Irrigation & Drainage Systems Engineering

The sandy soil of coastal areas of rivers and oceans due to permeable nature and high water table always provide weak foundations for construction purposes. Due to shear failure and excessive settlements, the sandy soil reduces the safe bearing capacity for high rise building and dam construction purposes. Because of these poor soil properties, several methods are reported to enhance the capability of the soil and apply different grouting materials for its improvement. In this study, several tests were applied to investigate the physicochemical properties of sandy soil and to improve their properties such as shear strength, reduction in settlements and increase the bearing capacity. The properties of sandy soil was measured such as size and moisture content by Sieve analysis, in-situ density by sand cone replacement method, specific gravity by using pycnometer. In similar fashion, cement was characterized such as fineness by sieve analysis, standard consistency, initial and final settlement time was measured by vicat apparatus, soundness and specific gravity of cement was checked by Le-chatlier flask. After material characterizations, shear strength and permeability tests were done to investigate the suitability of sandy soil for grouting applications. Normal and shear stress was measured by direct shear stress apparatus and both stresses increases with increase in load. The permeability of sandy soil was measured by constant head permeability and hydraulic conductivity was reported in medium range which is suitable for plate load test. The plate load test was done by Universal Testing Machine (UTM) for sandy soil. The high settlement of sandy soil by applying load revealed the low bearing capacity and grouting was needed. Cement grout was applied in different water cement ratios, such as 7:1 to 4:1 range. At ratio 7:1 (G1) the settlement was higher while applying the load than 4:1 (G4), which has the lesser settlement. However, when the water content was decreased than G4, then the work ability and flow of the grout was much less for applications. It is concluded that G4 is the best combination of cement grout which has least settlement and maximum bearing capacity which can be preferred combination for construction on sandy soils at coastal areas and deserts.

This study was aimed at analytically examine the convectional layout of Felix Gated Pipe in irrigation field and come up with new approach that enhance approach to optimize economical affordability and durability. With conventional method Flexi Gated Pipe was installed in field stay in the field until harvesting time. Flexi Gated Pipe can irrigate left and right in the in the reach of 100 m, therefore if Flexi Gated Pipe 100 m length was considered in conventional method it irrigate only 2 ha through the crop growing season. With new practice that was introduced, the same 100 m long flexi-gated pipe can irrigate at least 20 ha in 10 days (including five days of idle time) by implement aided rotation within the estate. Metehara sugar Estate in Ethiopia which is about ten thousand hectares, 50000 meters of Flexi Gated Pipe will be required 35,000,000 ETB. A total of 10,500,000 ETB can be saved from one sugar estate. Therefore, 75% of the initial investment costs will be reduced with minimum input of labour and implement cost

This experiment was conducted for the last two years to evaluate the effect of furrow irrigation systems on onion yield and water use efficiency in Melokoza woreda. Specifically to evaluate the effect of alternative, fixed and farmer practice irrigation system and identify the furrow irrigation type which allow achieving optimum onion yield and water use efficiency. The experiment had four level of treatments (alternative, fixed farmer practice and 50% of alternative irrigation system) and which were arranged in RCBD with four replications. Different data were collected and analyzed using SAS software in probability of 5% confidence level. The experiment result shown that alternative furrow irrigation system has highest yield and water use efficiency. The total yield obtained from alternative furrow irrigation was 25.4 t/ ha and the minimum yield obtained from 50% of ETc with alternative furrow irrigation, which was 17.8 t/ha. The water use efficiency of alternative furrow irrigation was 3.3 kg/m3 and fixed furrow irrigation had relatively highest water use efficiency than farmer practice, which were 2.6 kg/m3. The lowest water use efficiency was obtained from farmers practice. From this experiment the result of alternative furrow irrigation is better in yield and water use efficiency in areas where there is water scarcity and laborer expensiveness.

The improvement of water productivity in olive cultivation and its production on sustainable basis in areas marked as water deficit. The most essential, natural and cheapest water resource in such water-prone areas of the world is rainfall. The collection and constructive use of rain-water runoff, also known as water harvesting, has the potential to cope with the water scarcity in the semi-arid and dry, sub-humid regions of the world to sustain olive production. Among all the available micro-irrigation techniques, construction of micro catchments can help farmers to produce crops such as olive orchards with minimum water resources. Research experiments were conducted at Barani Agricultural Research Institute (BARI), Pakistan situated in region where the climate is semi-arid subtropical and the annual rainfall varies from 500-1000 mm. To compare water productivity of different micro-catchment methods, three field plots with three different shapes i.e., square, rectangular, and triangular (V shape) were constructed with 3-5% slope. Olive trees, due to their expensive premium quality edible oil and natural adaptability to grow in marginal lands and better drought tolerance, were used as subject crop to evaluate the performance of micro catchments rain water harvesting techniques. Results concluded that micro catchment structures showed significantly better yield (8-9%) as compared to control and are best suitable to sloppy terrene. Only three supplement irrigations were required for sustainable olive plant cultivation through drip/bubbler irrigation system. Average effective rainfall of both years was 594 mm from which 505 mm (85%) was used by olive plants in micro catchments. Conclusively, micro-catchment structure can be utilized as efficient technique to harvest rain water and sustainable cultivation of olive in semi-arid and arid climates.