سید مسعود سلیمان پور

The amount of sediment production, the manner and time of sedimentation, the size and composition of sediment grains, and transport among the waterways network are important features of the sedimentation regime of Watersheds; Because changes in each of these factors cause changes in Watershed performance. Therefore, sediment production is a reflection of the importance and amount of erosion processes and sediment sources in the upstream parts of the Watershed and how sediment is transported and deposited from the moment of movement of erosion materials from the point of separation to the exit of it. Sediment connectivity indicators indicate the spatial changes of connectivity patterns in different parts of the Watershed and provide a suitable estimate of the contribution of sediment sources and sediment transport routes. For this purpose, investigating the spatial pattern of sediment flux at the Watershed scale is of particular importance in developing comprehensive management plans and measures to control erosion and sedimentation. Although various indicators and models have been developed in this field, their performance has not been evaluated based on observational data and statistical methods. This research aims to analyze the sediment flux pattern of the Neyriz Watershed located in the east of Fars Province, based on sediment connectivity and sediment transfer capacity indicators, and compare their performance based on field sediment evidence.

At first, a digital model of the ground elevation of the Neyriz Watershed with a spatial resolution of 12.5 m was prepared and its drainage network was extracted. Then, the sediment connectivity index was calculated by considering the upstream and downstream features of the Watershed and by considering the roughness factor as the sediment movement resistance factor, and the sediment connectivity map of the Watershed was made. Then, the sediment transport capacity index map was also prepared based on the concept of topography and using the digital model layer of land height. For this purpose, the sediment transport capacity index was calculated for each pixel of Neyriz Watershed in SAGA-GIS software, and a sediment transport map was prepared. Based on field visits to different parts of the Watershed, 30 positions that had evidence of sediment transfer were recorded as observation points of the sediment transfer event. Also, 30 other positions that did not have signs and evidence of sediment transfer were added to the validation database as observation points of no sediment transfer event. The corresponding values of each index were also extracted in the geographic information system and based on the available information, using evaluation methods based on the error matrix including true skill statistic (TSS), efficiency (E), and F score (F-score), the validation of the mentioned indicators was done quantitatively.

The value of the sediment connectivity index of the Neyriz Watershed in Fars Province varied from -7.24 to 2.43 and its median value was -4.36. The spatial pattern of the sediment connectivity index in this Watershed is such that the middle and western parts have a low amount and the northern, southern, and eastern parts have more amounts. In this research, the drainage network of the Watershed was introduced as the target of receiving the sediment; Parts of the slopes of the Watershed level, which had the conditions of sediment production and transfer were connected to the drainage network in terms of the transfer path, have shown a higher value of connectivity index. This index provides valuable information for land management by considering the upstream characteristics of each point as well as the characteristics of the transfer path to the sediment-receiving target. The value of the sediment transfer capacity index varied from 7.2 to 23.16 and the average value was 10.19. The value of this index is high in the marginal parts of the Watershed where there are sloping lands, and the middle parts of the Watershed have a small value. Based on the findings, the index of sediment connectivity with the true skill statistic (TSS) of 0.833, the efficiency value (E) of 0.916, and the F score of 0.915 is a better performance than the sediment transport capacity index (TSS= 0.633, E=0.816, F-score=0.825). In addition, based on the values of the false positive component in the error matrix, the sediment transport capacity index predicts high sediment flux potential in many situations; While in the field observations, it was not true.

Based on statistical evaluation criteria, the sediment connectivity index has been able to better describe the state of sediment flux and is more consistent with field realities. So that the sediment connectivity index, in addition to considering the characteristics of the upstream area of each point of the Watershed, is possible to consider the path of the sediment particle to the target location of the receiver (such as the nearest branch of the network drainage) has made it possible. Based on the findings obtained in this research, although the sediment transfer capacity index in some parts of the Neyriz Watershed of Fars Province was in line with the sediment connectivity index; However, due to the energy-based nature of the flow, this index only considers the local conditions of the points and ignores the features of the upstream area as well as the process of transporting sediment particles to the downstream. Therefore, it is suggested to use the sediment connectivity index in the erosion and sedimentation studies of Watersheds. Because when information about the amount of sediment production is not available; the Sediment connectivity index can provide useful information about the sediment transfer process in the Watershed.

Currently, drought poses a significant threat to food security due to reduced rainfall and increased agricultural demand. Its impact is particularly severe in arid and semi-arid regions, where populations are more vulnerable. Drought affects groundwater systems by initially lowering water supply, followed by a decline in groundwater levels and discharge. Compared to other types of drought, characteristics such as duration, intensity, and frequency alter groundwater systems.

