Geovisualization of land use and land cover using bivariate maps and Sankey flow diagrams

Georgianna Strode,Marjorie Jerez,Tyler Mcalear,Benjamin Thornton,Thomas Tricarico,Victor Mesev

doi:10.5194/ica-proc-1-106-2018

Abstract

Abstract. The terms ‘land use’ and ‘land cover’ typically describe categories that convey information about the landscape. Despite the major difference of land use implying some degree of anthropogenic disturbance, the two terms are commonly used interchangeably, especially when anthropogenic disturbance is ambiguous, say managed forestland or abandoned agricultural fields. Cartographically, land use and land cover are also sometimes represented interchangeably within common legends, giving with the impression that the landscape is a seamless continuum of land use parcels spatially adjacent to land cover tracts. We believe this is misleading, and feel we need to reiterate the well-established symbiosis of land uses as amalgams of land covers; in other words land covers are subsets of land use. Our paper addresses this spatially complex, and frequently ambiguous relationship, and posits that bivariate cartographic techniques are an ideal vehicle for representing both land use and land cover simultaneously. In more specific terms, we explore the use of nested symbology as ways to represent graphically land use and land cover, where land cover are circles nested with land use squares. We also investigate bivariate legends for representing statistical covariance as a means for visualizing the combinations of land use and cover. Lastly, we apply Sankey flow diagrams to further illustrate the complex, multifaceted relationships between land use and land cover. Our work is demonstrated on data representing land use and cover data for the US state of Florida.

Highlights

The land use/ land cover dichotomy is firmly related to anthropogenic disturbance; yet there are very few parts of the Earth where human presence is not evident at some level
We use statistical legends to further represent this close interplay of land use and cover by plotting their percentage co-occurrences. This facilitates an immediate visual and quantitative identification of the exceptionally high and the exceptionally low co-occurrences of land use/ land cover co-occurrences. These levels of land use/ land cover interactions are further illustrated with Sankey flow diagrams
We argue that co-occurrence nested symbology demonstrates this complex interplay

Summary

Introduction

The land use/ land cover dichotomy is firmly related to anthropogenic disturbance; yet there are very few parts of the Earth where human presence is not evident at some level. The distinction typically has taken on a more ontological approach, where an emphasis is on the epistemological understanding of the types of data that are collected and organized (Comber et al, 2005; Fisher & Comber 2005) To this end, land cover is defined less as a term to identify ‘natural’ landscapes and more on the products related to the geology, ecology and hydrology of the landscape. The technique employs nested symbology where circles representing land cover fit within larger squares representing land use These circle/square combinations are de-signed to illustrate the duality of their mixed occurrence, emphasizing the complex interplay of land use and land cover at the same geographic locations. We find this type of bivariate symbology to be most efficiently plotted on gridded raster frames. We argue that co-occurrence nested symbology demonstrates this complex interplay

Bivariate Mapping

Findings

Conclusions