Hydrogeological System Analysis in Ziway–Shala Lakes Area Using Hydrochemistry and Isotope Techniques, Central Ethiopia
| dc.contributor.advisor | Ayenew, Tenalem (PhD) | |
| dc.contributor.author | Fikre, Shemelis | |
| dc.date.accessioned | 2018-07-10T13:01:42Z | |
| dc.date.accessioned | 2023-11-09T14:09:51Z | |
| dc.date.available | 2018-07-10T13:01:42Z | |
| dc.date.available | 2023-11-09T14:09:51Z | |
| dc.date.issued | 2006-06 | |
| dc.description.abstract | In this work, hydrochemical and isotopic study has been carried out in order to conceptualize the groundwater circulation and to evaluate the subsurface hydraulic connection between the lakes in the Ziway-Shala lakes basin, located 190km south of Addis Ababa in the central sector of the Main Ethiopian Rift and covers a large portion of the lakes district in Ethiopia. Lacustrine sediments and volcano-clasitic succession (in the floor), volcanics (on the highlands and escarpment) are the main geological units in the area. The area is highly affected by rift structures and recent tectonic features. The hydraulic characteristics of the aquifers in the area show high spatial variability, which is the result of the complex nature of the lacustrine sediments and the degree of fracturing of the volcanic rocks. The most permeable unit is the basalts and local ignimbrites with hydraulic conductivity grater than 40m/day, where as the least are those rift volcanoes and volcanic ridges having less than 1m/day. The others volcanic rocks lie in between depending on the degree of weathering, fracturing or faulting. The hydrochemical and isotopic analysis of δ2H, δ18O & 3H result signifies that groundwater of the floor, escarpment and highland is found in different flow regime. 75% of the total groundwater samples collected in the area has concentration range of sodium (the dominant cation) and range of bicarbonate (the dominant anion) between 60-300 mg/l and between 200-600 mg/l respectively. These high ionic variabilities show the presence of different groundwater flow systems. Groundwater in the recharge area evolves from a dilute Na -Ca– HCO3 type water (statistically determined Subgroup-1: average TDS is ~332 mg/l ) to a fresh Na–HCO3 type water (Subgroup-2: average TDS is ~475 mg/l) to a more concentrated Na–HCO3 type water (Subgroup-3: average TDS is ~1184 mg/l) to a brackish Na–HCO3-Cl type water (Subgroup-4: average TDS is ~6538 mg/l) along the topographic flowpath Overall, the waters from the area can be classified as recharge area waters (Subgroup-1), transition zone waters (Subgroup-2) and discharge area waters (Subgroup-3 and Subgroup-4).Hydrochemical and Isotope concentrations of groundwater and surface water samples between the lakes help to study the subsurface interconnection between the lakes.18O and 2H signatures in relation with the hydrochemistry of waters from the highlands, escarpments and rift valley helps to conceptualize the groundwater flow system in the area. | en_US |
| dc.identifier.uri | http://10.90.10.223:4000/handle/123456789/7713 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa Universty | en_US |
| dc.subject | Hydrochemical and Isotopic | en_US |
| dc.title | Hydrogeological System Analysis in Ziway–Shala Lakes Area Using Hydrochemistry and Isotope Techniques, Central Ethiopia | en_US |
| dc.type | Thesis | en_US |