Delimitação e caracterização morfométrica da bacia hidrográfica do Riacho do Navio, Pernambuco, a partir de dados SRTM processados no QGIS

A bacia hidrográfica do Riacho do Navio, em Pernambuco, tem importante papel ao atender as demandas hídricas de animais, culturas agrícolas e da população local, sendo fundamental estudá-la de maneira mais específica, a fim de que sejam geradas informações que subsidiem a gestão de seus recursos ambientais. O objetivo deste estudo foi delimitar a bacia hidrográfica do Riacho do Navio e descrever suas características morfométricas (forma, rede de drenagem e relevo) a partir de dados Shuttle Radar Topography Mission (SRTM) processados no programa livre Quantum GIS (QGIS), via a ferramenta Terrain Analysis Using Digital Elevation Models (TauDEM). A bacia em questão possui 3.312,97 km2, sendo considerada de quinta ordem, com densidade de drenagem de 0,50 km km-2. Observou-se que a declividade média foi de 5,23%, sendo que mais de 86,61% da área da bacia apresentou declividades menores que 8%. O fator de forma, o coeficiente de compacidade e o índice de circularidade atingiram valores de 0,29; 2,10 e 0,22, indicando que a bacia possui formato alongado e, por conseguinte, baixa tendência a enchentes. Por outro lado, a sinuosidade e a declividade média do álveo podem favorecer a ocorrência de cheias em situações de chuvas intensas. O uso do QGIS e do TauDEM para tratamento de imagens SRTM se mostrou uma ferramenta eficiente, podendo auxiliar na gestão e no gerenciamento dos recursos hídricos da bacia do Riacho do Navio. Delimitation and morphometric characterization of the hydrographic basin of Riacho do Navio, Pernambuco, based on SRTM data processed at QGIS A B S T R A C TThe Riacho do Navio watershed, in Pernambuco, has an important role in meeting the water demands of animals, agricultural crops and the local population, and it is essential to study it more specifically, in order to generate information that supports the management of its environmental resources. The objective of this study was to delimit the Riacho do Navio watershed and describe its morphometric characteristics (shape, drainage network and relief) from Shuttle Radar Topography Mission (SRTM) data, processed in the free program Quantum GIS (QGIS), via the Terrain Analysis Using Digital Elevation Models (TauDEM) tool. The watershed in question has 3,312.97 km2, being considered of fifth order, with drainage density of 0.50 km km-2. It was observed that the average slope was 5.23%, with more than 86.61% of the watershed area showing slopes less than 8%. The shape factor, the compactness coefficient and the circularity index reached values of 0.29; 2.10 and 0.22, indicating that the watersehd has an elongated shape and, therefore, low tendency to flooding. On the other hand, the sinuosity and the average slope of the riverbed can favor the occurrence of floods in situations of intense rains. The use of QGIS and TauDEM for the treatment of SRTM images proved to be an efficient tool, which can assist in the management and administration of water resources in the Riacho do Navio watershed.Keywords: physiographic analysis, Hydrology, digital elevation model, Semiarid, TauDEM.

Stagnation of the Pensilungpa glacier, western Himalaya, India: causes and implications

This study investigates stagnation conditions of the Pensilungpa glacier, western Himalaya. Multiple glacier parameters (length, area, debris extent and thickness, snowline altitude (SLA), velocity, downwasting and ice cliffs) were studied using field measurements (2016–18), high-resolution imagery from GoogleEarth (2013–17) and spaceborne Landsat, ASTER and SRTM data (1993–2017) to comprehend the glacier's current state. Results show a moderate decrease in length (6.62 ± 2.11 m a−1) and area (0.11 ± 0.03% a−1), a marked increase in SLA (~6 m a−1) and debris cover (2.86 ± 0.29% a−1) and a slowdown of ~50% during 1993–2016. Notable thinning of −0.88 ± 0.04 m a−1 was observed between 2000 and 2017 showing a similar trend as field measurements during 2016–17 (−0.88 m) and 2017–18 (−1.54 m). Further, results reveal a stagnation of the lower ablation zone (LAZ). Less mass supply and heterogeneous debris growth (6.67 ± 0.41% a−1) over the previous decade resulted in slowdown, margin insulation and slope-inversion, leading to stagnation. Stagnation of LAZ caused bulging in the dynamic upper ablation zone and favored the development of supraglacial ponds and ice cliffs. Ice cliffs have grown significantly (48% in number; 41% in area during 2013–17) and their back-wasting now dominates the ablation process.

