Validation and Adaptation of the Simulation Model HELP for Calculating the Water Balance of Landfills under German Climatic Conditions

Project Description

Simulation models can be powerful tools for suitability tests, water balance calculations, and the hydraulic dimensioning of landfill liner systems. They can be used in planning, risk assessment, and during aftercare. Precondition for the practical application of any model is a sufficient trust in the model's results, i.e. a sufficient validation. In the U.S.A. the "Hydrologic Evaluation of Landfill Performance" (HELP) model was developed for simulating the water balance of liner systems and covers. The current version 3.07 of HELP (Schroeder et al. 1994) was examined in a validation study under German climatic conditions (Berger 1998). The study consists of three parts:

• a methodological part (review of the concept, methods and limitations of validation),
• a theoretical part (comparison of the modeling approach of HELP to the state of the science, comparison of HELP to four other models for the soil water budget), and
• a practical part (sensitivity analyses for the top soil layer and the vegetation, and for lateral drainage layers, respectively; operational validation using measured data of the test fields in the cover of the landfill Hamburg-Georgswerder).

Limitations of the HELP model, some errors and pitfalls of applying the model were shown, conclusions for the user were drawn, and suggestions for a further development of HELP and future research needs were pointed out. HELP is a suitable tool for experienced users who are familiar with the model and its limitations.

Furthermore, the HELP model was adapted for the application in Germany (HELP 3.07 D).

Practical Application

An accompanying working group of the German Geotechnical Society published three recommendations; one of them is concerned with the application of the HELP model in Germany (GDA-Empfehlung E 2-30, available only in German). In September 2000 the working group held a conference to discuss the recommendations with professionals. The conference proceeding are published as Hamburger Bodenkundliche Arbeiten 47 (available only in German).

HELP 3.07 D and the enhanced successor versions are used by engineering companies, authorites and universities in Germany and beyond esp. in planning.

Selected Literature

• Berger, K., 1998: Validierung und Anpassung des Simulationsmodells HELP zur Berechnung des Wasserhaushalts von Deponien für deutsche Verhältnisse. Umweltbundesamt, Fachgebiet III 3.6 (PT AWAS des BMBF), Berlin, 569 S. (in German)
• Berger, K., 2000: Validation of the Hydrologic Evaluation of Landfill Performance (HELP) Model for Simulating the Water Balance of Cover Systems. Environmental Geology 39 (11), pp. 1261-1274
• Berger, K., 2002: Potential and Limitations of Applying HELP Model for Surface Covers. Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management, Vol. 6, No. 3, July 2002, pp. 192-203
• Schroeder, P.R. et al., 1994: The Hydrologic Evaluation of Landfill Performance (HELP) Model. 2 Bände: User's Guide for Version 3; Engineering Documentation for Version 3; EPA/600/R-94/168a,b; US Environmental Protection Agency, Cincinnati, Ohio
• Schroeder, P.R., Aziz, N.M., Lloyd, C.M., Zappi, A.P., Berger, K., 1998: Das Hydrologic Evaluation of Landfill Performance (HELP) Modell. Benutzerhandbuch für die deutsche Version 3 (HELP 3.07 D, program with English user interface and user's guide in German). Institute of Soil Science, Universitaet Hamburg

For further literature visit the HELP-D successor versions.