جستجوی مقالات مرتبط با کلیدواژه "آب مصرفی کشاورزی" در نشریات گروه "آب و خاک"

Achieving food security in the future with sustainable use of water resources will be a big challenge for the current and future generations. Population increase, economic growth and climate change intensifythe pressure on existing resources. Agriculture is a key consumer of water, and it is necessary to closely monitor water productivity for it and explore opportunities to increase its productivity. Systematic monitoring of water productivity through the use of remote sensing techniques can help identifying the gaps in water productivity and evaluate appropriate solutions to address these gaps.
 
Qazvin plain is known as a hub of modern agriculture by providing about 5% of the country's agricultural products. Therefore, estimating water demand and water productivity in agricultural management in the region is considered important and necessary. In order to monitor water productivity through access to various data across Africa and the Middle East, the WaPOR database provides the possibility to examine the rate of evapotranspiration, biomass and gross and net biomass volume productivity based on the land use map in the period of years 2009 to 2021. In this database, it is possible to check the mentioned items at three levels with different spatial resolution, which according to the scope of the study, it is possible to check values with a spatial resolution of 250(m). In order to determine the efficiency and accuracy of the land cover classification map of the WaPOR database, the results obtained are examined and compared with the Dynamic World model, which represents a global model with high accuracy. For this purpose, the latest land use map related to 2021 Using the WaPOR database and Dynamic World in the GEE system, it was prepared and based on the classification of the region in order to check the accuracy of the user map of the WaPOR database and to determine the percentage of each class compared to each other. Finally, all estimable indicators were calculated and checked by the WaPOR database during the years 2009 to 2022.
 
The amount of evapotranspiration of the plants covered by the irrigation network in the period of 2009 to 2016 has been associated with a relatively stable trend, but this trend has decreased in 2017 onwards, which is one of the reasons for the decrease in the amount of evapotranspiration in this the period of time and can refer to the lack of water available to the plant due to the limited water resources in recent years. The investigation of the total amount of biomass in different lands shows that during the years 2009 to 2022, this index has been accompanied by a gradual increase in all uses, so that the amount of TBP index in 2020 was 17% more than in 2009. It shows the amount of biomass in different lands. The amount of biomass in the lands covered by the water network is 5 to 6 times higher than that of the rainfed lands. Among the influential parameters in estimating the TBP index, we can mention the amount of evaporation, transpiration, and transpiration, the increase or decrease of each of these parameters will have a significant impact on the estimated amount of biomass. The results showed that the amount of biomass production in the areas covered by the irrigation network largely depends on the high transpiration rate in these areas. From the beginning of 2009 to 2016, the gross amount of biomass water in the lands covered by the irrigation network has been accompanied by an increase, but in 2017, drastic changes in the process of underground changes will decrease the area of the lands covered by the network and many of these lands. It has been turned into fallow and rainfed lands. The analysis of NBWP index also showed that the amount of net productivity in rainfed lands is strongly dependent on the annual increase rate, and much of the crop yield in rainfed lands is dependent on the amount received. Among the influential parameters in estimating the total amount of biomass, we can mention the amount of evaporation, transpiration and transpiration, the increase or decrease of each of these parameters will have a significant impact on the amount of estimated biomass.
 
WaPOR database data can play an important role in estimating the rate of delayed transpiration and parameters related to water productivity in the region due to its ten-day spatial resolution and the absence of data gaps. In general, the WaPOR database can be used as a guide in the reliable determination of evapotranspiration values and planning related to water resources in the agricultural sector.

Due to the critical conditions of Lake Urmia, improving irrigation methods as one the effective solutions is considered by the country's water managers. The present study was conducted to evaluate the effect of improving agricultural activities with the aim of reducing water consumption on greenhouse gas emissions in the provinces of East Azerbaijan (five cities) and West Azerbaijan (six cities) during the autumn and spring crop season on tomato, wheat, and sugar beet crops. The results of autumn wheat cultivation showed that the amount of CO2 produced in East and West Azerbaijan decreased by 22 and 28%, respectively, compared to the control treatment. Carbon footprint in East and West Azerbaijan in the treatment compared to the control shows a decrease of 39 and 35%, respectively. The results of spring cultivation for tomatoes showed that the amount of CO2 produced in the treatment was reduced by 25% compared to the control So that this amount decreased from 3925 in the control to 2917 kg/ha in the treatment. The carbon footprint of tomato production also showed that it was equal to 0.04 in the treatment and equal to 0.06 in the control (Kg CO2/kg) and had a decrease of about 33%. For sugar beet in West Azerbaijan province, the amount of CO2 produced and carbon footprint in the treatment decreased by 11.7% and 28.5%, respectively, compared to the control.

Determination of agricultural water consumption, as the main consumer of the country's water resources, is very important in order to plan and manage resource consumption and establish food security, water security and improve the livelihood of the growing population. Water consumption or actual evapotranspiration is the part of water used or delivered to the agricultural sector that is out of reach and cannot be reused. Estimating the spatial distribution of actual evapotranspiration (ETa) based on valid satellite data is a new approach in planning and determining water balance. In the study, amounts of actual evaporation, transpiration and evapotranspiration in the country and agricultural, horticultural and rainfed land uses were extracted using the methodology introduced by Food and Agriculture Organization (FAO), which is presented in the WaPOR database. The results showed that the highest actual evapotranspiration about 2500 mm occurs on the north coast and Lake Urmia. The results showed that the average amount of actual evapotranspiration in irrigated horticultural lands was 299.30 mm and in irrigated agricultural lands was 301.52 mm in a 12-year period. Accordingly, the amount of actual evapotranspiration of irrigated lands on a national scale and for the year 2018-2019 was calculated to 28.84 billion cubic meters, which is equal to 20.78 and 8.06 billion cubic meters for agriculture and horticulture, respectively. Furthermore, 72.1% of that belongs to transpiration and the other of that 27.9% belongs to evaporation.

About two-thirds of rivers, lakes and groundwater are applied for agricultural production in the world. Same as other countries, a significant fraction of surface and groundwater resources are used in agricultural sector in Iran. Water balance at country scale is the origin of estimation of applied water as agricultural consumption. The variability of annual precipitation is as the origin of the components of water balance in hydrological cycle, caused changeability in the water consumption of agricultural sector which are important reasons for estimating and re-estimating consumptive water in agricultural sector. Therefore, in this study, consumptive water of agricultural sector was analyzed based on long term (50 years) and short term (current 7 years) measured data for precipitation with the method of water balance in hydrological cycle in the country. Results revealed that average annual precipitation were 249±53 and 206±33 mm for two long and short studied periods, and the consumption water in agricultural sector were 67 ±18 and 83±6 km3 for long (50 years) and short (7 years) periods for non-modified conditions. The modified consumption water for the short period was 75±6 MCM.Results revealed that for the long period, the water consumption in agricultural sector was 0.50 of renewable water in the country. The outstanding of this study was up to date estimating of the water consumption in agricultural sector and its analysis. But applying water balance method for this purpose has some substantial limitations and non-reliable simplifications. Therefore suitable experiments are needed to reliably the results.