Irrigation
M. Goodarzi; F. Abbasi; A. Hedayatipour
Abstract
IntroductionThe lack of water resources and increase in water demand are among the effective factors in the imbalance of the water resources in each region, and it is necessary to manage the proper use of available water resources in all activities. Water in the agricultural sector is one of the main ...
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IntroductionThe lack of water resources and increase in water demand are among the effective factors in the imbalance of the water resources in each region, and it is necessary to manage the proper use of available water resources in all activities. Water in the agricultural sector is one of the main factors of production, which should be conveyed by irrigation systems to the field level and made available for the plant roots. The necessity of macro-planning in water management and consumption imposes a comprehensive study of the amount of water consumed in the agricultural sector. Hence, this study was conducted with the objective of directly measuring and field-assessing the applied water, water productivity, and water footprint associated with the primary crops cultivated in Markazi Province, all managed by local farmers.MethodologyFor this purpose, 141 farms were selected in the major production areas of the main agricultural and horticultural crops of Markazi province with the coordination of the Agricultural Jihad centers. Then, the volume of water applied was measured without interfering in the irrigation scheduling of the users. To do so, first, the flow rate of the water source (canal, well, aqueduct or spring) was measured with a suitable device (flume and meter) in each of the selected farms. Then, by carefully monitoring the irrigation schedule of the farm, including the time of each irrigation, the number of irrigation throughout the year, as well as measuring the area under crop cultivation, the amount of water used by the crop was measured for each of the selected farms during the season. Also, based on the measured data, the amounts of blue, green and gray water footprints were determined for each of the examined crops. For this purpose, the blue, green and gray water footprints of different crops were calculated using the framework provided by Hoekstra and Chapagain (2008), and Hoekstra et al., (2011).Results and DiscussionThe irrigation intervals in the studied fields varied between 3 and 15 days with an average of 8 days and the average irrigation depth varied between 26.2 and 99 mm with an average of 67.8 mm in different crops. The results showed that the average volume of applied water for the studied crops in Markazi province was 10782 cubic meters per hectare. Also, the minimum and maximum amount of applied water for the evaluated crops was as follows: barley 3783 and 7232, alfalfa 10382 and 19797, beans 8280 and 17840, watermelon 5333 and 7174, walnuts 4420 and 29600, almonds 3850 and 13932, peaches 6872 and 17727, cherries 7050 and 14645, pomegranates 7156 and 20790, and grapes 5937 and 18168 cubic meters per hectare. Furthermore, the average value of irrigation water efficiency index and water footprint was as follows: barley 0.46 and 1642, alfalfa 0.92 and 700, bean 2924 and 0.24, watermelon 9.37 and 117, walnut 0.1 and 6706, almonds 0.16 and 6857, peach 2.48 and 242, cherries 0.73 and 875, pomegranates 1.33 and 636, and grapes 11.2 and 322. Based on the obtained results, the average total water footprint index was equal to 2102 cubic meters per ton. On average, the almond with a water footprint of 6857 cubic meters per ton had the highest share in allocating the water footprint in the crop production of the province. Whereas, the lowest water footprint related to the watermelon with a water footprint of 117 cubic meters per ton. he average values of the irrigation application efficiency index, irrigation water productivity, and water footprint for the examined farms were 72.5%, 1.79 kg/m3, and 2,102 m3/ton, respectively. In summary, the results indicate that the combined volume of irrigation water and beneficial rainfall in the irrigated fields within Markazi Province surpasses the actual water demand of the crops. This underscores the substantial impact of irrigation management on water utilization in the region.ConclusionOn average, the total volume of irrigation water and effective rainfall in irrigated fields and gardens in Markazi Province is more than the actual water requirement of the plant. In general, the results showed that irrigation management has a great impact on the amount of water use in the region. Based on the obtained results, considering that most of the farms and gardens receive water in an intermittent manner, in principle, no special attention is paid to the need for water and even effective rainfall, and the amount of water availability has the greatest impact on water consumption. Therefore, in order to reduce water consumption and improve water efficiency, it is suggested to manage the delivery of water to farmers during the season and according to their crop water needs. Also, the results of the water footprint can be used to improve water resource policies at the province level, land use studies, cropping pattern modification, and environmental sector policies.
Hadi Ramezani Etedali; Alireza Shokoohi; S. Amin Mojtabavi
Abstract
Introduction: Qazvin plain is one of the most important agricultural regions in the central part of Iran. Because of recent continuous droughts and the increases in the demands of different sectors such as agriculture, industry, environment and domestic, the plain is faced witha severe shortage of water ...
