نشریه پژوهش های آبخیزداری
پیاپی 137 (زمستان 1401)

The aim of the current study is to evaluate the effectiveness of the watershed management operations by using the quantitative values obtained from the field survey in Khor-Sefidarak, Fashand, and Azimiyeh watersheds, and indicating a clear result of deposited sedimentation rate and vegetation improvement in reservoir tank of the structures. Field evaluation of watershed management structures showed that since 1991, a total of 652 gabion structures, 20 masonry structures, 533 small stone structures, and 15 embankment dams have been implemented in Khor-Sefidarak, Fashand, and Azimiyeh watersheds of Alborz province. A study of the stability of the structures showed that masonry structures had the most stability with the least need for restoration (92% of them). Also, 80% of gabion structures and 83% of small stone structures in the studied watersheds were stable. The study of sediment deposition in reservoirs tanks of structures in the study area showed that a total of 332,100 m3 of sediment has been deposited and stabilized by the structures and has prevented its transferring to rural and urban residential areas. Of this amount, 45960 m3 have been deposited by embankment dams and 286140 m3 by masonry structures, gabion and small stone structures. Sediment volume to structure volume index showed that it was 4.4, 15.3, and 1 for gabion, masonry, and small stone structures, respectively. Evaluation of vegetation and tree cover development of whining reservoirs tanks of watershed structures showed that 4880 trees and seedlings (97% of all them) have been grown and developed in the reservoirs of gabion structures. If the gabion structures are constructed, it is suggested that they be constructed in non-stone beds, and cement cover be used to prevent their destruction.

Accurate information about the amount of moisture and its fluctuations can provide a suitable solution for preparing soil surface moisture maps, predicting the occurrence of soil storms and dust, forecasting floods, droughts, and other climatic phenomena, determining the irrigation time table and the grazing season. In this study, the Perpendicular Soil Moisture Index (PSMI) extracted from Landsat 8 images was used to estimate and determine surface soil moisture. Using field data, the relationship between this index and soil moisture was determined. After radiometric and geometric corrections of images and normalization of field data, processing of satellite images and extraction of PSMI index were performed. Simple regression analysis between field data and index values ​​was performed at different times. Then, the accuracy of produced maps was determined with statistical indicators including coefficient of correlation (R2), root mean square error (RMSE), mean absolute error (MAE) and Nash Sutcliffe efficiency coefficient. The results showed that estimated values with the PSMI index are completely dependent on the season and vegetation status. In the growing season and with high greenness coefficient, the accuracy of estimation was high. In dormant seasons, vegetation had a weak and moderate correlation with field data. The average coefficient of R2 in all sampling times was about 0.65. From the findings of this study, it can be concluded that this index can be used to monitor soil moisture in areas with suitable vegetation, irrigation planning in agricultural areas, and the beginning and end of the livestock grazing season.

This study examined the attitude of watershed stakeholders to watershed management plans in the Rimleh watershed from the perspective of residents. Rimleh is one of the watersheds of the Kashkan river basin. All heads of rural households in the basin were selected as the statistical population. Practical indicators for measuring the attitude of users towards watershed management measures were prepared from related scientific articles and books. The validity and reliability of the questionnaires were tested (Cronbach's alpha = 0.827). On the basis of the Cochran formula, 135 respondents were chosen in a stratified sampling scheme among the local communities of the watershed. The effects of watershed management measures on economic and social criteria were classified and evaluated using the Friedman test. Among the indicators of improving the economic income level of watershed residents, the index of converting low-yielding meadows into sloping land gardens (rank 16.44) had the highest score. Also, among the indicators of improving the level of knowledge and awareness and economic power of watershed households, the index of proper use of the capacity of other institutions had the highest score (7.9 mean rank). The results of this research can be used by managers and decision-makers to promote soil and water resources protection as well as to promote the adoption of management actions at the watershed scale.

