Cropland Water Use: A Global Perspective

Globally, only about 6% (3,091 km3/y) to 7% (3,798 km3/y) of the available renewable water (54,695 km3/y) is currently withdrawn (but not necessarily used) by irrigated croplands (Table 16.4). However, a country-by-country assessment (Table 16.5) shows water withdrawal of more than 100% (meaning importation or groundwater mining) in countries such as United Arab Emirates, Saudi Arabia, and Libya; more than 50% in countries such as Jordan, Cyprus, Yemen, Israel, and Tunisia, 20–50% in countries such as China, India, Uzbekistan, Iran, and Iraq; less than 10% in countries such as the United States, Italy, and Greece; and less than 1% in countries such as the Democratic Republic of Congo, Canada, and Brazil. This implies a highly uneven spatial distribution in water availability and water withdrawal for irrigation around the world. Further, such spatial variabilities are also very high within countries such as the United States, Australia, and China. Intracountry Table 16.4

Water Use by Croplands for the Nominal Year 2000 Blue Water Use by

Irrigated Crops (km3/yr)

Green Water Use by Irrigated Crops

(km3/yr)

Green Water Use by Rainfed

Crops (km3/yr)

Total Water Use by Irrigated and Rainfed Crops

(km3/yr) Reference

1180 919 4586 6685 Siebert and

Dửll (2009)

1800 - 5000 6800 Falkenmark and

Rockstrửm (2006)

7500 Postel (1998)

Table 16.5 Global Water Withdrawal and Water Use by Irrigated Croplands: A Country-by-Country Assessment Water: RenewableWater: Withdrawal for Irrigation Water: Withdrawal for Irrigation Water: Requirement (eT) for Irrigation Water Green: Requirement (eT) for Irrigation

Water Blue: Requirement (eT) for Irrigation Glieck et al. (2009)Wisser et al. (2008)Wisser et al. (2008)Siebert and Dửll (2009, 2008)Siebert and Dửll (2009, 2008)Siebert and Dửll (2009, 2008) Annual Renewable Water Resource km3/y A22

Total Water Withdrawal for Irrigation Based on IWMI GIAM Irrigated Areas km3/y A26 Total Water Withdrawal for Irrigation Based on FAo/UF V4.0 Irrigated Areas km3/y A27 Blue Water Requirement for Irrigation Based on Irrigated Areas of FAo/UF V4.0 km3/y A28 Green Water Availability over Irrigated Areas Based on FAo/UF V4.0 km3/y A29 Total (Blue & Green) Water Requirement for Irrigation Based on FAo/UF V4.0 km3/y A30

Rank Based on Total IWMI GIAM Cropland Areas # A1Country name A2 1China2830755606147257404 2India19081694844287175462 3USA3069122.3141.2139.179.1218.3 5Russia449871.317.111.613.425.0 14Brazil823328.114.28.318.026.4 6Argentina814.047.411.15.85.711.5 11Australia398.025.012.813.610.924.5 9Kazakhstan109.640.012.78.93.212.1 20Canada3300.05.12.22.72.35.1 26Ukraine139.58.511.43.53.67.1 16Indonesia2838.046.353.413.643.256.8 21France189.05.64.93.26.09.2 4Pakistan233.8136.2414.7117.019.3136.3 18Spain111.113.713.118.69.227.8 7Thailand409.9123.9124.319.130.849.9 164Zambia105.20.00.10.40.20.6 107Tanzania91.00.20.81.00.81.8 (Continued)

Table 16.5 (Continued ) Global Water Withdrawal and Water Use by Irrigated Croplands: A Country-by-Country Assessment Water: RenewableWater: Withdrawal for Irrigation Water: Withdrawal for Irrigation Water: Requirement (eT) for Irrigation Water Green: Requirement (eT) for Irrigation

