مجله مهندسی و مدیریت آبخیز
سال چهاردهم شماره 1 (بهار 1401)

Some parts of “morpho-climatic classification of Iran's gullies” national project in Soil Conservation and Watershed Management Research Institute, refer to the amount of produced sediments and reclamation measures for their management and the amount of damages resulting from their development. The results of this research indicate that Iran's gullies are categorized in two classes, small (<1 m) and medium gullies (1-10 m). One meter of gully has produced 19 m3 of sediment. Generally, they are distributed in rainfed lands and rangelands with loam, sandy loam and clay loam soil textures. The most important causes of gully formation and development are rangeland destruction, rangeland change to cropland and garden, and non-proper road and culvert construction. The present research showed that more than 50% of Iranian gullies had no management and reclamation measures, so that in 90% of some provinces and 30-50% in other areas, no management measures have been taken. More mechanical measures such as loose rock dams, rock and cement dams and gabions dams with the aim of sediment trapping are taken in Iran's provinces. Most measures are taken in small gullies, but just a few in medium ones. Management measures for prevention of gully formation are negligible in rainfed lands and serious attention is recommended to be paid to the design and construction of culverts and roads in mountainous and steep areas. Biological methods, blankets and rip-rap methods are used less in Iran. Demolition and abandoned old Ab-anbars had a role in have gully formation and development.

Since most of soil erosion studies in the watersheds are conducted by consultant and executive companies (as contractors) using the semi-quantitative MPSIAC model under the supervision of provincial natural resources and watershed administrations (as employers), so in this study, the results and findings of the aforesaid studies in West Azerbaijan Province were considered. Analysis of the studies showed that in the last three decades a total of 76 watersheds of the province with an approximate area of 4100 km2 have been studied in terms of soil erosion and sediment yield states using the MPSIAC Model. Estimated mean annual soil erosion was 13.95, 16.30, and 15.59 t.ha−1.yr−1 for northern, central, and southern sections, respectively. Meanwhile, based on the model, the mean sediment yield of mentioned sections has been calculated equal to 5.39, 5.64, and 6.09 t.ha−1.yr−1. Nevertheless, a detailed investigation based on the resistance of different lithology units to erosion in the studied watersheds, as well as land use and vegetation cover as the two most important factors of the MPSIAC Model showed less reliability of the reported results. It seems one of most important reasons for such unreliable results refers to one of the most important weaknesses of the MPSIAC model which estimation of the soil erosion is depended on the estimated amounts of sediment yields and sediment delivery ratio. According to our findings, it can be concluded and suggested that the Forests, Rangelands, and Watershed Management Organization should replace the MPSIAC Model, with USLE family models, especially RUSLE, at least in estimating the soil erosion, in the services description of consultant and executive companies. Implementation of this change should also be taken seriously by the provincial natural resources and watershed management administrations.

One of the most common and effective problems in long-term climate studies is the presence of gaps in the time series of various climatic and hydrological data. Therefore, the present study evaluates the accuracy of methods for infilling missing data of daily, monthly and annual temperature time series in the arid regions of Iran. For this purpose, the observed daily minimum, average and maximum temperature data for the period 1987-2014 measured at 73 synoptic stations distributed all over arid regions of Iran were used. Methods of readjustment used include: Normal ratio method, linear regression, multivariate regression and Inverse Distance Weighting (IDW). In this study, the capability of each mentioned methods for infilling missing data of daily, monthly and annual precipitation time series in the arid regions of the Iran was investigated, while the proportion of missing data varies from 5 to 50% of total data. In order to compare and evaluate the accuracy of the four mentioned methods three statistical indicators, namely the correlation coefficient (R), the Root Mean Square Error (RMSE) and Nash coefficient were used. The results showed that in general, each of the methods mentioned had different functionalities at a special level of readjustment and time scale. On annual and monthly scales, linear regression and normal ratio methods are the most accurate method in readjustment temperature data in the arid region of Iran. The correlation value between the readjustment and observational data at different levels reaches more than 0.95 using these methods. On the daily scale, there is no significant difference between the accuracy of the methods used in the readjustment of temperature data, and almost all four of these methods have appropriate accuracy because in all methods the correlation between readjustment and observed data is more than 90%. However, multivariate regression methods with an average correlation of 0.99 showed the most accurate performance in readjustment daily data at different levels of readjustment. Generally, each method should be used in accordance with the conditions, and therefore it is recommended to develop a software package for infilling missing data.

