The run-up of long water waves traveling at high speed across the oceans is one of the most important factors in the design of a coastal structure. As a result, a number of empirical formulas, analytical results, and numerical techniques have been developed to predict the wave run-up elevation. The utility of these formulas and schemes depends on their ability to predict the wave run-up and their convenience of use. However, in the empirical formulas, the coefficients can not provide insight into the nature of the physical processes involved. But analytical asymptotic formulas, indeed could provide considerable insight into the process because, the parameter dependence is explicit in the coefficients. The first objective of this study is to generalize the wave run-up formulas for both periodic and solitary waves on composite (multi-slope) beaches using the linear shallow water wave equations. This task will be accomplished by expanding the existing solution of simple slope beaches for periodic and solitary waves.The second objective is to solve the linear shallow water equations numerically using finite difference method to check the validity of the derived formulas. A number of figures are presented showing a comparison between the analytical and numerical results.

The effect of a placement pattern of antifer units on the wave run-up and transmission was investigated in more than 380 laboratory tests. The main variables in the experiments were as follows: An antihero unit placement pattern, the breakwater front slope angle, the incoming wave height and steepness, and the still water depth. It was concluded that the wave run-up can be reduced by about 25% by changing the placement pattern from regular to irregular. The measured data were also applied to estimate the wave run-up on the antifer-covered breakwaters as a function of the standard run-up on smooth and impermeable slopes. The measured data of the wave transmission are applied to inspect the prediction equations mentioned in literature, and the predicted and measured data were compared and the deviations were discussed. Some modifications were proposed to improve the accuracy of prediction equations of the wave transmission, especially for breakwaters covered by antifer units in regular and irregular placements.

Armoured breakwaters are important hydraulic structures as they protect the non-rocky against erosion. As the berm width affects the run-up height, therefore, its determination is of almost importance. It is interesting to note that most researchers have studied the berm recession thus ignoring the wave run-up. Therefore, this study enhances our understanding of these vital structures. As a whole, 350 numerical models were developed to investigate the relationships of the linear wave run-up over the armoured breakwaters to the berm width employing the Flow-3D software. The main variables in this study were berm width, wave height, wave period, the seaside slope of the breakwater, and the distance to the static water surface. It was observed that the numerical results were close to those of the analytical results with a correlation coefficient of 96%. A 45% increase in the berm width decreased the wave run-up height by 36%. Furthermore, a 67% increase in the wave height resulted in a 53% increase in the wave run-up height, and a 53% increase in the period resulted in a 36% increase in the wave run-up height. To sum up the stability, an optimum performance of breakwaters is determined by their berm widths.

Iran, due to its geographical location, has low rainfall and is considered a dry land. As a result, different regions of the country grapple with drought. The presence of water management systems, such as aqueducts and reservoirs, in most parts of the country, along with a variety of methods for conserving water for irrigation, may contribute to this claim. Considering that drought is an inherent phenomenon in Iran's climate, people have invented and used numerous methods to combat it and store water. The aim of this study is to monitor and evaluate drought in Iran. In order to realize this goal, precipitation data from synoptic, rain gauge, and climatology stations were extracted over a 51-year period, from 1970 to 2020. The results obtained from examining drought occurrences in five ten-year periods reveal that, with the exception of the third decade (1991 to 2000), drought has prevailed in the majority of Iran's regions compared to other decades. On the other hand, in the recent decades leading to 2020, the intensity of drought occurrences, especially in the Middle Zagros, has intensified, which has consistently been among the regions with the highest rainfall in Iran after the Caspian region. This situation can cause concern in Iran, a country where its agricultural production hub is established along the Zagros mountain range. Moreover, the fluctuating behavior of Iran's droughts, with return periods of 2 to 5 years, has complicated the management strategies for these types of hazards. These conditions appear to have created numerous issues in many areas of Iran, particularly in the agricultural sector of the western provinces, due to the lack of conformity with these types of occurrences.