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92-549: Middle Rio Grande may refer to: Middle Rio Grande Basin , a hydrological basin in central New Mexico Middle Rio Grande Valley , the valley created by the river as it traverses the basin Middle Rio Grande Conservancy District , which manages irrigation and flood control in the Albuquerque basin of central New Mexico Middle Rio Grande Development Council ,

184-461: A structural high running in a northwest direction. There is a west-tilting area in the southwestern margin of the basin, but it is just 15 to 30 kilometres (9.3 to 18.6 mi) wide. There were volcanic eruptions throughout the period while the Santa Fe Group sediments were being deposited, and these continued into the late Pleistocene . Most of the resulting basalt and andesite rock is on

276-562: A confined channel and is free to spread out and infiltrate the surface. This reduces the carrying capacity of the flow and results in deposition of sediments. The flow can take the form of infrequent debris flows or one or more ephemeral or perennial streams. Alluvial fans are common in the geologic record , such as in the Triassic basins of eastern North America and the New Red Sandstone of south Devon . Such fan deposits likely contain

368-558: A debris flow can come to a halt while still on moderately tilted ground. The flow then becomes consolidated under its own weight. Debris flow fans occur in all climates but are more common where the source rock is mudstone or matrix-rich saprolite rather than coarser, more permeable regolith . The abundance of fine-grained sediments encourages the initial hillslope failure and subsequent cohesive flow of debris. Saturation of clay-rich colluvium by locally intense thunderstorms initiates slope failure. The resulting debris flow travels down

460-563: A given year or place in the basin is unpredictable. Droughts lasting several years are not unusual. Throughout the basin, potential evapotranspiration is much higher than rainfall, meaning the ground is dry most of the time unless it is irrigated. Vegetation includes desert scrub and grassland in the lower levels, riparian woodland (bosque) along the Rio Grande, and woods on the mountain slopes. The Rio Grande, which flows from southwestern Colorado for 2,000 kilometres (1,200 mi) before entering

552-508: A hiatus of 70,000 to 80,000 years between the old and new fans, with evidence of tectonic tilting at 45,000 years ago and an end to fan deposition 20,000 years ago. Both the hiatus and the more recent end to fan deposition are thought to be connected to periods of enhanced southwest monsoon precipitation. Climate has also influenced fan formation in Death Valley , California , US, where dating of beds suggests that peaks of fan deposition during

644-506: A huge aquifer that would take centuries to exhaust. In the late 1980s there were declines in the water levels near Coronado Center causing concern that the water resource was not properly understood. Since 1992 the New Mexico Bureau of Geology and Mineral Resources has been undertaking extensive investigations of the geology of the basin and the aquifer. The groundwater has been deposited in three main phases. The lower Santa Fe group

736-652: A lag of gravel deposits that have the appearance of a network of braided streams. Where the flow is more continuous, as with spring snow melt, incised-channel flow in channels 1–4 meters (3–10 ft) high takes place in a network of braided streams. Such alluvial fans tend to have a shallower slope but can become enormous. The Kosi and other fans along the Himalaya mountain front in the Indo-Gangetic plain are examples of gigantic stream-flow-dominated alluvial fans, sometimes described as megafans . Here, continued movement on

828-497: A large proportion of non-native species including Siberian elm , Russian olive , saltcedar , mulberries , Ailanthus , and ravenna grass . Some restoration to native species is occurring, similar to the limited species of Populus and Salix used in the 1930s. One prominent species of native mountainous trees is the piñon pine . At the east end of the city, the Sandia foothills receive about 50 percent more precipitation than most of

920-443: A million people were rendered homeless, about a thousand lost their lives and thousands of hectares of crops were destroyed. Buried alluvial fans are sometimes found at the margins of petroleum basins. Debris flow fans make poor petroleum reservoirs, but fluvial fans are potentially significant reservoirs. Though fluvial fans are typically of poorer quality than reservoirs closer to the basin center, due to their complex structure,

1012-495: A minimum, major structural flood control measures are required to mitigate risk, and in some cases, the only alternative is to restrict development on the fan surface. Such measures can be politically controversial, particularly since the hazard is not obvious to property owners. In the United States, areas at risk of alluvial fan flooding are marked as Zone AO on flood insurance rate maps . Alluvial fan flooding commonly takes

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1104-409: A part of the fan with a steeper gradient, where deposition resumes. As a result, normally only part of the fan is active at any particular time, and the bypassed areas may undergo soil formation or erosion. Alluvial fans can be dominated by debris flows ( debris flow fans ) or stream flow ( fluvial fans ). Which kind of fan is formed is controlled by climate, tectonics , and the type of bedrock in

