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This study develops a set of models to investigate the water budget of Lake Urmia in Iran, a permanent hypersaline lake that has suffered a declining water level since the late 1990s. The models are of the regressive-stochastic type, a combination of multilinear regression and autoregressive integrated moving average stochastic models. The multilinear regression models were used to construct the core of the relationship of lake water level to streamflow, precipitation, evaporation and groundwater depth. Afterward, stochastic models were used to generate data for each independent variable to estimate the oscillation in the lake water depth. Several criteria were used to compare the performance of the models in the aggregated and disaggregated cases with which the pre- and post-encroachment periods are considered, respectively. The regressive-stochastic models are found to be competitive with the existing models developed so far for Lake Urmia water level. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to examine an empirical method and identify the possible linkage between energy consumption and commodity prices in the context of Iran's agriculture. Different linear and non-linear models are estimated using quarterly data over 26 years from the second quarter of 1991 to the first quarter of 2017. Our results confirm the asymmetric impact of energy consumption shocks on agricultural commodity prices. Results of the Markov switching model show that agricultural prices respond negatively to any shock from energy consumption whereas, the effect of energy consumption on agricultural commodity prices in the high inflation rate regime is less than the low inflation rate regime. The empirical evidence indicates that the probability of remaining in the high inflation rate regime equals 93%, which is more than the other regime. The agricultural inflation rate is low and in 36 seasons and high in 63 seasons. Additionally, this study found an asymmetry in the agricultural price volatilities due to most of the coefficients changing across regimes. [ABSTRACT FROM AUTHOR]