The Effect of Global-Scale Map-Projection Knowledge on Perceived Land Area

Map projections are required to represent the globe on a flat surface, which always results in distorted representations of the globe. Accordingly, the world maps we observe in daily life contexts, such as on news sites, in news bulletins, on social media, in educational textbooks or atlases, are distorted images of the world. The question raises if regular contact with those representations of the world deforms people’s global-scale cognitive map. To analyze people’s global-scale cognitive map and if it is influenced by map projections, a short playful test was developed that allowed participants to estimate the real land area of certain regions, countries, and continents. More than 130,000 people worldwide participated. This worldwide dataset was used to perform statistical analyses in order to obtain information on the extent that map projections influence the accuracy of people’s global-scale cognitive map. The results indicate that the accuracy differs with the map projection but not to the extent that one’s global-scale cognitive map is a reflection of a particular map projection.

Download Full-text

Evaluating Young People’s Area Estimation of Countries and Continents

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi8030125 ◽

2019 ◽

Vol 8 (3) ◽

pp. 125 ◽

Cited By ~ 3

Author(s):

Lieselot Lapon ◽

Philippe De Maeyer ◽

Nina Vanhaeren ◽

Sarah Battersby ◽

Kristien Ooms

Keyword(s):

Personal Characteristics ◽

Global Scale ◽

Land Area ◽

Map Projection ◽

Map Projections ◽

Web Mapping ◽

Mercator Projection ◽

The World ◽

Mental Map ◽

The Web

For decades, cartographers and cognitive scientists have speculated about the influence of map projections on mental representations of the world. The development of Web 2.0 and web mapping services at the beginning of the 21st century—such as Google Maps, OpenStreetMap, and Baidu Map—led to an enormous spread of cartographic data, which is available to every Internet user. Nevertheless, the cartographic properties of these map services, and, in particular, the selected map projection or the Web Mercator projection, are questionable. The goal of this study is to investigate if the global-scale mental map of young people has been influenced by the increasing availability of web maps and the Web Mercator projection. An application was developed that allowed participants of Belgium and the US to scale the land area of certain countries and continents compared to Europe or the conterminous United States. The results show that the participants’ estimation of the actual land area is quite accurate. Moreover, an indication of the existence of a Mercator effect could not be discovered. To conclude, the young people’s mental map of the world does not appear to be influenced by a specific map projection but by personal characteristics. These elements are varied and require further analysis.

Download Full-text

Sensitivity of water scarcity events to ENSO-driven climate variability at the global scale

Hydrology and Earth System Sciences ◽

10.5194/hess-19-4081-2015 ◽

2015 ◽

Vol 19 (10) ◽

pp. 4081-4098 ◽

Cited By ~ 20

Author(s):

T. I. E. Veldkamp ◽

S. Eisner ◽

Y. Wada ◽

J. C. J. H. Aerts ◽

P. J. Ward

Keyword(s):

Climate Variability ◽

Water Availability ◽

Water Scarcity ◽

Southern Oscillation ◽

Global Scale ◽

Socioeconomic Conditions ◽

Land Area ◽

Sensitivity Assessment ◽

Wide Range ◽

Global Population

Abstract. Globally, freshwater shortage is one of the most dangerous risks for society. Changing hydro-climatic and socioeconomic conditions have aggravated water scarcity over the past decades. A wide range of studies show that water scarcity will intensify in the future, as a result of both increased consumptive water use and, in some regions, climate change. Although it is well-known that El Niño–Southern Oscillation (ENSO) affects patterns of precipitation and drought at global and regional scales, little attention has yet been paid to the impacts of climate variability on water scarcity conditions, despite its importance for adaptation planning. Therefore, we present the first global-scale sensitivity assessment of water scarcity to ENSO, the most dominant signal of climate variability. We show that over the time period 1961–2010, both water availability and water scarcity conditions are significantly correlated with ENSO-driven climate variability over a large proportion of the global land area (> 28.1 %); an area inhabited by more than 31.4 % of the global population. We also found, however, that climate variability alone is often not enough to trigger the actual incidence of water scarcity events. The sensitivity of a region to water scarcity events, expressed in terms of land area or population exposed, is determined by both hydro-climatic and socioeconomic conditions. Currently, the population actually impacted by water scarcity events consists of 39.6 % (CTA: consumption-to-availability ratio) and 41.1 % (WCI: water crowding index) of the global population, whilst only 11.4 % (CTA) and 15.9 % (WCI) of the global population is at the same time living in areas sensitive to ENSO-driven climate variability. These results are contrasted, however, by differences in growth rates found under changing socioeconomic conditions, which are relatively high in regions exposed to water scarcity events. Given the correlations found between ENSO and water availability and scarcity conditions, and the relative developments of water scarcity impacts under changing socioeconomic conditions, we suggest that there is potential for ENSO-based adaptation and risk reduction that could be facilitated by more research on this emerging topic.

