# Integrated Hydrological Analysis of Little Akaki Watershed Using SWAT-MODFLOW, Ethiopia
## 4 Conclusions  
In the Little Akaki watershed, areal recharge was estimated using SWAT model. The SWAT model simulates average monthly and annual groundwater recharge at sub-basin scale for 21 sub-basins in the Little Akaki watershed. SWAT model is a good tool to estimate the spatial and timely variability of the recharge. Recharge in the watershed mostly occurs in the months of July to October with maximum values in August. On average, the estimated annual catchment recharge was 179 mm.  
In general, the groundwater recharge estimated was lower for sub-basins dominated by urban land covers. As the cities of Addis Ababa and other cities of the Oromia region in the area are located in a high rainfall area (potential recharge area), the expansion of the cities could significantly affect the recharge of the groundwater. This could be alarming for the sustainability of the increasing groundwater exploitation in the area as a result of a fresh water shortage.  
The groundwater recharge estimated was used as an input for the MODFLOW model simulation. The model simulations indicate that groundwater converges towards the outlet, near the Akaki well field. The groundwater contours indicated that the water table of the groundwater varies with the topography. The hydraulic conductivity value near the center of the watershed, below the Gefersa Lake, shows high level of sensitivity to the water table  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Estimated**} & \multicolumn{5}{c}{**Simulated Baseflow under Pumping and Recharge Change Scenarios**} \\ \hline \multirow{7}{*}{126,359} & \multirow{3}{*}{Pumping scenario} & \multicolumn{5}{c}{If pumping rate increased by:} \\ \cline{3-7}  & & +10\% & +25\% & +50\% & +100\% & +200\% \\  & Simulated BF (m\({}^{3}\)/day) & 124,728 & 122,281 & 117,692 & 108,433 & 92,728 \\  & Change from observed (\%) & \(-1.3\) & \(-3.23\) & \(-6.9\) & \(-14.2\) & \(-26.62\) \\ \cline{2-7}  & \multirow{3}{*}{Recharge scenario} & \multicolumn{5}{c}{If recharge value changes by:} \\ \cline{3-7}  & & +10\% & \(-10\%\) & +25\% & \(-25\%\) & +50\% & \(-50\%\) \\  & Simulated BF (m\({}^{3}\)/day) & 131,392 & 121,294 & 138,910 & 113,727 & 151,494 & 100,971 \\  & Change from observed (\%) & +4 & \(-4\) & +10 & \(-10\) & +20 & \(-20\) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Effect of pumping and recharge scenarios on baseflow from the watershed at Little Akaki.  
and the base flow simulation during calibration, indicating there could be significantly different geological feature in those areas. The study clearly indicated areas of interactions between the river and groundwater.  
The scenario examination result reveals a substantial risk of over-abstraction of the groundwater as a result of the increasing freshwater demand in the area. Increasing the present pumping rate by over fifty percent (50%, 100%, and 200%) will surely cause noticeable groundwater head decline near the outlet of the watershed, and substantial river baseflow reduction which is estimated from the aquifer outflow from the head-dependent boundary. The recharge reduction scenario also indicates the huge risk of groundwater sustainability in the area.  
All authors contributed in conceiving and designing of the approach and realizing this manuscript. [PERSON] prepared the input data and implemented the SWAT and MODFLOW models. [PERSON] and [PERSON] worked on the analysis of the results and contributed the presentation of the results. Both authors jointly wrote the paper and have approved the final manuscript. All authors have read and agreed to the published version of the manuscript.  
This research was supported by a grant from the Development Program of Minimizing of Climate Change Impact Technology funded through the National Research Foundation of Korea (NRF) of the Korean government (Ministry of Science and ICT, Grant No. NRF-2020M3H5A1080735) and the Korea Ministry of Environment (MOE) as a Demand Responsive Water Supply Service Program (146515).  
The authors declare no conflict of interest.