1196-621: A six-month moratorium on further exploration. Alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment . They are characteristic of mountainous terrain in arid to semiarid climates , but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation . They range in area from less than 1 square kilometer (0.4 sq mi) to almost 20,000 square kilometers (7,700 sq mi). Alluvial fans typically form where flow emerges from

1288-510: A steady decline in irrigation due to "droughts, sedimentation , aggradation of the main channel, salinization , seepage and waterlogging". The acequia running through the city of Albuquerque, parallel to the river, became an unsanitary drainage ditch, serving as a common sewer. In 1925 the Middle Rio Grande Conservancy District (MRGCD) was formed. It built a levee to reduce the impact of Rio Grande floods, drained

1380-473: A streamflow-dominated alluvial fan shows nearly the same depositional facies as ordinary fluvial environments, so that identification of ancient alluvial fans must be based on radial paleomorphology in a piedmont setting. Alluvial fans are characteristic of mountainous terrain in arid to semiarid climates , but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation. They have also been found on other bodies of

1472-543: A voluntary association of cities, counties and special districts in southern Texas Middle Rio Grande Project , a set of irrigation, flood control and water conservation facilities in central New Mexico Middle Rio Grande Valley AVA , an American Viticultural Area located in the watershed of the Rio Grande in central New Mexico The middle of the Rio Grande Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with

1564-419: A water content between 40 and 80 weight percent. Floods may transition to hyperconcentrated flows as they entrain sediments, while debris flows may become hyperconcentrated flows if they are diluted by water. Because flooding on alluvial fans carries large quantities of sediment, channels can rapidly become blocked, creating great uncertainty about flow paths that magnifies the dangers. Alluvial fan flooding in

1656-525: Is an accumulation of sediments that fans out from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment . This accumulation is shaped like a section of a shallow cone , with its apex at the source of sediments. Alluvial fans vary greatly in size, from only a few meters across at the base to as much as 150 kilometers across, with a slope of 1.5 to 25 degrees. Some giant alluvial fans have areas of almost 20,000 square kilometres (7,700 sq mi). The slope measured from

1748-438: Is approximately in equilibrium with erosion, so the river annually carries some 100 million cubic meters (3.5 × 10 ^  cu ft) of sediment as it exits the mountains. Deposition of this magnitude over millions of years is more than sufficient to account for the megafan. In North America , streams flowing into California's Central Valley have deposited smaller but still extensive alluvial fans, such as that of

1840-401: Is composed of deposits from the ancestral Rio Grande and the size of its annual recharge follows fluctuations in weather and climate phenomena. There may be natural gas in the basin, but opponents of gas extraction fear the impact on the groundwater and on the quality of life. The Albuquerque Basin covers 8,000 square kilometres (3,100 sq mi) of New Mexico . The basin is bounded by

1932-432: Is described as fanglomerate . Stream flow deposits tend to be sheetlike, better sorted than debris flow deposits, and sometimes show well-developed sedimentary structures such as cross-bedding. These are more prevalent in the medial and distal fan. In the distal fan, where channels are very shallow and braided, stream flow deposits consist of sandy interbeds with planar and trough slanted stratification. The medial fan of

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2024-548: Is dominated by grassland species such as fluffgrass ( Erioneuron pulchellum ), purple threeawn ( Hilaria mutica or Pleuraphis mutica ), bush muhly ( Muhlenbergia porteri ), and black grama ( Bouteloua eriopoda ). Some woody plants occur in overall grassy areas, mainly fourwing saltbush ( Atriplex canescens ) and snakeweed ( Gutierrezia microcephala ). Isolated stands of creosote bush ( Larrea tridentata ) were reported by long-time residents on gravelly, desert pavement soils existing above arroyos and warm breaks, prior to urbanization in

2116-553: Is located adjacent to low-relief terrain. In Nepal , the Koshi River has built a megafan covering some 15,000 km (5,800 sq mi) below its exit from Himalayan foothills onto the nearly level plains where the river traverses into India before joining the Ganges . Along the upper Koshi tributaries, tectonic forces elevate the Himalayas several millimeters annually. Uplift

2208-438: Is most likely composed of round grains of water ice or solid organic compounds about two centimeters in diameter. Alluvial fans are the most important groundwater reservoirs in many regions. Many urban, industrial, and agricultural areas are located on alluvial fans, including the conurbations of Los Angeles, California ; Salt Lake City, Utah ; and Denver, Colorado , in the western United States, and in many other parts of

2300-558: Is one of the oldest of the irrigation systems in North America. The Spanish arrived in Santa Fe de Nuevo México in the 16th-17th centuries, and steadily expanded their presence, Albuquerque was founded as a trading and military outpost in 1706. The Hispanos of New Mexico used them as the backbone of the Pueblo and Hispano acequia (shared irrigation ditch) into which water was diverted from

