Geological study of Gondoro Small Scale Irrigation Project

  Ebissa G. K

The geological and geotechnical investigation for the final study of Gondoro small scale irrigation project has been conducted in parallel with the topographic survey. The investigation is conducted mainly to provide data: on foundations of structures along the main canal, water tightness of the irrigation canals, stability of canals, quality and availability of natural construction materials. The study comprises of: gathering available information about the regional geology, characterization of the geology of the project area, assessment of Ground water condition of the project area in view of the design of structures and drainage condition of the irrigation land, evaluation of the nature and distribution of foundation materials for the proposed structures as well as natural construction material to define the required construction materials quality availability. For the final investigation of Gondoro Irrigation development project the available information on geological maps, satellite images and local information were reviewed. To attain the objectives of the study initially surface local geological study of the project area has been conducted followed by subsurface investigation on the weir axis along the main canal alignment and the proposed sources of construction materials. These Sites were investigated to evaluate the foundation conditions and to study possible available construction material sources. Laboratory tests were conducted on disturbed samples retrieved from canal alignment and proposed construction materials sources, in Addis Ababa, at Transport Construction Design Company central laboratory. The results of these tests are given in annexed in this report. Alternative weir site options have been assessed and all the options are not better than the traditional diversion site from geological point of view and the depth of the bed rock for the structure foundation cannot be encountered at shallow depth in all cases due to deep rock weathering in the area. The alluvial deposit in the entire river course is composed of coble and large boulders with traces of block sizes. The weir site is located in the upper course of the river where large boulders are reworked and mobilized. Naturally deposited Construction materials such as concrete aggregate and quarry for masonry stone are not available within the project area consequently the. River deposit is proposed by crushing to the required size and shape. The entire length of the main canal to the command area extends along the loose organic top soil underlying thick reddish stiff clayey silt residual soil layer. In all the stretches of the main canal alignment there is no stability problem of natural slopes. For the entire length of the canal alignment considerable amount of seepage is not expected if the canal prism lies within the residual soil layer.

Keywords- Geology, Gondoro SSIP, Geotechnical Investigation, Engineering Geology, Construction materials.

Unique Identification Number - IJEDR1702191
Page Number(s) - 1148-1156
Pubished in - Volume 5 | Issue 2 | May 2017
DOI (Digital Object Identifier) -    http://www.dx.doi.org/10.5281/zenodo.583716
Publisher - IJEDR (ISSN - 2321-9939)

  Ebissa G. K,   "Geological study of Gondoro Small Scale Irrigation Project", International Journal of Engineering Development and Research (IJEDR), ISSN:2321-9939, Volume.5, Issue 2, pp.1148-1156, May 2017, Available at :http://www.ijedr.org/papers/IJEDR1702191.pdf