Abstract

Multilayer Artificial Neural Networks (ANNs) with the backpropagation algorithm were used to estimate the decrease in relative saturated conductivity due to an increase in sodicity and salinity. Data from the literature on the relative saturated hydraulic conductivity measured using water having levels of sodicity and salinity in different types of semiarid soils were used. The clay content of these soils is predominantly montmorillonite. The input data consisted of clay percentage, cation exchange capacity, electrolyte concentration, and estimated soil exchangeable sodium percentage at equilibrium stage with the solution applied. The data was divided into three groups randomly to meet the three phases required for developing the ANN model (i. e. training, evaluation, and testing).The activation function selected was the TANSIG layer in the middle, while the exit function was the PURELIN layer. The comparisons between the experimental and predicted data on relative saturated hydraulic conductivity during training and testing phases showed good agreement. This was evident from the statistical indicators used for the evaluation process. For the training phase, the values of mean absolute error (MAE), root mean square error (RMSE), the correlation coefficient (r) and the determination coefficient (R2) were 0.08, 0.13, 0.91, and 0.83, respectively. The performance of the ANN model was evaluated against a part of the data selected randomly form the whole set of data collected (i. e. data not used during the model testing phase). The resultant values for MAE and RMSE, r and R2 were 0.12, 0.16, 0.82 and 0.68, respectively. It should be noted that many factors were not considered, such as soil pH, type of clay, and organic matter, due to the limitations of the data available. Using these factors as input in ANNs might improve model predictions. However, the results suggested that the ANN model performs well in soils with very low levels of organic matter.

DOI number: 10.5027/jnrd.v4i0.05

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Abstract

Egypt, as with other developing countries, faces a major energy security problem, which strongly impacts all national plans for economic development. A sound energy strategy is crucially needed, and should be based on two pillars: first, boosting the production of clean energy from various renewable and non-renewable sources, and second, managing and rationalizing energy demand, with related reforms. Some steps were taken by previous Egyptian governments regarding these two pillars. In February 2008, the Ministry of Electricity and Energy of Egypt put a target of 20% of electricity to come from renewable energy resources by 2020. In July 2012, the Ministerial Cabinet approved both the Egyptian Solar Plan targeting 3500 MW of solar energy by 2027, and the National Energy Efficiency Action Plan (NEEAP) to reduce energy consumption 5% during the period from 2012-2015 compared to the average consumption of the previous 5 years. We believe that these plans will not bring their expected fruits unless they are well orchestrated with other sectoral development plans in areas such as agriculture, transport, housing and services, amongst others. This paper aims to investigate the Egyptian NEEAP and assess whether the adopted national energy efficiency plan and the associated policies on all other development sectors adopted by the government have sound implications. We aim to find out whether the development policies with a focus on energy policy are set in an integrated or fragmented way.

DOI number: 10.5027/jnrd.v4i0.03

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Abstract

This paper assessed encroachment of streams due to physical development in Wa Urban Area of the Upper West Region of Ghana. The assessment was informed by the recognition that the roles played by streams in flood control are undermined by physical developments. This affects sustainable urban development and renders the urban area vulnerable to floods. The assessment was based on the 300m buffer zone standard set by the Ghana Water Resources Commission as a protective zone for such streams in the country. It is mandatory to offset all physical development from this zone but that is not the situation on the ground. For the purpose of this study each buffer zone was divided into sub-buffer zones of 100m in order to appreciate how far development has moved into the prohibited buffer zone. The streams and physical structures were mapped with a Trimble GPS receiver while land owners and tenants were purposively selected and interviewed. The buffer zone and sub-buffer zones were defined using GIS and overlaid with map of the physical structures. The categories of structures found in the buffer zones were residential (93.4 %), commercial (5.1%), public (1.3%) and agriculture (0.2%). The results of the study indicates that more than 50 % of physical structures mapped are located in the inner buffer and the land acquisition process for development of these structures amongst others in Wa is mostly initiated by developers.

DOI number: 10.5027/jnrd.v4i0.02

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Abstract

A vast array of scientific literature is concerned with simulation models. The aim of models is to predict the unknown situation as close to as real one. To do this, models are validated and examined for their performance under known condition. In this paper, commonly used model performance evaluation indices are overviewed and examined under different situations. Difference based, efficiency based (Nash and Sutcliffe coefficient, model efficiency of Loague and Green, Legates and McCabe’s index) and composite indices (such as index of agreement, d, and dr) were found ambiguous, inconsistent and not logical in many cases. A new index, Percent Mean Relative Absolute Error (PMRAE), is proposed which is found unambiguous, logical, straight-forward, and interpretable; thus can be used to evaluate model performance. The model evaluation performance ratings based on PMRAE are also suggested.

