نشریه مرتع و آبخیزداری
سال هفتاد و چهارم شماره 2 (تابستان 1400)

Wind erosion is one of the most important aspects of land degradation in arid and semi-arid regions, which 20% of land area of the world has been influenced by wind erosion. The wind increases the desertification process by displacing sand dunes. Therefore, the stabilizition and preventing the moving sands is essential. A strategy to combat this phenomenon is to reduce wind speed or to increase surface cover and soil resistance against erosion winds. The application of mulch or soil cover is one of the methods widely used to stabilize moving sands. For this purpose, a study was done at the Research Station International Desert Research Centre in Kashan city. The main purpose of this study was to investigate the effect of Multivariate biopolymer treatment at three concentrations (15%, 30% and 60%) on the moisture content of three sand depths (first depth of 0-5 cm, second depth of 5-10 cm and depth of third 10-20 cm), and study this mulch Compared with levels without mulch on the sand. Results showed soil moisture retention in Mulching compared to the control treatment, and statistically, there was significant differences between different depths of soil moisture Mulching compared to the control treatment and in between the first, second and third depths, the first depth had the highest increase in moisture holding compared to the Control treatment.

Extreme events such as drought and floods in Iran have always been one of the most important and harmful issues in the country and their occurrence and prediction have been in the focus of most researchers. Occurrence of floods in recent years and the inability of the management system to act in a timely manner to reduce its effects on flood-prone communities have led everyone to use various methods to predict floods. However, the lack of facilities for monitoring and collection of meteorological and hydrological data in the country's watersheds is considered a major obstacle to flood studies. Therefore, using the minimum available data to predict floods can be a good way to plan and study floods in Iran quickly. Therefore, in this study, the application of ARIMA time series modeling and ARIMA-Fourier hybrid model for modeling the maximum instantaneous discharge on an annual scale in 6 stations of Gorganroud watershed was investigated. The results showed that the use of ARIMA model alone cannot have an acceptable result, especially in the annual data scale, but the application of ARIMA-Fourier model could well increase the accuracy and efficiency of the model, so that the accuracy and efficiency indices of the model were significantly improved. As a result, the use of hybrid models such as ARIMA-Fourier can be used to improve the modeling efficiency of flood flows time series.

It is clear that the ENSO phenomenon affects the hydrological and climatic regimes in different parts of the world, but the extent of this effect in different parts of the world has not yet been answered. Therefore, this research has been done to answer this important question. In this research, using the Oceanic Niño Index (ONI), the effect of the positive phase of the El Niño-Southern Oscillation (ENSO) on the Frequency of Dust Stormy Days (FDSD) in 12 synoptic stations located in Khuzestan and Sistan and Baluchestan provinces over a period of 40 years (2019-1980) has been reviewed. For this purpose, hourly dust data, codes of the World Meteorological Organization, Adaptive Neural-Fuzzy Inference System (ANFIS) and time changes of FDSD index in two neutral phases and the occurrence of El Niño were used. The results of ANFIS model estimation and observational values of FDSD index showed that at the occurrence time of El Niño in Khuzestan and Sistan and Baluchestan provinces, equal to 33 and 17 events, respectively, the observable values of the frequency of days with dust storm were less than the estimated values. The results also showed that the positive phase of ONI is more effective on dust storms in Khuzestan province than in Sistan and Baluchestan province. Therefore, during the hot phase of ENSO, more measures should be taken to control and manage dust storms and their destructive effects in areas where the source of dust storms is external.

Today, the dust problem has become a regional and global crisis. Dust and sandstorms can be considered as funding sources for the formation of sand dunes. The purpose of this study is to investigate the movement of dust production sources and their role in the formation of sand dunes in the Jalali sandy area located in the east of Qom province. The research data includes library information, sampled points as well as information obtained from meteorological stations in Qom province and using the HYSPLIT model. The tools used in the research include climatic data from ArcGIS, WRPLOT, Google earth, Excel and NOAA satellite data. During the years (1987-2019), 89% of dust occurrence occurred in the warm half of the year and 11% in the cold half of the year. The drawn flowers of the three stations of Kuh-e-Sefid, Qom and Kushk-e-Nusrat show the superiority of the east, southeast, west and southwest directions towards Qom city. Dust also emphasizes dominance in the east in hot seasons. Routing and movement of dust in the sampled points at altitudes up to 1000 m and 1000 to 1500 m in reverse using the HYSPLIT model showed the external origin, deserts of Saudi Arabia, Syria and Iraq and the internal origin of the salt lake and plain Abandoned agricultural lands and lands have a more prominent role in the production of dust sources and the formation of glorious sand dunes.Keywords: Dust, Rose, HYSPLIT, WRPLOT, Jalali Sands.

