**2. Study area**

Located in the southern hemisphere (**Figure 1**), Ma'adim Vallis (21,98° S; 177,5° E in planetocentric coordinates) is a channel that ends at the Gusev Crater (14,44° S;

**Figure 1.** *Location of the study area.*

175,29° E also in planetocentric coordinates). In general terms, the length of the channel is about 700 km while its width can reach 20 km and its depth 2 km.

Several studies [15, 16] suggest that Ma'adin Vallis originated as a result of the overflow of a lake located in the Eridania basin. As a result of this event, Ma'adim Vallis has a peculiar topography (**Figure 2**) characterized by a network of channels of variable width (8–25 km), as well as a system consisting of step terraces and several inner channels that flow into the main one.

According to [15], Ma'adim Vallis enters Gusev crater through an opening in its southern edge, and a separate crevasse opens northwestward toward the northern lowlands, suggesting past flow into Gusev crater. It should be noted that the divides of Gusev crater and the Eridania basin are only partially incised, so volumetrically reduced central basins still exist. However, the northern divide of the intermediate basin was downcut to below its floor level, opening the basin completely for through-flowing drainage [16].

On the other hand, and considering the longitudinal profile of Ma'adim Vallis (**Figure 3**), it can be divided into three different areas. The first one, descends from the beginning (445 m high) to the first 324.48 km (796 m high) with an average slope of 0.38%. This is followed by a 0.17% slope area in 193,820 km, where the elevation difference is 332 m. The last part, with a slope of around 0.21%, has a length of 198.18 km, being the mouth towards the Gusev crater.

In relation to the above, it is necessary to specify that both at the beginning and at the end of the longitudinal profile considered in the present work, the width of the main channel is practically constant, being much greater in the central part, which corresponds to the area of less slope. This fact may be due to the fact that, logically, in the steepest areas, water erosion wears down the channel in depth, while in those with a lower slope value, the erosion occurs mainly in the width of the channel.

**Figure 2.** *Topography of Ma'adim Vallis.*

*Prediction of the Transported Soil Volume by the Presence of Water in the Vicinity… DOI: http://dx.doi.org/10.5772/intechopen.102985*

**Figure 3.** *Longitudinal profile of study area.*

As is evident, the causes of water erosion are varied (rainfall, continuous flow of water "river erosion", existence of tides and associated waves, or even occasional dripping on the ground), although the water erosion produced by subsurface runoff should not be forgotten.

Based on the characteristics of the study area, as well as those corresponding to areas of Earth with evidence of water erosion, it is clear that Ma'adim Vallis has been shaped by water.

Perhaps, this is one of the reasons why Ma'adim Vallis is one of the most important areas of Mars, which shows that in the past there was a predominant constant hydrological cycle on the planet, and therefore, more favorable conditions for the existence of life.
