**4. Discussion**

The findings of this study showed that the overall unmet demand under the long-term development future scenario by 2050 was from 6 <sup>×</sup> 106 m3 to 35.9 <sup>×</sup> 106 m3 in August and May, respectively. Water deficiency was observed in the dry season, especially in May. All scenarios showed an increase of unmet demand throughout the simulation years. The water demand was fully satisfied under each scenario because of the priority given for water allocation for each demanding site. Water shortage is aggravated by the expansion of irrigation lands and this, in turn, resulted in the failure of production. The spatiotemporal unmet demand of each demand site under the current scenario is shown (Figure 8). The population in the Awash River Basin is projected to increase and put more pressure on the limited water resources of the basin. With this trend of water consumption, the basin could face more water deficiency in the future. Sustainable and integrated water resources management approaches in the basin may overcome the observed problems that could affect the water resources. This may be done by developing reservoirs to store more water for the dry, low-flow season and create awareness among the public to use the water efficiently and sustainably. Strategic exploitation of additional water supplies and a paradigm reformation of policy of the basin management, which encourages sustainable use of water resources of the basin, should be done to improve the water shortage.

**Figure 8.** Mean monthly unmet demands of the current scenario for each irrigation sites.

Decrease of streamflow at the main outlet of the Awash River Basin could cause high pressure on available water resources. Thus, all the basin sections are impacted by the risks and cause conflicts between upstream and downstream dwellers [31]. No measurement is taken by the concerned entity of the basin to enhance the streamflow of the basin. The Awash River Basin has the most suitable space for future development of irrigation and will likely face huge population increases and industrial expansion. This will cause increased water consumption and large waterwork capacity deficits for the basin. As a result, prioritizing building and expansion of more water supply lines or reservoirs should be considered. Normally, warmer and wetter scenarios of the Awash River Basin are expected to increase the river discharge substantially and could serve to alleviate current local water shortages. The results of this study are consistent with other findings, such as [27,30,34,35]. The WEAP model in this study could not model reservoir water quality and cannot account for stream attenuation. Therefore, this can be a future research work for researchers to model the reservoir water quality by developing appropriate hydrological models in the study basin.