This research was conducted in two watersheds Dasht-e-Room in Boyerahmad county and Kareh in Dena county using IntErO model. After collecting basic information; the 26 input variables were extracted and calculated using topographic, pedologic, and geologic and land use maps and climatic data i. The results showed that the maximum outflow from the watersheds of Kareh and Dashtrom in 100 year return period are 235 and 179 cubic meters per second, respectively, In other words, the amount of runoff produced in the Kareh watershed is approximately 1.3 times the oufflow from the Dasht-e- room basin and the amount of soil erosion in Dasht-e-Room and Kare watersheds, 105162.22 and 71402.58 cubic meters per year, respectively. Considering sediment delivery ratio of 0.195 in Dasht-e-Room watershed and 0.487 in the Kareh watershed, the amount of soil eroded transferred to the outlet of the watersheds (sediment yield) is 20521.32 and 34800.46 cubic meters per year respectively. The erosion intensity coefficient in Dasht-e-Room watershed is 0.338 and as a result, based on the degree of erosion intensity of IntErO model, the erosion process intensity in this watershed is low and the dominant erosion of the region is deep. The erosion intensity coefficient in Kareh watershed is 0.403 and as a result, the erosion process intensity in this watershed is moderate and the dominant erosion of the region is superficial. The amount of sediment yield per unit area in Dasht-e-Room watershed is 133.53 and in the Kareh watershed it is 347 cubic meters per year.

Water deficit caused by climate change due to the extent and magnitude of the social and economic damages it causes, is one of the most dangerous natural disasters that causes irreparable damage to the agricultural and water resources of the country. In other words, it has devastating effects on the productive, economic, social and environmental sectors. The purpose of this study was to analyze the components of resilience and present a model of resilience of the local community in the face of climate change. The statistical population of the study consisted of rural community of Nodushan watershed which was used for sample size of Cochran formula and 100 people were surveyed based on a researcher-made questionnaire. The Resilience Component Analysis Questionnaire was used. Data were analyzed using SPSS25 and LISREL8.8 software. To investigate the fit of the resilience component measurement model, the data was analyzed used LISREL software. The results showed that among the resiliency indices, the indicators of "local networks" and "financial and infrastructure" with 91 percent and 84 percent path coefficients were better than other indices, respectively. "Compatible management status" and "risk-taking" with 10 percent and 8 percent path coefficients, respectively, are not appropriate. Also, results showed that the goodness-of-fit indices had values and confirmed the resilience dimension measurement model with the data. Therefore, it can be acknowledged that the results of this study can in actions and can be effective in promoting and adopting climate change crisis mitigation mechanisms to create resilience in the local community.

To evaluate the effects of hydropriming and drought stress on germination traits of cymbopogon olivieri the experimental design was two factors factorial arranged in a completely randomized design, with four replications and 50 seeds per replicate. The first factor was hydropriming (in four levels), the second, polyethylene glycol 6000 (in four levels), in laboratory conditions. That data were analyzed using spss software. The difference between the means was compared using duncan test (p<0.05). ANOVA Results indicated that the interaction between hydropriming time treatment and polyethylene glycol treatment caused significant differences in germination rate, shoot length, shoot wet and dry weight (P<0.01) and vigor index (P<0.05 ). But it caused no significant differences in parameters of percentage of germination, average germination time, root length, root wet and dry weight. The highest percentage of germination was related to the treatment by -4 bar PEG and without priming (control). The lowest percentage of germination was resulted under hydropriming in 48h and treatment by -8 bar polyethylen glycol respectively 49 and 14 percent. The highest rate of germination was related to the treatment by -8 bar PEG and hydropriming in 48h. Also seeds didn’t germinated in -16 bar of PEG in all hydropriming times. The results showed that the treatments by -4 and -8 bar PEG during 48 and 72 hours hydropriming caused the most positive effects on seed germination percentage, germination rate, vigor index, root length, shoot length of cymbopogon olivieri seeds.