2392-663: Is present in the Albuquerque Basin." In 2007-2008 the Houston-based Tecton Energy had obtained the mineral rights to about 50,000 acres (20,000 ha) owned by SunCal, and had been exploring for natural gas on the Southwest Mesa. About 46 test wells had been drilled in the basin. Plans to exploit gas were opposed by activists concerned about damage to groundwater and to the environment if exploitation were allowed. In January 2008 Governor Bill Richardson imposed

2484-420: Is the greater roadrunner . Other birds include the common raven, American crow, great-tailed grackle, Gambel's and scaled quail, several species of hummingbirds, house finch, pigeon, mourning dove, white wing and European collared doves (both recent appearances), curve-billed thrasher, pinyon jay, and Cooper's, Swainson's, and red-tail hawks. The valley hosts sandhill cranes each winter. Within city limits,

2576-554: Is the largest and oldest of the three major basins in the Rio Grande rift. The depth of the sediments filling the basin typically ranges from 4,407 to 6,592 meters (14,459 to 21,627 ft). These sediments, assigned to the Santa Fe Group , accumulated in the basin between the middle Miocene and early Pliocene , from fifteen to one million years ago. Alluvial sediment came from the adjacent highlands and fluvial sediments came from southern Colorado and northern New Mexico. During

2668-604: The Apennine Mountains of Italy have resulted in repeated loss of life. A flood on 1 October 1581 at Piedimonte Matese resulted in the loss of 400 lives. Loss of life from alluvial fan floods continued into the 19th century, and the hazard of alluvial fan flooding remains a concern in Italy. On January 1, 1934, record rainfall in a recently burned area of the San Gabriel Mountains , California , caused severe flooding of

2760-577: The Jemez River and Rio Puerco from the west, and the Santa Fe River and Galisteo Creek from the east. In 1848 Mexico ceded the territory to the United States. Railways arrived in 1880, bringing Anglo settlers. The federal government encouraged more irrigation, which probably peaked in the early 1890s. The newcomers developed the vineyards, orchards and vegetable farms, and by 1900 were exporting produce as far as California. Over-exploitation caused

2852-712: The Kings River flowing out of the Sierra Nevada . Like the Himalayan megafans, these are streamflow-dominated fans. Alluvial fans are also found on Mars . Unlike alluvial fans on Earth, those on Mars are rarely associated with tectonic processes, but are much more common on crater rims. The crater rim alluvial fans appear to have been deposited by sheetflow rather than debris flows. Three alluvial fans have been found in Saheki Crater . These fans confirmed past fluvial flow on

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2944-509: The Main Boundary Thrust over the last ten million years has focused the drainage of 750 kilometres (470 miles) of mountain frontage into just three enormous fans. Alluvial fans are common in the geologic record, but may have been particularly important before the evolution of land plants in the mid-Paleozoic. They are characteristic of fault-bounded basins and can be 5,000 meters (16,000 ft) or thicker due to tectonic subsidence of

3036-643: The Sandia and Manzano mountains on the east, the Jemez Mountains to the north, the Rio Puerco on the west and the Socorro Basin to the south. It is 160 kilometres (99 mi) north-south and 86 kilometres (53 mi) east-west at its widest point. The Rio Grande, at an elevation of 1,420 metres (4,660 ft) runs through the basin from north to south. To the east, alluvial fans and stream terraces descend to

3128-667: The Solar System . Alluvial fans are built in response to erosion induced by tectonic uplift . The upwards coarsening of the beds making up the fan reflects cycles of erosion in the highlands that feed sediments to the fan. However, climate and changes in base level may be as important as tectonic uplift. For example, alluvial fans in the Himalayas show older fans entrenched and overlain by younger fans. The younger fans, in turn, are cut by deep incised valleys showing two terrace levels. Dating via optically stimulated luminescence suggests

3220-678: The Valles Marineris canyon system. These provide evidence of the existence and nature of faulting in this region of Mars. Alluvial fans have been observed by the Cassini-Huygens mission on Titan using the Cassini orbiter's synthetic aperture radar instrument. These fans are more common in the drier mid-latitudes at the end of methane/ethane rivers where it is thought that frequent wetting and drying occur due to precipitation, much like arid fans on Earth. Radar imaging suggests that fan material

3312-405: The coyote , rock squirrel , Gunnison's prairie dog , desert cottontail , and black-tailed jackrabbit . Striped skunks, raccoons, and several mouse species can be found in the city, and mule deer and woodrats occur in the foothills. The broader area is home to bobcat, black bear, and mountain lion, and is at the north end of the range of the ringtail and javelina . Larger arthropods include

