The slope of the Bilate catchment was classified into five slope classes: very high slope, high slope, medium slope, low slope, and very low slope. The slope of the Bilate catchment fluctuates from 0° to 66° (Figure 3(c)). It is observed that the slope range (0°–3.4°) covered the largest land 2,133.2 km2 (37.9%) (Table 5). In hydrological research, slope is a significant topographic factor in controlling the flow of surface water (Tehrany et al. 2013). According to Zaharia et al. (2019), regions with slopes greater than 15° have less water accumulation. The obtained average slope causing flood in the catchment was 5.13°.
The slope factor of the Bilate catchment
| Slope (°) . | Area (km2) . | Area (%) . |
|---|---|---|
| 0–3.4 | 2,133.2 | 37.9 |
| 3.5–7.3 | 1,902.3 | 33.8 |
| 7.4–13 | 560.5 | 10 |
| 14–22 | 892.9 | 15.9 |
| 23–66 | 136.0 | 2.4 |
| Total | 5,625 | 100 |
| Slope (°) . | Area (km2) . | Area (%) . |
|---|---|---|
| 0–3.4 | 2,133.2 | 37.9 |
| 3.5–7.3 | 1,902.3 | 33.8 |
| 7.4–13 | 560.5 | 10 |
| 14–22 | 892.9 | 15.9 |
| 23–66 | 136.0 | 2.4 |
| Total | 5,625 | 100 |