Given the critical need for drought assessment and monitoring, this study investigated drought conditions in 12 areas within the Daranjir Watershed from 2002–2003 to 2017-2018. The watershed spans approximately 50,736.44 km² across Yazd and Kerman provinces, with elevations ranging up to 1,857.90 meters. Highlands cover 58.99% of the area, while plains cover 40.99%. Data on groundwater levels from observation wells were obtained from Iranian Water Resources Research Organization (Tamab) and regional water organizations in Yazd and Kerman provinces. Average monthly groundwater level values were then extracted from maps using inverse distance weighting interpolation in MATLAB. Groundwater drought conditions were subsequently calculated based on the Groundwater Resources Index (GRI) in MATLAB.

The GRI index calculations revealed severe droughts in Daranjir, Bardsir, and Qaryeh al-Arab deserts, with deficits of 81.38, 77.75, and 75.66, respectively. Qaryeh al-Arab experienced the longest drought, spanning 121 months, indicating the area's high intensity and prolonged drought conditions compared to other study areas. Mild droughts were the most frequent after normal drought across all study areas based on GRI index class frequencies.

Due to insufficient and highly variable atmospheric precipitation, drought is inevitable, especially in arid and semi-arid climates. Understanding drought severity and its impact on ecosystems is crucial for effective watershed resource management and optimal resource utilization. Continuous monitoring of groundwater levels due to drought and preparation of a comprehensive atlas for other watersheds in the country are recommended. Additionally, comparing drought conditions using appropriate models is essential. Short and long-term strategies are advised to mitigate this natural phenomenon, such as expanding greenhouse crop cultivation, utilizing drought-resistant crop varieties with high water efficiency, adopting pressurized irrigation systems, and implementing infrastructure projects to enhance groundwater and surface water storage, such as cement dams, reservoirs, and floodwater spreading systems in the study area.

Desertification in arid and semi-arid areas is an invisible and very dangerous phenomenon, and if it continues, it leads to the destruction of the land and the loss of renewable natural resources. Several factors play an effective role in the occurrence of desertification in a region, among which the phenomenon of land subsidence can be mentioned. Land subsidence is a geological process that occurs in a long-term balance and coordination between human activities and the hydrogeological environment. Today, land subsidence caused by the extraction of underground water has become a global problem, and it can even be the site of other hazards and threaten the society. The challenge of establishing a balance between groundwater consumption and land subsidence control is essential for sustainable development and curbing desertification. In order to meet their needs, including agriculture, industry and drinking, human societies depend on underground water sources and provide the required water through underground water. These conditions have become more severe in Iran due to its location in the arid and semi-arid belt, along with the improper distribution of rainfall with excessive extraction of underground water. In Iran, this phenomenon has extensive ecological, economic, social and environmental consequences due to the multiplicity, extent and complexity of the environmental and human factors that cause desertification. Hence, the precise monitoring and analysis of the intensity of desertification is of great importance for risk assessment and risk assessment. Therefore, it is necessary to know the criteria and indicators effective in the occurrence of desertification in order to achieve a model that can monitor the intensity of desertification in order to manage and plan the desert areas correctly and on principles. For this purpose, the aim of this research is to evaluate the state of desertification by IMDPA model based on two criteria of underground water and subsidence in the Rafsanjan watershed located in the northwest of Kerman province.

In this research, two criteria of underground water and subsidence rate were used as key criteria to prepare the desertification intensity map. According to the available information and the goals of this research, the criteria of underground water were scored based on electrical conductivity indicators, sodium absorption ratio, and groundwater level drop. For the subsidence criterion, the subsidence rate index was used in the year 2014-2015. In the next stage, a weight between 1 and 4 was given to each index based on its effect on desertification. The weighting is linear and equal in proportion; So that value 1 is the best and value 4 is the worst weight. Zoning of the mentioned indicators was also done by geographic information system and interpolation methods. The subsidence criterion was evaluated using the subsidence map prepared from Sentinel 1 satellite images in the year 2014-2015. In the end, the final map of the desertification situation was obtained according to the IMDPA model and based on the geometric mean of the criteria.

