فصلنامه حفاظت منابع آب و خاک
سال دوازدهم شماره 3 (پیاپی 47، بهار 1402)

Due to the high consumption of water in agriculture, considerable drainage is produced annually. Currently, a significant volume of drainages (almost 3 BCM) is entered into the Khuzestan province environment without any beneficial use, resulting soil and water contamination. On the other hand, according to Iran's water problems, the quality conservation of water resources and the use of unconventional water resources are essential, especially drainage quality management, and applying them to agriculture and the environment.

This research is carried out to evaluate the efficiency of biological filters with different beds for the treatment of agricultural drainage in Mirza Kooch Khan and Amirkabir Agro-Industry fields in Khuzestan province of Iran during the spring and summer of 2019. The research aims to reduce drainage contamination when discharged into the environment and drainage reuse in agriculture. In this research, the effect of four different types of biological filter including wheat straw, rice husk, cotton stalk, and wood sawdust as the main factor and three retention time of 2, 5 and 10 days as the secondary factor are investigated. The quality factors monitored include turbidity, EC (as a salinity index), total nitrogen (TN), total phosphorus (TP), and BOD.

Analysis of variance demonstrates a significant difference between the mentioned treatments in terms of the studied parameters (at the level of 1%), except for pH. According to the results, the highest average refinement of qualitative factors based on filter type for turbidity equals 37.87% and relates to the treatment of cotton stalk. For EC, TN, TP, and BOD equal to 9.23%, 49.60%, 46.50%, and 97.59%, respectively, and relate to wood sawdust. Moreover, the average of the highest percentage of pollution reduction for the investigated factors is related to the retention time of 10 days, which for turbidity, EC, TN, TP, and BOD are equivalent to 56.79%, 12.97%, 66.51%, 53.49%, and 80.20%, respectively.

Observed results indicate that wood sawdust treatment has a relatively better performance than other treatments. This issue is important since the existence and abundance of this material in the country is high. In addition, due to the importance and effectiveness of hydraulic retention time in treating, it has a direct relationship with efficiency of treating. However, the increase in efficiency from the retention time of 2 days to 5 days is more significant than the increase of retention time from 5 days to 10 days, which can be considered an important factor in selecting the retention time based on pollutants concentration in the drainage. As a result, based on the concentration of input and output quality parameters, it is suggested to use a wood sawdust filter with a 5-day retention time due to its proper performance and being more economical in terms of volume and dimensions of the system.

Climate change has negative effects on water resources and human societies, especially in arid and semi-arid regions. Remote sensing is widely used in studies such as monitoring the environment, agriculture, and climate of the earth. This technology makes it possible to research and investigate such studies in large areas with the high spatial and temporal resolution, especially inaccessible areas or areas that do not have ground measurement stations (such as synoptic stations) provides. Considering the expansion of the cold semi-desert climate in the northwestern region of the country and the changes in land use in the Meshkinshahr region in recent years, the purpose of this research is to investigate the interrelationship between climatic components of temperature, precipitation, and soil moisture with land use changes.

Meshkinshahr city is located in the northwest of Iran and is one of the important cities of Ardabil province. In the present research, the studied area using satellite images of Landsat 5 for 2002 and Landsat 8 for 2021 in seven classes of irrigated agriculture, rain-fed agriculture, residential area, water areas, snow cover, good pasture, and poor pasture for investigation of the changes in land-use has been classified. In the following, temperature and precipitation components (along with verification with ground data) respectively using the single-channel algorithm and GPM database and soil moisture using the optical thermal algorithm (TOTRAM) by applying LST and NDVI parameters as a time series were reviewed for the years 2002, 2006, 2011, 2016, 2019 and 2021.

By examining the resulting maps, it has been observed that there have been significant changes in different land uses, and most of these changes have been related to the increase of irrigated agricultural lands and poor pastures, and the loss of quality pastures. Also, temperature and precipitation fluctuations in the studied years are quite clear and do not have a regular trend, so for example, in 2011, a sudden increase in precipitation to the amount of 46 mm is observed. But the minimum temperature compared to its maximum in different years shows a greater increase compared to 2002. Vegetation and soil fertility do not have a particular upward or downward trend and show different values ​​in different years, but the maximum vegetation cover, i.e. value 1 in the case of the NDVI index, is observed in 2002.

