required to enable this impact to be assessed in terms of proposed intermittent water quality standards.

Development of SPRAT has ceased for the foreseeable future and as a result the model described in this report is not a fully supported software product. Readers may wish to consider further development of the model but the FWR bears no liability for its use in its present form.

III CONCLUSIONS

The introduction of transient pollution standards for the control of intermittent storm sewage discharges requires a new planning/design framework. Within this framework, the use of mathematical tools such as MOSQITO, SPRAT and MIKE-11 will become increasingly important. SPRAT has been developed as a stepping stone between the existing "best available approach" (CARP) and the more sophisticated approach in the MIKE-11 model. As such, the development of SPRAT has served to allow the detailed requirements of the more sophisticated approach to defined and provides the basis for sewerage engineers and river water quality planners to gain experience in the use of the new standards, while still using existing sewer flow models, such as WASSP in conjunction with simple pollution load assessment techniques (SRM2).

IV RECOMMENDATIONS

  1. SPRAT may continue to provide a useful intermediate approach between the simple event load method CARP and the sophisticated MIKE-11 model. Consideration should be given to providing support to enable it to fulfil this role.
  2. The current version of SPRAT needs further development to enable it to be widely utilised within the new planning/design framework. Funds should be sought to allow this work to be undertaken in the near future.

V RESUME OF CONTENTS

Section 1 gives a brief background to the development of SPRAT within the context of the Urban Pollution Management research programme.

Sections 2 to 7 gives details of the requirement specification of SPRAT and the various components of the model. These components are flood routing, pollutant routing, sediment transport and biochemical processes.

Sections 8 and 9 cover the operation of the model. Details of the various input and output files utilised and generated by SPRAT during a model simulation are given.

Section 10 is the final section of the report and covers the conclusions and recommendations for future work.

Copies of the report are available from FWR, price 35.00, less 20% to FWR Members.