Vegetable Cultivation – an overview

5.2.3 Oman, Qatar, and Bahrain

Oman, although is a part of Gulf country, is strategically located and has several advantages over other countries in terms of water resources and food. It has considerable internal water resources (Fig. 5.5) compared with other Gulf countries. Owing to its geographical location, it receives both southwest and northeast monsoon rain. The country receives about 100 mm of rain annually during these seasons and over the mountain region it is 350 mm and is not very frequent. The volume of water the country receives from monsoon is of the order of 19,250 Mm3 and more than 80% of it evaporates, thus leaving only about 1400 Mm3 that goes as runoff and part of it infiltrates into the ground. The surface runoff and Wadi flow are estimated to be of the order of 1050 Mm3. During a period of intense rainfall, the groundwater recharge from the surface runoff is considerable [30]. Check dam are constructed to increase infiltration. Owing to such dams only about 119 Mm3 of the surface runoff drains into the sea. There are more than 59 such dams in Oman. Maximum amount of groundwater and water from Aflaj are used for agricultural purposes. The amount of water withdrawn from these two sources for agricultural purposes is about 1131 Mm3/yr while only 169 Mm3/yr of water from these sources is used for domestic purpose [30]. The remaining domestic demand is supported by water from desalination plants. Nearly 52% of groundwater is utilized for date cultivation and only 7% is used for vegetable cultivation. Apparently, Oman has to rely heavily on food imports (Fig. 5.5) and the import of virtual water in 1 year is about 1700 m3/capita. According to FAO [31], Oman needs 3000 kcal/capita/day of food by 2030. Although a part of this is supplied by meat, even for growing animal/birds for meat, freshwater is required. Estimates indicate that Oman may need 1300 m3/capita/yr of water to support its kcal requirements [32,33]. Being water stressed country, by 2050, the per-capita freshwater requirement may not reach the above figure. Besides water, land available for agricultural activity is meagre. For example, the total land area of Oman is about 320 × 103 km2. About 7% of it is arable and only 0.2% of it is fit for agriculture. Thus, even if water is manageable through desalination for irrigation, there is no land available to make the country food secure [33]. The first desalination plant, MSF plant, in Oman was installed in 1976 with a capacity of about 23,000 m3 per day. Subsequently, six plants with similar capacity started functioning. Recently, RO plant with a capacity of 120,000 m3/day and in future 281,000 m3/day will soon be in place to supply drinking water to the growing population of Oman (Membrane Technology 2016). It is projected that the production of desalinated water will cross 3 Mm3/day mark by 2025 consuming electricity of the order of 12,150 GWh [34] releasing 2 million tons of CO2 equivalent to one-tenth of per-capita emissions of CO2 of the country [21,34]. Oman lacks geothermal systems which can support power generation but it can use geothermal heat pumps for space cooling and space heating thereby reducing the consumption of oil/gas and CO2 emissions. The saved energy can be used for desalination thereby reducing the dependence on the volume of virtual water (Fig. 5.5) and eventually achieve self-sufficiency in food production. In addition, the country can adopt hydroponic method of cultivation and greenhouse technology over the sea to meet water demand. This will to some extent solve the land problem for agriculture and increase food production and self-sufficiency [33]. Further CO2 mitigation can be accomplished using RO technology for desalination. This will be further discussed elsewhere in this chapter. Qatar, with a surface area of 11,651 km2, is one of the highly water stressed countries in the Gulf (Fig. 5.5) with meagre annual rainfall of 80 mm [35]. The population of Qatar is growing at 10% annually and currently it is 2 million. The country’s GDP stands at 7%. The groundwater reserves estimated from the northern aquifer is about 2500 Mm3 and this water is mainly used for irrigation. It is about 33% of water that is being utilized by the country and rest 57% is supplied by five desalination plants generating about 987,000 m3/day. Two more desalination plants are being constructed with production capacity of 490,000 m3/day. MSF distillation units generate about 81% of freshwater while only 19% is generated by multieffect distillation (MED). In addition, two RO plants with generation capacity of 1880 m3/day is being planned to increase freshwater supply by 60% although the demand is 87% [35]. Nearly 36% of the available water is utilized by the agricultural sector. A major part of it goes for growing fodder for the animals and flood irrigation, although flood irrigation wastes a large amount of water. Groundwater balance reported by MDPS [35] indicate that the total water that is being infiltrated into the aquifer is about 63 Mm3/yr from the precipitation and 2.2 Mm3/yr flows from the aquifers in Saudi Arabia. Out of this volume about 18 Mm3 of water flows into the sea. Hence, in effect the total water being recharged into the aquifer is about 47 Mm3/yr. The total water extracted from the aquifer annually for agriculture is about 230 Mm3/yr. Besides groundwater, 55 Mm3/yr of treated sewage effluent (TSE) is also used for irrigation. The current policy of the government is to store 7 days of water to tide over any emergency situations. Qatar has a vision to produce 40% of its food within the country without depending on VWT by 2025. Achieving self-sufficiency in agricultural production may be expensive relative to VWT since it has to generate large volume of desalinated water. However, depending on VWT over a long period time is detrimental to the country as this may lead to food risk issue due to geopolitical conflicts [36,37]. Increasing the desalinated water using MSF will emit large CO2 compared with SWRO. The reported CO2 emission from MSF units is 3.6 million tons/yr while SWRO units emit 0.9 M tons/yr. The CO2 emission per cubic meter of water generated from MSF units is 8.2 kg while for SWRO units it is 2 kg/m3[38]. The total CO2 emissions by Qatar from fuel combustion is 78 million tons (oil 17 million tons; gas 61 million tons, electricity generated is 5 × 1011 GWh, per-capita CO2 emissions is 36 tons) and share of emissions from residential sector is 8 million tons [21]. Owing to the geographic location, Qatar uses about 60% of its energy for space cooling and heating [39]. This amounts to about 3 × 1011 GWh of electricity. Assuming minimum CO2 emission quantity of 198 kg/MWh (from oil combustion), cooling and heating of buildings will emit 594 × 109 tons of CO2. Since Qatar’s energy demand grows with increase in population, to meet the water and food demand, the country has to increase the number of desalination plants to generate freshwater. Part of this energy can be drawn from energy used for space cooling and heating by using geothermal heat pumps for space cooling and heating. There is no in-depth data on the heat flow and heat conduction data for Qatar. Since Oman and Qatar fall within similar geographic domain, there should be suitable sites to tap this source of energy to establish GHPs. A large part of CO2 emitted from the energy source used for air conditioning of the building can be saved using geothermal energy.