According to the results and fluctuations in the values ​​of climatic components, especially sudden changes in some years, signs of climate change can be observed in the region, but a definite opinion cannot be expressed regarding the trend of land use changes and climate changes. Examining the results shows that land use changes, especially in the agricultural sector, can be affected by climatic conditions. The dependence of climatic components on each other and the influence of soil moisture and vegetation on these components are other results of this study. So, with the increase in temperature, we see a decrease in the amount of humidity and the level of vegetation. The times when soil moisture is higher than in other years, due to the cooling role of evaporation, low temperature, and vegetation cover are favorable. As a result, there is a clear dependence between the different components and the change in one parameter affects the other parameters, but it seems that the temperature component plays a more colorful role than the other parameters.

Climate changes caused by the progress and industrialization of human societies have caused changes in the intensity and frequency of heavy precipitation and floods, which have caused irreparable damages. In order to reduce these damages, it is necessary to identify the changes in the threshold values ​​of precipitation and factors affecting it each region. Quantile regression methods are able to examine the trends not only in the median, but also in different ranges of the data series. Therefore, the purpose of this research is to investigate the seasonal trend of different amounts of precipitation and also to investigate the relationship between the climatic parameters of minimum temperature, maximum temperature, minimum relative humidity, maximum relative humidity and wind speed on different amounts of precipitation in different climates of Iran.

In the first step, the daily time series of climate data including precipitation, minimum and maximum temperature, minimum and maximum relative humidity and wind speed for a period of 45 years in different seasons for 5 synoptic stations of Babolsar, Shiraz, Bandar Abbas, Khorram Abad and Torbat Heydarieh were formed. In the selection of study stations, we tried to select stations with different climates and with appropriate statistical period. Then, to investigate the trend of seasonal changes of different amounts of precipitation in different quantiles (quantiles 0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 0.9, 0.95 and 0.99) was analyzed using the quantile regression method in all study stations. In the next step, the relationship between the climatic parameters on different amounts of precipitation (low to very high amounts of precipitation) in different seasons was investigated for each of the stations using the quantile regression method. Then the results were analyzed.

The results of examining the changes trend of daily precipitation are showed that the high amounts of precipitation in the spring season in Bandar Abbas, Shiraz, and Torbat Heydarieh stations were reduced significantly, but very high amounts of precipitation (0.95 and 0.99 troughs) in the station Babolsar and Khorramabad have increased. Also, very high daily precipitation amounts in summer have decreased in Bandar Abbas station but increased in Torbat Heydarieh and Khorram Abad stations, significantly. While in the winter season, different amounts of precipitation in all seasons have a decreasing trend and there was only a significant positive slope in very high amounts of precipitation (slope of 0.99) in Babolsar station. In the investigation of the parameters affecting the extreme precipitation, the results showed that the amount of impact on the occurrence of heavy rainfall was relatively higher than low to median rainfall. The parameters of minimum temperature, minimum humidity, maximum humidity and wind speed have a positive effect and the maximum temperature parameter has a negative effect on heavy rainfall in different seasons and stations.The highest positive effect coefficients were in spring for wind speed in Babolsar (1.8), in summer for wind speed in Babolsar (3.8), minimum and maximum temperature in Bandar Abbas (-4.03 and 1.53), in Autumn season for maximum humidity and wind speed in Babolsar (2.57 and 2.99) and wind speed in Khorram Abad (1.54) and in winter, for wind speed in Babolsar and Bandar Abbas (1.94 and 6. 2), and minimum temperature in Torbat Heydarieh (0.96). Also, the highest negative effect coefficients of maximum temperature were in autumn and winter seasons (-0.88 and -0.72) in Babolsar and autumn season (-0.63) in Shiraz.

