An-Najah University Journal for Research - A (Natural Sciences)

Article info

Keywords

• Palestine.
• Catchment;
• Al-Badan
• unit
• direct
• Ungauged
• hydrograph;
• sub-catchment;
• Synthetic
• runoff

Abstract

Developing unit hydrographs is critical in gauged catchments. Due to the lack of local data, engineers should strive to estimate discharges based on empirical (synthetic) methods in ungauged catchments. Synthetic unit hydrograph methods, such as the Snyder and Soil Conservation Service are popular and play an essential role in hydrology. These methods are simple, requiring only catchment characteristics. Therefore, these methods are valuable tools for simulating runoff in ungauged catchments. This research paper focuses on the Al-Badan sub-catchment, which is located in the northeastern part of the West Bank in Palestine with an area of 83 km2. The study used a de-convolution matrix approach to develop an average one-hour unit hydrograph by selecting four significant rainfall events in the period (2005-2007), and the direct runoff hydrographs which are measured by Al-Badan flume located in the outlet of the sub-catchment. By computing the characteristics of the average one-hour UH with a peak discharge of 4.52 m3/sec and time to peak of 5 hours, Snyder and SCS UHs were developed to suit Al-Badan sub-catchment physical characteristics. The parameters were determined for the Snyder; peaking coefficient depends on the storage capacity of the catchment Cp = 0.88 and the non-dimensional regional coefficient representing catchment storage effects and slope Ct = 1.26 and for the SCS; Cp = 1.90 and the coefficient depending on the total runoff volume occur before peak discharge C = 2.92. These synthetic one-hour UHs were examined for two selected rainfall events that occurred in the period (2017–2019) by comparing observed and simulated direct runoff hydrographs. The performance was tested statistically. Results showed that the synthetic UHs are suitable for application and that the SCS method is more applicable.

معلومات المقال

الكلمات الإفتتاحية

• Palestine.
• Catchment;
• Al-Badan
• unit
• direct
• Ungauged
• hydrograph;
• sub-catchment;
• Synthetic
• runoff

الملخص

Developing unit hydrographs is critical in gauged catchments. Due to the lack of local data, engineers should strive to estimate discharges based on empirical (synthetic) methods in ungauged catchments. Synthetic unit hydrograph methods, such as the Snyder and Soil Conservation Service are popular and play an essential role in hydrology. These methods are simple, requiring only catchment characteristics. Therefore, these methods are valuable tools for simulating runoff in ungauged catchments. This research paper focuses on the Al-Badan sub-catchment, which is located in the northeastern part of the West Bank in Palestine with an area of 83 km2. The study used a de-convolution matrix approach to develop an average one-hour unit hydrograph by selecting four significant rainfall events in the period (2005-2007), and the direct runoff hydrographs which are measured by Al-Badan flume located in the outlet of the sub-catchment. By computing the characteristics of the average one-hour UH with a peak discharge of 4.52 m3/sec and time to peak of 5 hours, Snyder and SCS UHs were developed to suit Al-Badan sub-catchment physical characteristics. The parameters were determined for the Snyder; peaking coefficient depends on the storage capacity of the catchment Cp = 0.88 and the non-dimensional regional coefficient representing catchment storage effects and slope Ct = 1.26 and for the SCS; Cp = 1.90 and the coefficient depending on the total runoff volume occur before peak discharge C = 2.92. These synthetic one-hour UHs were examined for two selected rainfall events that occurred in the period (2017–2019) by comparing observed and simulated direct runoff hydrographs. The performance was tested statistically. Results showed that the synthetic UHs are suitable for application and that the SCS method is more applicable.