Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province.
A popular way for describing the link between storm rainfall depth and direct runoff is the curve number (CN) method. It is a straightforward approach that has been extensively studied and widely adopted. However, there has been less focus on the impact of slope and the initial abstraction ratio, w...
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| Format: | Article |
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Sulaimani Polytechnic University
2024-06-01
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| Series: | Kurdistan Journal of Applied Research |
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| Online Access: | https://kjar.spu.edu.iq/index.php/kjar/article/view/927 |
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| author | Farhan Ahmad Abdulrahman Tarq Hama Karim |
| author_facet | Farhan Ahmad Abdulrahman Tarq Hama Karim |
| author_sort | Farhan Ahmad Abdulrahman |
| collection | DOAJ |
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A popular way for describing the link between storm rainfall depth and direct runoff is the curve number (CN) method. It is a straightforward approach that has been extensively studied and widely adopted. However, there has been less focus on the impact of slope and the initial abstraction ratio, which is a crucial factor for accurately estimating direct runoff when utilizing the soil conservation service- Curve Number (SCS-CN) method. The initial abstraction ratio is typically assumed to be 0.20, as initially proposed by the method's developers. In this study, we analyzed daily rainfall data from seventeen watersheds in different physiographic locations in the Kurdistan region of Iraq, recorded between 2022 and 2023. Our aim was to assess the effect of slope adjusted curve number and modified the initial abstraction ratio (0.1) on estimation of direct runoff. The results demonstrated that adjusting the CN for slope and using a modified initial abstraction ratio increased the estimated runoff compared to the original method (without adjustment for slope and initial abstraction ratio=0.2). Therefore, when applying the SCS-CN method, it is crucial to correct the CN for slope in steeper areas and consider the initial abstraction ratio rather than relying on the suggested value of 0.2. this study highlights the importance of considering local conditions and estimating the initial abstraction ratio based on specific watershed characteristics to enhance the accuracy of direct runoff estimation using the CN method.
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| format | Article |
| id | doaj-art-af050b8e92ca4a65bdb5ca9740e9bd19 |
| institution | Kabale University |
| issn | 2411-7684 2411-7706 |
| language | English |
| publishDate | 2024-06-01 |
| publisher | Sulaimani Polytechnic University |
| record_format | Article |
| series | Kurdistan Journal of Applied Research |
| spelling | doaj-art-af050b8e92ca4a65bdb5ca9740e9bd192025-02-09T20:59:33ZengSulaimani Polytechnic UniversityKurdistan Journal of Applied Research2411-76842411-77062024-06-019110.24017/science.2024.1.7Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province.Farhan Ahmad Abdulrahman0https://orcid.org/0000-0001-8946-2225Tarq Hama Karim1https://orcid.org/0000-0001-5743-4406Department of Soil and Water, College of Agricultural Engineering Sciences, Salahaddin University, Erbil, IraqDepartment of Survey and Geomatics Engineering, Faculty of Engineering, Tishk International University-Erbil, Erbil, Iraq A popular way for describing the link between storm rainfall depth and direct runoff is the curve number (CN) method. It is a straightforward approach that has been extensively studied and widely adopted. However, there has been less focus on the impact of slope and the initial abstraction ratio, which is a crucial factor for accurately estimating direct runoff when utilizing the soil conservation service- Curve Number (SCS-CN) method. The initial abstraction ratio is typically assumed to be 0.20, as initially proposed by the method's developers. In this study, we analyzed daily rainfall data from seventeen watersheds in different physiographic locations in the Kurdistan region of Iraq, recorded between 2022 and 2023. Our aim was to assess the effect of slope adjusted curve number and modified the initial abstraction ratio (0.1) on estimation of direct runoff. The results demonstrated that adjusting the CN for slope and using a modified initial abstraction ratio increased the estimated runoff compared to the original method (without adjustment for slope and initial abstraction ratio=0.2). Therefore, when applying the SCS-CN method, it is crucial to correct the CN for slope in steeper areas and consider the initial abstraction ratio rather than relying on the suggested value of 0.2. this study highlights the importance of considering local conditions and estimating the initial abstraction ratio based on specific watershed characteristics to enhance the accuracy of direct runoff estimation using the CN method. https://kjar.spu.edu.iq/index.php/kjar/article/view/927Runoff estimationSCS-CN methodSlope adjusted CNInitial abstraction ratioSulaimani watersheds |
| spellingShingle | Farhan Ahmad Abdulrahman Tarq Hama Karim Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province. Kurdistan Journal of Applied Research Runoff estimation SCS-CN method Slope adjusted CN Initial abstraction ratio Sulaimani watersheds |
| title | Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province. |
| title_full | Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province. |
| title_fullStr | Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province. |
| title_full_unstemmed | Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province. |
| title_short | Assessing the Impact of Modified Initial Abstraction Ratios and Slope Adjusted Curve Number on Runoff Prediction in the Watersheds of Sulaimani Province. |
| title_sort | assessing the impact of modified initial abstraction ratios and slope adjusted curve number on runoff prediction in the watersheds of sulaimani province |
| topic | Runoff estimation SCS-CN method Slope adjusted CN Initial abstraction ratio Sulaimani watersheds |
| url | https://kjar.spu.edu.iq/index.php/kjar/article/view/927 |
| work_keys_str_mv | AT farhanahmadabdulrahman assessingtheimpactofmodifiedinitialabstractionratiosandslopeadjustedcurvenumberonrunoffpredictioninthewatershedsofsulaimaniprovince AT tarqhamakarim assessingtheimpactofmodifiedinitialabstractionratiosandslopeadjustedcurvenumberonrunoffpredictioninthewatershedsofsulaimaniprovince |