Most of the studies on dust storms are concentrated in the western-eastern provinces of the country and less research has been done in other parts of Iran. In this research, some of the southern plains of Alborz; which have the potential to produce dust were selected. Daily data of 18 meteorological stations with long-term statistical period from 2008 to 2017 and to calculate the indicators of agricultural drought, MOD13Q1 and MOD11A1 products were used in the same period. Standardized precipitation index and standardized precipitation-evapotranspiration index were calculated and from the dust hourly meteorological codes, the experimental dust storm index was obtained. Then the relationships between climatic indices, vegetation and experimental index of dust storm were investigated using Pearson correlation and multivariate regression statistical method. The highest frequency of DSI index during 10 years is related to Imam Khomeini station with a value of 30.5 and the lowest is Taleghan station with 0.05. The Year-on-year changes in the dust index show that in the early years, the central and southeastern parts of the region were affected by dust storms, and sudden decrease had a significant effect on the results and reduced the long-term trend. The highest and the lowest correlation is respectively wind speed and Temperatur .Regarding the results of monthly multivariate regression, are somewhat variable in different months of the year, so that the effect of climatic elements and vegetation changes in different months, in general wind speed, TCI and SPEI have the most important effect on increasing

Intergovernmental Panel on Climate Change report shows that the world average temperature has increased to 0.6 ° C ± 0.2 ° C in the twentieth century. Therefore, long-term prediction of climate variables and the consideration of measures to mitigate the adverse effects of climate change is evident. The SDSM model was used to downscale observation data of the minimum and maximum temperatures of the Vazvan Meyme station in Isfahan province. The CanESM2 global model data under new emission scenarios: RCP2.6, RCP4.5, and RCP8.5 are used to predict the near future (2006-2036), mid-term (2037-2078) and far-away future (2079-2100). The studies show the ability of the SDSM model to model maximum and minimum temperatures in the base period. The results of this study necessary indicate that as we get closer to the 21st century, the minimum and the maximum temperatures increase in the area of study. The average maximum temperature changes will have the highest increase under the RCP8.5 scenarios in the (2079-2100), in July, which will reach 7.9 ° C. The average changes in minimum temperature show the highest increase in August under the RCP8.5 scenarios. Therefore, considering that this temperature increase in future periods will affect the status of the study area, water resources, and natural resources. Planners and authorities of the relevant departments will take the necessary measures, such as measures to correct irrigation systems, methods for reducing evaporation and improving the cultivation system, to adjust the damage caused by heating or adapt to the new climatic conditions.

In this study, the surface water collection systems of districts 10 and 11 of Mashhad were modeled and evaluated using risk analysis. Sub-basins were also ranked in order to locate the implementation of low impact development (LID) practices. The results showed that although the collection system has no particular problem with floods with a two- year return period, it does not have a suitable capacity for floods with a higher return period, so that for floods with 5 and 50 years of return period, it has 80 percent discharge capacity of surface runoff and in these year returns, 29.1 and 38.2 percent of the canals, respectively, face waterlogging and back flow.In order to final ranking of the sub-basin for prioritizing the location of LID practices, in addition to risk analysis, the sub-basins were classified based on economic priorities, social conditions and land use. The final ranking that 6.6% of the studied sub-basins, which includes 22.8% of the study area are in groups 4 and 5 (the highest Priority). Ranking puts areas with high flood risk under pressure to accept LID control and make an investment in it, as well as benefits areas where are at lower risk of flooding but are more likely to implement LID practices and invest in them.

Environmental flow (EF) is the quantity, quality and timing of water needed for ensuring the sustainability of aquatic ecosystems. The Karaj River is one of the five protected rivers in Iran. It provides drinking water for the cities of Tehran and Alborz, water needed for agriculture, and is also an important power supply source for the country. While the river has fulfilled for a long time environmental requirements of downstream areas, this has been threatened in recent years by increasing demands of the rapidly growing population in Tehran and Karaj. In the present study, we tried to find an acceptable environmental flow range by using Flow Duration Curve (FDC) and Indicators of Hydrological Alteration and compared the results with the Tennant method which has been officially used by the Energy Ministry of Iran. Results are presented in monthly resolution and at the scale of sub-watersheds to provide a spatio-temporal EF analysis that can be used in watershed management planning. Based on the results, highest and lowest amounts of EF were calculated by FDC-Q95 and Tennant methods, respectively. For instance, the monthly mean Q95 in last gauge (Sira-Karaj) equals 5.75 m3/s, while the mean value estimated by Tennant is just 2.35 m3/s. Eventually, this study suggests a range of the EF values obtained by the FDC method as the upper monthly threshold and the Indicators of Hydrological Alteration as lower monthly threshold for Environmental Flow in Karaj River.

