مجله علوم و مهندسی آبخیزداری ایران
پیاپی 62 (پاییز 1402)

Rainfall is one of the most important meteorological variables. Trend analysis is one of the most effective methods to observe the impacts of climate change on rainfall. Recently, new graphical methods have been proposed as an alternative to classical trend analysis. Innovative Polygon Trend Analysis (IPTA), which evolved from innovative trend analysis (ITA), is currently one of the proposed methods and there are no presuppositions in it. The purpose of this study is to compare IPTA and ITA with MMK and PETIT methods. To achieve this goal, the total monthly rainfall trend of six synoptic stations in the Lake Urmia Basin in 1988 to 2017 was examined. Based on the results of MMK test, it was observed that only in Tabriz, the rainfall trend was increasing, which was not significant at the 95% confidence level. In other stations, the rainfall trend was decreasing, which was significant in Maragheh and Mahabad. Also, the results obtained from ITA were consistent with the MMK. This indicates that the ITA method can be used to analyze the trend of meteorological variables. Using the IPTA, the slope of rainfall transfers from one month to the next can be calculated with the amount of trend length, which can not be calculated using classical methods such as MMK.

Water resources management needs to consider the effects of climate change on its main hydrologic cycle components. Therefore, the present study was conducted to analyze the impact of high and low flow variables from rainfall and temperature changes in the rivers of Sabalan in Ardabil Province. The rainfall and temperature gauge stations corresponding to hydrometric stations were selected. Then, the dependency of discharge and climatic components were examined during 1969 to 2019. The Change Point Analysis was used to test the significant changes in rainfall and temperature time series. Then, the discharge data were divided into periods before and after the change of climatic variables. For both periods, 41 variables of high and low indicators were calculated using RAP software. Based on the results in Lay, Nir and Pol-e-Soltani stations, the maximum flow discharge in the period after the change in climatic components has a decreasing trend compared to the before period. The trend of the average value of rising rate in most stations was decreasing. The number of zero days in Ahl-e-Iman and Pol-e-Soltani stations has increased by 201 and 947 percent in the post-effect period, respectively. The mean values ​​of the 3-day moving maximum in Ahl-e-Iman, Nir, Pol-e-Soltani and Viladaraq hydrometer stations decreased by 29.53%, 45.58%, 35.24% and 39.42%, respectively. In conclusion, the hydrological behavior of the stations has changed under the influence of precipitation and temperature components.

It is necessary to predict the influencing parameters on homogeneous watersheds for the future in order to make decision and correct management. In this research, 19 bioclimatic variables extracted from the ESM4-GFDL general circulation model based on ssp126 scenario and then were clustered in two statistical periods, including the years average of 1981-2010 and the average of 2041-2070, and also homogeneous watersheds were identified for two statistical periods. Also, the intensity of utility in homogeneous watersheds was investigated. The results showed that the homogeneous watersheds located in cluster 4, will be involved with the highest changes in increasing temperature and decreasing precipitation and it will cover about 16% of the area of Chaharmahal va Bakhtiari province. On the other hand, in all homogeneous watersheds, the seasonal changes in precipitation and average air temperatures of the wettest quarter have an increasing trend, which shows the disproportionate temporal distribution of precipitation will be occurred, then the problems lead to destructive floods, the reduction of plants and agricultural productions and destruction of native habitats of the regions. In this regard, Kohrang city has been studied as the most critical city and has the least desirable area, 23.38 and 22.35 in two periods, respectively.

Urban runoff management models are considered as a useful tool in planning, design and development. One of the most usable models in this field is the SWMM. One of the main problems in studying urban drainage network with these models is the correct choice of parameters. To overcome this problem, the sensitivity analysis method could be used, which shows the relationships between variables included in the model with each other and the priority of their impacts on the model output. The purpose of this study is to determine the sensitivity of affective variables that influence urban flood peak using the SWMM model in Azimiyeh region of Karaj. In order to that, the estimated initial value of the percentage of impervious area, slope, width, curve number, N-Manning for impervious area, depth of depression storage on impervious area, percent of impervious area with no depression storage reduction were decreased and increased to a constant value in the range of acceptable changes and their effect on peak discharge was investigated as a dependent variable. Based on the results, the amount of impervious areas and the percent of impervious area with no depression storage had highest and lowest effect on peak discharge, respectively. 30% increase in the amount of impervious areas, as the most effective parameter, caused peak discharge to be increase 5.09 percent.

The present study aimed to determine the most appropriate methods to increase moisture retention in the soil profile. This research was designed in the form of a randomized complete block design with six treatments including three treatments using wheat straw with different compositions and methods, one treatment using sponge waste and gravel filter, one treatment using animal manure and natural soil treatment (control). The soil moisture content of the treatments was measured every 15 days by gypsum blocks for 3 years and their weight percent moisture content was compared to each other and the control treatment. The results showed that the treatment using sponge and gravel filter was significant and effective in increasing the soil moisture retention compared to the control treatment with values of 15.2 and 10.8 percent moisture at the 1 percent level of significance, respectively. It is worth to mention that between the three treatments using wheat straw with different compositions and methods, with a range of 12.3 to 12.8 percent moisture content, no significant difference was observed therefore none of them has a preference over the other in terms of maintaining soil moisture content.