The average electrical conductivity measure in Rafsanjan watershed was 9351.4, which with a score of 4, is in a very severe desertification situation. Also, in terms of absorbable sodium, this watershed with an average of 12.28 and a score of 1, put it in a state of low desertification. In addition, according to the results of the groundwater quantity criterion based on the average level drop for the aquifer located in the Rafsanjan watershed, it was determined that the average drop of groundwater is about 54 cm with a score of 4, and is in a severe state of desertification. The subsidence of the aquifer located in the Rafsanjan watershed has varied from seven to less than one centimeter per year. Also, based on the average values, the average subsidence in the water year 1394-1395 in the region was in the low category with an average of -1.25 and a score of 1. Examining the areas with subsidence and the level of the drop in the underground water level showed that the drop in the underground water level can be considered as the main reason for the subsidence in the Rafsanjan aquifer. The overlap of three indicators of groundwater criteria, including: electrical conductivity, sodium absorption ratio and level drop, showed that 2.74, 59.07, 37.15 and 1.02 percent of Rafsanjan watershed are in low, medium, severe and There is a lot of desertification. Also, the overlap of the underground water and land subsidence criteria showed that the intensity of desertification is placed in three levels: low, moderate and severe, and the highest level corresponds to the moderate severity.

Rafsanjan watershed is one of the critical areas of subsidence. For this purpose, it is very important to evaluate land degradation caused by subsidence and drop in the underground water level in the Rafsanjan watershed. The results of this research confirm that according to the underground water criteria, the average electrical conductivity, absorbable sodium, and the drop in the water level of the region are in very severe, low, and severe desertification. In addition, in terms of the intensity of desertification from the point of view of water quality, the region is located in low, medium, severe and very severe classes. Finally, the intensity of desertification according to the two investigated criteria (underground water and subsidence) is placed in three levels: low, medium and severe, and the highest level is related to moderate severity. The results of this research will create a clear horizon for managers and planners of the natural resources sector, which will lead to a precise understanding of the criteria and indicators effective in the occurrence of desertification in the region. In addition, it is suggested to identify other effective factors in the region and introduce them to the desired model for accurate estimation of this phenomenon.

One of the important natural hazards is land subsidence. This phenomenon has also been observed in Iran due to the indiscriminate extraction of underground water resources, and unfortunately, more areas are exposed to it. The DPSIR tool or Driving Force, Pressure, State, Impact, Response framework is a tool that describes environmental problems through cause and effect relationships between human activities and the environment. This framework provides a background to combine different types of indicators and considers not only the environmental effects but also the economic and social effects resulting from changes in the status of ecosystems. The purpose of this research is to present the cause and effect relationships for the most important issues and problems of the risk of land subsidence in one of the important and critical plains of Fars province (Seydan-Farooq) and the most appropriate management responses using the DPSIR tool. and provide non-management to improve the current situation.

First, the problems of Seydan-Farooq Plain were determined based on library studies, asking experts and referring to the region, and based on this, possible strategies were determined. Then, the DPSIR tool was used to identify the cause and effect relationship analysis between the factors that determine the characteristics affecting land subsidence in the plain, and the DPSIR table was prepared for the risk of land subsidence in this plain. In order to prioritize and determine the importance of the problems, pressures and management strategies of the plain, a Likert scale questionnaire was used as a measurement tool and 40 experts were surveyed. Friedman's test was used to rank the items and Cronbach's alpha method was used to check the reliability of the questionnaire using SPSS version 22 software. Then Friedman's test was used for two-way analysis of variance by ranking and also comparing the average ranking of different groups using SPSS software.

The ranking of the items of the driving force component in Seydan-Farooq plain of Fars province showed that the range of the average values of the ratings varies from 1.86 to 4.45. The ranking of the items shows a significant difference in the items of the driving force component, so that the item "Population" with an average rating of 4.45 and also the item "Development of Industries" with an average rating of 1/86, it has been ranked first and fifth respectively. Therefore, in the "driving force" component, according to the factors: population, agricultural development, garden development, climate change and industrial development, the highest priority in intensifying the risk of land subsidence in this plain. assigned Regarding the ranking of the pressure component items, the range of the difference in the average values of the ratings in the pressure component varies from 1.25 to 5.40. The ranking of the items showed a significant difference in the items of the pressure component, so that the item "withdrawal from the underground water table in the agricultural sector" with an average rating of 5.40 and also the item "withdrawal from "Underground water table in the domestic sector" with an average rating of 1.25 has been ranked first and sixth respectively. Therefore, in the "pressure" component, according to the factors: withdrawal from the underground water table in the agricultural sector, failure to comply with the environmental rights of the aquifer, decrease in rainfall, withdrawal from the underground water table in the garden sector, From the underground water table in the industrial sector and the withdrawal from the underground water table in the domestic sector, they have assigned the highest priority in intensifying the risk of land subsidence in this plain. The average values of the ranks in the response component vary from 2.35 to 5.75. The ranking in the items of the response component also shows a significant difference, so that the item "increasing irrigation efficiency" with an average rating of 5.75 and also the item "nutrition" Point of water in the plain" with an average rating of 2.35 has taken the first and sixth place, respectively. Therefore, in the "response" component, in the order of the factors: increasing irrigation efficiency, changing the cultivation pattern, controlling the harvesting of authorized wells, aquifer operations, blocking unauthorized wells, cultural measures and spot nutrition. Water in the plain has the highest priority in reducing the risk of land subsidence in this plain.

