Evaluation of groundwater level drop and management of its effects (case study: Chahardoli plain of Asadabad)

One of the major challenges of groundwater is its over-consumption in agriculture. Therefore, it is necessary to pay attention to water resources management to prevent the drop in groundwater levels. Chahardoli Plain in Hamadan Province has faced an increase in groundwater abstraction in recent years due to the lack of surface water resources. In this study, due to limited water resources and irregular use of groundwater, the drop in water level and its management in the aquifer of Chahardoli Plain of Asadabad was considered.

This is an applied study in which both documentary and survey methods were used for data collection. In the documentary method, the statistics of annual rainfall in a 27-year period of the General Meteorological Department of the province, and the amount of groundwater level drop (43 wells) were used. In the survey method, interviews with farmers that used groundwater resources of Chahardoli Plain (56 subjects), experts of the regional water company (40 subjects), and the necessary tools were designed to investigate the decrease in groundwater level and its side effects. Cronbach's alpha of the instrument was 0.86, which showed that it had good reliability.

The results showed that the groundwater level has dropped by an average of 67.1 cm per year over 27 years. In contrast, the rainfall chart showed an average of 303.3 mm of precipitation per year. The overall slope of the equation for the drop in groundwater level data was -0.77 m and the overall slope of the equation for the rainfall data was 0.083 mm. This means that the slope of the groundwater was higher than the slope of the increase in rainfall. Meanwhile, the SPI index was negative in the first 21 years. The correlation coefficient between the drop in water level and precipitation was equal to r = 0.14 and p = 0.08. This showed that the relationship between groundwater level drop and precipitation was not significant. In order to interview farmers and experts on water management problems, according to the results, nine factors were examined and prioritized from the perspective of participants. Participating in farm water management courses from the experts' point of view and the existence of educational programs on radio and television for the farmers were the two main priorities. The priorities of farmers and experts regarding the factors of responsibility, risk-taking, and understanding the severity of water resource degradation were quite similar. In the case of water resources protection, non-leveling of lands was the first priority of both groups of experts and farmers. In the planning section, the first priority of farmers and experts was to develop optimal water distribution laws for the optimal use of water resources. In the case of water productivity management, the first priority of both was to replace rain-fed crops with products with high water requirements. In financial problems, according to experts, the lack of a proper and timely budget was the first priority, while farmers considered it to be reducing the price of manufactured products at the time of sale.

The results showed that management problems were related to the drop in groundwater levels in the region. Considering the consensus of experts and farmers on taking responsibility for the destruction of water resources and the effectiveness of educational programs, it seems that the preparation of educational programs on radio and television, and improving educational programs of regional water departments and agricultural institutions will increase the desire to maintain groundwater. According to the results, the decrease of groundwater level is not related to the amount of precipitation and human factors have a more important role in this regard. Therefore, all users of the plain, i.e. farmers, experts, officials in charge of water resources, agricultural jihad, and the environmental organizations have a role in reducing this problem. Therefore, these organizations should prioritize their goals in codified and integrated plans for short-term and long-term plans to conserve groundwater resources. Also, according to the results of the research, the downward trend of the aquifer level will continue in the next few years, which necessitates a serious review of water abstraction laws in the plain.