DOI number: 10.5027/jnrd.v4i0.01

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Abstract

There are very little attempts of DEM evaluation in such a disturbed or discontinuous surface (e.g., in tillage area). Present study aims to evaluate common interpolation methods (triangulation, nearest neighbor, natural neighbor, minimum curvature, multiquadratic radial basis function (MRBF), ordinary kriging, and inverse distance weight) in representing the detail topography of two different tillage types, namely bench terrace and furrow. Evaluation procedure was conducted through a stepwise analysis by using combination between the accuracy level (coefficient of determination (R2), mean error (ME) and standard deviation error (S)) and the shape similarity analysis. This study also shows the application of break-line function during the interpolation process in order to optimize some interpolation methods and the usage of drainage sink area as another step in evaluating DEM quality. To achieve the aim of this study, two field-size of dry-land agriculture (tegalan) were observed by using a set of total station Nikon DTM 322 with 3” angle accuracy. These plots, namely Tieng (1652 m²) and Buntu (673 m²), are situated in the upper part of Wonosobo District, Central Java Province, Indonesia. Tieng plot represents the bench terrace system embedded with stones on its terrace risers and showing relatively smooth ground surface. On the other side, Buntu plot shows the ridges and furrows system that lays perpendicularly to the contour lines. In terms of R², ME and S, there were slight differences in results between each method, except the multiquadratic radial basis function which was failed to generate terrace form in Tieng. The final result shows that triangulation is the best fit method followed by natural neighbour at representing the bench terraces in Tieng plot. In the case of furrow in Buntu plot, natural neighbour is the most accurate method. Despite its superiority at representing the bench terrace, triangulation has larger sink drainage area compared to natural neighbour. This study has confirmed the robustness of a stepwise analysis between quantitative and qualitative assessment techniques for DEM accuracy. A fine value of quantitative parameter does not necessarily mean that it will fairly possess a good spatial accuracy.

DOI number: 10.5027/jnrd.v3i0.13

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Abstract

The upward movement of water by capillary rise from shallow water-table to the root zone is an important incoming flux. For determining exact amount of irrigation requirement, estimation of capillary flux or upward flux is essential. Simulation model can provide a reliable estimate of upward flux under variable soil and climatic conditions. In this study, the performance of model UPFLOW to estimate upward flux was evaluated. Evaluation of model performance was performed with both graphical display and statistical criteria. In distribution of simulated capillary rise values against observed field data, maximum data points lie around the 1:1 line, which means that the model output is reliable and reasonable. The coefficient of determination between observed and simulated values was 0.806 (r = 0.93), which indicates a good inter-relation between observed and simulated values. The relative error, model efficiency, and index of agreement were found as 27.91%, 85.93% and 0.96, respectively. Considering the graphical display of observed and simulated upward flux and statistical indicators, it can be concluded that the overall performance of the UPFLOW model in simulating actual upward flux from a crop field under variable water-table condition is satisfactory. Thus, the model can be used to estimate capillary rise from shallow water-table for proper estimation of irrigation requirement, which would save valuable water from over-irrigation.

DOI number: 10.5027/jnrd.v3i0.12

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Authors

Alexander Neaman: Área del Medio Ambiente, Facultad de Agronomía, Pontificia Universidad Católica de Valparaíso, Quillota, Chile

Andrés Marió: Departamento de Formación Pedagógica, Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile

Photo credits to: Francisco Vio

DOI number: 10.5027/jnrd.v3i0.11

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Abstract

Soil is an important natural resource which when effectively managed, could increase the livelihoods of households in sedentary agricultural communities. Soil erosion is however an emerging challenge as a cause of environmental degradation and this paper sought to ascertain the nature of soil erosion on maize farms, the effects of soil erosion on maize crop farmers and the effectiveness of local control measures on output levels and the livelihoods of the farmers. A cross-section of the community was taken and participants were selected non-probabilistically by snow-balling for questionnaire administration and focus group discussions. The study revealed that the local farmers perceived soil erosion as the wearing away of the top soil and nutrients, under the influence of running water during rainy periods and the slope of the land. The major effects of soil erosion were found to be the loss of fertile soils, reduction in the cultivable land area, the reduction in the crop yield and a fall in the living standards of farmers’ households. The findings also indicated that some of the adaptive strategies to reduce the effects of soil erosion include shifting cultivation, ridging across slopes, planting on raised mounds and avoidance of deep ploughing. It was further revealed that farmers who successfully applied the traditional methods improved upon their output levels per land area and the standards of living of their families It was recommended that modern agricultural extension services were needed, not to replace, but to complement the local knowledge systems in order to ensure sustainability.

DOI number: 10.5027/jnrd.v3i0.10

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Abstract

Many regions of the world face the challenge to ensure high yield with limited water supply. This calls for utilization of available water in an efficient and sustainable manner. Quantitative models can assist in management decision and planning purposes. The FAO’s newly developed crop-water model, AquaCrop, which simulates yield in response to water, has been calibrated for winter wheat and subsequently used to simulate yield under different sowing dates, irrigation frequencies, and irrigation sequences using 10 years daily weather data. The simulation results suggest that “2 irrigation frequency” is the most water-efficient schedule for wheat under the prevailing climatic and soil conditions. The results also indicate decreasing yield trend under late sowing. The normal/recommended sequence of irrigation performed better than the seven-days shifting from the normal. The results will help to formulate irrigation management plan based on the resource availability (water, and land availability from previous crop).

DOI number: 10.5027/jnrd.v3i0.09

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