3404-469: The plains cicada , vinegaroon , desert centipede , white-lined sphynx (hummingbird moth), two-tailed swallowtail , fig beetle , New Mexico mantis , and harvester ant . Settlements in the region depend on groundwater. In the 1960s the City of Albuquerque began to extract large quantities of potable groundwater from wells drilled in the southeast and northeast heights. It was thought that this water came from

3496-620: The southwestern fence lizard and New Mexico whiptail ( Aspidoscelis neomexicanus ) are common. Snakes include the New Mexico garter snake and the bullsnake in the Rio Grande Bosque , and at the edges of the city, the venomous Western diamondback rattlesnake . Woodhouse toads and non-native bullfrogs are common around the Rio Grande. Retention ponds within the city often serve as breeding pools for New Mexico spadefoot toads and tadpole shrimp ("Triops"). Commonly seen mammals include

3588-483: The 1930s and upstream dams stifling the river's annual flood. New Mexico olive ( Forestiera pubescens var. neomexicana ) and Torrey wolfberry are common native understory shrubs. Discontinuous, small stands of , Arizona walnut ( Juglans major ), and velvet ash ( Fraxinus velutina ) occasionally occur. Screwbean mesquite ( Prosopis pubescens) can be found further south in the Albuquerque basin, but may be extirpated in its former range near Albuquerque. The forest now has

3680-452: The Albuquerque Basin is a half-graben that slopes down towards the east to terminate on the Sandia and Manzano mountains. The basin is the largest and oldest of the three major basins in the Rio Grande rift, containing sediments whose depth ranges from 4,407 to 6,592 meters (14,459 to 21,627 ft). The basin has a semi-arid climate, with large areas that count as semi-desert. Paleo-Indian traces dating back 12,000 years show that

3772-524: The Gulf of Mexico, was classified in 1993 as one of North America's most endangered or imperiled rivers. The Rio Grande flows south into the Albuquerque Basin between the Sandia and Jemez mountains. The Pueblo people of the Rio Grande Valley had developed irrigation systems by the 10th century AD, and by the 13th century most of the major pueblos had been established. The Pueblo system of irrigation ditches

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3864-578: The Middle to Late Miocene era the Albuquerque and Espanola basins formed one basin, an irregular half-graben tilting west, formed by high-angle faulting on reactivated structures from the Laramide orogeny . The Embudo-Pajarito-La Bajada-San Francisco-Rincon fault system became active at the end of the Miocene. When this happened, the Albuquerque basin reversed its half-graben tilt from west to east, and now slopes down to

3956-642: The Northeast Quadrant of Albuquerque. Today only remnants of creosote bush scrub remain in similar soils in foothill areas of Kirtland Air Force Base according to "Biologic Surveys for the Sandia National Laboratories Coyote Canyon Test Complex – Kirtland Air Force Base Albuquerque, New Mexico (Marron and Associates, Inc., May 1994)", then southward along sections of the western Manzano Foothills in Valencia County. In

4048-620: The Rio Grande. Some of the sites date back 12,000 years from the present. During the period of Paleo-Indian occupation the playas (dry lake basins) contained wetlands with more vegetation than in today's dry conditions. Remains of the Folsom people include flaked stone tools, pottery sherds and the bones of bison. Modern communities in the hydrological basin include, from north to south, Cochiti , Santo Domingo , San Felipe , Algodones , Bernalillo , Rio Rancho , Albuquerque , Isleta , Los Lunas , Belen and Bernardo . The Albuquerque basin

4140-509: The Tertiary deposits, but found numerous shows of oil and gas. After 1953 most of the wells were deeper, probing the Cretaceous deposits below the Tertiary fill. Royal Dutch Shell and other companies drilled wells in the 1970s and 1980s, mostly from 11,000 to 14,000 feet (3,400 to 4,300 m) deep. They found gas in the Cretaceous rocks, but not in commercial quantities. Exploration was halted in

4232-596: The alluvial fan on which the towns of Montrose and Glendale were built. The floods caused significant loss of life and property. The Koshi River in India has built up a megafan where it exits the Himalayas onto the Ganges plain . The river has a history of frequently and capriciously changing its course, so that it has been called the Sorrow of Bihar for contributing disproportionately to India's death tolls in flooding. These exceed those of all countries except Bangladesh . Over

4324-409: The apex is generally concave, with the steepest slope near the apex (the proximal fan or fanhead ) and becoming less steep further out (the medial fan or midfan ) and shallowing at the edges of the fan (the distal fan or outer fan ). Sieve deposits , which are lobes of coarse gravel, may be present on the proximal fan. The sediments in an alluvial fan are usually coarse and poorly sorted, with

