Global(hydrobelts:(A(new(method( to(define(the(world s(river(basins((

Size: px

Start display at page:

Download "Global(hydrobelts:(A(new(method( to(define(the(world s(river(basins(("

Rudolph Rogers
6 years ago
Views:

Globalhydrobelts:Anewmethod todefinetheworld sriverbasins MichelMeybeck a,mattikummu b,andhansdürr c a NationalCentreforScientificResearch,UniversityParis6, France; b

1 Globalhydrobelts:Anewmethod todefinetheworld sriverbasins MichelMeybeck a,mattikummu b,andhansdürr c a NationalCentreforScientificResearch,UniversityParis6, France; b WaterandDevelopmentResearchGroup,AaltoUniversity, Finland; c UniversityofWaterloo,Canada DiscussionPaper1344 November2013 Thisarticleproposesanovelunitofanalysis for water security issues that aggregates river basins to create cross;continent hydrobelts. TheGlobalWaterForumpublishesdiscussionpapers to share the insights and knowledge contained within our online articles. The articles are contributed by experts in the field and provide: original academic research; unique, informed insightsandarguments;evaluationsofwaterpolicies and projects; as well as concise overviews and explanations of complex topics. We encourage our readers to engage in discussion with our contributingauthorsthroughthegwfwebsite. Keywords:watersecurity,unit,analysis,watersecurity,river basins,hydrobelts. Global water assessments are generally performed on the basis of countries, political regions, or continents. However, these units cannot accurately perform this task because they: i) mask or minimize the great disparity of water resources within continents and large countries e.g. USA, Russia, Brazil, China, Australia), ii) do not support integrated analysis of water-related issues at the river basin level, which is generally considered to be the optimum scale 1,2, and, iii) are ill-suited for research into the response of river basins to current Global Change including climate change and other human-induced environmental changes) 3. On the other hand, considering individual river basins at the global scale is of limited practical use because there are approximately 8,000 basins in total 4,5. Selecting the fifty greatest basins exceeding 500,000 km 2 would only account for half of the continental area. An approach to assessments is therefore SuggestedCitation:Meybeck,M.,Kummu,M.andH.Dürr2013), Globalhydrobelts:Anewmethodtodefinetheworld sriverbasins,

2 needed that combines the level of detail found at the basin scale with a global level of coverage. The answer is river basin aggregation. In a recent study 6 we have proposed a novel reporting scale for water issues that generates cross-continent hydrobelts. These regions are generated through: 1) natural hydrological basin boundaries, and 2) an aggregation based on the characteristic hydroclimatic features of types of river basins: annual water runoff q, mm/year) and average annual air temperature T, C) see Table 1). The result is eight hydrobelts see also Figure 1): Boreal belt BOR), only developed in the Northern Hemisphere and centered around 62 N, North and South Mid-Latitude belts NML and SML) centered around 43 N and 34 S respectively, North and South Dry belts NDR and SDR) centered around 29 N and 27 S respectively, North and South Sub-tropical belts NST and SST) centered around 17 N and 17 S respectively, and Equatorial belt EQT) centered at 3 S. This delineation was facilitated by previous global aggregations of the 8,000 river basins into 156 coastal catchments that allowed reporting of river outflows into oceans. 7,8 The final aggregation arose from multiple attempts in which the main criteria were: i) hydrobelts are delineated by natural hydrological basins that cannot be divided e.g. headwaters are not separated from lowlands), ii) belts are defined on the basis of their hydroclimate, and iii) the belts follow continental boundaries [with one minor exception]. Hydroclimatic characteristics of hydrobelts This new approach defines eight hydrobelts with similar hydrological and thermal river regimes, glacial and postglacial history of basins, internal drainage distribution, and sensitivity to climate variations. A general symmetry is observed for temperature and annual water runoff between corresponding North and South belts Table 2). The runoff types, varying from 31 to 960 mm/y, are particularly well characterised by the hydrobelt segmentation. Hydrological similarities between rivers within a given belt and in analogous North and South belts are also very clear. Boreal belt

