Irrigation Engineering

EFFECT OF DRIP LATERAL SPACING ON WATER PRODUCTIVITY AND ONION YIELD (ALLIUM CEPA L.) AT RARE, HARAMAYA UNIVERSITY, EAST HARARGHE ZONE, ETHIOPIA

Fri, 01 Mar 2024 00:00:00 GMT

EFFECT OF DRIP LATERAL SPACING ON WATER PRODUCTIVITY AND ONION YIELD (ALLIUM CEPA L.) AT RARE, HARAMAYA UNIVERSITY, EAST HARARGHE ZONE, ETHIOPIA MUSTAFA KEDIR HAJI; Dr.Degnent sultan (PhD) Drip irrigation or trickle irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surface. Field experiment was conducted at Haramaya University to evaluate Effect of Drip lateral spacing on Water Productivity and Onion yield (Allium cepa L.) at rare, Haramaya University, East Hararghe Zone, Ethiopia the experiment was laid out in completely randomized block plot design. After the installation of drip irrigation system, the hydraulic characteristics of the drippers that were determined include emitter flow rate, emitter flow variation, and uniformity coefficient, coefficient of variation and emission uniformity. Water application uniformity test of irrigation system was determined for drip lateral spacing in every row and lateral spacing between two rows at the beginning and end of the experiment. Drip irrigation spacing (100cm, 50cm, 30cm, 25 and 20cm) the lateral spacing were arranged with four blocks. The highest seasonal water requirement of onion was 426.9 mm at 100% ETc under every drip irrigation spacing. The analysis of variance revealed that there was significant (p<0.05) difference in yield among treatments and the highest yield (37.26t/ha) was obtained from drip irrigation of lateral spacing with 20cm of ETc application and while the lowest (29.61 t/ha) was obtained from plots treated 100cm treatment. The highest (4.14kg/m3) and the lowest (1.54kg/m3) water productivity were recorded from the plots treated with drip irrigation at 100cm and drip irrigation at 20cm treatments, respectively. In terms of water productivity and natural resource scarcity, irrigating with drip irrigation system with 30cm spacing can be recommended for production of onion production. 94

COMPARISON OF SOIL MOISTURE SIMULATION TECHNIQUES IN EERER SUB-BASIN, WABI-SHEBELE RIVER BASIN, ETHIOPIA

Sun, 01 Dec 2024 00:00:00 GMT

COMPARISON OF SOIL MOISTURE SIMULATION TECHNIQUES IN EERER SUB-BASIN, WABI-SHEBELE RIVER BASIN, ETHIOPIA Ayela Tade Ararsa; ( Assis Prof ) Negash Tessema Soil Moisture is a key component of the hydrological cycle and plays a crucial role in agricul- tural productivity, water resources management, and ecosystem health. The present study aims to simulate soil moisture using a SWAT semi-distributed hydrological model and Landsat 8 satellite images with a Thermal Optical Trapezoid Model (TOTRAM) in the Eerer Sub-basin, Wabi Shebele River Basin, Ethiopia. The Soil Water Assessment Tool (SWAT) was used to ex- amine the components of its water balance in both space and time. The parameters of Curve Number, Alpha base flow, groundwater delay, return flow threshold depth, and soil evaporation composition factor were shown to be sensitive for stream flow modeling based on the Global Sensitivity Analyses.Calibration and validation of SWAT using stream flow data to enable the water balance components such as soil moisture. Temporally the amount of rain fall in 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022 were 824.80mm, 781.65mm, 766.77mm, 464.71mm, 614.72mm, 864.55mm, 917.91mm, 834.05mm and 521.17mm which respons 116.23mm, 93.73mm, 72.04mm, 64.50mm, 74.12mm, 102.14mm, 124.37mm, 105.98mm,and 67.23mm soil moisture respectively. Spatially the highest soil moisture was observed in Eastern, Northwestern and the lowest soil moisture was observed in Northern and Southern part of the watershed. This study intended to apply the optical and thermal remote sensing data for esti- mating soil moisture in the Eerer sub-basin. Monthly simulation of stream flow modeling during the calibration with the SUFI2 algorithm provides a good result with a Nash Sutcliffe Efficiency (NSE) of 0.8 and R2 of 0.82. Besides stream flow data the SWAT model soil moisture product was validated by in situ soil moisture content performs well having NSE (0.56), R2 (0.80), RMSE (0.23), and PBIAS (-0.63). TOTRAM-based soil moisture estimates provide an overall perfor- mance of NSE, R2, RMSE, and PBIAS values of 0.64, 0.79, 0.039, and 22.52 respectively. The result indicates that validation of SWAT and TOTRAM models with in situ soil moisture data leads to acceptable accuracy with 0.031 cm3 cm-3, and 0.022 cm3 cm-3 standard errors respec- tively. The overall result indicates that the Landsat 8 image has a higher potential to simulate soil moisture comparable with Theta Prope 114p.

