UNCERTAINTY IN THE RETURN PERIOD OF MAXIMUM HYDROLOGIC EVENTS: A BAYESIAN APPROACH

The effect of uncertainty in parameters of rainfall inputs on the return period of maximum rainfall amounts and runoff volumes in a thunderstorm season is ascertained. First, the return period T sub R of the maximum seasonal rainfall amount is considered using an event-based rainfall model which possesses the following features: (1) the distribution of the number of events per season N is Poisson with mean m; (2) the distribution of point rainfall amount R per event is exponential with mean 1/u; and (3) N and R are independent. Then, the case of uncertainty in the return period T sub Q of the maximum seasonal runoff volume Q for an ungaged streamsite is studied. T sub Q is calcualted on the basis of the above event-based rainfall model coupled with a linear rainfall--runoff relationship. A correct distribution function for the return period T sub R and T sub Q is obtained by integrating out the uncertainty in m and u, which is encoded in prior conjugate distribution. It is found that the expected values of the return periods possess a certain bias, and that the variances are substantial even for a record length of twenty years. This demonstrates the advantage of following this approach for a decision- theoretic analysis of a water-resource design problem. The approach enables us furthermore to design structrures, relying only on rainfall data on watersheds with ungaged streams, by taking into account uncertainty of design site parameters. Also, the design can be tailored to a specific problem rather than rely on the strict use of a prespecified T-year design flood. /Auther/

  • Corporate Authors:

    Elsevier

    Radarweg 29
    Amsterdam,   Netherlands  1043 NX
  • Authors:
    • Davis, D R
    • Duckstein, L
    • Fogel, M M
  • Publication Date: 1976-9

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 81-95
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00141512
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 17 1976 12:00AM