On the Exploratory Function of Agent-Based Modeling

Agent-based models (ABM) derive the behavior of artificial socio-economic entities computationally from the actions of a large number of agents. One objection is that highly idealized ABMs fail to represent the real world in any reasonable sense. Another objection is that they at best show how observed patterns may have come about, because simulations are easy to produce and there is no evidence that this is really what happens. Moreover, different models may well yield the same result. I will rebut these objections by focusing on an often neglected, but crucial function of ABMs. Building on Gelfert’s (2016) account of the exploratory uses of scientific models I show that, in the absence of an accepted underlying theory, successful ABMs lend inductive support to assumptions concerning certain structural feutures of the behavioral rules employed. One core step towards this goal is what I call multiple-model robustness analysis.

Economic and Environmental Impacts of Geothermal Resource Development in Hunan, China

The global warming and soaring energy consumption have motivated many scholars and policymakers to pursue energy conservation and environmental improvement. As a renewable cleaning energy, geothermal resources have been actively developed in recent years. Taking six geothermal projects in Hunan, China as examples, this paper determines the input and output indices for each project. The input indices cover both economic and environmental dimensions. Then, the authors deeply explored how much geothermal resource quantity, single-well yield, total investment, and annual cost investment influence dynamic investment recovery period, coal reduction of summer operation, coal reduction of winter operation, environmental protection and energy saving, standard coal reduction, and emission reduction. The results show that total investment, single-well yield, and total investment have significant effects on economic indices, while geothermal resource quantity, single-well yield, and total investment have significant effects on environmental indices.

Assessment of groundwater potential zone using GIS-based multi-influencing factor (MIF), multi-criteria decision analysis (MCDA) and electrical resistivity survey techniques in Raipur city, Chhattisgarh, India

The present study involved the combined applications of advanced techniques and tools like remote sensing, GIS, electrical resistivity, MCDA, to assess the potential zones of groundwater occurrence. Several prepared thematic layers, including geology, geomorphology, rainfall, lineament, LULC, drainage density, soil type, slope, and soil texture, were assigned with a weight, depending on their influence on groundwater potential. Normalization concerned with relative contribution is applied in this study using the AHP method. Vertical electrical sounding has been conducted on different points to locate water-bearing formations/fracture zones. The resulting groundwater potential areas that are delineated applying these methods have been categorized into five zones, low, medium, medium-high, high, and very high potential. The groundwater potential zones demarcated show that high potential zones are present in the west and north-eastern portion, while low to medium groundwater potential is located in the central and eastern portion. The obtained result was validated using well yield data, and ROC method from which result accuracy obtained is 80% and the area under the ROC curve is found to be 0.857 at a significance value of less than 0.001, which justifies the efficacy of the proposed approach in the demarcation of groundwater potential zone.

Monitoring nitrate reduction: hydrogeochemistry and clogging potential in raw water wells

The mainly agricultural input of NO3- and compliance with drinking water guideline values pose major challenges for many water suppliers. Additionally, associated changes in hydrochemistry, especially concerning products of NO3- reduction (Fe2+/3+, Mn2+/4+, Ca2+, Mg2+, SO42-, HCO3-) and subsequent reactions, can have a major influence on mineral saturation states and well yield: well productivity can be strongly reduced by mineral precipitation and silting. To evaluate hydrogeochemical evolution and clogging potential for a given well field, thorough hydrochemical and geochemical investigations are required. Therefore, time-dependent and depth-specific ion concentrations in water samples (n = 818) were analysed in a catchment area of a waterworks in western Germany. The sediments of the aquifers were extensively investigated for their geochemistry (CS, scanning electron microscope, aqua regia digestion and dithionite solution; n = 253). In addition, PhreeqC was used to model saturation indices in order to identify possible mineral precipitation in the wells. Results show a high NO3- input into deep wells screened in Tertiary sediments due to an admixture of Quaternary groundwater. Directly at the Quaternary-Tertiary boundary, chemolithotrophic NO3- reduction consuming pyrite occurs. Protons released during the process are pH-buffered by dissolving carbonate minerals. Overall, the hydrochemistry and especially the saturation indices are strongly influenced by NO3- reduction and its degradation products. A change in well yield has not yet been observed, but future clogging by ochre formation or sintering cannot be excluded.

Estimation of Aquifer Protective Capacity, Soil Corrosivity and Dar-Zarrouk Parameters in Kaura Area of Kaduna State, Nigeria

This study presents an estimation of aquifer protective capacity, soil corrosivity and Dar-Zarrouk parameters for Kaura area of Kaduna State in northern Nigeria. Electrical resistivity sounding data and borehole pumping test data obtained from 20 locations within the LGA were obtained and used for this study. The geoelectric data exhibited curve types generally consisting of H, HA, KH or K-A-H types from which five-layer lithology were delineated across the entire study area. Well yield varies from 16 – 400 litres/min, pumping rate ranges from 16 to 140 l/min, drawdown varies from 1 – 22m, while specific capacity ranged from 1 – 95 litres/min. The aquifer protective capacity characterization was based on values of longitudinal unit conductance of the overburden, and 35% of the locations showed good protective capacity, while the remaining 65% exhibited moderate protective capacity. From the soil corrosivity evaluation, the upper soil layers were classified as moderately corrosive at one location, four locations were marked as slightly corrosive, while the remaining locations were found to be practically non-corrosive. Based on thicknesses and resistivities of the overburden layers, Dar-Zarrouk parameters were determined. The reflection coefficient ranged from 0.29 to 0.92, resistivity contrast occurred between 0.35 to 25.38, while the coefficient of anisotropy ranged from 0.70 to 3.84 with mean value of 1.57. Values above 1.0 are generally considered high and they occurred more toward the western part of the area than the middle and eastern parts. Both the longitudinal unit conductance map and coefficient of anisotropy map were generated for the area.