Any plant according to its needs selects an optimal location of the environment as habitat. The aim of this study was to evaluate the relationship between plant species composition and edaphotopopographic factors in the steppe rangelands of Marvdasht in Fars province. Soil and vegetation sampling was carried out by random sampling and transect method, respectively. In this study, transects with a length of 30m were used. After sampling the soil samples were transported to the laboratory. In the laboratory content of OM, EC, pH, sand, silt and clay, Na, K and P were measured. The relationship between environmental factors and species composition was determined using DCA and CCA multivariate analyzes. The most important factors in the distribution of vegetation, were soil EC and Na. Altitude and slope were identified as effective topographic factors the composition of plant species.

Tectonic activities by the occurrence of earthquakes and the creation of driving force, tectonic uplifts, fissures and fractures caused by faults, creating and seam and cracks in rocks and accelerating the process of mechanical and chemical weathering, creating fault gouges and fault shear as the materials prone to landslides, increasing the penetration of rocks, changes in the direction and slope of geological layers, etc. cause landslides. The study area is located in the structural zone of Central Alborz and Central Iran between the coordinates of 49.22 to 51.15 east longitude and 35.81 and 36.9 north latitude. In this study, after library surveys and field observations, the location of 280 landslides with fault zones of faults in the region was compared with the relevant software and it was found that 34% of the total landslides identified in Fault zone. Due to the 5% area of fault zones, the high percentage of landslide occurrence indicates the relationship between tectonic activity and landslide occurrence. Therefore, it can be said that tectonic activities have caused landslides in the study area and due to the large number of landslides in the study area, the area can be assessed tectonically with high activity. Vulnerability of residential areas is also high in areas near active and Quaternary faults, because in addition to seismic waves and surface rupture during an earthquake, they threat by another hazard called landslides.

An appropriate amount of soil was picked up from the surface horizon (0-30 cm) from the rangeland of Darab city. After air drying and passing through a 2 mm sieve, some physical and chemical properties of the soil were measured. A factorial pot experiment was conducted in a completely randomized design with four replications. The first factor includes biochars in 7 levels (no application of biochar (C), wheat biochar (1.5 % w/w) (GB1), wheat biochar (3 % w/w) (GB2), corn biochar (1.5 % w/w) (ZB1), corn biochar (3 % w/w) (ZB2), cotton biochars (1.5 % and 3% w/w) and the second factor includes the use of lead (Pb) at 3 levels (0 (Pb0), 150 (Pb150) and 300 (Pb300) mg kg-1 soil) under forage panicum cultivation. After copmpleting vegetative growth, the plants were cutted and harvested from 0.5 cm of the soil surface. This study indicated that with increasing the biochar levels from 0 to 3 % (w/w), the electrical conductivity (0.31, 0.15 and 0.02 dS/m), soil organic carbon (53, 59 and 63%) and soil pH (0.13, 0.05 and 0.15 units) were increased and the Pb availabity (16.12, 12.83 and 10.25%) was decreased, respectively. With enhancing the Pb levels from 0 to 300 mg kg-1 soil, the concentration of soil manganese (17.27%) and potassium (4.54%) availability were significantly reduced.

Soil depth temperature is one of the most effective factors on agricultural products. However, the it has highest missing data in synoptic weather stations. Hence, this research aims to evaluate soil depth temperature changes and determine the accuracy and applicability of ECMWF re-analysis data in estimation of SDT. To do so, soil depth temperature data for different depths (5,10, 20, 30, 50 and 100 cm) of Mehrabad, Geophysic, Shomal-e-Tehran and Doushan Tapeh stations were extracted in hourly time intervals (03, 09, 15 UTC) from Iran’s Meteorology Organization. Then, trend analysis was carried out by Mann-Kendall test. Also, gridded re-analysis SDT data of ERA5 were extracted from ECMWF from 1997 to 2018 statistical period. Re-analysis data were convert from Netcdf format to text using GIS. Then, their accuracy was analyzed by ME, MAE and RMSE tests. The climatic trend of soil depth temperature presents the general increase trend in all studied stations during the 1997-2018. Furthermore, the results showed close correlations between observational and re-analysis data at different depths. Re-analysis data could mainly reproduce the temporal-spatial distributions of soil depth temperature in study area. The correlation coefficient between observational and re-analysis data was 0.97 and 0.95 for first and second studied depths of the soil, respectively. It indicates a significant linear relationship between observational data and ERA5 re-analysis data in hourly time intervals. However, the ERA5 overestimates the SDT data in comparison with observational data