0 [Type here] Irrigation in Africa in figures - AQUASTAT Survey - 2016 Transboundary River Basin Overview – Indus Version 2011 Recommended citation: FAO. 2011. AQUASTAT Transboundary River Basins – Indus River Basin. Food and Agriculture Organization of the United Nations (FAO). Rome, Italy The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned. 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FAO information products are available on the FAO website (www.fao.org/ publications) and can be purchased through [email protected]. © FAO 2011 1 Indus transboundary river basin GEOGRAPHY, CLIMATE AND POPULATION Geography The transboundary Indus river basin has a total area of 1.12 million km2 distributed between Pakistan (47 percent), India (39 percent), China (8 percent) and Afghanistan (6 percent) (Table 1). The Indus river basin stretches from the Himalayan mountains in the north to the dry alluvial plains of Sindh province in Pakistan in the south and finally flows out into the Arabian Sea. In Pakistan, the Indus river basin covers around 520 000 km2, or 65 percent of the territory, comprising the whole of the provinces of Punjab and Khyber Pakhtunkhwa and most of the territory of Sindh province and the eastern part of Balochistan. The drainage area lying in India is approximately 440 000 km2, nearly 14 percent of the total area of the country, in the States of Jammu and Kashmir, Himachal Pradesh, Punjab, Rajasthan, Haryana and Chandigarh. Only about 14 percent of the total catchment area of the basin lies in China, covering just 1 percent of the area of the country, and Afghanistan, where it accounts for 11 percent of the country’s area. Very roughly, at least 300 million people are estimated to live in the Indus basin. TABLE 1 Country areas in the Indus river basin Area % of Countries Area of country in As % of total area As % of total area Basin 2 km2 Southeast included basin (km ) of the basin of the country Asia Pakistan 520 000 47 65 India 440 000 39 14 Indus 1 120 000 5.4 China 88 000 8 1 Afghanistan 72 000 6 11 Climate Climate is not uniform over the Indus river basin. It varies from subtropical arid and semi-arid to temperate subhumid on the plains of Sindh and Punjab provinces to alpine in the mountainous highlands of the north. Annual precipitation ranges between 100 and 500 mm in the lowlands to a maximum of 2 000 mm on mountain slopes. Snowfall at higher altitudes (above 2 500 m) accounts for most of the river runoff (Ojeh, 2006). The Upper Indus river basin is a high mountain region and the mountains limit the intrusion of the monsoon, the influence of which weakens northwestward. Most of the precipitation falls in winter and spring and originates from the west. Monsoonal incursions bring occasional rain to trans-Himalayan areas but, even during summer months, not all precipitation derives from monsoon sources. Climatic variables are strongly influenced by altitude. Northern valley floors are arid with annual precipitation from 100 to 200 mm. Totals increase to 600 mm at 4 400 m, and glaciological studies suggest accumulation rates of 1 500 to 2 000 mm at 5 500 m. Winter precipitation (October to March) is highly spatially correlated across the Upper Indus basin, north and south of the Himalayan divide. 2 Irrigation in Southern and Eastern Asia in figures - AQUASTAT Survey - 2011 Figure 1 Indus River Basin Indus transboundary river basin 3 From 1961 to 1999 there were significant increases in winter, summer and annual precipitation and significant warming occurred in winter whilst summer showed a cooling trend. These trends will impact upon water resource availability (Fowler and Archer, 2005). The climate in the Indus plains is arid to semi-arid. In the lower plain December to February is the cold season and mean monthly temperatures vary from 14 to 20 °C. Mean monthly temperatures during March to June vary from 42 to 44 °C. In the upper plain mean temperature ranges from 23 to 49 °C during summer and from 2 to 23 °C during winter. Average annual rainfall on the Indus plains is about 230 mm. On the lower plain, Larkana and Jacobabad areas, on average receive about 90 mm of rainfall annually. On the upper plain, Multan receives 150 mm and Lahore about 510 mm of rain. Because of the hot climate, the evaporation rate is very high and the mean annual evaporation on the lower plain (Nawabshah) is 204 mm while on the upper plain (Sargodha) it is 1 650 mm (WCD, 2000). WATER RESOURCES Surface water The river flows are comprised of glacier melt, snowmelt, rainfall and runoff. Outside the polar regions, the Upper Indus river basin contains the greatest area of perennial glacial ice in the world (22 000 km2); the area of winter snow cover is an order of magnitude greater. The glaciers serve as natural storage reservoirs that provide perennial supplies to the Indus river and some of its tributaries (WCD, 2000). The Indus river system forms a link between two large natural reservoirs, the snow and glaciers in the mountains and the groundwater contained by the alluvium in the Indus plains of the Sindh and Punjab Provinces of Pakistan (Ojeh, 2006). The Indus river has two main tributaries, the Kabul on the right bank and the Panjnad on the left. The Panjnad is the flow resulting from five main rivers (literally Punjab means “five waters”): the Jhelum and Chenab, known as the western rivers with the Indus river, and the Ravi, Beas and Sutlej, known as the eastern rivers. This division came into effect at the time of settlement of a water dispute between India and Pakistan in 1960. Under this Indus Water Treaty, the following rules apply: Western rivers: Pakistan shall receive for unrestricted use all those waters of the western rivers, i.e. Chenab and Jhelum, which is India under obligation to let flow, except for restricted uses, related to domestic use, non-consumptive use, agricultural use and generation of hydroelectric power of which the amounts are set out in the Treaty. Annual flow from China to India in the Indus basin is 181.62 km3 and it is estimated that the flow generated within India is 50.86 km3, resulting in a flow from India to Pakistan in this part of 232.48 km3, of which 170.27 km3 are reserved for Pakistan and 62.21 km3 are available for India. Eastern rivers: All the waters of the eastern tributaries of the Indus river originating in India, i.e. the Sutlej, Beas and Ravi rivers taken together, shall be available for unrestricted use by India. Pakistan shall be under an obligation to let flow, and shall not permit any influence with, the waters (while flowing in Pakistan) of any tributary which in its natural course joins the Sutlej Main or Ravi Main before these rivers have finally crossed into Pakistan. The average annual flow in India before crossing the border is estimated at 11.1 km3. All the waters, while flowing in Pakistan, of any tributary which in its natural course joins the Sutlej Main or Ravi Main after these rivers have crossed into Pakistan shall be available for unrestricted use of Pakistan. All the rivers of the Indus system are perennial (WCD, 2000). Aided by a number of smaller rivers (Swat, Haro, Kunar [Chitral], Tochi, Shah Alam, Naguman, Adezai, Soan, etc.) and streams/Nullahs, these rivers supply water to the entire Indus Basin Irrigation System (NDMA-UNDP, 2010). The Indus river is the twelfth largest river in the world (Ojeh, 2006) and originates near lake Manasarovar to the north of the Himalayas range on the Kailash Parbat mountain in China at an elevation of 5 500 m. The Indus catchment area is unique in the sense that it contains seven of the world’s highest 4 Irrigation in Southern and Eastern Asia in figures - AQUASTAT Survey - 2011 peaks after Mount Everest. Among these are K2 (8 600 m), Nanga Parbat (8 100 m) and Rakaposhi (7 800 m). The river is 3 200 m long out of which 1 114 m are in India. The river has 27 major tributaries above Guddu barrage. The largest tributary is the Shyoke river (640 km long with a catchment area of 20 160 km2) (NDMA-UNDP, 2010). The flow of the Indus river depends on the season, it decreases during the winter and floods the banks during the monsoons.