Open Basin Lakes:

Surface Water Inventories and Sources of Water

Open vs. Closed Basins

Lakes that were once hydrologically open (basins with outlets) allow:• Confident recognition of where

water ponded• Measurement of the minimum

volume of water required (to activate an outlet valley)

In basins without clearly incised outlets, we cannot be sure that water ponded.

Closed Basin

OpenBasin

Open Basin Locations

Parameters Measured

All lakes:• Connections to other lakes

(lake chains)• Elevation• Area, volume, perimeter• Morphological characteristics

(resurfacing? sedimentary deposits? )

Where possible:• Watershed Area

Lake Size

Eridania Basin

Ma’adim Vallis(to Gusev Crater)

V=213000 km3, WA=2080000 km2, V/Aw=102 m

Irwin et al., 2002 (Science)

Lake Volume / Watershed Area

Volume/Watershed Area = a measure of the water that was delivered to the lake per unit area of the watershed

If groundwater is negligible, this is the integrated precipitation amount over time (in excess of evaporation / infiltration) necessary to flood the basin. in meters

Eridania

Lake Volume / Watershed Area

Cassini CraterV=30000 km3

WA=155000 km2

V/Aw=200 m in meters

Cassini

in meters

Antoniadi CraterV=31000 km3

WA=555000 km2

V/Aw=56 m

Lake Volume / Watershed Area

Antoniadi

Many basins that remained closed have V/Aw ~20-30 m.

Lake Volume / Watershed Area

128.75E, 8.3SV=1700 km3

WA=61000 km2

V/Aw=28 m

88.25E, 3.25SV=400 km3

WA=17000 km2

V/Aw=23 m

Lake Volume / Watershed Area

1. Especially high local ‘excess’ precipitation (*unlikely*),

OR2. A regional (non-local!)

groundwater contribution to flooding the basin.

Given that closed basins had V/Aw ~20-30 m, open basins with high V/Aw either had to have:

in meters

Anomalies in V/Aw are:

i) larger lakes than is typicalii) generally at low elevationsiii) most are concentrated in “greater Arabia” (70%)

Symbol size proportional to V/Aw

Lake Volume / Watershed Area

Andrews-Hanna et al., 2008Modeled Evaporation Rate (10-4 m/yr): a

proxy for where groundwater reaches surface

• Broad regional agreement between where models expect groundwater to outcrop and where we observe it.

• Some differences (e.g., for largest lakes): Cassini & Eridania clearly resolved as net positive groundwater flux.

Antoniadi+Tikhonravov, not resolved in regional models, but seen in higher res. models

Andrews-Hanna et al., 2008

• Lake/Watershed properties & modeling suggest an important role for groundwater input to some lakes

• Lakes that are not anomalies in V/Aw have volume proportional to watershed area: consistent with local precipitation + local precipitation-recharged groundwater as water sources.

Water Source

Resurfacingof large lake floors

HesperiaPlanum MOLA Roughness

MOLA Roughness data Kreslavsky and Head, 2000

The rule, not the exception.

>50% of catalogued lakes mapped have textures & morphological indicators of post-lacustrine resurfacing.

Resurfacingof large lake floors

Goldspiel and Squyres (1991) recognized that

“in many instances, the sedimentation basin floors appear to be covered by volcanic extrusions...post-dat[ing] the period of fluvial activity.”

“Other features to note...[are] the signs of volcanic extrusions on the crater floor.”

The rule, not the exception.

>50% of catalogued lakes mapped have textures & morphological indicators of post-lacustrine resurfacing.