Potential and Limitations of Applying HELP Model for Surface Covers

Berger, Klaus

doi:10.1061/(asce)1090-025x(2002)6:3(192)

Cited by 6 publications

(5 citation statements)

References 7 publications

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“…On the other hand, there is also no automatic correction of the global solar radiation due to exposure and slope gradient; thus, this step should be carried out separately before the simulation run. The HELP model also underestimates the influence of the leaf area index, structure, and evaporative zone depth and, therefore, the actual evapotranspiration, which was also already described in the literature [30].…”

Section: Limitations Of the Modeling Approachsupporting

confidence: 56%

“…This discrepancy can be explained by the dense installation of the recultivation layer resulting in root depths at a maximum of 0.35 m to 0.4 m and therefore limited transpiration capacity, as mentioned in the literature [48]. The HELP model also assumed a constant LAI of 3.5 m 2 /m 2 , underestimating the transpiration performance during the vegetative period [30]. Furthermore, the observed interception was determined according to a method in the literature [22], which included a risk of potential underestimation of the interception performance.…”

Section: Plausibility Of the Observed And Modeled Water-balance Compomentioning

confidence: 99%

“…Thus, the vegetative growth and decay submodel included in HELP was taken from the simulation model for water resources in rural basins (SWRRB) [28], whose developers adopted it in a simplified form from the EPIC model [29]. Therefore, FC (US: −33 kPa) is the lowest soil water content to allow unsaturated vertical flow (drainage) within the evaporative zone [30]. The interception-storage and interception-height capacity were calculated by the approach of reference [22], modified and adapted to German standards [31].…”

Section: Help Modelmentioning

confidence: 99%

“…The observed annual precipitation rates between 655 mm and 767 mm were plausible compared to the long-term average precipitation rate in the study area of 752 ± 186 mm between 1991 and 2015. Thus, the uncorrected precipitation data were used as input parameters for the HELP model as mentioned in the literature [30]. It should be kept in mind that the observed precipitation data could be underestimated by up to 17% [25,44], caused by wetting failures and wind-induced precipitation losses [45].…”

Section: Plausibility Of the Observed And Modeled Water-balance Compomentioning

confidence: 99%

“…In our analysis, we assumed static soil conditions to establish the modeling process [30], but structure formation processes could be attributed to swell shrink and biological processes over time, which can be also explained by the in situ matric potential dynamics [1], resulting in possible changes of water-storage capacity [49]. Furthermore, aging or drying of the mineral layer would also not be considered, so the Ks value did not vary during the complete period.…”

Section: Limitations Of the Modeling Approachmentioning

confidence: 99%

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Assessment of Leachate Production from a Municipal Solid-Waste Landfill through Water-Balance Modeling

2018

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Mineral temporary capping systems of landfills are required to accomplish the long-term coverage prerequisites or to use them as a basis layer prior to later permanent sealing. Such a capping system for a municipal waste landfill in Rastorf (Northern Germany) was developed and tested for its sealing capability on the basis of observed and simulated water balance components for the period between 2008 and 2015, considering observed local weather data and complemented by the Hydraulic Evaluation of Landfill Performance (HELP 3.95 D) model. The modeling results of this case study could be improved by the correction of previously used global solar radiation data due to the consideration of exposure and inclination angle of landfill surface areas. The model could positively be validated by comparing observed and simulated outflow (surface runoff and lateral drainage) data with R2 values ranging between 0.95 and 0.99, as well as for the leachate rates with R2 values of 0.78–0.87. The statistical-empirical HELP model was found useful in predicting the leachate generation of a temporary landfill capping system for specific soil and site conditions, even if only a restricted set of observed data was available.

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Section: Limitations Of the Modeling Approachsupporting

confidence: 56%

Section: Plausibility Of the Observed And Modeled Water-balance Compomentioning

confidence: 99%

Section: Help Modelmentioning

confidence: 99%

Section: Plausibility Of the Observed And Modeled Water-balance Compomentioning

confidence: 99%

Section: Limitations Of the Modeling Approachmentioning

confidence: 99%

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Assessment of Leachate Production from a Municipal Solid-Waste Landfill through Water-Balance Modeling

2018

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Leachate modeling for a municipal solid waste landfill for upper expansion

Min

Kim

et al. 2010

KSCE J Civ Eng

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This study sought to predict leachate levels within a municipal solid waste landfill and evaluate design alternatives for landfill expansion using the U.S. Geological Survey modular flow model with new flow and contaminant transport packages (MODFLOW-SURFACT). This was used to overcome the drawbacks of the more widely used Hydrologic Evaluation of Landfill Performance (HELP) model in predicting leachate levels and movement within a landfill. The valley landfill in this study had two imminent issues regarding leachate management. One was its current high leachate levels, and the other was the selection of a design option for the bottom of the expanded landfill above it. According to the model calibration, relatively high leachate levels in the current landfill were attributed to unsatisfactory leachate removal efficiency by the leachate collection system. Additional leachate pumping was necessary to prevent possible leachate level increase after the landfill expansion over the current landfill. Based on numerical investigations of the design options of the expanded landfill bottom, the separation of leachate generated in the upper (expanded) landfill from the lower (existing) one is recommended, indicating that a low permeable layer such as a liner is an essential component. MODFLOW-SURFACT can be successfully used to calibrate landfill properties and predict hydraulic performance with given landfill conditions, particularly for a valley landfill.

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Leachate Generation Modeling

Alibardi¹,

Cossu²

2018

Solid Waste Landfilling

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Potential and Limitations of Applying HELP Model for Surface Covers

Cited by 6 publications

References 7 publications

Assessment of Leachate Production from a Municipal Solid-Waste Landfill through Water-Balance Modeling

Assessment of Leachate Production from a Municipal Solid-Waste Landfill through Water-Balance Modeling

Leachate modeling for a municipal solid waste landfill for upper expansion

Leachate Generation Modeling

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