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Introduction: Qazvin plain is one of the most important agricultural regions in the central part of Iran. Because of recent continuous droughts and the increases in the demands of different sectors such as agriculture, industry, environment and domestic, the plain is faced witha severe shortage of water resources. Due to the declining share of surface waters, farmers increased the using of groundwater. And the overusing of groundwater for irrigation has caused the severe drop in water level of the aquifer. The critical situations in the Qazvin plain have made the agricultural water management and crop pattern modification vital and necessary.Due to the population increase, concepts and theories such as food security, environmental protection and sustainable management of groundwater and surface water resources, virtual water footprint and virtual water trading are a dynamic concept for water resource management in all sectors that has considered more in recent years.
Materials and Methods: The green (effective precipitation), blue (net irrigation requirement), gray (for diluting chemical fertilizers) and white (irrigation water losses) water footprints (WF) of main crop production were estimated for Qazvin plain. The average yield and fertilizer application in irrigated and rainfed lands, for main crops wasobtained from Agricultural-Jihad Bureau of Qazvin Province in for 2003-2014. Pe values were calculated by USDA method and ETc was calculated by FAO-Penman-Montieth method using the model CROPWAT. Values of α under irrigation and rain-fed were considered 5 and 10%, respectively. In this study, WFGray has been calculated just for nitrogen fertilizers. The maximum nitrogen concentration in the receiving waters based on the US-EPA Standard is 10 mg/lit. Due to the differences in crop yield under rainfed and irrigation conditions, the WF components were calculated using crop yield for different conditions, separately.
Results and Discussion: Canola and maize with 4066 and 185 m3/ton have maximum and minimum WF in the irrigated lands, due to the yield of two crops. Canola and maize have maximum and minimum yield between the irrigated crops, respectively. The total wheat WF of was estimated 2673 m3/ton in the area. The total WF in the rainfed lands is much more than the total WF in irrigated lands that is due to the significant yield differences in the irrigated and rainfed lands, especially for wheat and barley. In recent years, because of the decrease in precipitation, the rainfed crop yields have decreased considerably. Between the irrigated crops, wheat, barley, tomato, and canola are the four crops which have similar white WF (about 50%) and gray WF (about 10%). Also there are the same shares between white and gray WFs of corn and maize. The shares of white and gray WF in corn and maize are 28 and 18, respectively. These results show that agricultural practices and managements are similar. In other words, the irrigation system efficiency and fertilizer application are similar in farms and for crops. Also there aren’t significant differences in the green and blue WFs of corn and maize. These similarities in WF components are the result of approximate equalities in the evapotranspiration, effective rainfall, fertilizer application, and depth of irrigation. In irrigated lands, white WF contains about 46% of the total water footprint in the production of main crops. In irrigated and rainfed lands, about 42% of the WF is related to white water. Thus, irrigation losses are about 864 MCM/year in the region, which is really considerable for a region that faced with water shortage crisis. In rainfed lands, the gray WF component is about 13. In total. If this gray WF which is the environmental need for protecting water quality doesn’t meet, contamination of surface and groundwater resources will be occurred. Wheat has the most consumed and exported virtual water volume with 652 and 343 MCM/year, respectively. The export of wheat includes 28.4% of the total exported virtual water volume and 20.2% of the exported water resources volume. Total consumed and exported virtual water volume from the region are 1031 and 1022 MCM/year. The exported volume of blue, gray and white WFs consists about 783 MCM/year. Therefore, considerable volumes of groundwater and surface water resources exported from the region by exporting main crops. The exported weight of maize, corn, alfalfa and tomato from the region is greater than the weight of consumption in the region. The total of blue, gray and white WFs is much higher than the green WF of these crops. The export of these crops imports the most pressure on groundwater and surface water resources of the region.
Conclusions: Qazvin Plain as one of the most important plains in the central part of Iran faces to water shortage crisis. The concept of virtual water and WF of agricultural production help to better agricultural water management in the region. The total share of gray and white WFs in the region is about 907.5 MCM/year and 44% of the total WF in the agricultural main crop production. Low efficiency of irrigation systems and excessive use of nitrogen fertilizers in farms are the most important causes of high shares of these two WF components. The planting and export of summer crops hasa considerable share of VW trade in the region. Due to the high water requirements, the total share of blue, gray and white WFs is high in these crops. These WF components are supplied from the limited surface and groundwater resources of the region. Also, WF in rainfed crops is much greater than the irrigated crops. Droughts and rain reduction are the main reasons of severe decreasing in the yield of rainfed lands. Supplementary irrigation is a management for reducing WF and improving yield in rainfed land. VW trade volume is about 1,022 MCM/year.
majid montaseri; Negar Rasouli Majd; Javad Behmanesh; Hossein Rezaei
Abstract
Introduction: The water footprint index as a complete indicator represents the actual used water in agriculture based on the climate condition, the amount of crop production, the people consumption pattern, the agriculture practices and water efficiency in any region. The water footprint in agricultural ...