The significant changes in increasing and decreasing precipitation are mostly related to the amounts of heavy precipitation, which are different in different seasons and climates. Also, the precipitation of the stations near the north and south coasts have been influenced by climatic parameters to a greater extent. In general, it can be said that flood precipitations are influenced by climatic parameters such as wind speed, humidity and temperature in order of importance and this effect is different depending on the location and time and the influence of different factors. Therefore, it is necessary to apply accurate planning for the correct use of received rainfall and optimal management in the target area using the results of such studies.

Nowadays, due to the importance of sediments in watersheds, the integrated watershed management in the country requires a specific framework in planning related to monitoring and control of sediments.One of the most effective methods is the use of sediment connectivity index (IC). Connectivity process is an innovative concept to understand the processes which occur in the watershed area that affect water flow and sediment movement at different spatial-temporal scales. This index explains the degree of connection of the sediment flow throughout the watershed, especially between the sediment source and the downstream area, and in a way, expresses the sediment delivery ratio. Therefore, the current research is conducted with the aim of investigating the sediment connectivity in Taleghan watershed of Alborz province to extract the sediment connectivity index map and also verify the results with field investigations.

In this research, in order to investigate the spatial pattern of sediment production in the watershed, the sediment connectivity map of the basin was drawn from the method presented by Borselli et al. and the definition of connectivity index (IC). For this purpose, at first, topographic data from 30-Meter Digital Elevation Model and vegetation data at 10- and 30-meters spatial resolution are obtained with Sentinel-2A and Landsat 8 images, respectively, and by using data layers such as the average slope gradient, the average weighting factor and the upslope contributing area the amount of upstream component of the flow starting path in sediment transport was calculated. Then, using the layers of the length towards the downslope path, the weight factor of each cell and finally the slope gradient of each cell, the downstream component in the sediment connectivity network was calculated and by referring to catchment outlet in the ArcGIS 10-2-2 software, the connectivity index for all pixels Calculated and the sediment connectivity map was drawn. The IC can assume values ranging from -∞ to +∞ and as IC grows toward +∞, the connectivity increases, finally in order to evaluate the results of the field connection index model (FIC), it is implemented in 30 points of the watershed and the correlation between the IC index and FIC in these points are evaluated. 

According to the findings of this research as well as the fitting of IC sediment connectivity index values with FIC field sediment connectivity index in 30 points, the relationship between these two indicators is linear. The coefficient of determining the output of the model with a spatial accuracy of 30 meters was obtained with a numerical value of 0.62, It shows the higher accuracy of the sediment connectivity index results with a spatial resolution of 10 meters compared to 30 meters. Although the distribution of the points is irregular in some cases, the general trend of the results shows that with the increase in the amount of IC connection, the amount of FIC field computing sediment connection has also increased linearly. In calculating the index of connectivity, the factors such as the shape, slope and roughness of the basin which are easily accessible due to the less data requirement and high efficiency, can be the basis for improving the estimation of sedimentation models.

In this research, the results show that the sediment connectivity index with a spatial accuracy of 10 meters has a higher accuracy than the connectivity index with a spatial accuracy of 30 meters. In addition, the results demonstrate the slope and the vegetation factor are critical parameters in the sedimentation of the Taleghan watershed. It is also worth mentioning that in order to investigate the effect of the watershed area and the principal waterway length, the results of the sediment connectivity index can be evaluated more precisely at the sub-basin and even the hillslopes. Considering the importance of these items in the sedimentation of each sub-basin, including the flow direction map and flow accumulation in the assumptions of this model, is one of the advantages of this technique. The other important advantage of this model is its low data requirement, which can greatly reduce the complexity and data requirements of existing erosion and sedimentation models.

Creating land fertility maps are especially important in terms of determining the areas that need particular nutrients, optimizing the use of agricultural fertilizers, and facilitating the optimal management of soil and plant nutrition. Spatial changes in soil and plant nutrients are common, but knowing these changes is essential for accurate planning and management, particularly regarding agricultural lands. This research aims at zoning the spatial distribution pattern of nutrients, aka nitrogen, phosphorus, potassium, sulfur, calcium and magnesium, in the soil and leaves of Dezful orange orchards trees using the Gaussian model and geographic information system (GIS).