Water ponds play an important role in providing water needed for a large part of paddy lands. In addition to providing drinking water, these native structures play an important role in feeding underground water and preventing the drop of the underground water level, so their preservation is very important. In this research, by observing the distribution map of water ponds in Mazandaran province, a range of Haraz catchment with about 41 water ponds was selected. For this purpose, 20 water ponds were examined, then the catchment runoff was calculated for different return periods using the SWMM model, and the obtained results used for all the water ponds in the project area. Based on the obtained results, improvement of all water ponds in the region from one to two meters will collect the runoff from rainfall up to the return period of 50 years and increase the cultivated area of paddy fields. Therefore, by collecting runoff in non-agricultural seasons and using it in agricultural seasons, an important step can be taken in the optimal use of water resources, as well as increasing the amount of production of the dominant crops in the region.

Improvement of the natural tourism industry is considered as an important way for sustainable development of watersheds. Ecotourism should increase watershed income and consequently reduce the pressure caused by harvesting of natural resources. Sangtarashan watershed located in Khorramabad city, is a suitable area for tourism development. The main aim of this study was to identify the internal (strengths and weaknesses) and external factors (opportunities and threats) of the study area available for the development of regional tourism and present appropriate strategies. To conduct this study, first, based on the basic information available in the region and with the opinion of managers and stakeholders, a list of strengths and weaknesses as well as opportunities, opportunities and threats of the region was prepared and provided to experts and watershed residents to determine the importance and rank of each case to be determined. Then, internal and external factors were analyzed using SWOT model. The Quantitative Strategic Planning Matrix (QSPM) was used to select the best strategy for tourism development in the region. According to the results conservative strategies (WO) are the most appropriate strategies for development of Sangtarashan tourism.

The aim of this study is to identify the areas prone to gully erosion and landslide as a two-hazard map in the form of a single map in Gorganrood watershed. In addition, the use of two machine learning models such as RF and SVM to establishing the spatial relationship between these hazards and the GEFs and any hazard susceptibility mapping separately. In addition, the validation of the hazards susceptibility maps was conducted based on the ROC curve method, and the best model was chosen with the highest predictive performances. Finally, by combining the susceptibility landslides and gully maps, the two-hazard probability maps were produced, which were a combination of different models and the best model. The results showed a RF model with (AUC = 82.9) for landslide and (AUC = 96.9) for gully erosion have higher accuracy compared to the SVM model with a value of (AUC = 0.76) for landslide and (AUC = 93.9) for gully erosion. Finally, a single and comprehensive map was obtained by combining of the each hazard susceptibility map for identification the areas prone to both hazards based on both models. The final two-hazard map can be used as a valuable tool for sustainable land use planning in multi-hazard prone areas.

The aim of this study was to evaluate the relative resilience of the Samian watershed located in Ardabil province using five indicators including specific erosion and sediment, drought, flood potential, climate, and socio-economic in different weighting conditions. At the equal weighting, the average relative resilience index of Samian Watershed was 0.53, which indicates the average relative resilience. Considering the weight of each indicator at the same level in 27 different sub-watersheds of Samian, sub-watershed 8 located in the east with priority 1 had the highest relative resilience. Considering the equal weight and with emphasis on climate, flood potential and socio-economic indicators, sub-watershed 27 located in the central part of Samian Watershed was at the lowest level of relative resilience and was given priority 27 and sub-watershed 8 has been recognized as the most resilient sub-watershed. Sub-watershed 27 has been permanently in utilization due to the use of rainfed cultivation. Emphasizing erosion and sediment, and drought indicators, respectively sub-watersheds 25 and 23 located in the center of Samian Watershed were ranked in 27 priority.

Rainfall is one of the variables that have the most impact on runoff. In this study, the inflow of Karun 4, Dez, Karun 3, Rudbar, Sardasht and Zayandeh-Roud dams was modeled using the NAM rainfall-runoff model and past meteorological and hydrological data. In order to determine the amount of rainfall input to the model of North America were received. Then, to select the best precipitation forecasting model, precipitation temporal clustering method and artificial neural network with radial basis function were used. After determining the rainfall and predicting the inflow to the dam to check the performance of the rainfall model selection, the predicted monthly inflow was compared with the actual monthly inflow. The results showed that more than 60 percent of the time in Karun 4 and Sardasht dams, with the cooperation of the best climate model, the rainfall values are close to the observed values. The normalized mean error rate, normalized root mean sum of squares and Nash Sutcliffe in Karun Dam 4 are calculated as -0.064, 0.046 and 0.649, respectively. The results of this research show the importance of rainfall time clustering method to choose the best rainfall climate model to improve irrigation results.