This study was conducted in Arsi Negelle woreda of West Arsi Zone, Oromia regional state. The main objective of the study was to investigate the impacts of soil bund on soil physical and chemical properties in Arsi Negelle woreda. The soil data was collected from sites namely: lowland, midland and highland and from soil bunds aged >4 years, <4 years and control of farmland. Three representative sites were selected purposively for soil sample collection. Stratified random sampling techniques were used for soil samples collection. Fifty-four disturbed and undisturbed soil samples were collected for soil properties analysis from two soil depths (10 and 20 cm). Statistical analysis was done following a completely randomized design (CRD) with factorial experiments and treatments as fixed effect and location of sampling as a random effects. The analysis was carried using R software. Regression analysis was used to relate physical properties of soil with each other. Tukey test was used for comparison of means of treatments when statistical significance is found at P ≤ 0.05. Bulk density (BD) and air-filled porosity (AFP) showed significance difference on treated and non-treated site, respectively. The mean of electric conductivity (EC), total nitrogen (TN), available phosphorous (AP) and organic carbon contents were recorded to be significantly higher (p≤ 0.05) on soil bund ages greater than 4 years (>4years) at both soil sampling depths. Aged soil bunds (treated plots) showed a significant changes on soil physical and chemical properties than control plots. The mean of total nitrogen (TN), available phosphorous (AP) and organic carbon contents were recorded significantly higher (p≤ 0.05) in lowland than highland at both soil sampling depths. In generally, ages of soil bunds and sites had significant effect on many soil physical and chemical properties. The sites and ages interaction had significant effect on bulk density (BD) at both depths at P ≤ 0.05. In conclusion, this study showed that soil bunds had significant effect on many physical and chemical properties of soil in the study area.

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This study aims to calculate the water balance, interaction with irrigation water inflow, and hydrodynamics of the Lake Beseka by a spreadsheet-based model using climatic, hydrological, multi-temporal satellite images, groundwater, and lake chemistry data. The rainfall for the catchment was estimated as 558.4 mm/year, whereas the mean evaporation was computed as 2,214 mm/year by the Penman method. The annual direct rainfall contribution to the lake was obtained to be 25.84 MCM (million cubic meters) and a runoff inflow in the catchment area of 37.2 MCM. This balance pointed to the mean evaporation of 108.2 MCM/year in the lake indicating that the water inflow was greater than the outflow. A major cause for the rise of the lake level was the drainage of excess irrigation water toward the lake, mainly from the Fentale Irrigation Farm. The average increment of the groundwater level in the area was 12 cm/year from 2010 to 2014. From 1998 to 2014, the electrical conductivity was reduced by 25.6%, and calcium was increased by 96%. The study outlined that appropriate irrigation drainage should be implemented in the catchment to ensure the balance between the rainfall, infiltration, and surface runoff to optimize economic and social welfare in the area.

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