A total number of 130 sampling points are set on the map in the vicinity of orange orchards of Dezful City with an area of 3200 hectares. Factors such as soil, cultivation and irrigation system, slope, elevation, and the manner of orange trees growth are considered to determine sampling locations. Following sampling the soil (0-60 cm depth) and plants, the samples are transferred to the laboratory and the concentration of the most consumed nutrients is measured. After preliminary statistical analyzes on the data, the correlation level of the variables that are measured in the soil and leaves of orange trees, are calculated with the Pearson correlation test. The location of sampling points is simulated via Gaussian model by using the R software. The interpolation is computed using simple kriging and kernel methods. The model sensitivity analysis for the changes applied in the base values for implementing the algorithm, is done based on the replacement of the desired values from the posterior functions as well.

Analysis of dispersion indices show that the highest coefficient of variation is related to phosphorus element in soil and nitrogen element in leaf samples. The results illustrate that the mean square error values for elements of nitrogen, phosphorus, potassium and sulfur are calculated respectively as 0.171, 0.152, 0.132 and 0.153 in simple kriging in soil, and as 0.212, 0.152, 0.229, and 0.166 in kernel method in soil; and respectively as 0.121, 0.188, 0.116 and 0.131 in simple kriging in samples of orange tree leaves, and as 0.184, 0.206, 0.172 and 0.229 in kernel method in the leaves samples as well. The results of the spatial distribution pattern of each of the measured elements in the soil and leaves of orange trees demonstrate that the lowest amount of nitrogen is in the south of the region (0.42 to 1.33 mg/kg) and its distribution pattern is similar to the distribution in the leaves of orange trees (0.9 1 to 1.29 mg/kg). Magnesium has the lowest in the north and part of the south (3.11 to 4.57 mg/kg), and sulfur in most soil of the region is between 21.31 and 26.25 mg/kg.

In examining the effectiveness of the Gaussian statistical model in the distribution of nutrients in the soil and leaves of orange trees in the gardens of Dezful city, the results display that the calculated Pearson linear correlation coefficient  has the highest correlation between calcium and potassium, as well as magnesium and calcium in the soil, but there is no linear correlation between any of the nutrients in the leaves of orange trees. In estimating the best interpolation method, calcium element in soil has the least error in both kernel and simple kriging methods, whereas in plant leaves, magnesium in kernel method and potassium in simple kriging method have less error. The highest error for soil and plant is related to potassium and calcium respectively, in the Cornell method.

Gully erosion is one of the types of water and intensified erosion, which causes a significant change in the landscape and environment. Although engineering methods are important for erosion control, biological methods are very efficient and low-cost methods for soil erosion. Therefore, it is essential to pay attention to the characteristics of plant organs for erosion ability, which has yet to be studied. Thus, the purpose of the study is to evaluate the ability of native plants to slow gully erosion in the semi-arid Konar Takhteh region in Fars province.

Based on four criteria of resistance to concentrated erosive flow, the ability to stabilize the walls, the bending threshold due to water flow, and the ability to trap suspended load, and by using five quantitative indices, the power of plants to control gully erosion is evaluated. The comparison and scoring of plants are done based on the above criteria and based on multi-criteria analysis. After measuring the indices of stem density (SD), sediment obstruction  potential (SOP), plant stiffness (MEI), relative soil detachment rate (RSD) and root cohesion (Cr), each index is divided into five grades according to the scale (zero is the lowest and four are the highest). In the following, the score of each index is shown in a radar chart. Finally, in order to evaluate better, different species to control the gully erosion, the occupied surface of radar chart is examined.

The measurement results of SD, SOP, MEI, RSD and Cr indices for Ziziphus spina-christi species equal to 0.0027, 0.097, 108, 0.398 and 8.34 kPa, respectively, which demonstrates the best performance in comparison with other species. Overall, with a total of 18 points, it is the most suitable specie to control ditch erosion. Atriplex canescens with 13 points is in the second place and the other species are in the next places with lower performance.

Species such as Ziziphus spina-christi and Atriplex canescens may be beneficial in the revitalization and development of vegetation in the region due to their adaptation to the climate, dry conditions of the region, their resistance to concentrated currents as well as the stabilization of the gullies’ wall. The use of a combination of plant species is helpful in controlling erosion due to their different capabilities. Therefore, it is recommended to use perennial and herbaceous resistant indigenous species for biological combat against intensifying erosions, especially gully erosion in semi-arid areas. It is suggested to use the findings of this research in other semi-arid regions of the country.