The protection and management of each user in different areas should be based on ecological conditions, which can be achieved by assessing the ecological potential in each area. Assessing ecological potential means examining the potential power of the land and determining its natural use by humans. The main purpose of this study is to identify the ecological potential in Khodaafarin City with an area of ​​161,607 ha, using the multi-criteria assessment method, the common land management model of Dr. Makhdoom and using GIS. In this study, after identifying ecological resources (sustainable and unstable), the resources were analyzed and summarized. Then, in the software environment (ArcGIS 10.6), the information layers were combined and then the maps were evaluated. Finally, according to the existing values, the potential strengths and bottlenecks of the region were estimated and the permitted uses were prioritized in the region. As a result, after combining the necessary maps and correcting them, the environmental capacities and ecological potential of the region were estimated as area (percentage) in Khodaafarin City. According to the objectives of the research, areas prone to segregation of aquaculture-agriculture (2.65), aquaculture-rangeland management (0.14), aquaculture-urban and rural development (0.2), aquaculture-extensive tourism (0.049), conservation-extensive tourism (0.45), conservation-forestry (0.12), centralized tourism-forestry (0.021), aquaculture (6.34), extensive tourism (12.61), centralized tourism (2.64), rangeland management (33.1), agriculture (7.51), conservation (13.57), urban, rural and industrial development (1.8), forestry (18.8) were zoned and identified. The results also showed that the highest potential is related to the rangeland management with an area of 61567.55 ha of which less than 50% (30457 ha) is consistent with the current conditions.

Determining the effectiveness of flood spreading schemes, especially from the point of view of effective economic and social indicators, over a quarter century after their implementation in the country, plays an important role in their assessment. In this study, indicators related to the effects of flood spreading plans on Ab-Barik Aquifer of Bam were identified and then ranked based on nonparametric statistical tests from the experts' point of view. For this purpose, first the indicators related to the effects of flood spreading projects on the aquifer based on library studies, expert inquiries as well as site visits and face-to-face interviews with local residents and users were identified and finally the validity of the questionnaire based on expert opinions was identified. Finally, the validity of the questionnaire based on the experts' opinions and their comments was finally confirmed. Also, the reliability of the measuring instrument was tested by calculating Cronbach's alpha component. In this research, based on the multi-response coding method, the variables of the questionnaire were of the type of qualitative and qualitative variables consistent with the Likert scale, so at this stage, a survey was conducted from 30 experts. The range of changes in mean rank values varies from 4.15 to 22.88. The results of the ranking of indices based on Friedman test showed a significant difference in the effectiveness of the effective variables in evaluating flood spreading projects on aquifer, so that the question of “reducing the damage to flood lands and gardens” with the rank mean of 22.88 and also the question of “conflicting among the villagers in the area” with the rank mean of 4.15 have maximum and minimum priority, respectively. In addition, the results of the study indicate the high effectiveness of flood spreading schemes in the Ab-Barik Aquifer of Bam.

Drought is one of the natural disasters related to climate and one of the most important threats to human survival leading to adverse effects on social, economic, and environmental sustainability. In this study, it has been tried to evaluate the changes in reliability, resilience, and vulnerability of the Chalous Watershed under the influence of drought in the period of 1982-2017. In this vein, rainfall data of nine stations were interpolated using invers distance squared method to the whole watershed. The SPI drought index was then determined through determining the mean and standard deviation of the data. To calculate Rel, Res and Vul indices, the mean value of SPI Index was used. By calculating the geometric mean value of these indicators, the general health status of the watershed was determined and quantified. The results showed that the SPI Index in this period varied between -1.43 and 2.25. Drought index had a similar pattern to that of rainfall with an increasing trend at the end of the period. The watershed health assessment also showed that the indicators of reliability, resilience, and vulnerability were found 0.5, from 0.23 to 0.62 and from 0.06 to 1, respectively. The geometric mean of these indices was also ranged between 0.19 and 0.58. The overall health condition of the Chalous Watershed based on the dynamics of drought index with a mean index of 0.45 was classified as “moderate”. The findings of the current research will play an important role in explaining the methods of adaptive management of the watershed.