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Introduction: The water footprint index as a complete indicator represents the actual used water in agriculture based on the climate condition, the amount of crop production, the people consumption pattern, the agriculture practices and water efficiency in any region. The water footprint in agricultural products is divided to three components, including green, blue and gray water footprint. Green water footprint is rainwater stored in soil profile and on vegetation. Blue water refers to water in rivers, lakes and aquifers which is used for irrigation purposes. Gray water footprint refers to define as the volume of contaminated water. The water footprint in arid and semiarid regions with high water requirement for plants and limited fresh water resources has considerable importance and key role in the planning and utilization of limited water resources in these regions. On the other hand, increasing the temperature and decreasing the rainfall due to climate change, are two agents which affect arid and semiarid regions. Therefore, in this research the water footprint of agriculturalcrop production in Urmia Lake basin, with application of climate change for planning, stable operating and crop pattern optimizing, was evaluated to reduce agricultural water consumption and help supplying water rights of Urmia Lake.
Materials and Methods:Urmia Lake basin, as one of the main sextet basins in Iran, is located in the North West of Iran and includes large sections of West Azerbaijan, East Azerbaijan and Kurdistan areas. Thirteen major rivers are responsible to drain surface streams in Urmia Lake basin and these rivers after supplying agriculture and drinking water and residential areas in the flow path, are evacuated to the Lake. Today because of non-observance of sustainable development concept, increasing water use in different parts and climate change phenomena in Urmia Lake basin the hydrologic balance was perturbed, and Urmia Lake has been lost 90% of its volume and has a critical condition. Therefore, planning, managing and optimizing utilization of water resources in the basin have a high research priority and this requires the concentration on the consumption of water resources. In this study five major products including, wheat, sugar beet, tomato, alfalfa and corn, were studied. For this purpose, seven synoptic meteorological station data including,Salmas, Urmia, Mahabad, Takab, Tabriz, Maragheh and Sarab were used to calibrate the downscaling atmospheric-ocean general circulation model LARS.WG5 and forecast meteorological data in the future periods time (2011-2030) and (2046-2065) with the A2 scenario.The reason to selectA2 scenario was the most critical situation for the mentioned scenario. Then the obtained data were used to estimate the water requirement and water footprint of mentioned plants separately blue and green water footprint in the future periods.
Results and Discussion:The resultsof themeteorological data prediction showed thatall synoptic stations except for Tabriz station the average annual predicted rainfallvalues had the deviationfromhistoricalvalues.The mentioneddeviation in the south (Tekab, Mahabad) and West (Urmia, Salmas) ofUrmia lake basin will showincreaseanddecrease in theannual rainfallin the future, respectively.Moreover,the average annual of predicted temperature values for all studied stations showed that the temperature will increase about1°Cduring2011-2030 period and 2°C during 2046-2065 period. Potential evapotranspiration, as another important meteorological parameter has essentialrole in the estimation of crop water requirements which will be slightly affected by climate change phenomena and it will increase in the summer. The results of agricultural products water footprint show that the maximum amount of green water footprint in all studied stations was related to wheat and alfalfa, and this water footprint depend on the time and growth period. For corn, tomatoandsugar beetproducts the ratio of blue and green water footprint is greater 9. By comparing the water footprint of products it can be seen that in Urmia, Salmas and Tekab stations water footprint is decreased with decreasing rainfall and this decrease during 2065 – 2045 periods is higher than 2030 – 2011 periods.
Conclusions: According to the results, annual precipitation in southern and western regions of the Lake Urmia basin will be increased and decreased, respectively in the future periods. However, increasing approximately one Celsius degree in temperature is expected for each of the periods all over the basin. In addition,the results showed that the amount of potential evapotranspiration will be increased in the warm months (June to September) in the future periods, and agricultural water consumption pattern will be changed affected by evapotranspiration variations. In the future periods, the blue and green water footprint of most agricultural products will be increased and decreased, respectively.