The Homotopy Analysis Method (HAM) was first proposed by Liao (1992) to solve functional equations. This method is based on homotopy and provides an approximate-analytical solution for functional equations. In recent years, this method and its modifications have been effectively used to solve a wide range of linear and nonlinear problems in applied sciences to find solutions to series of various types of nonlinear equations, including algebraic equations, ordinary differential equations, partial differential equations, and differential-integral equations (Abbasbandy et al. 2006). The purpose of this research is to provide an analytical solution of time delay with acceptable accuracy for the non-linear equation of non-Darcy flow in coarse-grained media using the HAM method, which previous researchers had recommended to conduct further research in this field.

In this research, the governing equation of the non-Darcy flow was solved by the HAM method for the first time, then the water level profiles of the final equation of the HAM method obtained for the 6 inlet flow rates with different boundary conditions and in two coarse-grained porous media including rounded and sharp-edged materials. The results of the water level profile using the HAM method have been compared with the laboratory data of Sedghi Asal (2010) reported at the Stuttgart laboratory in Germany. The normal objective function (NOF) has been used to compare the HAM method results with the experimental data of Sedghi Asal (2010).
 

The comparison of the results of HAM method with the experimental data of Sedghi Asal (2010) has been done under upstream and downstream boundary conditions for different discharges and with a slope close to the horizon S = 0.00001. The results have shown that flow rates of q=30 lit/s, with a NOF error percentage of 0.000099828 in the porous medium of sharp corners and q = 26.25 lit/s, with a NOF error percentage of 0.000102162 in the porous medium of round corners depict better accuracy than the experimental data in higher input flow rates. This method has logical solutions in horizon slopes and the water level profiles in HAM method and experimental data have coincided or are close to each other in most of the points. However, the subject of permanent and uniform flow needs a dependent research.

The results showed that the water level profiles are close to each other in most cases. This illustrates the accuracy of the developed approach based on HAM method. However, when the difference between the upstream and downstream water levels increases, the percentage of error escalates. In other words, with the increase of the hydraulic gradient in the porous medium, the error also grows. Finally, by evaluating the results of the HAM method compared to the laboratory data, it can be concluded that this method shows better accuracy in the porous medium with sharp-cornered materials compared to round-cornered materials due to higher flow rates and higher porosity of this media.

One of the management measures that can play an important role in reducing flood damage is preparing a flood zoning map. The preparation, compilation, and having a comprehensive and complete plan in the field of flood controlling and determining the boundaries and bed of rivers is an obligatory and necessary matter that lead to flood management and damage assessment. In this research, for Til River and 2 branches of the tributaries entering this river, in order to determine the bed and the boundary, produce flood zoning map and obtain the quantitative boundary of the river  by using the DLSRS standard, the HEC-RAS hydraulic model and Arc-GIS software with the HEC-GeoRAS connector plugin has been used.

First, the HEC-RAS input file was prepared by using the topographical map of the Til river area from Arc-GIS software and by using the HEC-GeoRAS extension, and after entering the geometric data and data of the processing flow and related calculations in the environment of this software for zoning. The flood took place.to determine the boundaries of the river beds and these waterways, floods with a return period of 25 years are used.Eventually, with the application of HEC-GeoRAS extension and Arc-GIS, flood zoning maps are extracted. Moreover, by using the DSLRS standard, the quantitative boundry of the Til River and tributaries 1 and 2 in the studied area are determined according to the field visits and appropriate engineering advice, and the numbers related to each index and finally the amount of quantitative boundry are calculated.

In accord with the extrcated maps and satellite images and according to the investigations and visits, the width of the hydraulic bed calculated is different from the bed width defined in the law due to many uncertainties. Therefore, at this stage of the studies, expert surveys should be conducted through step-by-step visits to both banks of rivers and waterways along the study area, and eventually, legal bed width should be recognized and marked on the maps.