Rank Based on Total IWMI GIAM Cropland Areas # A1Country name A2 15Mexico457.236.932.026.824.251.0 124Congo, Dem. Rep.1283.00.00.00.00.10.1 56Poland63.10.70.30.10.30.4 103Mozambique216.00.20.80.20.20.4 112Angola184.00.20.20.20.10.3 10Myanmar (Burma)1045.640.025.35.96.512.4 32Turkey234.014.625.014.66.621.3 19Germany188.04.51.90.20.91.1 102Belarus58.00.00.00.20.50.6 43South Africa50.03.18.38.86.515.3 13Vietnam891.278.970.07.424.732.1 74Ethiopia110.01.71.91.21.42.6 70Nigeria286.22.31.50.90.61.5 30Sudan154.017.711.210.12.913.0 8Bangladesh1210.665.083.318.724.343.0 28Romania42.38.111.90.91.32.2 31Philippines479.017.625.13.810.414.2 22Italy175.08.78.36.58.815.2

73Bolivia622.52.20.40.40.30.8 146Zimbabwe20.00.00.50.90.71.6 12Uzbekistan72.232.935.524.15.529.7 24Iran137.532.764.240.810.751.5 37United Kingdom160.62.10.30.20.60.9 83Kenya30.20.60.40.50.30.8 53Colombia2132.03.310.61.03.74.6 25Japan430.021.131.41.79.110.7 120Paraguay336.00.10.40.10.50.6 94Madagascar337.00.45.72.84.47.2 66Malaysia580.01.32.80.62.83.5 60Peru1913.03.711.55.11.46.5 85Cote d’Ivoire81.00.00.00.10.30.5 113Uganda66.00.10.00.00.00.0 41Cambodia476.119.510.61.01.82.8 36Morocco29.05.54.19.02.211.2 33Nepal210.214.216.14.24.08.2 72Hungary120.00.81.40.20.40.6 38Bulgaria19.44.94.20.10.10.2 46Venezuela1233.27.08.12.03.45.4 23Iraq96.442.044.620.92.123.0 34Chile922.07.13.63.02.15.1 49Czech Republic16.00.80.10.00.10.1 61Uruguay139.04.11.70.61.01.6 42Afghanistan65.09.825.19.42.612.0 78Algeria14.30.81.14.31.05.2 27Korea, Dem. Rep.77.18.57.91.15.66.7 17Egypt86.819.037.846.90.847.7 48Greece72.03.95.86.92.59.4 35Korea, Rep.69.75.35.70.84.04.9 142Botswana14.70.00.00.00.00.0 67Serbia0.00.00.00.20.20.4 (Continued)

Rank Based on Total IWMI GIAM Cropland Areas # A1Country name A2 65Ecuador432.02.19.62.72.14.8 63Portugal73.61.32.43.21.95.1 96Ghana53.20.50.10.10.10.1 47Kyrgyzstan46.52.64.13.12.65.7 110Lithuania24.50.10.00.00.00.0 51Cuba38.15.911.51.66.27.8 106Cameroon285.50.40.40.20.20.4 29Turkmenistan60.916.817.010.61.311.9 59Mongolia34.80.60.10.30.10.4 62Guinea226.02.81.50.10.10.2 158Central African Republic144.40.00.00.00.00.0 179Congo832.00.00.00.00.00.0 64Senegal39.43.20.60.60.20.8 45Sri Lanka50.019.411.22.23.05.2 44Azerbaijan30.37.510.93.81.25.0 99Mali100.00.95.11.30.41.7 137Latvia49.90.00.00.00.00.0 128Burkina Faso17.50.20.50.10.10.2

