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Map algebras are used for the manipulation of spatial data and form the basis for many types of spatial analyses and modeling efforts. The most basic form of a map algebra applies the same function (e.g., addition, subtraction) across the study area. To account for local variation of modeling parameters, we present a spatially dynamic map algebra to demonstrate the need for and utility of algebraic functions where the function is determined based on a specific and relative location. The need for such an algebra comes from the growth of complex models where the values of variables or parameters are not fixed across space. Locally derived parameters are not new, as shown by geographically weighted regression. This type of algebra is needed in cases of complex models, such as those found in flow networks, where network dynamics vary across space. This includes hydrologic processes, movement of people and goods, and the transmission of ideas. We test the approach on a case study of nitrogen flow in the Niantic River watershed, Connecticut. Findings show that the results from a spatially dynamic map algebra can differ from a fixed function. Fixed functions can result in model outputs that under‐ or overestimate by up to 50%. [ABSTRACT FROM AUTHOR]

This article presents a new methodology for data fitness-for-use assessment. Most current measures of data quality rely on metadata and other data producer-derived information. This creates a void of options for a user-driven assessment of data quality when metadata are sparse or unavailable, as is often the case with citizen science and volunteered geographic information. This article puts forward data fitness-for-use (DaFFU), a method that can be adapted for a wide range of data uses. Using the mathematical framework of multiple criteria decision making (MCDM), we create a method to select the best data set from multiple options using a select set of user criteria. The DaFFU methodology is demonstrated with both a simple exemplar and a detailed case study for watershed management. The simple exemplar illustrates how varying parameters and weights influence the outcome. The case study on watershed management considers four possible data sets and six data quality criteria for wetland delineation and an application toward watershed nitrogen retention, each of which has a claim on being of the “best” quality, depending on which data quality aspect the user evaluates. The DaFFU methodology allows the user to consider these data in terms of how they will be used and to use selected data quality measures. Case study results show this methodology is a robust and flexible approach to quantitatively assessing multiple data sets in terms of their intended use. [ABSTRACT FROM AUTHOR]