The results show that integration of HEC_RAS model and GIS geographic system is an efficient and useful tool in determining river floods. According to the investigations, the comparison of existing maps and land uses around the Til River and 2 sub-channels demonstrate that in the event of a flood with a return period of 25 years, it does not cause sever damage to the areas around the river. In accordance with DSLRS standard, qualitative boundary of Til River and sub-channels 1 and 2 in the study area are carried out with field visits and ultimately, the amount of boundry is calculated,As a result, the amount of the quantitative sanctuary of the Tail river in the scope of the study plan was calculated to be 8 meters and also the quantitative sanctuary of Mesil 1 and 2 was calculated to be 4 and 5 meters, respectively.

Over-groundwater exploitation leads to severe water table decline and critical consequences in Iran’s fields. Water level at wells (dynamic water level) has reduced due to groundwater table decrease. It may reach the pump level and would result in air entrance into the suction pipe. Such two-phase flow would damage the electromotor finally. On the other hand, field measurement of the dynamic water level is always very difficult. Hence, it is aimed at this study to present a model to estimate the dynamic water level indirectly.

Water well Videometry is a useful tool to read the dynamic water level. It is however costly and not always possible. Therefore, a method to find the dynamic water level is of great practical importance. In this regard, energy balance equation is applied to a well pumping system to formulate the dynamic water level. Also, the empirical Jacob’s (1947) and Rorabaugh’s (1953) equations describing the well and aquifer losses are employed to develop a mathematical model of the dynamic water level. Finally, Buckingham analysis was employed to present a dimensionless model of the dynamic water level. Dimensional analyses could be applied using the information on the well discharge, well depth, and pump performance curve to estimate the well loss. The models were calibrated using the observed data of 17 water wells in Karaj, Kamalshahr, and Garmdareh of Alborz province.

The results indicated that the performance of Jacob’s (1947) and Rorabaugh’s (1953) methods are similar with the associated mean relative error of 5.1% compared to the measured dynamic water well values. Also, employing the dimensional analysis and energy balance methods the dynamic water level could be estimated with the mean absolute relative errors of 4 and 12.39% respectively. The results indicated that the three first models were much better than the energy balance model to predict the dynamic water level. Well performance is directly connected to the position of the dynamic water level, hence, the proposed methods could be used effectively to evaluate the well efficiency.

To evaluate the relative error of estimating the dynamic water level RMSE values of different methods were calculated for the areas under study. The results indicated the proposed methods could be used more accurately for Kamalshahr area. The associated RMSE values of 6.58, 6.5, and 16.87 m was found for Jacob (1947) and Rorabaugh (1953), dimensional analysis, and energy balance models respectively. The method proposed based on the energy balance could not predict the observed dynamic water levels correctly. The reason might be attributed to the fact that there was no information about the pressure values at the outlet pipe. Also, there was no significant difference between the performances of Jacob (1947), Rorabaugh (1953) models. Among all, with the advantage of having dimensionless parameters, the model proposed based on the dimensional analysis was the best with the least mean absolute relative error.

Climate change is one of the most significant global challenges threatening food security now, in the near and far future. This mainly occurs in the form of increasing temperature, change in rainfall pattern, and increase in extreme weather events. There are strong evidences demonstrating the vulnerability of agriculture sector in arid and semi-arid regions to climate change. This may directly impact on crops growth and production or indirectly impact on their environments. The ability of soil to produce a crop depends on its physical and chemical properties and these properties are directly and indirectly affected by climatic factors such as temperature and rainfall. Most predictions show that in arid and semi-arid regions, including many regions of Iran, climate change will lead to an increase in temperature and a decrease in rainfall. Therefore, considering the importance and role of temperature and humidity in physical and chemical quality indicators of soil and production stability, it seems that the phenomenon of climate change will have adverse effects on soil and then on crop production. Therefore, it is very important to use the necessary solutions to mitigate these adverse effects and adapt to the upcoming conditions. In this article, by reviewing and summarizing the research on the effects of climate change on the characteristics of arid and semi-arid soils, an attempt has been made to provide some kind of foresight of possible changes in the physical, chemical, and biological properties of soil due to climate change.