Geomorphological analysis of Tinto-B Vallis on Mars

This work analysis an 81 km long 1.85 km wide fluvial valley on Mars (at 2°55’ South and 111°53’ East) for the first time, located near to the so-called Palos carter and Tinto Vallis, called Tinto-B hereafter. The length of the valley is approximately 81 km, and the average width is ~1.85 km, depth ~250 m. The hypsometric curves were created in 5 different buffer sizes on the main valley and the biggest tributary valley. The tributary valley shows a youth stage in the geomorphological evolution opposite to the main valley, which shows a mature stage. The crater statistical analysis based age of the main valley (2.9 Ga) poorly correlates with the early wet period of the red planet, thus, formed somehow later than most Martian valleys. Using the model SIMWE (SIMulated Water Erosion), for the to identify the small-scaled tributary valley systems and the small-scaled erosional landforms showed area elevated drainage density. The highest density of the tributary sections is 29.02 km/km2 , and the average is 3.09 km/km2. Considering only the main valley 0.017 km/km2 would have been measured, suggesting dozen(s) early tributaries were heavily eroded.

Eventos Neocenozoicos de reorganização de rede de drenagem: um paleovale do Rio das Velhas (Minas Gerais, Brasil) em seu médio curso?

Resumo: O presente trabalho teve como objetivo apresentar e discutir indícios de processos de reorganização da rede de drenagem na média bacia do Rio das Velhas resultantes da reconfiguração de seu vale principal. Nesse sentido, diversos depósitos fluviais foram identificados, descritos e, alguns, datados por Luminescência Opticamente Estimulada (LOE). Os resultados sugerem que a descontextualização de um conjunto de depósitos fluviais em cotas superiores e topos de colinas e a existência de anomalias na organização da rede de drenagem nesse trecho seriam resultantes da mudança do traçado do canal principal do Rio das Velhas no Quaternário Superior. Palavras-chave: Níveis deposicionais fluviais; Luminescência Opticamente Estimulada; Evolução de rede hidrográfica. Abstract: Neocenozic events of drainage network reorganization: a paleovalley of the Velhas River (Minas Gerais, Brazil) in its middle course?This paper aimed to present and discuss clues of reorganization processes of the drainage network in the middle Velhas River catchment resulting from the reconfiguration of its main valley. In this sense, several fluvial deposits were identified, described and, some, dated by Optically Stimulated Luminescence (OSL). The results suggest that the decontextualization of a set of fluvial deposits in higher elevations and tops of hills, as well as the existence of anomalies in the organization of the drainage network in this stretch would results of the change of the main channel of the Velhas River during the Late Quaternary. Keywords: Fluvial depositional levels; Optically Stimulated Luminescence; Evolution of hydrographic network

Testing the SIMWE (SIMulate Water Erosion) model on a Martian valley system

<p>Surface erosion happened intensively of Mars in the Noachian, partly from precipitation and/or ice melting. However the exact method of erosion is poorly understood, despite various models are used for the Earth successfully. In this work we present the first test results of an erosion simulation GIS based system for Mars. The testing area is (2°55’ S, 111°53’ E) next to the Tinto Vallis,  was named after that Tinto-B. The main valley is ~ 81 km long, the average width is ~1.85 km, the average depth is ~ 250 m. From West there are several other but heavily eroded valleys, what join to the main valley. The used erosion-deposition model is SIMWE (SIMulated Water Erosion) (Mitasova et al, 2004) was applied to simulate the time limited erosion and deposition rate.</p><p>With the erosion-deposition simulation can also be used for targeting surface sampling missions beside reconstructing the ancient transport processes These ideal sampling locations might be barely visible on the DTMs or on the CTX, or HiRISE images - thus the modelling approach might help here also..</p><p>GRASS GIS 7.6 was used during the modeling starting from an elevation model and the x/y derivatives of the slope map. The script r.sim.water estimates the water depth and discharge from a simple rain event (mm/hr in min). For the erosion modelling r.sim.sediment script was used, what is the second part of the SIMWE model, what requires to calculate the detachment and transport coefficient and the shear stress of the analysed area.</p><p>The shear stress was determined az 1.0 as a default value, like the transport coefficient (value=0.01). The detachment  coefficient was calculated from the estimated K-factor of the analysed area and the calculated specific weight of water. The model use a 15mm/hr rain in 5 minutes long.</p><p>The results from the test area clearly show the main falls and debris skirts and also show the smaller erosion areas, what are not abundant on CTX and can’t be determined on the HRSC DTM. Using Earth based values as a first and rough approach, the transport limited erosion-deposition ranges from 0.0180 kg/ms<sup>2</sup> to -0.0166 kg/ms<sup>2</sup> where the positive values show the erosion and the negative values the deposition. Based on the experiences, we aim to develop further the model and adjust the physical parameters for more Mars relevant conditions. In the future we plan to running simulation, what show the possible landscape evolution in the past and in the future</p><p>Reference: Mitasova, H., Thaxton, C., Hofierka, J., Mclaughlin, R., Moore, A., & Mitas, L. (2004). Path sampling method for modeling overland water flow, sediment transport, and short term terrain evolution in Open Source GIS. Computational Methods in Water Resources: Volume 2, Proceedings of the XVth International Conference on Computational Methods in Water Resources Developments in Water Science, 1479-1490.</p>

Application of Electrical Resistivity Tomography Technique for Characterizing Leakage Problem in Abu Baara Earth Dam, Syria

Electrical Resistivity Tomography (ERT) survey was carried out at Abu Baara earth dam in northwestern Syria, in order to delineate potential pathways of leakage occurring through the subsurface structure close to the dam body. The survey was performed along two straight measuring profiles of 715 and 430 m length in up- and downstream sides of the dam’s embankment. The analysis of the inverted ERT sections revealed the presence of fractured and karstified limestone rocks which constitute the shallow bedrock of the dam reservoir. Several subsurface structural anomalies were identified within the fractured bedrock, most of which are associated with probable karstic cavities, voids, and discontinuity features developed within the carbonates rocks. Moreover, results also showed the occurrence of a distinguished subsiding structure coinciding with main valley course. Accordingly, it is believed that the bedrock and the other detected features are the main potential causes of water leakage from the dam’s reservoir.

Glacio-Periglacial Landforms within the Susquehanna Great Bend Area of New York and Pennsylvania

Previous attention has been called to the morphology of the glaciated Appalachian Plateau, including periglacial phenomena (Coates, 1970; Conners, 1969). This paper deals with an unusually well-developed hierarchy of small landforms in the Great Bend area of the Susquehanna River. Essential properties of these features include: (1) concentration in N-S valleys, (2) till composition, (3) concavo-convex form, sometimes ending in a hill on the valley floor, (4) alternation with steep, truncated bedrock spurs, (5) a col in the interfluve at their head. These characteristics could be explained by the following sequence of events. A prior fluvial landscape was eroded with tributary streams forming lateral valleys that head in cols along the divides. The main stream flowed south between interlocking spurs. Ice then widened the valley, leaving truncated spurs and a straightened stream. Deposition of locally derived till filled tributary valleys, similar to till shadows (Coates, 1966). In periglacial conditions, while nivation was widening the tributary valley heads, solifluction in the unstable till was forming the concavo-convexities that alternate with the truncated bedrock spurs. The hierarchy of forms range from minor convexities to small hills on the main valley floor. Thus, the features are primarily of periglacial origin, but owe their development and position to prior subaerial and glacial events. The cycle may have occurred during more than a single glacial episode. The recession of bedrock spurs and the valley floor convexity of the till features have caused a reversal in stream sinuosity of the main valley.