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Posts tagged Orthorectification

The Kyzylsu River and Mountains of Southern Tajikistan

37.9N 69.7E

November 30th, 2009 Category: Rivers

Tajikistan - October 5th, 2009

Tajikistan - October 5th, 2009

Landlocked Tajikistan is the smallest nation in Central Asia by area. It is covered by mountains of the Pamir range, and more than fifty percent of the country is over 3,000 meters (approx. 10,000 ft) above sea level. This orthorectified image focuses on the mountains in the south near the city of Tulob (or Tulyab) and the border with Afghanistan.

Visible in the Kyzylsu Valley (left) is the Kyzylsu River, which rises on the southern slopes of the Vakhsh Range in the north-east of Tajikistan’s Khatlon Province and runs south-west for a length of 230 km until joining Panj River on the border with Afghanistan. Near Kulob it merges with the Yakhsu River as a major left tributary. The river irrigates the cotton-growing Kyzylsu Valley between Kulob and Panj in the south-east of Khatlon Province.

Santander and Mountains of the Cantabria Region, Spain

43.4N 3.8W

November 28th, 2009 Category: Snapshots

Spain - November 12th, 2009

Spain - November 12th, 2009

Cantabria is a Spanish historical region and autonomous community, bordered on the north by the Cantabrian Sea. Its capital city is Santander, visible at the top center of this orthorectified image along the shores of Santander Bay, the most prominent indentation in the coastline.

Cantabria is a mountainous and coastal region, with important natural resources. The coastal area is a strip of low, wide and gently rolling valleys some 10 kilometers in width, whose altitude does not rise above 500 meters, and which meets the ocean in a line of abrupt cliffs broken by river estuaries, creating rias and beaches.

To the south, the coastal strip rises to meet the Cantabrian mountains. This is a long barrier made up of abruptly rising mountains parallel to the sea. The ranges are mostly made of limestone with karst topography, and occupy most of Cantabria’s area. They form deep valleys oriented north-south. The torrential rivers are short, fast flowing and of great eroding power, so the slopes are steep.

The valleys define different natural regions, delimited physically by the intervening mountain ranges: Liébana, Saja-Nansa, Besaya, Pas-Pisueña, Miera, Asón-Gándara and Campoo. The Escudo Range, a mountain range of 600 to 1,000 metres high that covers 15 or 20 km in a parallel line to the coast in the west part of Cantabria.

Towards the south are higher mountains, whose crests mark the watershed between the drainage basins of the Rivers Ebro, Duero and those that flow into the Bay of Biscay. These peaks generally exceed 1,500 m from the Pass of San Glorio in the west to the Pass of Los Tornos in the eastern part: Peña Labra, Castro Valnera and the mountain passes of Sejos, El Escudo and La Sía. The great limestone masses of Picos de Europa also stand out in the southwest of the region: most of their summits exceed 2,500 m, and their topography is shaped by the former presence of glaciers.

Sandstone Buttes in Northern Arizona, USA

35.3N 110.3W

November 27th, 2009 Category: Snapshots

USA - November 15th, 2009

USA - November 15th, 2009

Clusters of high sandstone buttes characterize this part of the Colorado Plateau in Navajo County, in the state of Arizona, USA. The largest buttes in this orthorectified image reach 6400 feet above the valley floor.

A butte is a conspicuous isolated hill with steep, often vertical sides and a small, relatively flat top; it is smaller than mesas, plateaus, and tables. In some regions the word is used for any hill; however, in differentiating mesas and buttes, geographers use the rule that a mesa has a top wider than its height, while a butte’s top is narrower.

The buttes here are located in Navajo County, in the northern part of Arizona. The county contains parts of the Hopi Indian reservation, the Navajo Indian Reservation and Fort Apache Indian Reservation.

According to the U.S. Census Bureau, the county has a total area of 9,959 square miles (25,795 km²), of which, 9,953 square miles (25,779 km²) of it is land and 6 square miles (16 km²) of it (0.06%) is water.

Volcanoes Near Lake Taupo, New Zealand

38.7S 175.8E

November 27th, 2009 Category: Lakes, Rivers, Volcanoes

New Zealand - November 13th, 2009

New Zealand - November 13th, 2009

Several volcanoes are visible near Lake Taupo, the large lake at the upper right, in this orthorectified image of New Zealand’s North Island. Following the Tongariro River, one of the lake’s main tributaries, upstream from the lower end of the lake, one comes to a smaller lake known as Lake Rotoaira.

Between these two lakes is Mount Pihanga, a 1325m volcanic peak on the North Island Volcanic Plateau. Another smaller body of water, Lake Rotopounamu, is at the north-west foot of the mountain. Mt. Pihanga and Lake Rotopounamu are part of the 5,129ha Pihanga Scenic Reserve, which in 1975 was added to the Tongariro National Park.

South of Mount Pihanga is Mount Tongariro, a volcanic complex located 20 kilometres to the southwest of Lake Taupo. It is the northernmost of the three active volcanoes that dominate the landscape of the central North Island. This volcanic massif, often simply referred to as Tongariro, has a height of 1,978 metres.

The volcano consists of at least 12 cones; Ngauruhoe, while often regarded as a separate mountain, is geologically a vent of Tongariro. It is also the most active, having erupted more than 70 times since 1839.

Continuing south of Ngauruhoe is Mount Ruapehu, an active stratovolcano at the southern end of the Taupo Volcanic Zone. It is 23 kilometres northeast of Ohakune and 40 kilometres southwest of the southern shore of Lake Taupo, within Tongariro National Park.  Ruapehu is one of the world’s most active volcanoes and the largest active volcano in New Zealand. It is the highest point in the North Island and includes three major peaks: Tahurangi (2,797 m), Te Heuheu (2,755 m) and Paretetaitonga (2,751 m).

Volcanoes on Coastal Plain of El Salvador – November 26th, 2009

13.4N 88.1W

November 26th, 2009 Category: Image of the day, Volcanoes

El Salvador - November 14th, 2009

El Salvador - November 14th, 2009

Many volcanic peaks dot the landscape of central-eastern El Salvador, to the east of the Lempa River and north of Jiquilisco Bay, in this orthorectified image. To the east of these clusters of volcanoes is San Miguel, the fourth most populous city in El Salvador.

San Miguel is also the name of the stratovolcano located about 15km southwest of the city. The volcano, also known as Chaparrastique, is one of the most active volcanoes in the country.

North of the San Miguel volcano is Chinameca (also known as El Pacayal), a stratovolcano that rises over the town of Chinameca. The volcano is topped by a 2 km wide caldera known as Laguna Seca del Pacayal. A satellite cone on the west side, Cerro el Limbo, rises higher than the caldera rim. Fumaroles can be found on the north side, and it has been the site of a geothermal exploration program.

Continuing westward, the large stratovolcano Usulután can be identified as the peak on the coastal plain closest to the bay. The volcano is topped by a 1.3 km wide summit crater which is breached to the east.

West of Usulután is the Taburete stratovolcano. It is topped by a well-preserved, 150-300 m (500–1000 ft) deep summit crater, with the true summit on the south side of the crater rim.