Download Full-text

Global-scale analysis of river flow alterations due to water withdrawals and reservoirs

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-6-4773-2009 ◽

2009 ◽

Vol 6 (4) ◽

pp. 4773-4812 ◽

Cited By ~ 18

Author(s):

P. Döll ◽

K. Fiedler ◽

J. Zhang

Keyword(s):

Water Use ◽

River Discharge ◽

River Flow ◽

Global Scale ◽

Low Flow ◽

Western Coast ◽

Land Area ◽

Operation Rules ◽

Western Asia ◽

Water Withdrawals

Abstract. Global-scale information on natural river flows and anthropogenic river flow alterations is required to identify areas where aqueous ecosystems are expected to be strongly degraded. Such information can support the identification of environmental flow guidelines and a sustainable water management that balances the water demands of humans and ecosystems. This study presents the first global assessment of the anthropogenic alteration of river flow regimes by water withdrawals and dams, focusing in particular on the change of flow variability. Six ecologically relevant flow indicators were quantified using an improved version of the global water model WaterGAP. WaterGAP simulated, with a spatial resolution of 0.5 degree, river discharge as affected by human water withdrawals and dams, as well as naturalized discharge without this type of human interference. Mainly due to irrigation, long-term average river discharge and statistical low flow Q90 (monthly river discharge that is exceeded in 9 out of 10 months) have decreased by more than 10% on one sixth and one quarter of the global land area (excluding Antarctica and Greenland), respectively. Q90 has increased significantly on only 5% of the land area, downstream of reservoirs. Due to both water withdrawals and dams, seasonal flow amplitude has decreased significantly on one sixth of the land area, while interannual variability has increased on one quarter of the land area mainly due to irrigation. It has decreased on only 8% of the land area, in areas with little consumptive water use that are downstream of dams. Areas most affected by anthropogenic river flow alterations are the western and central USA, Mexico, the western coast of South America, the Mediterranean rim, Southern Africa, the semi-arid and arid countries of the Near East and Western Asia, Pakistan and India, Northern China and the Australian Murray-Darling Basin, as well as some Arctic rivers. Due to a large number of uncertainties related e.g. to the estimation of water use and reservoir operation rules, the analysis is expected to provide only first estimates of river flow alterations that should be refined in the future.

Download Full-text

Global-scale analysis of river flow alterations due to water withdrawals and reservoirs

Hydrology and Earth System Sciences ◽

10.5194/hess-13-2413-2009 ◽

2009 ◽

Vol 13 (12) ◽

pp. 2413-2432 ◽

Cited By ~ 259

Author(s):

P. Döll ◽

K. Fiedler ◽

J. Zhang

Keyword(s):

Water Use ◽

River Discharge ◽

River Flow ◽

Global Scale ◽

Land Area ◽

Operation Rules ◽

Western Asia ◽

Water Withdrawals ◽

The Impact

Abstract. Global-scale information on natural river flows and anthropogenic river flow alterations is required to identify areas where aqueous ecosystems are expected to be strongly degraded. Such information can support the identification of environmental flow guidelines and a sustainable water management that balances the water demands of humans and ecosystems. This study presents the first global assessment of the anthropogenic alteration of river flow regimes, in particular of flow variability, by water withdrawals and dams/reservoirs. Six ecologically relevant flow indicators were quantified using an improved version of the global water model WaterGAP. WaterGAP simulated, with a spatial resolution of 0.5 degree, river discharge as affected by human water withdrawals and dams around the year 2000, as well as naturalized discharge without this type of human interference. Compared to naturalized conditions, long-term average global discharge into oceans and internal sinks has decreased by 2.7% due to water withdrawals, and by 0.8% due to dams. Mainly due to irrigation, long-term average river discharge and statistical low flow Q90 (monthly river discharge that is exceeded in 9 out of 10 months) have decreased by more than 10% on one sixth and one quarter of the global land area (excluding Antarctica and Greenland), respectively. Q90 has increased significantly on only 5% of the land area, downstream of reservoirs. Due to both water withdrawals and reservoirs, seasonal flow amplitude has decreased significantly on one sixth of the land area, while interannual variability has increased on one quarter of the land area mainly due to irrigation. It has decreased on only 8% of the land area, in areas downstream of reservoirs where consumptive water use is low. The impact of reservoirs is likely underestimated by our study as small reservoirs are not taken into account. Areas most affected by anthropogenic river flow alterations are the Western and Central USA, Mexico, the western coast of South America, the Mediterranean rim, Southern Africa, the semi-arid and arid countries of the Near East and Western Asia, Pakistan and India, Northern China and the Australian Murray-Darling Basin, as well as some Arctic rivers. Due to a large number of uncertainties related e.g. to the estimation of water use and reservoir operation rules, the analysis is expected to provide only first estimates of river flow alterations that should be refined in the future.

