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28-503: The LNVA is governed by a board of nine directors appointed by the Texas Water Development Board . Until 1943 the authority was without any facilities to produce revenue. Since 1943 the irrigation system has been renovated many times. It supplies water to the cities (except Beaumont ), industry, and rice growers of Jefferson County and portions of Chambers and Liberty counties. The LNVA has also cooperated with

56-461: A stereoplotter . Modern mapping also employs lidar and other Remote sensing techniques. Older topographic maps were prepared using traditional surveying instruments. The cartographic style (content and appearance) of topographic maps is highly variable between national mapping organizations. Aesthetic traditions and conventions persist in topographic map symbology, particularly amongst European countries at medium map scales. Although virtually

84-557: A 650-foot-long overflow barrier; five forty-five foot wide tainter gates ; and a fifty-six foot wide navigation lane regulated by two thirty-foot sector gates. It also allows the conservation of 200,000 acre-feet per year of freshwater upstream in Sam Rayburn Reservoir. The salt water barrier project also provides recreational opportunities. Public launching ramps are located on the Jefferson County side of

112-406: A 700 sq mi (1,800 km). The canals deliver fresh water to "...eight cities and water districts, 26 industries, and over 100 irrigated farms..." Water is drawn from the lower Neches River and Pine Island Bayou in north Beaumont, with 21 large pumps delivering between 20,000 and 110,000 gallons of water a minute; it has a capability of delivering more than one billion gallons of water

140-517: A central access point for Texas Natural Resources data, census data, digital and paper maps, and information about datasets collected by state agencies and other organizations. It publishes historical and current aerial photography and printed topographic maps from the United States Geological Survey as part of its public domain data warehouse. It also provides GIS educational services. The TxGIO offices are located in

168-543: A day. Up to 1 × 10 ^  US gal/d (3.8 × 10 L/d) maximum Prior to construction of the permanent barrier, the LNVA installed temporary barriers across Pine Island Bayou and the Neches River upstream of their confluence 36 times between 1940 and 2000, to prevent contamination of their waters from salt water. A permanent saltwater barrier across the Neches River is located downstream about one-half mile from

196-402: A topographic map to show both natural and artificial features. A topographic survey is typically based upon a systematic observation and published as a map series , made up of two or more map sheets that combine to form the whole map. A topographic map series uses a common specification that includes the range of cartographic symbols employed, as well as a standard geodetic framework that defines

224-446: A topographic map. This includes not only how to identify map features, but also how to interpret contour lines to infer landforms like cliffs, ridges, draws, etc. Training in map reading is often given in orienteering, scouting, and the military. The various features shown on the map are represented by conventional signs or symbols. For example, colors can be used to indicate a classification of roads. These signs are usually explained in

252-657: The Carte géométrique de la France , was completed in 1789. The Great Trigonometric Survey of India, started by the East India Company in 1802, then taken over by the British Raj after 1857 was notable as a successful effort on a larger scale and for accurately determining heights of Himalayan peaks from viewpoints over one hundred miles distant. Topographic surveys were prepared by the military to assist in planning for battle and for defensive emplacements (thus

280-625: The United States Army Corps of Engineers in planning, financing, and constructing several large multipurpose dams on the Neches River and Angelina River . Other projects sponsored by the authority include the construction of a permanent saltwater barrier on the Neches River, a comprehensive water-quality management program, and the construction of boat ramps and other recreational facilities on area waterways. The LNVA system includes 400 miles (640 km) of canals covering

308-751: The federal government of the United States ' TIGER initiative compiled interlinked databases of federal, state and local political borders and census enumeration areas , and of roadways, railroads, and water features with support for locating street addresses within street segments. TIGER was developed in the 1980s and used in the 1990 and subsequent decennial censuses . Digital elevation models ( DEM ) were also compiled, initially from topographic maps and stereographic interpretation of aerial photographs and then from satellite photography and radar data . Since all these were government projects funded with taxes and not classified for national security reasons,

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336-773: The map projection , coordinate system , ellipsoid and geodetic datum . Official topographic maps also adopt a national grid referencing system. Natural Resources Canada provides this description of topographic maps: These maps depict in detail ground relief (landforms and terrain), drainage (lakes and rivers), forest cover , administrative areas, populated areas, transportation routes and facilities (including roads and railways), and other man-made features. Other authors define topographic maps by contrasting them with another type of map; they are distinguished from smaller-scale " chorographic maps" that cover large regions, " planimetric maps" that do not show elevations, and " thematic maps " that focus on specific topics. However, in

364-585: The Interior migrated to the newly created United States Geological Survey in 1879, where it has remained since. 1913 saw the beginning of the International Map of the World initiative, which set out to map all of Earth's significant land areas at a scale of 1:1 million, on about one thousand sheets, each covering four degrees latitude by six or more degrees longitude. Excluding borders, each sheet

392-592: The Stephen F. Austin Building, 1700 North Congress Avenue, in Austin, Texas . Topographic map In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but historically using a variety of methods . Traditional definitions require

