The first step in building an irrigation project such as a dam, barrage, or weir is to survey the entire area. The purpose of surveying for an irrigation project is to determine if dams or other irrigation structures are required. When the irrigation structure is completed, the area should benefit to a greater extent. As a result, a survey is required to bring this to a conclusion.
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Examine Water Availability
The presence of water and its availability should be the first and main consideration when building an irrigation project, whether it is a dam, weir, or barrage. The availability may be of various types, but prior to building, a thorough evaluation is required.Here are some key points to consider: If there is a river in the area, we need to determine whether it is a perennial or inundation sort of river. If it’s a perennial, the water will be available all year. If the river is Inundation River, look up its previous annual releases. The river should be able to supply the area’s water needs. It must be possible to build an irrigation project on a suitable site.
The topography map of the area is analysed once the water availability has been investigated. This analysis is more effective when determining the tentative irrigation project alignment. This stage investigates the behaviour of agricultural areas.Site selection for construction When there is enough of water or a big source of water, the location for an irrigation project is chosen. It’s possible that the project will be a dam, a barrage, or a weir. The following factors are taken into account when choosing a site. Boring and pile testing are used in the soil survey to determine the required foundation depth. There should be enough basin area available, and the capacity must be sufficient to meet the demand. The website should be simple to navigate. Access to materials and labour should be simple.
River Gauging
River gauging is the measurement of water output at a specific location. The site chosen for the project is the location where river gauging is done in this case. Following river gauging, the following information is obtained: The river’s discharge is computed on a daily basis, and annual discharge records are examined.The HFL (high flood level) and LWL (lowest water level) are calculated using historical data. Silt analysis is carried out to determine the possibility of river bed silting, and the manorial value of fine silt is documented. River metering CCM labelling CCM stands for cultivable command area, which is ideal for growing crops. On the topographic map, the area falling within this category should be indicated. As a result, the construction should not cause any disruption or harm.
Following the site selection for the irrigation structure, the tentative alignments for canals or branch canals must be chosen. Topographical and contour maps should be used to mark these alignments. The following factors should be used when marking. When the canal is cut, the alignment marked should encompass the entire area. The alignment should reduce earth filling and save money. It should avoid passing through valuable agricultural lands, religious sites, and other sensitive areas. It should cross rivers, roads, trains, and other obstacles in a perpendicular manner. Irrigation Projects Reconnaissance Survey After identifying the tentative alignments, a reconnaissance survey of all alignments is carried out. The following information is provided by this survey.
Irrigation Projects Reconnaissance Survey
The slope of the ground along the alignment. Magnetic bearings of traverse lines are recorded along the alignment. Alignments that travel through holy sites and precious areas are removed. If they are inevitable, they are designated as special areas with appropriate compensation. On both sides of the alignment, the nature of the ground up to a distance of 100m is documented. The crossings are cut perpendicularly by alignments. Pacing is a method of measuring distance.Flooding in that area has been documented in the past. Cross drainage works that are appropriate should be noted.If there is a river that runs through the alignment, it should be cut across its shortest width.Irrigation Projects Reconnaissance Survey Irrigation Projects: A Preliminary Survey Following the conclusion of the reconnaissance survey, a suitable alignment is chosen.
On both banks of the river, pillars are built to indicate the irrigation project’s centre line. Similarly, pillars are built to designate the centre lines of both bank canals’ headworks. To determine the depth of the foundation, a bore is made along the centre line of the irrigation structure. The value of a permanent benchmark is determined by connecting it to a nearby GTS benchmark via fly levelling. A plane table survey, also known as a prismatic survey, is carried out on both sides of alignments up to 100 metres, and a route survey map is created. A 20-meter interval is used for longitudinal levelling. A 100-meter interval is used for cross levelling. Permanent bench marks are placed along the alignment with a space between them.
Survey of the Final Location
A survey of the soil along the alignment is conducted. To plan cross drainage works, the specifics of road and railway crossings are noted. The cross section details of the river are provided at river crossings. The river’s cross sections are collected from both the upstream and downstream sides, covering a distance of 500 metres. All of the maps and cross sections have been drawn out. Estimate sheets for earthworks, land compensations, and other projects are prepared. Irrigation Projects: A Preliminary Survey Following the preliminary survey, the most cost-effective alignment is chosen, and a final site study is done. The following steps are engaged in the final stage: The final alignment’s centre line is indicated with pillars and pegs. The pillars also indicate the alignment’s width.
It is the final stage of the procedure, and at this point, a report detailing the final alignment should be written. This report is used to seek approval for an irrigation project from higher authorities. Introduction Project justification and need Justification for final alignment selection Estimation sheets for earthworks, compensation, and head work, among other things.Project specifications in detail The project’s advantage The project is being re-recommended.Along with the aforementioned, the following maps must be submitted. A general map of the area where the canal runs Map of the route of the survey Alignment’s longitudinal section Alignment in cross section Alignment contour Madam, headworks, cross drainage works, and other drawings.
Irrigation Project Final Survey Report
Engineering Field Surveys and Irrigation Schemes Design of 10 Irrigation Schemes (Sites) in Nangrahar and Laghman Provinces were carried out by DV. Irrigation systems were planned for over 2,565 hectares of command land and 35.5 kilometres of main and branch irrigation channels. The command area and irrigation channel length have modified to meet the needs of the various sites.Engineering Field Surveys, Drawings and Maps, and Periodic Reports were all given by DV for the irrigation schemes listed below. Field surveys for detail engineering and plotting of drawings, maps, cross sections, and profiles. Design and charting of irrigation schemes on drawings, maps, and profiles (using software and procedures compatible with those used by OFWMP).
DV completed a digital topographical survey (with reports) at a level of precision that enabled irrigation structures to be designed. Altitude deviations of more than 10 cm are not permissible. In general, 16 points per hectare were required in reasonably level terrain (25m x 25 m grid). When micro-relief is increased, this can be significantly higher. More data was needed around canals and drains. DV used proper surveying equipment (Total stations) to measure coordinates and elevations.The topographic survey includes the positions of the area’s relevant natural (waterways, trees, hills, forest, wetland, etc.) and built (houses, fences, roads, all kinds of structures, etc.) characteristics. Where applicable, these features were located on maps, profiles, and cross-sections.
Topographical Survey: It includes river and reservoir survey; survey for dam, head-works, canal structures.
The preliminary planning of an irrigation project consists of collecting and analysing all available data for the purpose.
Selecting a system must include the following major items: Management, water, soil, and crops.
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