Hydraulic modeling of the tributary and the outlet of a Martian paleolake located in the Memnonia quadrangle

We present a steady state hydraulic model of the tributary and the outlet of a Martian paleolake located in the Memnonia quadrangle between 167°0'0''W and 167°30'0''W longitude and between 9°25'0''S and 9°45'0''S latitude. The Mars Express High-resolution stereo camera (HRSC) digital elevation model, H31850000DA4, with a spatial resolution of 75 m is used to describe the geometrical features of the hydraulic system. A steady state hydraulic model, through a Monte Carlo procedure, is adopted to investigate the assumption that the tributary-lake-outlet hydraulic system was acting simultaneously during its last water-related evolutionary phase. Through our analysis, we infer the roughness coefficient and the discharge of both the tributary and the outlet channels. Geomorphic evidence, such as river terraces, were used to constrain the water discharge and the Manning's roughness coefficient, thereby obtaining estimates of the water level in the lake, during the last evolutionary phase of the system. Our analysis of the outlet reveals a median paleodischarge of 7135 m3 s-1 and a median Manning's roughness coefficient of 0.067 m-1/3 s. Tributary analysis provides a median flow and a median roughness coefficient of 6405 m3 s -1 and 0.123 m-1/3 s, respectively. Moreover, the hydraulic analysis suggests that the paleolake water surface level was -1397 m (median value, HRSC elevation), which is consistent with the observed paleoshoreline. The results imply that the tributary, the lake, and the outlet were hydraulically synchronized, therefore confirming the presence of a connected water system. This study demonstrates that hydraulic analysis can provide valuable information regarding ancient Martian water fluxes.