81Laos333.61.32.61.31.42.7 149Malawi17.30.00.10.30.40.7 87Austria84.00.30.10.00.20.2 50Taiwan, Province of China67.00.00.00.72.63.3 93Slovakia80.3/50.10.00.00.20.40.6 68Moldova11.70.91.10.70.61.3 57Tajikistan99.72.74.73.31.04.3 55Belgium20.80.80.30.00.00.0 192Papua New Guinea801.00.00.00.00.00.0 77New Zealand397.00.10.90.72.12.8 168Liberia232.00.10.00.00.00.0 109Croatia105.50.00.00.00.00.0 58Somalia15.73.01.91.00.71.6 39Netherlands89.71.31.00.10.80.9 89Guatemala111.30.00.00.71.21.9 40Denmark6.12.01.20.00.50.6 52Syria46.16.97.69.52.211.7 92Honduras95.90.30.40.40.60.9 86Tunisia4.60.72.32.60.73.3 115Sierra Leone160.00.20.20.10.10.2 130Bosnia and Herzegovina37.50.00.00.00.00.0 122Nicaragua196.70.20.50.30.40.7 97Sweden179.00.10.30.00.20.3 69Albania41.70.90.80.70.61.4 181Gabon164.00.00.00.00.00.0 108Panama148.00.00.00.10.30.4 129Estonia21.10.00.00.00.00.0 116Chad43.00.30.20.10.10.2 76Georgia63.30.81.60.50.61.1 (Continued)

Rank Based on Total IWMI GIAM Cropland Areas # A1Country name A2 79Macedonia6.40.00.00.20.10.3 136Burundi3.60.10.10.10.10.1 95Finland110.00.20.20.00.10.1 100Rwanda5.20.30.00.00.00.0 121Togo14.70.10.00.00.00.0 111Switzerland53.30.00.00.00.00.0 141Niger33.70.00.60.60.20.8 127Benin25.80.40.10.00.00.0 135Namibia45.50.00.10.10.00.1 185Ireland46.80.00.00.00.00.0 90Dominican Republic21.00.83.10.91.52.4 71Libya0.61.84.32.70.33.0 54Saudi Arabia2.416.925.712.40.713.1 145Lesotho5.20.00.00.00.00.0 88Swaziland4.50.50.30.30.30.6 165Slovenia32.10.00.00.00.00.1 104Haiti14.00.50.60.20.50.7 80Armenia10.51.12.30.60.30.9

155Norway381.40.00.10.00.10.2 131Montenegro0.00.00.00.00.00.0 75Guinea Bissau31.01.70.20.10.00.1 134El Salvador25.20.10.20.20.30.5 84Guyana241.00.51.10.31.21.6 91Yemen4.10.92.62.90.53.4 101Gambia0.00.00.00.00.00.1 132Eritrea6.30.10.50.00.00.1 147Belize18.60.00.00.00.00.0 143East Timor0.00.00.00.00.00.0 82Israel1.71.10.91.50.21.7 157Bhutan95.00.10.20.10.20.3 139Cyprus0.40.10.30.30.10.4 119Lebanon4.80.20.61.00.21.2 133Puerto Rico0.00.00.00.00.20.2 105Jordan0.91.00.80.80.10.9 125Mauritania0.00.00.00.20.00.2 187Luxembourg1.60.00.00.00.00.0 123Suriname122.00.20.30.10.30.4 114Oman1.00.52.31.10.11.1 160Brunei8.50.00.00.00.00.0 98United Arab Emirates0.21.84.73.30.13.4 140Jamaica9.40.00.00.10.30.3 154West Bank0.00.00.00.00.00.0 150Equatorial Guinea26.00.00.00.00.00.0 117Qatar0.10.80.20.10.00.1 118Kuwait0.00.80.10.10.00.1 148French Guyana0.00.00.00.00.00.0 153Trinidad and Tobago3.80.00.00.00.00.0 (Continued)

Rank Based on Total IWMI GIAM Cropland Areas # A1Country name A2 195Singapore0.60.00.00.00.00.0 138Gaza Strip0.00.00.00.00.00.0 175Andorra0.00.00.00.00.00.0 186Liechtenstein0.00.00.00.00.00.0 162San Marino0.00.00.00.00.00.0 144Mauritius2.20.00.00.10.20.3 152Guadeloupe0.00.90.80.00.10.1 156St. Kitts and Nevis0.00.00.00.00.00.0 159Virgin Islands0.00.00.00.00.00.0 161Reunion5.00.00.00.00.10.1 163Djibouti0.30.00.00.00.00.0 166Comoros1.20.00.00.00.00.0 167Anguilla0.00.00.00.00.00.0 173Monaco0.00.00.00.00.00.0 169Turks and Caicos Islands0.00.00.00.00.00.0 170Montserrat0.00.00.00.00.00.0 171St. Pierre and Miquelon0.00.00.00.00.00.0

