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Determination of Sediment Retention Service Trends Using the InVEST Model and Compensation of Economic Losses Due to Soil Erosion with a Replacement Cost Approach in the Efin Watershed, South Khorasan
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Javad Chezgi *   , Reza Chamani , Hadi Memaryan , Halimeh Joloro , Negin Rashidi |
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Abstract: (6 Views) |
Introduction
Today, in various parts of the world, especially in dry and semi-dry regions, land degradation, soil erosion, and loss of nutrients due to various climatic, human, and environmental factors have increased. This has led to a decline in the soil’s developmental capacity, as well as the germination, establishment, and growth of plants in pastures, reducing the productivity of agricultural plants. In other words, after every heavy rainfall and runoff, soil erosion occurs, which moves soil from the watershed area downstream, depleting soil nutrients and impoverishing the local soil. However, a lack of understanding of the amount of displaced nutrients and the costs associated with this issue has resulted in its minimal inclusion in the policies and planning of managers. Therefore, identifying and quantifying the extent of erosion and the lost nutrients due to it, as well as the replacement costs of these elements, can significantly aid in understanding the various dimensions of soil erosion. Accordingly, this study aims to determine the soil loss in the Efin watershed of South Khorasan and subsequently assess the costs of replacing the lost phosphorus and potassium elements to quantify the costs of compensating for soil erosion damages.
Materials and Methods
For this research, daily precipitation data from three meteorological stations (Efin, Zohan, and Moghilan), located at the outlet, mid, and upstream of the watershed, as well as sediment and flow data recorded at the Efin station at the outlet of the watershed, were collected for the available period (2007 to 2023) from the Meteorological Organization and the Regional Water Company of South Khorasan. Subsequently, the model inputs for InVEST, including Rainfall Erosion (R), Soil Erodibility (K), Digital Elevation Model (DEM), Normalized Difference Vegetation Index (NDVI), and Land Management (P) corresponding to the precipitation and flow data for the period of 2007 to 2023, were prepared and resampled to 30-meter cells. The period from 2007 to 2016 was considered for calibration, and from 2017 to 2023 for model validation. After calibrating and validating the InVEST model, the amount of sediment output from the watershed was estimated for each year. The levels of phosphorus and potassium in each kilogram of sediment were extracted from previous studies. Finally, based on the determined amounts of phosphorus and potassium in the eroded soil each year, as well as their market prices from agricultural jihad data, the replacement costs for these elements were calculated for each year.
Results and Discussion
The results of this study indicate that the InVEST model exhibited sufficient efficiency, with errors of 0.58% and 13.30% in reproducing observed sediment during the calibration and validation periods, respectively, and the model is applicable for this research. Additionally, rainfall analysis shows a decrease in precipitation from the beginning to the end of the period at the Efin and Moghilan stations, while an increase was noted at the Zohan station. The maximum NDVI index value remained relatively stable in most years due to the presence of jujube orchards relying on groundwater resources, though the minimum value varied. Moreover, the sediment output during the evaluation period ranged from 31,910 to 142,310 tons across different years. Ultimately, the replacement costs for phosphorus and potassium were estimated to be between 393.57 to 1,755.17 million rials and 2,890.42 to 12,887.02 million rials, respectively, with total costs ranging from 3,284.00 to 14,642.19 million rials over the statistical period. Given the approximate stability of land use throughout the statistical period, climate has a greater impact, with sediment increasing alongside precipitation. While the presence of jujube orchards, influenced by spring and qanat irrigation, shows a relatively stable NDVI maximum, degradation in pasture and barren land could exacerbate erosion due to its greater extent.
Conclusion
Soil erosion and the loss of nutrient resources in the long term have a significantly negative impact on the lives of local communities and soil-dependent organisms. In other words, the lack of nutrients not only reduces agricultural soil productivity but also leads to the destruction of biodiversity. Therefore, adequate attention to this issue can illuminate hidden aspects and provide a clear picture of the negative effects of erosion. As the study results indicate, erosion in the Efin watershed is influenced by rainfall, and sediment levels change with variations in rainfall shape and volume. In this context, the extensive and less-covered rangelands in the Efin watershed play a significant role in erosion and the increase of replacement costs. It is recommended that, considering the region’s dry and fragile climate, measures be taken to prevent surface soil degradation. Although rainfall is beyond human control and biological cover does not establish well due to the lack of precipitation, erosion can be prevented from intensifying and spreading by implementing biological-engineering projects and controlling the terrestrial factors affecting erosion.
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Article number: 4 |
| Keywords: Agricultural Productivity, Erosion, Nutrient Elements, Soil Economics, Soil Management |
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Type of Study: Research |
Subject:
Special
Received: 2026/05/3 | Revised: 2026/08/3 | Accepted: 2026/06/3 | Published: 2026/08/3 | ePublished: 2026/08/3
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Chezgi J, Chamani R, Memaryan H, Joloro H, Rashidi N. Determination of Sediment Retention Service Trends Using the InVEST Model and Compensation of Economic Losses Due to Soil Erosion with a Replacement Cost Approach in the Efin Watershed, South Khorasan. jwmseir 2026; 20 (72) : 4 URL: http://jwmsei.ir/article-1-1230-en.html
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