The management of freshwater resources in the coastal aquifers of salt lakes requires understanding the dynamics of the flow system, geochemical evolution, etc. The salinity of coastal aquifers is mainly due to direct saltwater intrusion, or is associated with complex geochemical interaction of lake and Ground water. The purpose of this study is to investigate the extent of intrusion and entry of saline water of Maharlu Lake into the coastal aquifer of the Maharlu aquifer, employing hydrochemical parameters and delineating the chemical evolution of its groundwater. The information used in this study includes the water level fluctuations and spatial, depth, and temporal changes in water salinity, and the chemical composition of the aquifer groundwater. For this purpose, several methods including water table maps and salinity changes, diagram of hydrochemical evolution of water, Stiff diagram, and chloride to bromide ions ratio have been used. According to the results obtained in the whole study period (February 1997 to February 1998), the water table elevation of a large area of the aquifer is lower than the elevation of the lake floor and, therefore, the Lake saline water flows into the aquifer under the reverse hydraulic gradient. Hence, in addition to the normal phenomenon of saline water intrusion, which occurs due to density gradients, aquifer salinization is also strongly influenced by the entry of saline water under the influence of hydraulic gradients. Based on the results of this study, the aquifer in terms of salinity and the effect of the Lake water on its salinity is subdivided into three zones, including; an area that starts from the lake margin up to a maximum distance of 1000 meters, which is completely affected by the entry of saline lake water, an area starts from 1000 meters to about 1500 meters as a middle area affected by both phenomena and the area from 1500 meters to about 2200 meters, located in the foothills of the southern karst boundary,  the alluvial feeding area of the aquifer, which it's water quality is relatively suitable for agriculture.

Evaluation of mechanical and biological operations in watersheds is always emphasized by managers and executive organs. To achieve this, there is a need for an integrated evaluation and management approach in which processes and all physical, economic, and social effects are considered. The purpose of this study was to evaluate the effects of biological operations performed based on physical, economic, and social criteria in Bushkan watershed in the east of Bushehr province. Four scenarios of biological operations in the area were identified, including planting, planting with creating curved pits, contour furrow, and contour furrow with planting. To evaluate different scenarios, the indicators related to each scenario in terms of physical, economic, and social criteria were calculated. After standardizing the indicators and weighting them, the scenarios were prioritized by Delphi technique. The results showed that the scenario of contour furrows with planting, planting with creating curved pits, planting, and contour furrows are the first to fourth priorities in the region, With areas of 16554, 2155, 9655, and 428 ha and weights of 0.878, 0.741, 0.701 and 0.649, respectively. It is concluded, Scenario 4 (contour furrow with planting) was the best scenario in Bushkan watershed. Therefore, with the help of the scenario management approach and evaluation of biological management scenarios, planners and operators of watersheds are able to select the best possible scenarios after being aware of the results of various measures. It is suggested that considering all the limitations, indicators, criteria and other types of prioritization methods be used to examine the effects of biological operations scenarios in the study watershed.

Identification of sediment resources and their associated pollutants and contribution separation of land uses / land cover in sediment production is a valuable tool in spatial prioritization of soil conservation practices at watersheds. The present study was conducted with aim of bed sediment Fingerprinting using the geochemical method in Vaz watershed in Mazandaran Province. Thirty soil samples from different land covers were collected as sediment sources, and a sample of bed sediment at the basin outlet was measured. The geochemical characteristics including 59 elements were measured using ICP-OES. Then, using the combination of range tests, Kruskal-Valis and DFA test in FingerPro package at R software, 15 elements including K, Li, P, V, Cr, Fe, Cu, Ga, Ge, Rb, Sb, Ba, Nd, Ta, and W were selected as the optimal tracers. The results with a goodness index of fit of 78.31 showed that the contributions of agricultural, rangeland, forest, and stream bank lands in the bed sediment yield were with rates of 2.77, 3.61, 12.14, and 73.84 %, respectively. Finally, the relative contribution of each source in sediment yield for each hectare was calculated and the results showed that stream bank and rangeland with the relative contribution of 0.43 and 0.0008 percent for each hectare have the highest and lowest participation in sediment yield, respectively.

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.

Infiltration is one of the most parameters of hydrology that plays a fundamental role in streamflow, groundwater recharge, subsurface flow, and surface and subsurface water quality and quantity. According to the importance of the mentioned subject, the infiltration changes and modeling were investigated in the different soil textures in Kashkan watershed, Lorestan province. In this study, the double-ring infiltrometer was used to measure the infiltration in the different soil textures. Also, Support vector regression (SVM), Gaussian Process (GP), Multi-Layer Perceptron (MLP), and Random Forest (RF) were used to Modeling of infiltration rate in different soil textures. Three statistical comparison criteria including root mean square error (RMSE), coefficient of correlation (C.C), and Nash Sutcliffe (NSE) were used to determine the best-performing infiltration model. The results showed that Random Forest model better estimated infiltration rate (C.C= 0.9912, NSE= 0.98622, and RMSE = 0.0177) compared to the other models. Thus, RF was found to be the most suitable for modeling infiltration in the study area. Also, sensitivity analysis concludes that the parameter time is the most effective parameter for the estimation of infiltration rate. The results indicated that the infiltration varies in the different soil textures, which should be considered in the management of groundwater recharge.