Original Article
Irrigation network management
Omid Raja; Sajjad Veysi; Ali Barzegar
Abstract
Extend AbstractIntouductionMany factors have contributed to the drop in the water table of groundwater, including the increase in cultivated area, decrease in rainfall, climate change, and the continuation of drought in recent years, and withdrawing excessive amounts of surface water sources and groundwater ...
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Extend AbstractIntouductionMany factors have contributed to the drop in the water table of groundwater, including the increase in cultivated area, decrease in rainfall, climate change, and the continuation of drought in recent years, and withdrawing excessive amounts of surface water sources and groundwater from unauthorized wells, which has faced serious challenges in the water sector in Alborz province. The Hashtgerd plain is located in the Alborz province. The current situation of the Hashtgerd plain is the result of a series of human and natural factors over the past few decades, and the restoration and balance of the underground water of the plain is a priority. According to long-term statistics, the groundwater level has decreased by 19.8 m in 29 years (1990-2019) on average, there is a drop in the groundwater level of about 68 cm. per year. The total aquifer deficit is 487.85 million cubic meters, and the average annual amount of the aquifer deficit is 16.82 million cubic meters (6.2%). Given these conditions, it is essential to apply effective solutions for optimal and efficient water management.MethodologyThe purpose of this study was to provide practical and low-cost solutions to save water consumption in Hashtgerd Plain. There are different solutions with minimal cost, such as improving irrigation efficiency, changing the planting date, and different patterns of deficit irrigation. The approach of this study is to present and examine solutions that do not require changing the irrigation system or even changing the cultivation pattern and also not reducing the cultivated area in the region. It is the examination of the solutions that can be implemented at the lowest possible cost without adversely affecting the livelihood of farmers. The objective of the study was to reduce water consumption or prevent from excessive groundwater of Hashtgerd plain aquifer. The proposed solutions do not require new tools such as precision leveling machines and, so on. Each of the above strategies was evaluated based on the actual conditions in the region. The main objective was to evaluate and estimate the water requirements of the dominant crops in the Hashtgerd Plain, and to present different scenarios for improving irrigation efficiency according to the superior conditions in the region. The feasibility of saving water consumption through strategies to change the planting date and deficit irrigation was evaluated using the AquaCrop 6.0 model.Results and discussionIn this study, the AquaCrop model was used to simulate the yield of crops and the amount of water use in the region. The calibration of the AquaCrop model for regional conditions has demonstrated that the AquaCrop model is capable of predicting crop yield with the lowest relative error (RE) for wheat, barley, fodder corn, and alfalfa for the plains during the calibration phase of the simulation model. According to the levels of efficiency improvement in different regions and for different crops, it will lead to savings of 17.7 million cubic meters (5.9%) in the amount of allocated water consumption. This will can provide the possibility of supplying water to a larger area of land without reducing yield under water scarcity conditions. The outcomes of the scenario involving a change in planting date through AquaCrop model simulation demonstrated that this management pattern has the potential to reduce water consumption by 2.4 million cubic meters (0.8%) in the region. In addition, different levels of deficit irrigation can save 19.3 million cubic meters of water consumption.ConclusionThe obtained results show that in many cases, it is possible to provide without modern facilities and huge costs, applying different scenarios such as improving efficiency, changing planting dates and deficit irrigation has achieved significant savings in the required irrigation water consumption. Naturally, the share of each crop in the amount of savings is proportional to the average water consumption per hectare and the area of land under each crop. In general, the AcuCrop model can be used as a practical tool for simulating crop yield and evaluating management scenarios.