4416-431: The area feeding the flow onto the fan. Debris flow fans receive most of their sediments in the form of debris flows. Debris flows are slurry-like mixtures of water and particles of all sizes, from clay to boulders, that resemble wet concrete . They are characterized by having a yield strength, meaning that they are highly viscous at low flow velocities but become less viscous as the flow velocity increases. This means that

4508-429: The base of the newly formed Sandia Mountains . The northern part of the Albuquerque Basin was left with the appearance of a symmetrical basin, and is sometimes regarded as a separate geologic basin ( Santo Domingo basin ). A model of the basin based on seismic reflection data gathered by the oil industry was published in the early 1990s. In this model, the northern part of the basin was an east-tilted half graben, while

4600-728: The basin and uplift of the mountain front. Most are red from hematite produced by diagenetic alteration of iron-rich minerals in a shallow, oxidizing environment. Examples of paleofans include the Triassic basins of eastern North America and the New Red Sandstone of south Devon, the Devonian Hornelen Basin of Norway, and the Devonian- Carboniferous in the Gaspé Peninsula of Canada. Such fan deposit likely contain

4692-478: The bottom. Multiple braided streams are usually present and active during water flows. Phreatophytes (plants with long tap roots capable of reaching a deep water table ) are sometimes found in sinuous lines radiating from arid climate fan toes. These fan-toe phreatophyte strips trace buried channels of coarse sediments from the fan that have interfingered with impermeable playa sediments. Alluvial fans also develop in wetter climates when high-relief terrain

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4784-781: The city, and with granitic, coarse soils, rock outcrops, and boulders dominant, they have a greater and different diversity of flora in the form of savanna and chaparral, dominated by lower and middle zones of New Mexico Mountains vegetation, with a slight orientation at lower elevations. Dominant plants include shrub or piñon pine, desert live oak ( Quercus turbinella ), gray oak ( Quercus grisea ), hairy mountain mahogany ( Cercocarpus breviflorus ), oneseed juniper ( Juniperus monosperma ), piñon ( Pinus edulis ), threeleaf sumac ( Rhus trilobata ), Engelmann prickly pear ( Opuntia engelmannii ), juniper prickly pear ( Opuntia hystricina var. juniperiana ), and beargrass ( Nolina greenei , formerly considered Nolina texana ). Similar grasses occur that are native to

4876-449: The climate used to be wetter and more fertile than it is today. The Rio Grande flows through the basin from north to south, and its valley has been irrigated for at least 1,000 years. Intense irrigation began in the late nineteenth century with new dams, levees and ditches which has caused environmental problems. In times of low water levels in the Rio Grande, Albuquerque relies on groundwater for its potable water supply. The aquifer

4968-423: The coarsest sediments found on the proximal fan. When there is enough space in the alluvial plain for all of the sediment deposits to fan out without contacting other valley walls or rivers, an unconfined alluvial fan develops. Unconfined alluvial fans allow sediments to naturally fan out, and the shape of the fan is not influenced by other topological features. When the alluvial plain is more restricted, so that

5060-531: The eastern boundary of the basin. Finally, the modern Rio Grande cut down into the Santa Fe group sediments to create the present river valley. In the last 10,000 to 15,000 years the river valley has been receiving more sediment than it can carry away, building as much as 61 metres (200 ft) of new fill. There is groundwater in this new fill, which forms a thin aquifer very close to the surface and therefore very susceptible to contamination. Extraction of water from

5152-486: The eastern half of the city, but often of a higher density owing to increased precipitation. The foothills of Albuquerque are much less urbanized, the vegetation altered or removed than anywhere else in the city, though the lower areas have been mostly developed in a more dense suburban pattern in mostly developed communities including North Albuquerque Acres, Tanoan, High Desert, Glenwood Hills, Embudo Hills, Supper Rock, and Four Hills. An iconic bird often seen in Albuquerque

5244-420: The fan comes into contact with topographic barriers, a confined fan is formed. Wave or channel erosion of the edge of the fan ( lateral erosion ) sometimes produces a "toe-trimmed" fan, in which the edge of the fan is marked by a small escarpment. Toe-trimmed fans may record climate changes or tectonic processes, and the process of lateral erosion may enhance the aquifer or petroleum reservoir potential of

5336-400: The fan. Toe-trimmed fans on the planet Mars provide evidence of past river systems. When numerous rivers and streams exit a mountain front onto a plain, the fans can combine to form a continuous apron. This is referred to as a bajada or piedmont alluvial plain . Alluvial fans usually form where a confined feeder channel exits a mountain front or a glacier margin. As the flow exits