420-810: The Texas Water Development Board that maintains the geographic information system (GIS) of the government of Texas . It serves as the principal archive for natural resources data in the state. The Texas Geographic Information Officer servers as the director of TxGIO and also coordinates the Texas Geographic Names Committee. TxGIO was established by the Texas Legislature in 1968 as the Texas Water-Oriented Data Bank. In 1972, after four years of growth and diversification, it

448-511: The barrier. The area has a walking trail and playground. The state of Texas created its sixty-first (61st) canoe paddling trail in 2014, with the trail head at the salt water barrier. It progresses north into waters included in the Big Thicket National Preserve . Texas Water Development Board The Texas Water Development Board is an agency of the government of Texas with authority over water development in

476-438: The confluence of Pine Island Bayou and the Neches River. It is about eight miles north of Beaumont. The barrier, constructed between 2000 and 2003, prevents saltwater contamination during periods of low river flows. The permanent saltwater barrier project had a budgeted cost of $ 50 million, with the federal government paying 75% of the cost and the LNVA responsible for the remaining 25%. The barrier, over 1,000 feet long, includes

504-528: The datasets were in the public domain and freely usable without fees or licensing. TIGER and DEM datasets greatly facilitated geographic information systems and made the Global Positioning System much more useful by providing context around locations given by the technology as coordinates. Initial applications were mostly professionalized forms such as innovative surveying instruments and agency-level GIS systems tended by experts. By

532-528: The entire terrestrial surface of Earth has been mapped at scale 1:1,000,000, medium and large-scale mapping has been accomplished intensively in some countries and much less in others. Several commercial vendors supply international topographic map series. According to 2007/2/EC European directive , national mapping agencies of European Union countries must have publicly available services for searching, viewing and downloading their official map series. Topographic maps produced by some of them are available under

560-440: The first artifacts to record observations about topography. Topographic maps are based on topographical surveys. Performed at large scales, these surveys are called topographical in the old sense of topography , showing a variety of elevations and landforms. This is in contrast to older cadastral surveys , which primarily show property and governmental boundaries. The first multi-sheet topographic map series of an entire country,

588-459: The margin of the map, or on a separately published characteristic sheet. Topographic maps are also commonly called contour maps or topo maps . In the United States, where the primary national series is organized by a strict 7.5-minute grid, they are often called or quads or quadrangles. Topographic maps conventionally show topography , or land contours, by means of contour lines . Contour lines are curves that connect contiguous points of

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616-659: The mid-1990s, increasingly user-friendly resources such as online mapping in two and three dimensions, integration of GPS with mobile phones and automotive navigation systems appeared. As of 2011, the future of standardized, centrally printed topographical maps is left somewhat in doubt. Topographic maps have many multiple uses in the present day: any type of geographic planning or large-scale architecture ; Earth sciences and many other geographic disciplines; mining and other Earth-based endeavours; civil engineering and recreational uses such as hiking and orienteering . It takes practice and skill to read and interpret

644-581: The name and history of the United Kingdom 's Ordnance Survey ). As such, elevation information was of vital importance. As they evolved, topographic map series became a national resource in modern nations in planning infrastructure and resource exploitation. In the United States, the national map-making function which had been shared by both the Army Corps of Engineers and the Department of

672-530: The same altitude ( isohypse ). In other words, every point on the marked line of 100 m elevation is 100 m above mean sea level. These maps usually show not only the contours, but also any significant streams or other bodies of water , forest cover, built-up areas or individual buildings (depending on scale), and other features and points of interest such as what direction those streams are flowing. Most topographic maps were prepared using photogrammetric interpretation of aerial photography using

700-484: The state. The Board appoints directors for regional water development agencies such as the Lower Neches Valley Authority . In the 2007 Texas constitutional amendment election , Proposition 16 on the ballot passed with more than 60% of the vote, allowing the board to issue up to $ 250 million in bonds to find its operations. The Texas Geographic Information Office ( TxGIO ) is a division of

728-407: The vernacular and day to day world, the representation of relief (contours) is popularly held to define the genre, such that even small-scale maps showing relief are commonly (and erroneously, in the technical sense) called "topographic". The study or discipline of topography is a much broader field of study, which takes into account all natural and human-made features of terrain. Maps were among

756-428: Was 44 cm high and (depending on latitude) up to 66 cm wide. Although the project eventually foundered, it left an indexing system that remains in use. By the 1980s, centralized printing of standardized topographic maps began to be superseded by databases of coordinates that could be used on computers by moderately skilled end users to view or print maps with arbitrary contents, coverage and scale. For example,

784-671: Was renamed the Texas Natural Resources Information System (TNRIS). In 2023, the 88th Texas Legislature officially renamed TNRIS to the Texas Geographic Information Office. The mission of TxGIO is to provide a "centralized information system incorporating all Texas natural resource data, socioeconomic data related to natural resources, and indexes related to that data that are collected by state agencies or other entities." (Texas Water Code, 16.021). TxGIO provides

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