Total information content as an index of soil moisture

Accurate estimation of soil moisture through remote sensing technique has been a challenge till date. In optical and thermal remote sensing, there is no index developed to detect the changes in soil moisture levels. In microwave region, soil roughness and other target parameters equally affect the technique for soil moisture estimation. Therefore, a computational technique in C language based on Shannon’s Information Theory (Shannon, 1948) has been developed to calculate total information content from multispectral radiometer data. The total information content is a compressed single value, which quantifies the information content of soil spectral reflectance in the electromagnetic spectrum range (400–1100 nm) under study. This technique was tested over a wide range of soil moisture levels. The study revealed that as compared to other techniques total information content index is very sensitive to change in moisture content of soil. This technique could not only quantify the soil moisture content in optical and near infra red region, but also led to a simplified one dimensional separability and clustering analysis.     

Spatially-explicit sensitivity analysis of an agent-based model of land use change

The complexity of land use and land cover (LULC) change models is often attributed to spatial heterogeneity of the phenomena they try to emulate. The associated outcome uncertainty stems from a combination of model unknowns. Contrarily to the widely shared consensus on the importance of evaluating outcome uncertainty, little attention has been given to the role a well-structured spatially explicit sensitivity analysis (SSA) of LULC models can play in corroborating model results. In this article, I propose a methodology for SSA that employs sensitivity indices (SIs), which decompose outcome uncertainty and allocate it to various combinations of inputs. Using an agent-based model of residential development, I explore the utility of the methodology in explaining the uncertainty of simulated land use change. Model sensitivity is analyzed using two approaches. The first is spatially inexplicit in that it applies SI to scalar outputs, where outcome land use maps are lumped into spatial statistics. The second approach, which is spatially explicit, employs the maps directly in SI calculations. It generates sensitivity maps that allow for identifying regions of factor influence, that is, areas where a particular input contributes most to the clusters of residential development uncertainty. I demonstrate that these two approaches are complementary, but at the same time can lead to different decisions regarding input factor prioritization.     

Impact of proximity-adjusted preferences on rank-order stability in geographical multicriteria decision analysis

This paper presents a new approach to deriving preferences assigned to evaluation criteria in geographical multicriteria decision analysis. In this approach, the preferences, expressed by numeric weights, are adjusted by distance measures derived from the explicit consideration of a locational structure. The structure is given by locations of decision options and high importance reference objects. The approach is demonstrated on the example of a house selection case study in San Diego, California. The results show that proximity-adjusted preferences for the evaluation criteria can alter significantly the rank order of decision options. Consequently, the explicit modeling of spatial preference variability may be needed in order to better account for decision-maker’s preferences.     

Comparative performance of logistic regression and survival analysis for detecting spatial predictors of land-use change

Although survival analysis is known to outperform logistic regression, theoretically and according to evidence from other disciplines, little is known about how true this is in situations where the goal is detecting spatial predictors of land change. Furthermore, with the increasing availability of longitudinal land-change data, evidence is needed on the relative performance of these two different methods in situations with differing levels of data abundance. To fill this gap, we generated a pseudo land-change data set using an agent-based model of residential development in a virtual landscape. This agent-based model simulated the decisions of homebuyers in choosing residential locations based on the values of several spatial variables. Pseudo land-change maps, generated by the agent-based model with different weights on these spatial variables, were exposed to statistical analysis under the logistic and survival approaches. We evaluated how well the two approaches could reveal the spatial variables that were used in the agent-based model and compared the performance of the two methods when land-change data were collected under different sampling frequencies. Our results suggest that survival analysis outperforms logistic regression in detecting the variables that were included in agent decisions, largely because it takes into account time-dependent variables. Also, this research suggests that various properties of land-change processes (like amount of developed area and access of agents to information) affect the relative performance of these statistical approaches aimed at uncovering land-change predictor variables.