5428-745: The fan: Finer sediments are deposited at the edge of the fan, but as the fan continues to grow, increasingly coarse sediments are deposited on top of the earlier, less coarse sediments. However, a few fans show normal grading indicating inactivity or even fan retreat, so that increasingly fine sediments are deposited on earlier coarser sediments. Normal or reverse grading sequences can be hundreds to thousands of meters in thickness. Depositional facies that have been reported for alluvial fans include debris flows, sheet floods and upper regime stream floods, sieve deposits, and braided stream flows, each leaving their own characteristic sediment deposits that can be identified by geologists. Debris flow deposits are common in

5520-516: The feeder channel and onto the surface of the fan. Debris flow fans have a network of mostly inactive distributary channels in the upper fan that gives way to mid- to lower-level lobes. The channels tend to be filled by subsequent cohesive debris flows. Usually only one lobe is active at a time, and inactive lobes may develop desert varnish or develop a soil profile from eolian dust deposition, on time scales of 1,000 to 10,000 years. Because of their high viscosity, debris flows tend to be confined to

5612-554: The feeder channel onto the fan surface, it is able to spread out into wide, shallow channels or to infiltrate the surface. This reduces the carrying power of the flow and results in deposition of sediments. Flow in the proximal fan, where the slope is steepest, is usually confined to a single channel (a fanhead trench ), which may be up to 30 meters (100 ft) deep. This channel is subject to blockage by accumulated sediments or debris flows , which causes flow to periodically break out of its old channel ( nodal avulsion ) and shift to

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5704-400: The feeder channel. This results in sheetfloods on the alluvial fan, where sediment-laden water leaves its channel confines and spreads across the fan surface. These may include hyperconcentrated flows containing 20% to 45% sediments, which are intermediate between sheetfloods having 20% or less of sediments and debris flows with more than 45% sediments. As the flood recedes, it often leaves

5796-461: The fish are diversion and pumping of water. River volumes peak between March and June due to the spring runoff, but demand for irrigation peaks between July and October. During the irrigation period, the river downstream from the Isleta diversion dam may largely dry up unless irrigation water is returned to the river or a summer storm provides a brief influx of water. Native fish may be trapped in pools in

5888-530: The form of short (several hours) but energetic flash floods that occur with little or no warning. They typically result from heavy and prolonged rainfall, and are characterized by high velocities and capacity for sediment transport. Flows cover the range from floods through hyperconcentrated flows to debris flows, depending on the volume of sediments in the flow. Debris flows resemble freshly poured concrete, consisting mostly of coarse debris. Hyperconcentrated flows are intermediate between floods and debris flows, with

5980-402: The form of stream flow rather than debris flows. They are less sharply distinguished from ordinary fluvial deposits than are debris flow fans. Fluvial fans occur where there is perennial, seasonal, or ephemeral stream flow that feeds a system of distributary channels on the fan. In arid or semiarid climates, deposition is dominated by infrequent but intense rainfall that produces flash floods in

6072-599: The largest accumulations of gravel in the geologic record. Alluvial fans have also been found on Mars and Titan , showing that fluvial processes have occurred on other worlds. Some of the largest alluvial fans are found along the Himalaya mountain front on the Indo-Gangetic plain . A shift of the feeder channel (a nodal avulsion ) can lead to catastrophic flooding, as occurred on the Kosi River fan in 2008. An alluvial fan

6164-450: The largest accumulations of gravel in the geologic record. Several kinds of sediment deposits ( facies ) are found in alluvial fans. Alluvial fans are characterized by coarse sedimentation, though the sediments making up the fan become less coarse further from the apex. Gravels show well-developed imbrication with the pebbles dipping towards the apex. Fan deposits typically show well-developed reverse grading caused by outbuilding of

6256-411: The last 25,000 years occurred during times of rapid climate change, both from wet to dry and from dry to wet. Alluvial fans are often found in desert areas, which are subjected to periodic flash floods from nearby thunderstorms in local hills. The typical watercourse in an arid climate has a large, funnel-shaped basin at the top, leading to a narrow defile , which opens out into an alluvial fan at

6348-471: The last few hundred years, the river had generally shifted westward across its fan, and by 2008, the main river channel was located on the extreme western part of the megafan. In August 2008 , high monsoon flows breached the embankment of the Koshi River . This diverted most of the river into an unprotected ancient channel and flooded the central part of the megafan. This was an area with a high population density that had been stable for over 200 years. Over