ASSESSMENT OF LAND SUITABILITY AND IRRIGATION WATER POTENTIAL IN KERSA WATERSHED, WABESHEBELLE RIVER BASIN, ETHIOPIA

Mon, 01 Apr 2024 00:00:00 GMT

ASSESSMENT OF LAND SUITABILITY AND IRRIGATION WATER POTENTIAL IN KERSA WATERSHED, WABESHEBELLE RIVER BASIN, ETHIOPIA HUSSEN BEKER YUSUF; Arus Edo Harka (Assistant Professor) Ethiopia faces droughts due to population growth, water resource imbalances, and land degradation. Inadequate irrigation technology hinders food security and income. Kersa Watershed's irrigated agriculture lacks sustainability and suitable locations. Assessing feasibility, taking into account land and water resources, and creating maps are all critical. The study was to evaluate the land suitability and irrigation potential for surface irrigation development in the Kersa watershed using the analytic hierarchy process. Multiple factors which affect irrigated agriculture productivity such as elevation, slope, soil, LULC, and distance to source were considered and each physical parameter was mapped with the use of ArcGIS 10.4.1. All factors were measured to obtain the overall suitability and reclassified according to FAO guidelines. The overall suitability for surface irrigation potential was determined through an analytic hierarchy process and weighted overlay analysis with the aid of a model builder in ArcGIS 10.4.1. Accordingly, about 56.83% of the slope of the catchment, 92.56% of elevation, 87.60% of soil depth, 100% of texture, 84% of drainage, 85% of distance to source, 99.92% of LULC was highly to marginally suitable for surface irrigation. The overall weighted overlay of all parameter results revealed that 97.13% (58,481.1 ha) of the potential irrigable lands in the watershed were in the range of highly suitable to marginally suitable, and 2.87% (1725.87 ha) were unsuitable for surface irrigation. The gross irrigation water requirement, crop water requirement, and irrigation requirement of Maize and sorghum are estimated per decade with the use of the CROPWAT8.0 model. The result has shown that irrigation requirements of the identified command area vary according to the nearby climatic stations and the type of crops selected. The discharges at un-gauged sites were estimated from gauged sites by applying the runoff coefficient method and results were obtained monthly. By comparing the gross irrigation demand of irrigable land with the available flow in rivers, a gross irrigation demand of potentially irrigable land of 58,481.1 ha is not fulfilled with the present flow, so providing a means of water storage above the potential command area is necessary. The current study considered only seven factors, but other suitability factors like socioeconomics, environmental issues, method of irrigation, and other relevant parameters should be studied for a detailed assessment of irrigation development in the study area. 99

ASSESSMENT OF GROUNDWATER POTENTIAL AND RECHARGE ZONES IN ERER SUB-BASIN, WABESHEBELLE RIVER BASIN, ETHIOPIA

Sat, 01 Jun 2024 00:00:00 GMT

ASSESSMENT OF GROUNDWATER POTENTIAL AND RECHARGE ZONES IN ERER SUB-BASIN, WABESHEBELLE RIVER BASIN, ETHIOPIA Kibebew Damtew Groundwater is a valuable and important natural resource for humankind for drinking, industrialization and irrigation in present day, but the availability is reduced gradually due to over exploitation and lack of management. However, identifying the groundwater potential zones in certain areas of Ethiopia is still challenging in terms of time and cost for resolving water scarcity problems and the management system of groundwater. The broad aim of this study was to assess of groundwater potential and recharge zones using integrated approach of Geographical Information System (GIS) and Remote Sensing (RS) Technologies with Analytic Hierarchy Process in Erer Sub-Basin, Wabeshebelle River Basin. Nine parameters (lithology, geomorphology, slope, lineament density, topographic wetness index, land use/cover, rainfall, drainage density, and soil) that affect groundwater potential and recharge were identified based on theoretical selection criteria setting (frequency of usage, criticalness of the factor and ease/difficult of data access) according to their significant role in groundwater occurrence. The thematic layers of lithology, geomorphology, slope, lineament density, land use/cover, rainfall, topographic wetness index, drainage density, and soil were prepared, with the weight assigned to each thematic layer of feature for developing the groundwater potential and recharge zone map. The weights of each thematic layer were determined by AHP method through Pairwise Comparison Matrix (PCM) and the reclassified thematic maps were integrated by a weighted sum overlay analysis (WOA) tool in ArcGIS 10.4.1 to develop a groundwater potential and recharge zones map. Accordingly, the result groundwater potential zone of the study is highly influenced by lithology (30.7%) and lineament density (21.8%), whereas rainfall (30.7%) and lineament density (21.8%) highly influence the groundwater recharge zone of the study area when compared with other factor. The result of generated groundwater potential map has five reclassified classes namely: very high, high, moderate, low and very low. The areas of very high groundwater potential are estimated to cover 391.19 km2 (9.84% of the study area), high groundwater potential 1672.59 km2 (42.06% of the study area), moderate potential 1216.65 km2 (30.6%), low potential 600.71 km2 (15.11%), and very low potential 95.43 km2 (2.4%). It was also found that the groundwater recharge zones has five reclassified classes namely; very high, high, moderate, low and very low. The areas of very high groundwater recharge are estimated to cover 463.53 km2 (11.66% of the study area), high recharge 1199.96 km2 (30.18%), moderate recharge 1661.07 km2 (41.77%), low recharge 546.72 km2 (13.75%), and very low recharge 105.30 km2 (2.65%). Finally, the groundwater potential zone map was validated using the existing water source inventory point (pumping well yield), and so most well yields are observed in the high and moderate GW potential zones in the west and from the central to the south and southeast parts of the study area, respectively. This indicated a good prediction accuracy of 89%. Thus, potential zones identified and delineated in the Erer Sub-Basin, Wabeshebelle River Basin by the GIS and RS based multi-criteria decision analysis technique are reliable. 129p.