Download Full-text

Global-scale human impact on delta morphology has led to net land area gain

Nature ◽

10.1038/s41586-019-1905-9 ◽

2020 ◽

Vol 577 (7791) ◽

pp. 514-518 ◽

Cited By ~ 28

Author(s):

J. H. Nienhuis ◽

A. D. Ashton ◽

D. A. Edmonds ◽

A. J. F. Hoitink ◽

A. J. Kettner ◽

...

Keyword(s):

Human Impact ◽

Global Scale ◽

Land Area

Download Full-text

Sensitivity of water scarcity events to ENSO driven climate variability at the global scale

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-5465-2015 ◽

2015 ◽

Vol 12 (6) ◽

pp. 5465-5517 ◽

Cited By ~ 1

Author(s):

T. I. E. Veldkamp ◽

S. Eisner ◽

Y. Wada ◽

J. C. J. H. Aerts ◽

P. J. Ward

Keyword(s):

Water Stress ◽

Climate Variability ◽

Water Availability ◽

Water Scarcity ◽

Water Shortage ◽

Global Scale ◽

Socioeconomic Conditions ◽

Land Area ◽

Wide Range ◽

Global Population

Abstract. Globally, freshwater shortage is one of the most important risks for society. Changing hydro-climatic and socioeconomic conditions have aggravated water scarcity over the past decades. A wide range of studies show that water scarcity will intensify in the future, as a result of both increased consumptive water use and in some regions climate change However, less attention has been paid to the impacts of climate variability on water scarcity, despite its importance for adaptation planning. Therefore, we present the first global scale sensitivity assessment of water scarcity and water availability to El Niño–Southern Oscillation (ENSO), the most dominant signal of climate variability. We show that over the time period 1961–2010, both water availability and water scarcity conditions are significantly correlated with ENSO-driven climate variability over a large proportion of the global land area (> 28.1%); an area inhabited by more than 31.4% of the global population. We also found, however, that climate variability alone is often not enough to trigger the actual incidence of water scarcity events. The sensitivity of a region to water scarcity events, expressed in terms of land area or population impacted, is determined by both hydro-climatic and socioeconomic conditions. Currently, the population actually impacted by water scarcity events consists of 39.6% (water stress) and 41.1% (water shortage) of the global population whilst only 11.4% (water stress) and 15.9% (water shortage) of the global population is at the same time living in areas sensitive to ENSO driven climate variability. These results are contrasted however by differences in found growth rates under changing socioeconomic conditions, which are relatively high in regions affected by water scarcity events. Given the correlations found between ENSO and both water availability and water scarcity, and the relative developments of water scarcity impacts under changing socioeconomic conditions, we suggest that there is potential for ENSO-based adaptation and risk reduction which could be facilitated by more research on this emerging topic.

Download Full-text

A Photographic Map of the Moon

Symposium - International Astronomical Union ◽

10.1017/s0074180900178179 ◽

1962 ◽

Vol 14 ◽

pp. 113-115

Author(s):

D. W. G. Arthur ◽

E. A. Whitaker

Keyword(s):

Lunar Surface ◽

The Moon ◽

Map Projection

The cartography of the lunar surface can be split into two operations which can be carried on quite independently. The first, which is also the most laborious, is the interpretation of the lunar photographs into the symbolism of the map, with the addition of fine details from telescopic sketches. An example of this kind of work is contained in Johann Krieger'sMond Atlaswhich consists of photographic enlargements in which Krieger has sharpened up the detail to accord with his telescopic impressions. Krieger did not go on either to convert the photographic picture into the line symbolism of a map, or to place this picture on any definite map projection.

Download Full-text