Conclusion and Suggestions :

Five driving forces (D) have caused six pressures (P) on the water resources of this plain, the most important of which are "withdrawal from the underground water table in the agricultural sector" and "not respecting the environmental rights of the aquifer". are The pressures, in turn, have created a disordered (S) situation (dropping of the water table) in this plain. This situation has two adverse effects (I) "land destruction" and "aquifer destruction". In order to improve the situation, seven management responses (R) were presented, the most important of which are "increasing irrigation efficiency" and "changing the cultivation pattern". In the current situation, it is not possible to stop the pressures; However, their adjustment and modification should be specially considered by planners and managers. It is worth mentioning that if these cases are not corrected, there will still be pressures (P) and will lead to more critical conditions than the existing situation (S) and finally, its effect (I), destruction of lands, aquifers. and the destruction of water and soil resources of this plain will be more. Due to the fact that the executive structure of the country's natural resources management is more in line with the components of pressure (P) and situation (S); It is suggested to develop suitable, practical and operational answers (R). It is also necessary to pay serious attention to the preventive approach in reducing the risk of land subsidence; Because, unfortunately, this matter has not been paid attention to in the country. Therefore, it is suggested to consider and implement a preventive approach that both understands the driving forces (D) and prevents the implementation of policies that cause pressure.

Most watershed management projects are designed and implemented with the aim of controlling soil erosion and floods, reducing their destructive consequences. Therefore, evaluating their impact is one of the most essential and important prerequisites for success. The present study evaluated the of the effect of earth dam construction on gully erosion control from the perspective of watershed residents in Mazayjan Zarrinudasht watershed located in the south of Fars Province. A questionnaire consisting of 32 questions from a range of 5 Likert options was prepared, and filled with a face-to-face interview with 200 watershed residents. Responses were analyzed in terms of demographic characteristics (gender and occupation) by SPSS software (version 16). Findings showed that 38.3% of women, 32.7% of men, and 47.3% of farmers with land believed that the construction of earth dam has improved the region and the living conditions. 59.6% of women, 60.8% of men and 69.1% of farmers with land had a positive evaluation of the effect of earth dam construction on gully erosion control. 59.5% of women, 60.1% of men and 69.1% of farmers with land had the highest percentages of agreeing to similar activities in the region. It is suggested that considering the positive view and tangible experience of the watershed residents of this region in the effectiveness of the construction of the earth dam, serious efforts be made to promote, plan, implement, operate and maintain watershed management projects.

Severe soil erosion is a serious threat to the sustainable management of land and the use of water and soil resources in many parts of the world. In order to control erosion of sheet, rill, gully, and stream bank erosions and to reduce the resulting sediment at the outlet of watersheds, it is necessary to identify the share of sources that produce their sediment to make protective measures more successful. One of the most common methods that has been used in recent years to determine the share of different sources of sediment is the sediment fingerprinting method.

The purpose of this study is to investigate contribution of sheet, rill, gully and stream bank erosions in sediment production by using sediment fingerprinting method in Neyriz watershed, located in East of Fars province, with the help of sampling of sediment deposited in the bed. From each type of sediments, sheet, rill, gully and stream bank erosions, the main waterway within the basin and the outlet area of ​​the watershed, 10 samples (60 samples in total) were collected. In order to determine the optimal tracers, two tests of "domain" test and "multivariate detection analysis" were used. Furthermore, by using the model of Collins et al., the share of each of the different sources of sediment was obtained. Then, the uncertainty related to the share of potential sources of sediments was calculated using the Monte Carlo simulation method with 95% confidence in MATLAB software. In order to evaluate the results of the hybrid multivariate model, the Goodness of Fit (GOF) proposed by Collins et al. was used.

