Evaluation of Consequences of Climate Change and Adaptation Strategies in Bushkan Plain of Bushehr Province

Climate change and increasing global warming are intensifying droughts, changes in rainfall distribution and depletion of water resources over time. Persisting hot and dry weather has intensified the phenomenon of climate change and posed serious threats to the country's water resources, resulting in the inability to meet the needs like drinking, environmental, industrial and agricultural ones. The fifth report of the Climate Change Board also shows that the phenomenon of climate change in many parts of the world has had a negative impact on agricultural production; but the application of appropriate and timely adaptive scenarios against climate change can reduce the negative effects of this phenomenon on the agricultural crops yield. Bushehr province is mostly exposed to climate change and drought because of its geographical location. According to the National Meteorological Center, the area affected by drought in this province during the ten-year period ending in March 2019, was 83%. Up to 80% of the plains of the province have a negative groundwater level. This problem is more severe in some plains of the province, including Bushkan plain, the water level of this plain has decreased by 1.31 meters annually. This plain is considered as the agricultural hub of province and Dashtestan city. Thus the study of the effects of climate change on the hydrological and agricultural situation of the Bushkan plain and the analysis of the effectiveness of adaptive scenarios to reduce the negative effects of this phenomenon is very important.

In this study, in order to create optimistic and pessimistic scenarios of climate change, the LARS-WG microscale model was used. Then, in order to investigate the effects of climate change on the hydrological status of Bushkan plain, water needs of agricultural crops and crops yield, simulated climate change scenarios and adaptive scenarios include improve irrigation efficiency and deficit irrigation were entered into WEAP model and its agro-agricultural model, MABIA. For the purpose of investigating the adaptation of agricultural production systems to changes in available water and yield as well as to measure the effectiveness of adaptive scenarios, a positive economic planning model was used. For economic model, statistics and information related to the cultivation area, production costs, prices and yields of crops in different areas of Bushkan plain were obtained through the Jihad Agricultural Organization and also completed 100 questionnaires from farmers in the area. Random sampling method was used to calculate the sample size.

By applying two scenarios, optimistic A1B and pessimistic A2, in general, it can be concluded that the most changes in precipitation were in autumn and winter and the most temperature changes were at least in autumn and spring. Also, applying a pessimistic scenario will cause more drastic changes than an optimistic scenario. The results of MABIA model show that by applying both climatic scenarios, the average water requirement of all agricultural products increases during the simulation period compared to the base period.Increasing water demand and decreasing available water have caused water stress and as a result reduced the yield of various agricultural products in Bushkan plain. The results show that the average crop yields decreases, but the highest reduction of yield in both scenarios is related to wheat crop. The results of PMP model indicates that the application of optimistic and pessimistic scenarios will reduce the area under cultivation of this plain by 42% and 55%, respectively. On the other hand, among different crops, the area under cultivation of crops such as wheat, barley and watermelon has declined more sharply. However, the application of adaptive scenarios to improve irrigation efficiency and under-irrigation somewhat offsets the effects of climate change. In optimistic climate change, adaptive scenarios to improve irrigation efficiency and use of deficit irrigation method will improve the area under cultivation of agricultural products by 6 and 4 percent, and in pessimistic climate change by 3.8 and 2.3%.Comparison of the results of applying adaptive scenario shows that despite the less effect of deficit irrigation on improving the area under crops, the increase in profit in this scenario is more than the improvement of irrigation efficiency and the reason is the costs of improving irrigation efficiency compared to the deficit irrigation scenario.

Principles of resource management and low productivity have led to declining groundwater levels and as a result the ban on the exploitation of more groundwater in the plains of Bushehr province, including the Bushkan plain. Accordingly, in this study, the consequences of climate change on the hydrological and agricultural situation in the Bushkan plain of Bushehr province as well as the effectiveness of adaptive scenarios were investigated .Finally, based on the results of the present study, it is suggested that farmers use scenarios such as deficit irrigation methods and improve irrigation efficiency to prevent water loss and reduce the yield of these crops. However, since the results showed that using deficit irrigation method will improve agricultural profits more than improving irrigation efficiency, therefore, using deficit irrigation method has priority over improving irrigation efficiency. Also due to the low impact of climate change on water demand and canola yield, canola is suggested to local farmers as an alternative crop for wheat and barley crops.