Ariyan Matboo; Vahedberdi Sheikh; Ali Mohammadian Behbahani; Arash Zare Garizi
Abstract
Introduction
The hills surrounding the international wetlands of Almagol and Ajigol in the Golestan Province are exposed to severe erosion and every year a large amount of sediments from these hillslopes discharge into these wetlands. Whilst a large extent of these surrounding hills, covered with Biological ...
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Introduction
The hills surrounding the international wetlands of Almagol and Ajigol in the Golestan Province are exposed to severe erosion and every year a large amount of sediments from these hillslopes discharge into these wetlands. Whilst a large extent of these surrounding hills, covered with Biological Soil Crusts (BSC), has been destroyed due to lack of awareness of their values, sensitivity and ecological functions. Improving soil properties, preventing direct contact of raindrops with the soil surface, all indicate the important role of BSC in hydrological processes and soil loss control.
Materials and methods
In this study, the role of BSC in the hydrological processes of dry areas was investigated using a rain simulator. After a field survey and evaluation of the area, different treatments including biological crust with a dominant lichen cover, biological crust with a dominant moss cover, an area covered with vascular plants, an area without cover and areas covered with a combination of moss and lichen were selected to perform rain simulation and compare their effects on the hydrological processes of the selected region. Rain simulation was done in 2×1 meter plots for 30 minutes and intensity of 82 mm per hour. The start time of runoff and the volume of produced runoff at the outlet of the plot were measured and recorded. Also, at five-minute intervals from the beginning of the simulation process, 500 ml runoff samples were collected and transferred to the laboratory for testing in order to estimate the sediment concentration and mass. In addition, the depth of the wetting front caused by the infiltration of rain was measured at the beginning, middle and end sections of the plots.
Results and discussion
The results of rainfall-runoff simulations at a 2×1 m2 plot scale with a rainfall intensity of 82 mm.h-1 and a duration of 30 minutes plots, showed that the average mass of sediments from plots with the dominant cover of moss (104 g), lichen (91 g), lichen-moss combination (176 g) and bush (99 g) was significantly higher than bare soil (1133 grams). Therefore, in case of destruction of the existing BSC and the formation of bare lands, the sedimentation rate will increase by more than 5 times. A significant decrease in water infiltration into BSC causes a significant increase of 30-40% in runoff generation compared to the treatment covered with bushes and a significant increase of 8-18% compared to the bare soil treatment.
Conclusions
by reducing soil loss and sediment concentration, BSC cause the production and transfer of high-quality runoff to the wetlands and as a result maintain the ecological function and health of the region’s wetlands. The results of this research show the positive influence of BSC on the hydrological and ecological performance of arid areas in the north of Gorgan Plain and protection of Ramsar-listed wetlands in the region.
Maryam Sanjari Banestani; Vahedberdi Sheikh; Arash Zare Garizi; Amaneh Avarand
Abstract
The aim of this study is to assess the feasibility of monitoring precipitation, temperature and river stage variables in the Chehl-Chai Watershed with the participation of citizens/stakeholders. Simple and low-cost measurement tools were designed and provided to the local volunteers (two students, three ...
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The aim of this study is to assess the feasibility of monitoring precipitation, temperature and river stage variables in the Chehl-Chai Watershed with the participation of citizens/stakeholders. Simple and low-cost measurement tools were designed and provided to the local volunteers (two students, three women and one man) and they monitored the variables for five months. The data were recorded on paper forms and/or communicated through cellphones (text messages and social media applications of WhatsApp and Telegram). The citizen-collected data were compared with formal gauging stations using different statistical metrics including correlation coefficient, paired-sample t-test and kappa index. Results revealed that, the difference between the recorded data by the participants and those of gauging stations were not statistically significant. A female citizen with academic education of bachelor’s degree recorded the highest frequency of data that had the highest correlation with the recorded data in the formal precipitation and temperature monitoring stations, while the technical staff man from the Natural Resources Management Office recorded the least frequent data that had the least correlation with the recorded data in the formal monitoring stations. In overall, the promising level of citizens’ performance in monitoring the watershed, suggests that it is really feasible to collect reliable, on-time, and long-term data that can be used to obviate lack of data, particularly in remote mountainous areas and facilitates the decision-making and watersheds management process.
Arash Zare Garizi; Ali Talebi; Monireh Faramarzi
Abstract
In this study, SWAT model was used for simulating soil erosion and sediment transport in Gharesou Watershed, Golestan Province and for identifying and prioritizing critical areas of soil erosion. After model calibration, validation and uncertainty analysis using semi-automatic SUFI-2 method, the outputs ...
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In this study, SWAT model was used for simulating soil erosion and sediment transport in Gharesou Watershed, Golestan Province and for identifying and prioritizing critical areas of soil erosion. After model calibration, validation and uncertainty analysis using semi-automatic SUFI-2 method, the outputs of the calibrated model were used for assessing spatial pattern of soil erosion and sediment. For this purpose, four indices including: load per unit area index, concentration index, load index and total index were defined and analyzed based on the model outputs. The results indicated that, despite lack and uncertainty of available data, SWAT model performance in simulating soil erosion and sediment transport in Gharesou watershed is quite acceptable. During calibration, the simulated monthly sediment loads matched the observed values with a Nash-Sutcliffe coefficient of 0.24 and PBIAS of -17%. The values for validation period were 0.2 and -12.1% respectively, indicating the model’s weakness in simulating sediment dynamics and its capability in predicting average sediment load. Assessing spatial pattern of erosion and sediment indices showed that, in general, critical sub-watersheds based on load per unit area index are located in upstream areas of watershed while sensitive sub-watersheds in terms of sediment concentration are situated in the middle part of the watershed, and sensitive sub-watersheds with respect to sediment load are in downstream. Suitable conservation practices were recommended for each zone based on their ecohydrological conditions. The outputs of this study can help experts and managers in planning of management practices for the watershed.