Based on the range test, among the 51 tracers measured in the samples, twelve tracers (Ag, Ba, Be, Eu, Mn, Ni, Ta, Tb, Th, Tm, W, and Zn) are found as tracer’s non-conservative variables were identified, and these detectors were discarded in other statistical tests such as Kruskal-Wallis and discriminant analysis function. The results of the Kruskal-Wallis test showed that among the 39 tracers that passed the range test, sixteen tracers (Al, Ca, Co, Cr, Er, Fe, Gd, Lu, Mo, Na, Nd, Pb, Pr, S , Sc and Zr) with significance at one percent level (p ≤ 0.01), and 9 tracers (Cu, Ga, Hf, Ho, La, Sn, Sr, Y and Yb) with significance at five percent level (p ≤ 0.05) is that in total, these 25 detectors had a significant level and could separate sources; while fourteen tracers (As, Ce, Cs, Dy, K, Li, Mg, Nb, P, Rb, Sm, Te, Ti and V) were not statistically significant, these tracers were deleted from the DFA statistical test. In the first step of the DFA test, the Zr detector, the second step of Zr and Al detectors (with Wilkes lambda from 0.717 to 0.244), the third step of Al, Zr and Fe detectors (with Wilks lambda from 0.39 to 0.057), the fourth step of Zr, Al, Fe and Sn detectors (with Wilkes-lambda 0.362 to 0.04), the fifth step of Zr, Al, Fe, Sn and Lu detectors (with Wilkes-lambda 0.233 to 0.03) and the sixth step Zr, Al, Sn and Lu tracers (with Wilks lambda 0.289 to 0.045) were entered into the model. Based on the obtained results, among the 25 tracers that passed the Kruskal-Wallis test, five tracers (Al, Fe, Lu, Sn and Zr) were entered into the DFA test step by step. In the third stage, iron tracer (Fe) was added to the model and in the sixth stage, it was removed from the DFA test. In general, four Zr, Al, Sn and Lu tracers were selected as the final optimum tracers. These four detectors were able to correctly classify 95% of sediment sources. The findings of this research, which were obtained by using Monte Carlo simulation and the combined multivariable model and evaluating their results using GOF, showed the contribution of gully, sheet, rill and stream bank erosion to the order is equal to 45.21, 3.07, 16 and 35.72% of the total erosions that have occurred in this watershed. Also, considering the GOF value of 0.8869 and mentioning that the closer this value is to one, the more accurate the results of the model is true in this research and this analysis also confirms the high accuracy of the model.

In this study, the efficiency of sediment fingerprinting method was proved as a successful and effective method to determine sediment sources because the first and most important stage of the sediment source method is to choose a suitable combination of tracers that can isolate sediment sources, and this was done correctly in this research. Also, Monte Carlo uncertainty confidence levels showed that the scope of this uncertainty is large (0.8869) and therefore, it shows a greater lack of certainty on different sources of sediment production. Determining the share of four types of erosion in the Neyriz watershed and placing the share of gully erosion as the most important type of erosion in the production of productive sediments in it shows the importance of controlling erosions, especially gully erosion, with emphasis on biological plans.

Enhancing the soil organic carbon (SOC), not only sequesters the atmospheric CO2, but also often improves the processes and soil physical, chemical and biological properties. This investigation with the aim of evaluating vegetation cover and soil chemical properties on SOC was carried out in 2019 in the flood spreading fields of Kowsar station located in Gareh-Bygone Plain (Fasa, Fars Province). Flood spreading for feeding aquifers has been carried out since 1982 in an area of 2034 ha in this plain.

Land uses included Acaci (Acacia salicina Lindl), Eucalyptus (Eucalyptus camaldulensis Dehnh), Atriplex ([Atriplex lentiformis (Torr.) (Wats.)]) Plantation and natural rangeland, all of which are irrigated by flood spreading. By sampling of soils (depth 0-30 cm) in three replications in mentioned land uses, 13 characteristics: pH, ECe, CaCO3, SOC, TN, C/N, P, K, Na, Ca, Mg, Ca+Mg, SAR were measured and determined. After confirming the normality of the data by Kolmogorov-Smirnov test, the obtained data were analyzed in a randomized complete block design (RCBD) and the means were compared with Tukey test at p<0.05.

The analysis of variance showed that the effect of treatment (vegetation cover) on the all studied variables, except SAR was significant at p<0.01 and p<0.05.  Stepwise regression method was used to present the model. The results showed that C/N, TN, and ECe affect the amount of SOC and explain 99.7% of the changes in SOC. According to the standardized coefficients in the regression equation, for each unit increase of C/N ratio, the value of 0.939 units and for each unit of TN, the value of 0.338 units and with the increase of each EC unit, the value of 0.109 units is added to the SOC.