Bahrain consists of a group of 40 islands with a total surface area of 762 km2. Bahrain’s population has increased by 10 fold since 1940 and stands at 1.34 million today [40]. The Dammam and Rus Umm Eradhuma are the two main aquifers supplying 57% of water to domestic and agricultural sector. The industrial and agricultural sector use desalinated water (37%) and treated sewage water (9.7%). The Dammam aquifer’s production is declining while the Rus Umm Eradhma is able to supply 70% of the water to domestic and agricultural sectors [40]. The per-capita consumption is about 318 L/day. Besides normal irrigation, Bahrain adopted hydroponic cultivation to decrease food imports and move toward food self-sufficiency. The agricultural products include dates, alfalfa feed stock, and variety of fruits. Cereals are main food imported to the country. The contribution of agriculture to the GDP is about 3%. To decrease food imports, the government is extending heavy subsidies on agricultural machineries, irrigation equipment, pesticides, and fertilizers.

Owing to issues related to land availability, salinity of the soils, and man power, Bahrain imports 84% of food from Saudi Arabia and Australia [40]. This puts the country on high risk in terms of price and supply due to uncertain political equations between these countries. Desalination using low-carbon energy sources such as geothermal and hydrophonic cultivation may reduce this risk in future. Currently 36 gas turbines generate 4938 MWe to meet the current demand contributing 23 × 103 tons of CO2 annually. Industrial CO2 contribution is about 12 × 103 tons and waste contributes is 2 × 103 tons [41]. Bahrain gives heavy subsidies to its population and in 2012 the country spent US$ 1.7 billion on energy subsidy which amounts to 5.6% of the country’s GDP. The average monthly power consumption by one house hold is 3000 kWh (number of houses: 173,069). The solar pv contributes 12% of this consumption [41] offsetting about 413 × 106 of CO2 emissions (assuming 0.553 kg of CO2/kWh from natural gas thermal power plants, EIA [42]).

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