3 rivers are characterized by a long frozen low stage, and late-spring, early-summer peak flows generated by snowmelt e.g. the Yukon, Mackenzie, Nelson, Churchill, Pechora, Ob, Yenissei, Lena, Kolyma, and Amour rivers). Mid-latitude rivers have mixed regimes, often combining snowmelt and rain fed regimes e.g. the Columbia, Mississippi, Saint Lawrence, Danube, Volga, Indus, Ganges, Brahmaputra, Yangtze, and Yellow rivers). Rivers located in the Subtropical belts are characterized by highly seasonal runoff regimes with a marked low stage,e.g. the Magdalena, Senegal, Niger, Godavari, Irrawaddy, Mekong rivers Northern Subtropical belt), and the Sao Francisco, Parana, and Zambezi rivers Southern Subtropical belt). Equatorial belt rivers are characterized by high runoff throughout the hydrological cycle e.g. the Orinoco, Amazon, Congo rivers and some much smaller basins in SE Asia). The North and South Dry belts are characterized by their numerous endorheic basins, i.e. those not drained to the ocean e.g. the Great Basin, Aral Sea, Tarim, and Kerulen basins in the Northern Dry belt, and Altiplano, Mar Chiquita, Okavango, and Lake Eyre basins in the Southern Dry belt), and by their allogenic rivers, i.e. those fed by run-off mostly in their upper basins, including many of the world s water towers 9, e.g. the Colorado, Rio Grande, Nile, Chari/Logone, Shatt el Arab, Amu Darya and Syr Darya, Kerulen, and Tarim basins in the Northern Dry belt, and the Orange, Okavango and Murray basins in the Southern Dry belt. Dry belts also correspond to 94% of the arheic or desert land, that is conventionally considered to be land with runoff of less than 3 mm/y. 4,5 The average hydrobelt temperature is also very distinct, ranging from -6.6 C to C. The greatest difference between neighbouring belts occurs between the Boreal belt -6.6 C) and the Northern Mid Latitude belt +9.1 C). The Boreal belt is essentially frozen, with 74.8% of permafrost land, and 56.7% of its area was covered by glaciers during the last ice age. Although hydrobelts were designed to present the hydroclimate of continents in a symmetrical way, some important differences remain between corresponding North and South belts Figure 2 and Table 2) due to: i) the uneven distribution of land masses i.e. a larger land mass in the Northern Hemisphere) and lack of continental land mass south of 55 S i.e. absence of a Boreal belt in the Southern hemisphere), ii) the continental climate that is only found in the Northern belts, and iii) the Central Asian mountains and high

plateaux with no equivalent in the Southern hemisphere. For example, these three factors cause the Northern Mid Latitude belt NML) 9.1 C) to be much colder than its Southern equivalent the SML) 14.

4 plateaux with no equivalent in the Southern hemisphere. For example, these three factors cause the Northern Mid Latitude belt NML) 9.1 C) to be much colder than its Southern equivalent the SML) 14.5 C). Application of hydrobelts The hydrobelts concept facilitates the reporting of water resources and the analysis of world rivers basins, particularly within the earth system sciences. As they are derived from the geographic limits of river basins, hydrobelts are well-positioned to assess impacts of Global Change on rivers, aquatic biodiversity issues, and river geochemistry and biogeochemistry e.g. carbon and silica cycles). In addition to earth sciences, the hydrobelts concept can also be applied to the social sciences and used to inform water governance. In the second part of this two part series we will demonstrate this broader utility by using the hydrobelts framework to create a population-focused water security indicator at the sub-continental level. Figures Table 1. Target limits of annual average temperature T) and run-off q) for aggregated river basins defining hydrobelts.

Figure 1. Limits and coding of global hydrobelts. Name Mean lat. Area Temp Prec Runoff % of total area [ ] [10 3 km 2 ] [ C] [mm yr -1 ] [mm yr -1 ] Endorheic Arheism Permafr. Glaciat.

5 Figure 1. Limits and coding of global hydrobelts. Name Mean lat. Area Temp Prec Runoff % of total area [ ] [10 3 km 2 ] [ C] [mm yr -1 ] [mm yr -1 ] Endorheic Arheism Permafr. Glaciat. BOR 62 25, % 74.8% 54.3% NML 43 24, % 1.0% 6.1% 27.8% NDR 29 30, % 38.8% 6.1% 4.0% NST 17 10, , % 0.7% 1.7% 1.7% EQT -3 16, , % - - SST , , % 3.9% - 0.4% SDR -27 8, % 56.7% - 4.0% SML -34 4, % % TOTAL* , % 13.5% 17.6% 17.7% Glaciated** NA 15, % Table 2. General average characteristics of Hydrobelts cell averages, weighted averages and totals). BOR=Boreal, NML=Northern Mid Latitude, NDR=Northern Dry, NST= Northern Sub Tropical, EQT= Equatorial belts and SML, SDR, SST their Southern analogues see Fig. 2 for their spatial distributions and Table 2 for data sources of the used datasets). * total of non-glaciated land.

