On the current state of the Hydrologic Evaluation of Landfill Performance (HELP) model

• Published in: Waste management (Elmsford) Vol. 38; pp. 201 - 209
• Main Author: Berger, Klaus U.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.04.2015
• Subjects: Cover systems; Environmental Monitoring; Evapotranspiration; HELP model; Hydrology; Landfill liner systems; Landfills; Liners; Mathematical models; Models, Theoretical; Performance evaluation; Refuse Disposal - methods; Simulation; Soil - chemistry; Soil Pollutants - analysis; Validation; Waste Disposal Facilities; Water balance; Water Pollutants, Chemical - analysis; Germany, Berlin; Validation; Landfill liner systems; Water balance; Simulation; Cover systems; HELP model
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2015.01.013

•The history of the HELP model and the three current versions are summarized.•Validation studies of HELP 3 concerning covers are summarized.•Measured discharges were compared to simulation results of HELP 3.95 D for test fields in covers of two German landfills.•Further improvement of HELP model shall focus on percolation and evapotranspiration. The Hydrologic Evaluation of Landfill Performance (HELP) model is the most widely applied model to calculate the water balance of cover and bottom liner systems for landfills. The paper summarizes the 30year history of the model from HELP version 1 to HELP 3.95 D and includes references to the three current and simultaneously available versions (HELP 3.07, Visual HELP 2.2, and HELP 3.95 D). A sufficient validation is an essential precondition for the use of any model in planning. The paper summarizes validation approaches for HELP 3 focused on cover systems in the literature. Furthermore, measurement results are compared to simulation results of HELP 3.95 D for (1) a test field with a compacted clay liner in the final cover of the landfill Hamburg-Georgswerder from 1988 to 1995 and (2) a test field with a 2.3m thick so-called water balance layer on the landfill Deetz near Berlin from 2004 to 2011. On the Georgswerder site actual evapotranspiration was well reproduced by HELP on the yearly average as well as in the seasonal course if precipitation data with 10% systematic measurement errors were used. However, the increase of liner leakage due to the deterioration of the clayey soil liner was not considered by the model. On the landfill Deetz HELP overestimated largely the percolation through the water balance layer resulting from an extremely wet summer due to an underestimation of the water storage in the layer and presumably also due to an underestimation of the actual evapotranspiration. Finally based on validation results and requests from the practice, plans for improving the model to a future version HELP 4 D are described.