One important step in binary modeling of environmental problems is the generation of absence-datasets that are traditionally generated by random sampling and can undermine the quality of outputs.To solve this problem,this study develops the Absence Point Generation(APG)toolbox which is a Python-based ArcGIS toolbox for automated construction of absence-datasets for geospatial studies.The APG employs a frequency ratio analysis of four commonly used and important driving factors such as altitude,slope degree,topographic wetness index,and distance from rivers,and considers the presence locations buffer and density layers to define the low potential or susceptibility zones where absence-datasets are gener-ated.To test the APG toolbox,we applied two benchmark algorithms of random forest(RF)and boosted regression trees(BRT)in a case study to investigate groundwater potential using three absence datasets i.e.,the APG,random,and selection of absence samples(SAS)toolbox.The BRT-APG and RF-APG had the area under receiver operating curve(AUC)values of 0.947 and 0.942,while BRT and RF had weaker per-formances with the SAS and Random datasets.This effect resulted in AUC improvements for BRT and RF by 7.2,and 9.7%from the Random dataset,and AUC improvements for BRT and RF by 6.1,and 5.4%from the SAS dataset,respectively.The APG also impacted the importance of the input factors and the pattern of the groundwater potential maps,which proves the importance of absence points in environmental bin-ary issues.The proposed APG toolbox could be easily applied in other environmental hazards such as landslides,floods,and gully erosion,and land subsidence. 相似文献
AbstractThe quantification of the sediment carrying capacity of a river is a difficult task that has received much attention. For sand-bed rivers especially, several sediment transport functions have appeared in the literature based on various concepts and approaches; however, since they present a significant discrepancy in their results, none of them has become universally accepted. This paper employs three machine learning techniques, namely artificial neural networks, symbolic regression based on genetic programming and an adaptive-network-based fuzzy inference system, for the derivation of sediment transport formulae for sand-bed rivers from field and laboratory flume data. For the determination of the input parameters, some of the most prominent fundamental approaches that govern the phenomenon, such as shear stress, stream power and unit stream power, are utilized and a comparison of their efficacy is provided. The results obtained from the machine learning techniques are superior to those of the commonly-used sediment transport formulae and it is shown that each of the input combinations tested has its own merit, as they produce similarly good results with respect to the data-driven technique employed.
Rural production landscapes in Australia are experiencing a rapid rate of change as a result of, among other factors, climate change, biodiversity loss and changing societal values. Consequently, there is increasing pressure on producers to increase their sustainability. Understanding how producers perceive themselves in the context of this changing landscape is limited but important for the design of policy effective for achieving sustainability. This paper is based on a case study in the north-eastern Australian rangelands that included face-to-face interviews with 28 beef producers and a telephone survey with another 91 producers. The study investigated male and female beef producers' self-perceived roles in life through a lens of different farming discourses and the relationship between these roles and beliefs aligned with sustainability. Results revealed that although producers' self-percieved roles in life were being constructed through a mix of more or less ‘traditional’ discourses, tradition was still a strong influence. Producers who strongly identified with roles linked to ‘less traditional’ discourses were more likely than those who strongly identified with production-orientated roles to agree with beliefs that favoured nature conservation, learning and adapting to change. Increased opportunities for producers to participate in alternative discourses would appear important for fostering a self-identity that is open to learning, difference and change. 相似文献