6440-565: The last quarter of the twentieth century. Sandy soils include scrub and mesa vegetation such as sand sagebrush ( Artemisia filifolia ), fourwing saltbush ( Atriplex canescens ). Some similar grass and seasonal wildflower species occur that also occur in areas east of the Rio Grande, but in much lower densities. Sparsely as well, sandy soil grasses occur such as Indian ricegrass ( Oryzopsis hymenoides ), sand dropseed ( Sporobolus cryptandrus ), and mesa dropseed ( Sporobolus flexuosus ). Arroyos contain desert willow ( Chilopsis linearis ) while breaks and

6532-564: The late 1980s and early 1990s due to low global oil prices. In 2001 the U.S. Geological Survey published a report on the probability that gas would be found in the basin. It noted that the Albuquerque Basin, like other basins formed during the Laramide orogeny, contains a thick layer of coals, carbonaceous shales and marine shales from the Cretaceous era. These are thought to be the source of basin-centered accumulations of gas. Unlike other basins in

6624-422: The late nineteenth century. By the early 1960s many of the native species were no longer present in the northern part of the basin. Speckled chub and Rio Grande bluntnose shiner, two cyprinids, were last found in 1964. By the mid-1990s 45 species of fish were reported in the basin, of which only 17 were native. More than 40% of the native species of this section of the river have been eliminated. The main threats to

6716-424: The likely flood path, the likelihood of abrupt deposition and erosion of sediments carried by the flood from upstream sources, and a combination of the availability of sediments and of the slope and topography of the fan that creates extraordinary hazards. These hazards cannot reliably be mitigated by elevation on fill (raising existing buildings up to a meter (three feet) and building new foundations beneath them ). At

6808-541: The lower foothills of the Sandia Mountains, loose or granitic soils help provide habitat for other species, such as feather dalea ( Dalea formosa ), mariola ( Parthenium incanum ), and beebrush or oreganillo ( Aloysia wrightii ). Soaptree ( Yucca elata ) and broom dalea ( Psorothamnus scoparius ) are currently found or were once existing on sand hills and breaks on both sides of the Rio Grande Valley, roughly below

6900-704: The planet and further supported the theory that liquid water was once present in some form on the Martian surface. In addition, observations of fans in Gale crater made by satellites from orbit have now been confirmed by the discovery of fluvial sediments by the Curiosity rover . Alluvial fans in Holden crater have toe-trimmed profiles attributed to fluvial erosion. The few alluvial fans associated with tectonic processes include those at Coprates Chasma and Juventae Chasma, which are part of

6992-507: The present-day locations of the Petroglyph Escarpment west of Coors Road and along Interstate 25 south of Sunport Boulevard. The Rio Grande Valley proper bisects Albuquerque, and it has been urbanized the longest of all areas of the city. The present bosque or gallery forest of Rio Grande cottonwood ( Populus deltoides var. wislizeni ) and coyote willow ( Salix exigua ) is theorized to have been more savannah-like prior to replanting in

7084-621: The prominent volcanic escarpment include threeleaf sumac with less frequent stands of oneseed juniper ( Juniperus monosperma ), netleaf hackberry ( Celtis reticulata ), mariola ( Parthenium incanum ), and beebrush or oreganillo ( Aloysia wrightii ). Isolated littleleaf sumac ( Rhus microphylla ) occurs on the hillsides above Taylor Ranch and at the Petroglyph National Monument Visitor's Center. Other areas of Albuquerque have more fine clay and caliche soils, plus more rainfall and slightly cooler temperatures, so natural vegetation

7176-465: The proximal and medial fan even in a debris-flow-dominated alluvial fan, and streamfloods dominate the distal fan. However, some debris-flow-dominated fans in arid climates consist almost entirely of debris flows and lag gravels from eolian winnowing of debris flows, with no evidence of sheetflood or sieve deposits. Debris-flow-dominated fans tend to be steep and poorly vegetated. Fluvial fans (streamflow-dominated fans) receive most of their sediments in

7268-473: The proximal and medial fan. These deposits lack sedimentary structure, other than occasional reverse-graded bedding towards the base, and they are poorly sorted. The proximal fan may also include gravel lobes that have been interpreted as sieve deposits, where runoff rapidly infiltrates and leaves behind only the coarse material. However, the gravel lobes have also been interpreted as debris flow deposits. Conglomerate originating as debris flows on alluvial fans

7360-481: The region, the Albuquerque Basin is still actively subsiding. The temperature and pressure on the hydrocarbon source rocks in the deeper parts of the basin will be causing gas to generate, and the gas is probably migrating upward and accumulating in Upper Cretaceous sandstones. After discussing other factors, the report concluded "All of these characteristics suggest that a basin-centered gas accumulation of some sort

