1.   Purpose and objectives

     To review mass load estimation procedures and to recommend methods to improve the accuracy of load estimates.

2.   Description

     This component is a report containing a review of the methods most commonly employed in river load estimation based principally on key papers and reports. This is introduced by a brief explanation of some of the terms and concepts involved in error analysis and a definition of interpolation and extrapolation methods. Other topics covered in this review include transfer function models, flow proportional and probability sampling, real-time updated stratified sampling and hydrograph separation
with examples. Problems and sources of different types of error are discussed.

     This report also illustrates how a computer program for data generation might be used to help solve the problem of the lack of long time series of flow and concentration data. As an example, the use of a
prototype program, SMILER (Simulation and Methods Investigation of Load Estimates for Rivers), is demonstrated. To test the validity of this type of program, the results of the application of SMILER in a particular case concerned with nitrate loading are presented and assessed.

     There is a section on UK databases concerned with river quantity and quality, and one on UK river load surveys.

     The report concludes with recommendations and suggestions for further work relating to the topics discussed.

3.   Input

     Not applicable.

4.   Output

     Not applicable.

5.   Operational requirements and restrictions

     Not applicable.

6.   Form of presentation

     Report in English: Institute of Hydrology Report no. 117, 81 pages, 34 figures, 9 tables.

7.   Operational experience

     Not applicable.

8.   Originator and technical support

     Institute of Hydrology, Wallingford.

9.   Availability

     From the HOMS National Reference Centre for the United Kingdom.

10.  Conditions on use

     Free of charge.