In general, recognizing the factors affecting the organic carbon storage in the soil, can provide appropriate management strategies to increase the organic carbon content and develop carbon storage capacity in the soil, improve soil fertility and mitigate the negative effects of climate change to a great extent.

The main basis of ecological research is the accurate identification of vegetation. Because it is an effective factor in measuring and evaluating the current situation and predicting the future situation of the region and will play an important role in proper and scientific management. For this purpose, in this study, the flora, life form and chorothype of plants in Bardkal watershed located in the northwest of Shiraz were introduced. The results showed 127 plant species which belong to 34 families and 102 genera. There are species in this watershed. The largest families Asteraceae with 24 species, Fabaceae with 17 species and Poaceae with 15 species, are in the first to third ranks, respectively. In terms of life form, 48 species of Therophytes, 34 species of Hemichryptophytes, 18 species of Camophytes, 14 species of Geophytes and 13 species of Phanerophytes were identified. The results of Chorothype plants in this watershed also showed that 122 plant species, which is equivalent to 96.07% of the total species, are located in a single-zone or multi-zone in the Iran-o-Turanian region.

Land use change is a major factor in changes in soil organic carbon and nitrogen storage and the global carbon cycle. The aim of this study was to investigate the changes in soil organic carbon and nitrogen storage after afforestation and rangeland cultivation along with flood spreading.

This investigation was carried out on the sandy lands of Gareh-Bygone Plain of Fasa located at southeastern of Fars province. A total of 45 soil composite samples were collected from Acacia, Eucalyptus, Atriplex and Planted Range from a depth of 0-30 cm in two conditions with and without flood spreading. The organic carbon and the total nitrogen content were measured in laboratory. Then, the amount of carbon and nitrogen storage was calculated and their economic value was determined by carbon tax method. The data were analyzed using SAS software as a factorial experiment in a completely randomized block design and the means were compared with Duncan's test at p<0.05.

The results showed that the effect of flood spreading on the percentage of organic carbon and the amount of organic carbon storage in the soil was significant at the p<0.01, not significant on the percentage of the total nitrogen, but its effect on the amount of nitrogen storage at the p<0.05 was significant. The effect of land use (vegetation type) on all these indices were significant at the p<0.01. The interaction effect of flood spreading and land use on the percentage of organic carbon and soil nitrogen storage at the p<0.01 was significant, but its effect on the amount of carbon storage and the percentage of total nitrogen was not significant. The amount of organic carbon storage in the soils of Acacia, Eucalyptus, Atriplex and Range, from 10.23, 22.49, 12.3 and 6.21 Mg/ha in conditions without flood spreading, respectively, increased to 23.14, 40.23, 24.12 and 13.96 Mg/ha in flood spreading conditions. The spread of floods on these land uses increased the economic value of carbon and nitrogen storage equal to 53.59, 48.00, 75.46 and 43.52 percent, respectively.

On average, flood spreading increased the economic value of total carbon and nitrogen storage in the soil equal to 54.31%.

Marls as the most sensitive geological structure against erosion and weathering have a major role in sediment yield of watersheds. Due to the lack of vegetation or sparse pattern of vegetation cover in the Marl Formations; by identifying suitable plants and establishing and propagating them in these areas, the amount of erosion can be reduced. it is difficult to carry out the implementation of erosion control structures in Marl lands due to their mechanical properties; therefore, erosion control using biological measures is necessary and this requires accurate identification of species diversity. Due to the importance of this issue, suitable plants for the conservation of marls were identified in the Tanghesorkh Watershed of Fars Province.

Eleven points with dominance and the presence of marl outcrops were selected as sampling points. The sampling method for studying vegetation in these areas was based on physiognomic-floristic method and using transects and plot methods. Samples were collected in early autumn 2019, late winter 2019 and spring and summer 2020 and using valid scientific methods and plant species were identified. Also, biological form, longevity, vegetation form and chorology were determined. Then, different plant characteristics (density, frequency, canopy and root and rhizome status, amount of litter produced, generation method and longevity) and ranking of plants were studied in order to stabilize and protect the marl soils.

