Rahmah Elfithri

Modeling of methane oxidation in landfill cover soil using an artificial neural network

Knowing the fraction of methane (CH4) oxidized in landfill cover soils is an important step in estimating the total CH4 emissions from any landfill. Predicting CH4 oxidation in landfill cover soils is a difficult task because it is controlled by a number of biological and environmental factors. This study proposes an artificial neural network (ANN) approach using feedforward backpropagation to predict CH4 oxidation in landfill cover soil in relation to air temperature, soil moisture content, oxygen (O2) concentration at a depth of 10 cm in cover soil, and CH4 concentration at the bottom of cover soil. The optimum ANN model giving the lowest mean square error (MSE) was configured from three layers, with 12 and 9 neurons at the first and the second hidden layers, respectively, log-sigmoid (logsig) transfer function at the hidden and output layers, and the Levenberg-Marquardt training algorithm. This study revealed that the ANN oxidation model can predict CH4 oxidation with a MSE of 0.0082, a coefficient of determination (R 2) between the measured and predicted outputs of up to 0.937, and a model efficiency (E) of 0.8978. To conclude, further developments of the proposed ANN model are required to generalize and apply the model to other landfills with different cover soil properties. Implications: To date, no attempts have been made to predict the percent of CH4 oxidation within landfill cover soils using an ANN. This paper presents modeling of CH4 oxidation in landfill cover soil using ANN based on field measurements data under tropical climate conditions in Malaysia. The proposed ANN oxidation model can be used to predict the percentage of CH4 oxidation from other landfills with similar climate conditions, cover soil texture, and other properties. The predicted value of CH4 oxidation can be used in conjunction with the Intergovernmental Panel on Climate Change (IPCC) First Order Decay (FOD) model by landfill operators to accurately estimate total CH4 emission and how much it contributes to global warming.

OECD principles on water governance in practice: an assessment of existing frameworks in Europe, Asia-Pacific, Africa and South America

ABSTRACT Through the lens of the 12 OECD Principles on Water Governance, this article examines six water resources and water services frameworks in Europe, Asia-Pacific, Africa and South America to understand enhancing and constraining contextual factors. Qualitative and quantitative methods are used to analyze each framework against four criteria: alignment; implementation; on-ground results; and policy impact. Four main target areas are identified for improving water governance: policy coherence; financing; managing trade-offs; and ensuring integrity and transparency by all decision makers and stakeholders. Suggestions are presented to support practical implementation of the principles through better government action and stakeholder involvement.

Integrated Water Resources Management in Malaysia: Some Initiatives at the Basin Level

The concept of Integrated Water Resources Management (IWRM) was first introduced in Malaysia since 1990s in various forms. However, the key issue remained how to implement it? IWRM can be best implemented at the basin level by using an Integrated River Basin Management (IRBM) approach. IRBM as a subset of IWRM is an approach to water resource management that takes into account all the factors linked to the resources, including social and economic activities. The implementation of IWRM at basin level in Malaysia has been initiated in managing water resources and river basin in Langat River Basin, Malaysia. The Langat River Basin is a transboundary river basin and is one of the Evolving UNESCO-IHP HELP Basins since 2004. The basin is small but has inherited many problems of a large river basin. This is because the river plays an important role in conservation, agriculture and potable water supply, but is facing threat from rapid development in the industry sectors and urbanization in the basin. This is why the components of IWRM and IRBM is needed to be implemented as practical approaches toward sustainable water resources and river basin management in Langat. This paper highlights some initiatives that have been made in managing water resources in this basin, as well as describes the current development and existing commitments towards achieving sustainability of water resources and river basin. The implementation of IWRM and IRBM need to be enhanced and further strengthened in order to ensure the sustainability of the water resources and river basin in Langat.