6 Figure 2. Physical characteristics of hydrobelts

7 References 1. Millennium Ecosystem Assessment MEA) 2005), Ecosystems and Human Well-being: Synthesis. Island Press: Washington, DC. 2. World Water Assessment Programme WWAP) 2009), Water in a Changing World. UNESCO. Earthscan: London. 3. Steffen W. ed.) 2004), Global Change and the Earth System: A Planet under Pressure. Springer. 4. Vörösmarty, C.J., Fekete, B.M., Meybeck, M. and R.B. Lammers 2000a), Geomorphometric attributes of the global system of rivers at 30-minute spatial resolution, Journal of Hydrology 237: Vörösmarty, C.J., Fekete, B.M., Meybeck, M. and R.B. Lammers 2000b), The global system of rivers: its role in organizing continental land mass and defining land-to-ocean linkages, Global Biogeochemical Cycles 14: Meybeck, M., Kummu,M. and H.H. Dürr 2013), Global hydrobelts and hydroregions: improved reporting scale for water-related issues, Hydrolical and Earth System Sciences 17: Meybeck, M., Dürr, H.H. and C.J. Vörösmarty 2006), Global coastal segmentation and its river catchment contributors: a new look at land-ocean linkage, Global Biogeochemical Cycles 20:GB1S90, doi: /2005gb Dürr, H.H., Laruelle, G., van Kempen, C., Slomp, C., Meybeck, M., and H. Middelkoop 2011), Worldwide Typology of Nearshore Coastal Systems: Defining the Estuarine Filter of River Inputs to the Oceans, Estuaries and Coasts 34: Viviroli, D., Dürr, H.H., Messerli, B., Meybeck, M. and R. Weingartner 2007), Mountains of the world water towers for humanity: typology, mapping and global significance, Water Resources Research 43: W About the authors) This article summarises material from a full-length, open-access journal article in Hydrology and Earth System Sciences 17: , 2013, entitled Global hydrobelts and hydroregions: improved reporting scale for water-related issues?. Dr. Michel Meybeck is Director Emeritus of Research at the National Centre for Scientific Research, University Paris 6, France. He has been working on rivers hydrology and geochemistry at the global scale since He was scientific adviser in water-related international programmes as the GEMS -Water programme ), and was part of scientific committees of IGBP, BAHC-IGBP and LOICZ- IGBP. Dr. Meybeck can be contacted atmichel.meybeck@upmc.fr. Dr. Matti Kummu is Assistant Professor at the Water and Development Research Group, Aalto University, Finland. His research focuses on the linkages between human actions, food security, and water resources at different spatial scales, from local to global. Dr. Hans Dürr is Assistant Professor in the Ecohydrology Group at the University of Waterloo, Canada. He works on continental waters, rivers, grounwaters and estuaries, their typologies and geochemistry, at the global scale, at the University of Paris 6, at the Utrecht University, the Netherlands, and at Waterloo University. About the Global Water Forum The Global Water Forum GWF) is an initiative of the UNESCO Chair in Water Economics and Transboundary Governance at the Australian National University. The GWF presents knowledge and insights from leading water researchers and practitioners. The contributions generate accessible and evidence-based insights towards understanding and addressing local, regional, and global water challenges. The principal objectives of the site are to: support capacity building through knowledge

8 sharing; provide a means for informed, unbiased discussion of potentially contentious issues; and, provide a means for discussion of important issues that receive less attention than they deserve. To reach these goals, the GWF seeks to: present fact and evidence-based insights; make the results of academic research freely available to those outside of academia; investigate a broad range of issues within water management; and, provide a more in-depth analysis than is commonly found in public media. If you are interested in learning more about the GWF or wish to make a contribution, please visit the site at or contact the editors ateditor@globalwaterforum.org. The views expressed in this article belong to the individual authors and do not represent the views of the Global Water Forum, the UNESCO Chair in Water Economics and Transboundary Water Governance, UNESCO, the Australian National University, or any of the institutions to which the authors are associated. Please see the Global Water Forum terms and conditions here. Copyright 2013 Global Water Forum. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivative Works 3.0 License. See to view a copy of the license.

APPENDIX A. The Major River Deltas Of The World

APPENDIX A. The Major River Deltas Of The World APPENDIX A The Major River Deltas Of The World Selected High Quality Images Classified Examples of Delta Types Location, Landmass, Ocean Basin, Climate, Air Temperature, Tide, Discharge (water/sediment),