Around 108 plant species belonging to 29 families and 88 genera were identified. Asteraceae family with 18 species, Papilionaceae family with 17 species and Poaceae family with 13 species, are in the first to third ranks, respectively, and 16.67, 15.74 and 12.03% of the number of species to allocate them. In terms of longevity, 40 annual species (16 species of grass and 24 species of forb) and 68 species of perennials (8 species of grass, 30 species of forb, 18 bushes, 2 trees and 10 shrubs) were identified. A total of 37.04 and 62.96% of the total species accounted for plant. Life form included therophyte (36.12%), hemicryptophyte (24.07%), camphite (17.59%), geophyte (11.11%) and phanerophyte (11.11%). 55 species with a specific chorotype specific to the Iran-Turani vegetation zone had the highest frequency (50.93%). According to botanical characteristics, 30, 38, and 40 species in the first to third ranks for conservation of marl in this watershed were introduced.

Species such as Astragalus susianus, Astragalus faciculifolious, Astragalus gossypinus, Artemisia Aucheri, Convolvuvlus acathocladus, Convolvuvlus leiocalycinus, Amygdalus scoparia, Acantholimon asphodelinum, Stipa barbata and Glycyrrhiza glabra is recommended for the establishment and reproduction of in marl-covered areas in this watershed. Also, due to the irregular exploitation of these lands, it is necessary to protect these areas by controlling and managing livestock grazing. Therefore, this conservation provides opportunities for regeneration and survival of valuable plant species in this watershed.

Soil properties and land use affect the soil carbon content and reduce the adverse effects of climate change. This study aims to assess the effect of some physical properties of soil and land use on the amount of soil organic carbon content (SOC) and model development to estimate the amount of SOC. This investigation was carried out in 2020 in the areas of flood spreading in of Fasa (Kowsar station). Land uses included acacia (Acacia salicina Lindl.), eucalyptus (Eucalyptus camaldulensis Dehnh.), atriplex (Atriplex lentiformis (Torr.) Wats.) plantation, and natural rangeland, all of which are irrigated by flood spreading. By sampling in three replications of the soil of different land uses from the depth of 0-30 cm (15 composite samples), percentage of sand, silt, clay, silt+clay, percentage of soil saturation moisture (SP), bulk density (BD), particle density (PD), porosity percentage (PS), void ratio (VR) and SOC were determined. Obtained data were statistically analyzed in a complete randomized design and the means were compared with the Duncan test at P<0.05. The analysis of variance showed that the effect of land use (PT) on the percentage of sand, silt, silt + clay, SP, BD, PS, VR, and SOC has been significant at P<0.01, and the clay, at P<0.05. Comparison of the means of SOC in different land uses showed that the Eucalyptus forest, with 1.68%, has the highest value and the control with 0.14% organic carbon has the lowest value. There was no statistically significant difference between the SOC in Acacia forest, Atriplex, and rangeland. Stepwise regression analysis was used to present the model. Soil physical properties and land use were considered as independent variables and SOC was considered as a dependent variable. The results showed that the variable of silt explains 77.00% of the changes in organic carbon. Based on the principal component analysis (PCA) method, according to the specific values, considering the first two axes, about 91.70% of the changes can be explained. Considering the first axis, 69.71% and considering the second axis, 21.99% of the changes are justifiable. The PT, with 91.40%, sand with 84.30%, BD, 82.70%, showed a negative correlation with SOC. While the SP had 90.30%, percentage of clay+silt had 84.80%, PS, 80.70%, VR, 79.10%, silt, 78.50%, clay, 78.50%, had a positive correlation with SOC.

In this study, plant samples were identified using available scientific sources and by examining various plant characteristics including: density, frequency, canopy status, roots and rhizomes, amount of litter produced, vegetative form, propagation method and longevity, priority plants were classified in order to stabilize and protect the marls. According to the results, 34, 59 and 61 species, respectively, in the first to third priority in order to stabilize and conservation marls in these watershed were introduced. It is necessary to reproduce and establish bush, shrub, tree, forb and perennial grass species, and annual grass and forb species in these lands, respectively. Also, considering the botanical characteristics and natural characteristics of the region and emphasizing that in addition to the issue of erodibility and sediment production, marl lands are mainly low permeability and insufficient moisture for the establishment and growth of plants; It is recommended for the establishment and reproduction of species such as: Astragalus susianus Boiss.، Astragalus gossypinus Fisch. and Artemisia Aucheri Boiss. Take action in the areas covered by marl in this watershed. Because with the management and establishment of these species, in addition to soil conservation, the opportunity to reproduce and preserve these valuable plant species will be provided.