An investigation approach of the volcanic geomorphology in the Călimani – Gurghiu – Harghita volcanic chain, Romania

<p><span><span>In poorly-exposed forest-covered volcanic areas, the main challenge in classical geological and geomorphological studies is the interpretations of landforms and volcanic structures. The usage of 3D models provides modern opportunities in visualization of volcanic landforms in volcanological studies in areas with dense vegetation cover</span></span><span><span>. </span></span></p><p><span><span>Geological mapping of the Neogene Călimani-Gurghiu-Harghita (CGH) volcanic chain is challenging due poor exposure of area. The Călimani-Gurghiu-Harghita volcanic chain exhibits ~10 My age range spanning from North (> 10 Ma) to South (< 0.03 Ma) linked to the evolution of the adjacent intra-mountain sedimentary basins (</span></span><span>Bilbor, Borsec, Gheorgheni, Upper Ciuc, Lower Ciuc, Brașov </span><span><span>and </span></span><span>Baraolt </span><span><span>basins</span></span><span>)</span><span><span>. The geomorphological analysis of the CGH volcanic chain is currently performed using SRTM data. However, the SRTM data are affected by the vegetation cover. Instead, we used a digital elevation models (DEM) built from topographic maps in combinations with volcanological field observations.</span></span></p><p><span>Our method uses a DEM 3D spatial view with overlay standard geological maps, shaded relief complemented with terrain analysis and landform recognition. Then, the study integrates field-based observations and geomorphological mapping results in a new general overview of the complex volcanic topography of the CGH volcanic chain. </span></p><p><span><span>Using </span></span><span><span>digital</span></span><span><span> elevation models (DEM) allows the general identification of volcanic facies distribution (proximal, medial and distal) belonging to </span></span><span><span>an individual</span></span><span><span> volcanic structures as well as the regional assemblages of the whole volcanic chain. DEM studies also permit to reconstruct the erosion level of volcanic edifices in conjunctions with field-based volcanological studies. This approach may also help identifying volcanological formations and various types of volcanic facies resulting from both construction and destructions of the edifices in poorly exposed areas.</span></span></p><p><span><span>By using this methodology a broad range of volcanic morphological features have been observed along the CGH volcanic range including the </span></span><span>Călimani</span><span><span> caldera morphology, features of the old and young debris avalanche deposits of various volcanic edifices and the youngest lava-dome morphology of </span></span><span>Ciomadul</span><span><span> volcano. Our DEM approach provides better results than those obtained by previous studies pointing out, for instance, that the volcanic edifices are highly to moderately eroded in the north and progressively better preserved toward the south. </span></span></p><p><span>Acknowledgements. The research was funded through CNCS – UEFISCDI, project number PN-III-P4-ID-PCCF-2016-4-0014, within PNCDI III.</span></p>

Maping of faults on territory of the North Sakhalin plain by remote sensing data

The article presents the results of the research of the fault zones of earth’s crust within the North Sakhalin plain using the lineament analysis of the SRTM model. The faults be identified in order to increase the information content of the maps of geological content. SRTM data was used as input. The analysis performed using the functionality of the LEFA software package. The use of SRTM data made it possible to assess disjunctive disorders in territory of the north of Sakhalin Island. The images of surface were analyzed using the binary-morphological erosion operation or using Canny mathematical algorithms with further digital processing by means of Hough Transform. The paper reveals the position of linear elements in different parts of the North Sakhalin plain. Excellent test of the quality of performed definitions was the results of earlier studies of the eastern part of the North Sakhalin Plain, which were carried out in connection with the development of hydrocarbon deposits and after the strong Neftegorsk earthquake. The data obtained served as the basis for drawing up a map of disjunctive disturbances of Sakhalin Island at scale of 1:500,000. Depending from scale, spatial resolution, and level of generalization of image, disjunctive disturbances of different lengths (transregional, regional, sub-regional, local) and ranks (1 rank from a few to hundred meters, 2 rank from a hundred meters to a kilometer, 3 rank from 1 km to 35 km, 4 rank from 35 to 100 km, 5 rank more than 100 km). The analysis of the SRTM model with the help of the LEFA toolkit allowed us to identify the zones where the earth’s crust fractures are located. The analysis of the SRTM model with the help of the LEFA toolkit allowed us to identify the zones where the earth’s crust fractures are located. As aresult of the analysis, the West Sakhalin, Central Sakhalin, Hokkaido-Sakhalin (Upper Piltun segment), Piltun, Garomai, Val-Langri, Gyrgylany-Daginsky, South Baikal, Udyl and many other faults of less than rank 2 were identified. The main results of the work will be useful in choosing places for the construction of economic and industrial facilities, as well as in the search and exploration of mineral deposits.

DENSITY ANALYSIS OF LINEAMENTS USING REMOTE SENSING DATA

Lineament analysis is an important structural and geological indicator for determining general and local tectonic trends and fracture zones in rocks, especially in mining zones. In this study we used optical and radar satellite data to analyze the density map of lineaments structure data for territory of Kashkadarya region - one of the main gas producing regions in Uzbekistan. The results show that according to Landsat 8 high density of lineaments is located near geology faults. During a detailed exploration, the density map according to SRTM data found that at an azimuth of 1800, 2250, 2700, and 3150 the density is much higher than at an azimuth of 00, 450, 900, and 1350. KEYWORDS: lineaments, optical and radar data, density map, hillshade, rose-diagram