Engineering Field Surveys and Irrigation Schemes Designs in Nangrahar and Laghman Provinces (Nangrahar region) For On Farm Water Management Project (OFWMP)

LOCATION

Nangarhar (Kama, Goshta, Khewa) and Laghman (Qarghai) Provinces of Afghanistan

CLIENT

Islamic Republic of Afghanistan, Ministry of Agriculture, Irrigation and Livestock (MAIL), World Bank, On Farm Water Management Project (OFWMP)

DURATION OF ASSIGNMENT

4 months (It was completed in two months)

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START DATE / COMPLETION DATE

April 2017 – July 2017

DV has carried out Engineering Field Surveys and Irrigation schemes design of command areas of 10 irrigation schemes (sites) select in Nangrahar and Laghman Provinces. The anticipated irrigation schemes covered almost 2,565 hectares of command area and 35.5 km length of main and branches irrigation channels.  The command area and the length of irrigation channels has changed as per the requirements of the different sites.

DV provided services for carrying out Engineering Field Surveys, preparation of Drawings and Maps as well as periodic Reports for the irrigation schemes as detailed below;

  • Detail Engineering Field Surveys and plotting of Drawings, Maps, Cross sections and Profiles.
  • Irrigation Schemes design and plotting of Drawings, Maps and Profiles (using the Software and procedure compatible with ones adopted by OFWMP. For Irrigation Schemes Design (Maps, Long Sections, cross sections, Estimation, BOQ, etc.) software like Auto CAD, Civil 3D, Excel, Google Earth, etc. are to be used.
  • DV established all necessary permanent and temporary bench marks at appropriate locations and intervals. The locations were permanent structures that cannot be disturbed by construction, to the extent possible the benchmarks were marked with red paint. Reference of UTM for location and sea-level and were written on the benchmark. Where no possibility exists, a concrete benchmark was made in the field, it was visible, painted red, located on a place where it cannot be disturbed by traffic, livestock, or the like. A steel rod (Ø12 mm, 1m length, casted in sufficient 1:2:4 concrete) was formed the bench mark. The temporary bench marks was established after 300M length
  • DV performed digital topographical survey (including reports), to a precision that allows for design of irrigation-structures. Deviations of more than 10 cm in altitude are not acceptable. In general this was a need of 16 points per hectare in relatively flat areas (25m x 25 m grid). This can be substantially higher, when micro-relief increases. Around canals, drains, more data was needed.
  • DV measured coordinates and elevations using appropriate surveying equipment (Total stations.
  • The topographic survey included the locations of relevant natural (waterways, trees, hills, forest, wet-lands etc.) and manmade (houses, fences, roads, all kind of structures, etc.) features of the area. These features were located on the maps, profiles and cross-sections, where relevant.
  • Relevant natural and manmade features were outlined in field sketches.
  • The survey at the start of the canal extended 100 meters upstream from the agreed location of the structure.
  • Cross sections were perpendicular to the waterway and extend to 5 meter left and right from the canal, and was taken as directed by the OFWMP engineering team. In principle this was at 50 meter interval. The objective of the L-section, X-section survey and detail survey at specified locations along the secondary canals was to identify the need of rehabilitation, and estimation of volume of work for and repairing work along the secondary canal.
  • In the irrigation area field survey sufficient to produce maps of 1:2000 scale horizontal and suitable vertical for setting of main and secondary canal off-takes were carried out. In principle, contours of 20 cm interval were desired, especially in relatively flat areas.
  • Special attention was needed where canals split, e.g. where abstraction of water took place. The location and altitude of these points, relative to the direct environment is essential.
  • DV provided services for designing of Irrigation schemes, preparation of, Drawings and Maps (site plans, proposed structure plans topographic map, counter map), Profiles, Cross sections, and different types of structures drawings and calculations, estimations, Excel sheets, as well as periodic Reports for the irrigation schemes as detailed below:
  • Pre-design Walk through Survey of Irrigation Scheme were jointly carried out by relevant OFWMP staff, Community and the DV designer to identify critical reaches for lining and/or earthen improvement, decide about type of lining, major hydraulic structure, if any, and design discharge.