Researches in recent years have shown that the implementation of watershed management projects without the participation of the public has not been successful and has led to the inefficiency of projects in watershedchr('39')s protection. In order to solve this problem, prioritizing the indexes and sub-indexes affecting the non-participation of people is a fundamental step in the watershed management cycle, so that identifying the effective factors and prioritizing them will lead to maximum participation of the watershed residents. According to this goal, in this research, prioritization of effective factors was done on non-participation in watershed management projects from the exploiters viewpoint in Chikan and Morzian Sepidan watershed located in northwest of Fars province. The statistical population of this research was 51 exploiters (stakeholders) using Cochran formula. A questionnaire consisting of four indices and twelve sub-indices with Likert scale was used for data collection. The significance of indices and sub-indices was determined by SPSS software (version 23) using t-test and the Friedman nonparametric test was used to prioritize the effective indices and sub-indices. The results showed that in the prioritization of indicators from the beneficiarychr('39')s point of view "economic", "social", "educational-promotion" and "design-executive" indices were the effective factors, respectively and in sub-index "lack of training of basin residents on related plans and objectives" and "lack of attention to Non-Governmental Organizations (NGO) in watershed planning", had the highest and lowest priority in non-participation in watershed planning, respectively. In order to sustainable participation of exploiters in watershed management projects, it is necessary to solve the "economic" problems of beneficiaries and develop a comprehensive program of training and promotion of practical actions.

Engaging people to conserve natural resources is the most rational way. This by reducing the running costs will guarantee the success and implementation of the projects more effectively. For this purpose, the present study was conducted to identify and prioritize the effective indices and sub-indices on the lack of sustainable participation of rural communities in aquifer management projects from the beneficiarychr('39')s viewpoint in Bishezard watershed of Fars province. In this research, 83 stakeholders and residents of the watershed was chosen as statistical population using Cochran formula. To collect data, a questionnaire consisting of four indices and twelve sub-indices with Likert scale was used. The significance of indices and sub-indices was determined by SPSS software (version 23) using t-test and the Friedman nonparametric test was used to prioritize the effective indices and sub-indices. The results showed that in the prioritization of indices from the beneficiarychr('39')s point of view "educational-promotion", "design-executive", "social" and "economic" indices were ranked with an average of 9.75, 9.49, 6.98 and 5.93 as effective indicators, respectively and in sub-indices, "Lack of attention to local force in project implementation (employment)" and "Late-yielding projects" with an average of 11.40 and 5.74 had the highest and lowest priority in non-participation in aquifer management projects, respectively. This finding indicates that if employment is resolved in this watershed, people are willing to take the time accomplish projects. It is recommended that managers of natural resources plan and implement practical training and promotion activities related to natural resources and aquifer management issues.

Carbon storage by natural forests, plantation forests, pastures and soils is the best way to reduce atmospheric carbon. This study was conducted in 2018 with the aim of evaluating the effect of spate irrigation on the biomass and carbon storage in various organs of Eucalyptus camaldulensis and Acacia salicina plantation at the Kowsar station located in Gare-Bygone Plain. After truncating the trees, trunk, branches and leaves were separated. In addition, the amount of litter produced under the trees was also collected and weighed. Afterwards, the dried samples were powdered by electric milling and the carbon content in the samples including trunk, branch, leaf and litter was measured by electro-ash method. Data were analyzed using randomized complete block design and the means were compared by Tukey test at P<0.05. The results showed that leaves had the lowest amount of carbon storage and trunk had the highest amount of carbon storage. In eucalyptus stand (first strip), the highest carbon content of 187.56 t/ha was stored as living tissue including trunk, branch and leaf litter. Given that each ton of carbon equals 3.67 tons of carbon dioxide gas, it can be concluded that the amount of 688.34 tons of carbon dioxide gas in the air in different organs of the plant and in litter stored as organic matter. In acacia, however, the amount of carbon stored was 72.81 t/ha and the equivalent of stored carbon dioxide was 267.21 t/ha. The economic-environmental value of this amount of stored carbon was calculated to be $137619.05 and $5333.33 per hectare, respectively. With respect to 32 years of spreading water in these areas, each hectare of eucalyptus and acacia trees averages 21.51 and 8.35 tons of carbon dioxide gas have been stored as organic matter per year, respectively. In this respegt, the eucalyptus plantation has played a greater role in reducing air pollution. The economic value of the oxygen produced in the forests of eucalyptus and acacia ($11190.5 and $1774.28, respectively) is also adds to the economic value of reducing carbon dioxide, and their economic performance value reach to $148809.52 and $55238.10, respectively. Therefore, the development of eucalyptus afforestation toghether with spate irrigation method in similar prone areas is more economically justified and recommended from a carbon storage perspective.