172Cayman Islands0.00.00.00.00.00.0 174Seychelles0.00.00.00.00.00.0 176Bahrain0.10.00.00.00.00.0 177Barbados0.10.00.00.00.00.0 178Cape Verde0.30.00.00.00.00.0 180Fiji28.60.00.00.00.00.0 183Grenadand0.00.00.00.00.0 184Guam0.00.00.00.00.00.0 188Malta0.10.00.00.00.00.0 189Martinique11.40.30.90.00.10.1 190Northern Marianna Islands0.00.00.00.00.00.0 193Pitcairn Islands0.00.00.00.00.00.0 194Sao Tome and Principe0.00.00.00.00.10.1 196St. Lucia0.00.00.00.00.00.0 197St. Vincent and the Grenadines0.00.00.00.00.00.0 198Vatican City0.00.00.00.00.00.0 ToTAL54,6953,7983,0911,1809192,099

variations are large; for instance, China is facing severe water shortages in the north, including the Yellow River Basin, while the south still has abundant water resources.

Intracountry water transfers have been proposed as a solution to address such water scar- city issues (Xu, Ye, and Li 2008). However, it is not clear how to bring the water back to its origin to avoid potential environmental and socioeconomic consequences. In countries with large spatial variability in water availability, intracountry virtual water trade may help address the issue (Wichelns 2005), with a lower footprint on the environment albeit at a slightly higher economic cost (food transport may be more expensive than water transport; Sarkar et al. 2007). Shifting people instead of transferring water may be yet another alternative (Wichelns 2003), apart from global virtual water trade (Hanasaki et al. 2010).

In any case, precise estimates of water use and withdrawals can help evaluate the impacts of these alternative strategies as well as optimize the productivity of croplands and their water use.

Water used by crops is different from water withdrawal. Also, there are no clear assessments of water used by rain-fed croplands. This calls for water-use assessment based on blue water use (water used by crops from rivers, reservoirs, lakes, and groundwater in the saturated zone) and green water use (water used by crops in saturated zone of the ground;

Figure 16.5; Falkenmark 2007). Siebert and Dửll (2008, 2009) made such an assessment over the irrigated areas of the world. They determined that global irrigated areas consume 2099 km3/y, of which 919 km3/y is green water use (precipitation that falls directly on irrigated croplands) and the 1180 km3/y is blue water use (Table 16.4). A country-by-country

Blue to green ET flow Rainfall

Green water flow

Green ET flow

Green ET flow Blue water resource

Blue water resource

Green water resource Blue water flow

Saturated zoneUnsaturated zone FIGURe 16.5

Concept of blue water versus green water. (Adapted from Falkenmark, M., and J. Rockstrửm, J Water Resour Plann Manage, 132, 2006.)

water withdrawal versus water required (water approximately used) shows a consistent pattern of high water withdrawal to actual water required or used by irrigated croplands (Figure 16.6). Water withdrawals are even higher when irrigated areas computed by Thenkabail et al. (2009a) are used (Table 16.5). Typically, 1.6–2.5 times the water required (equivalent to the water used for optimal growing conditions) is actually withdrawn, thus achieving only 40–60% irrigation efficiency (Table 16.5). Clear assessments of green water use can improve the productivity of rain-fed agriculture and harness the potential of green water for increasing resilience to global environmental change (Hoff et al. 2010; Rockstrửm et al. 2008).

Cropland Water Use: A Global Perspective

Monitoring Forest Successional Stages with landsat Imagery

Moderate - Resolution Imaging Spectroradiometer Land Products