7452-473: The river bed, where introduced game fish may take them, or they may die from loss of water in which they can live. The river may not start running steadily until the end of October, when irrigation stops. Flora or vegetation surrounding the built portions of the city are typical of their desert southwestern and interior west setting, within the varied elevations and terrain. The limits are by significant urbanization, including much infill development occurring in

7544-590: The river from the mountains that form the eastern boundary of the basin. West of the river the Llano de Albuquerque contains only isolated mountains and volcanoes, sloping gradually up to the Rio Puerco. Throughout the basin, which receives little rainfall, there are sand dunes and dune fields, some vegetated and some active. The basin is rich in Paleo-Indian sites, most of which are found on terraces or other uplands near to

7636-457: The river passes three mainstream structures that divert water into 1,280 kilometres (800 mi) of levees, canals and drains in the section between Algodones and the Bosque del Apache National Wildlife Refuge . When the river is low, the diversion dams at Isleta and San Acacia can divert all water from the Rio Grande along a 177 kilometres (110 mi) stretch of the river. Tributaries include

7728-520: The river, with secondary ditches leading off the main channel named for specific families. Maintenance of the main acequia would be a community responsibility. Before entering the basin the river is impounded by the Cochiti Dam , built in 1975. After leaving the basin via Socorro, the river is impounded by the Elephant Butte Reservoir , built in 1916. Within the stretch between these dams,

7820-442: The southern portion was a west-tilted half graben. A transfer zone running in a southwest direction connected the two. More recently, gravity data has given support for a different model, which is consistent with other sources of information. In this new model, the northern portion is an ENE-facing half-graben, extending further east than had been thought, while the southern portion is an east-facing half graben. The two are connected by

7912-621: The swampy land and improved the acequias . During and since World War II , the city of Albuquerque has grown steadily. The MSGCD still maintains a large network of canals and irrigation systems that stretches from 30 miles (48 km) north of Albuquerque through the city down to the Bosque del Apache National Wildlife Refuge . As of 2012 the MRGCD was responsible for an area of 278,000 acres (113,000 ha), of which 128,787 acres (52,118 ha) could be irrigated and 70,000 acres (28,000 ha) were in fact being irrigated by 11,000 farmers. The MRGCD

8004-543: The title Middle Rio Grande . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Middle_Rio_Grande&oldid=1085725354 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Middle Rio Grande Basin Geologically,

8096-465: The valley floor aquifer is likely to cause subsidence and damage to buildings. Other basins in the Santa Fe rift hold oil and gas, which has been found in small quantities in wells east of Española and southwest of Santa Fe . The first known well to be drilled in the Albuquerque Basin in search of oil and gas was in 1914, and since then at least fifty exploratory wells have been drilled. Before 1953 most of these wells were shallow and only reached into

8188-913: The west side of the basin. The Albuquerque volcanic field contains volcanoes to the west of the city of Albuquerque that were active as recently as 156,000 years ago. The surface of the basin has extensive wind-blown deposits of sand sheets and dunes from the late Pleistocene and Holocene . The climate is semi-arid. A large part of the basin is so dry as to be considered a desert. Average annual temperatures are around 13 °C (55 °F), ranging from an average of about 1 °C (34 °F) in January to about 24 °C (75 °F) in July. Average annual rainfall ranges from 190 millimetres (7.5 in) at Belen to 760 millimetres (30 in) at Sandia Crest. Precipitation comes from local thunderstorms in summer and from storm fronts in winter. The amount of rain that falls in

8280-574: The world. However, flooding on alluvial fans poses unique problems for disaster prevention and preparation. The beds of coarse sediments associated with alluvial fans form aquifers that are the most important groundwater reservoirs in many regions. These include both arid regions, such as Egypt or Iraq, and humid regions, such as central Europe or Taiwan. Alluvial fans are subject to infrequent but often very damaging flooding, whose unusual characteristics distinguish alluvial fan floods from ordinary riverbank flooding. These include great uncertainty in

8372-431: Was created by dune fields and small streams draining into playa lakes and mud flats. The sediments in this group yield low volumes of poor quality water. Deposits in the upper Santa Fe group come from drainage of the ancestral Rio Grande and the tributaries of that river. Although a small part of the total, most of the potable water in the region comes from these later deposits, which lie within 2 kilometres (1.2 mi) of

8464-429: Was maintaining four diversion dams and reservoirs, 834 miles (1,342 km) of canals and ditches and 404 miles (650 km) of riverside drains. With growing urbanization, the role of the MRGCD has gradually shifted from supporting agriculture to preserving the riverside ecology and helping to recharge the Albuquerque aquifer. The Rio Grande in the Albuquerque basin had a diverse population of mainly endemic fish up to

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