Recognizing and analyzing the behavior of low flow indices is a prerequisite for water resource management and cropping pattern planning in arid and semi-arid regions. The purpose of this study was to analyze low flow in order to provide regional relations and identifying vulnerable areas. In this study, 26 stations with a common statistical period were selected by examining the daily stream flow data of hydrometric stations in Karkheh Basin. The daily stream flow time series was prepared for each year. Then, three, five, seven, 10, 15, 30 and 60 days low flow and average annual discharge were extracted for each year and each station. A new index was defined as the "low flow index". Then the trend detection of low flow index and its regional analysis was performed. Single and multiple regression between independent parameters of height, area, slope, distance to the outlet and related low flow indices extracted and results were analyzed. The accuracy of simulation was also estimated through the coefficient of determination. The results showed that by increasing the distance from the outlet of Karkheh basin upwards, the trend of the index was higher and in the branches, the obtained index was less than the downstream. This indicates that the branches were more vulnerable and should be focused on better water resources management in the branches.

Climate change affects the environmental, economic, and social aspects of rural communities. For this reason, proper measures are needed to reduce the vulnerability of watershed residents. The present research has investigated the vulnerability of villagers' livelihoods from climate change in Oghan Watershed of Golestan Province. The study population consisted of 1158 households, that 297 households were investigated using the stratified random sampling method. Data were collected by the questionnaire that its validity and reliability were confirmed by face validity and Cronbach's Test, respectively. The results showed that livelihood vulnerability to climate change was slightly above average. Among the five livelihood assets, the most and the least damage was related to the financial and human assets of households, respectively. With increasing household members, the number of livestock, and the area of owned agricultural lands, the vulnerability to climate change has increased. In contrast, by increasing monthly income and duration of stay in the village, the livelihood vulnerability has decreased. Joining cooperatives, using indigenous knowledge and technical skills to combat climate change, and getting help from change agents and facilitators, have resulted in less livelihood vulnerability of climate change. Studying livelihood status of the inhabitants of watersheds due to changes in weather parameters, prioritizing the restoration of financial assets, and organizing villagers to use indigenous knowledge for dealing with the negative effects of climate change are the present research suggestions.

The aim of this study was to investigate the pitting and contour rainfall harvesting systems and their role in rainwater collection and forage production in rainfed conditions. This study was performed with five treatments of pitting with seeding (B), contour furrows with seeding (A), pitting without seeding (E), contour furrows without seeding (C) and control treatment (D) in three replications. FAO standard plots measuring 5x40 meters were considered for the project at Tikmehdash Research Station. In seeded treatments, Agropyron elongatum and local sainfoin were cultivated due to the effects of soil protection and forage production. Statistical analysis of the results was performed using SPSS software in the form of randomized complete blocks. The results of statistical analysis showed that the highest to lowest percentage of total canopy cover is related to contour furrows and seeding treatment with an average of 80%, pitting operations with an average of 78% and pitting and seeding with an average of 80%, respectively. Comparison of the canopy cover and forage production in the treatments showed that the canopy cover in A, B, C, D and E were not significantly different and were in the same group. Production of rangeland and succulent plants was higher in E treatment and was significantly different from A, B, C and D treatments. Also, Treatments A, B and C were not significantly different in rangeland production, but were significantly different from D (control). The highest and lowest forage production of 729.17 and 315.33 kg.ha-1 belong to pitting and control treatments, respectively.

Earth's subsidence is one of environmental hazards that humankind faces in recent decades due to the extraction of groundwater resources in the plains. Over the past years, the desertification of plains in Iran has caused a great deal of economic and social damages to the country due to the decline in groundwater levels. Marvdasht Plain Aquifer has been significantly affected by this phenomenon in recent years. On the other hand, considering the location of historical monuments like Persepolis in this village, the issue of subsidence checking is important. Therefore, the present study investigates the relationship between the amount of groundwater extraction and subsidence situation in this region. In this study, Kriging statistical method was used to study the changes in groundwater level, and radar differential interferometry and COSMO-SkyMed radar images were used to estimate the rate of subsidence. Results showed that the average annual groundwater loss is 45 centimeters. On the other hand, the highest rate of subsidence in the oblast area is between 2.5 centimeters and about 15% of the area has a subsidence of less than one cm in the period from 2013/10/01 to 2014/02/01. Comparing the map of the groundwater level and the map of the earth's surface displacement, showed that the areas with the highest groundwater abundance have the highest displacement and ground falls about one cm for every 45 cm of groundwater level drop. Comparison between amplitude and subsidence pattern obtained from the results of radar interferometry technique with location, the density of wells and groundwater abstraction in this plain shows that subsidence has occurred in the same areas where the density of these wells and extraction of groundwater resources is high.