The study area Hewane is situated in the southern zone of Tigray Regional State, Hintalo Wajirat wereda. It is geographically located between 1444000 to 1454000m N and 550000 to 558000m E with an aerial extent of 47.66 sq. km. The study was conducted having an objective of assessing suitability of groundwater quality for drinking purposes through geographic information system (GIS) and water quality index (WQI). Ten groundwater samples were collected from the study area and 13 physicochemical parameters such as TDS, TH, Alkalinity, pH, EC, Temperature, Na , and TDS. The WQI estimated for the groundwater samples of the study area ranges from 86.1 to 180.5 at groundwater samples GWS_2 and GWS_5, respectively. Based on the analysis, most of the area under study falls 70% in poor water class and 30% in good water class. Hence, the result revealed that 70% of the groundwater samples of the study area are hardly suitable for drinking purposes without water quality management activities.

The study area Segen river dam site is situated in the southeastern zone of Tigray National Regional State in between Hintalo Wajirat and Enderta Weredas. It is geographically located at 37P between 541400 to 542600 UTME Latitude and 1481600 to 1482600 UTMN Longitude about 35 km southwestern part of Mekelle, the capital of Tigray National Regional State. The study was conducted having an objective of the geophysical assessment to provide important subsurface geophysical information useful in evaluating the subsurface geological formations, geological structures, cavities and others for the dam site under investigation. Ten vertical electical sounding (VES) points along the two profile lines and a total of two horizontal profiling (EP) with a Wenner electrode array were collected. The VES results have shown that weak zones at VES 2, 3 and 4 along Profile 1 and at VES 2, 3 and 5 along Profile 2 where the depth goes not more than 20 m deep in both profiles' pseudo cross section except at VES 4 profile which extends up to 30 m deep. Similarly, the electrical resistivity profiling results also have shown that the weak zones extend not more than 20 m of depth. Hence, the result revealed that the investigation requires further core drilling investigations.

The purpose of the project has been to assess the suitability of groundwater quality for irrigation purpose in the Hantebet catchment (24.4 km 2), Tigray region, northern Ethiopia. The total numbers of hand dug wells in the area are 154. Out of these, 110 are functional and the remaining dried out. Stratified and random sampling techniques were utilized to select representative samples of groundwater. Accordingly, twenty groundwater samples were collected from twenty hand dug wells for chemical analysis. Twenty soil samples were also collected from the command area of the hand dug wells from where the groundwater samples were collected. Both groundwater and soil samples were analyzed for Ca 2+ , Mg 2+ , K + , Na + , CO 3 2-, HCO 3-, Cl-, SO 4 2-, and NO 3 besides pH and electrical conductivity (EC). Further, the Sodium Adsorption Ratio (SAR) for the both the groundwater and soil samples and Exchangeable Sodium Percentage (ESP) for the soil samples were also computed. Out of the analyzed 20 groundwater samples, 8 show EC values below 0.7 and the remaining between 0.71 and 1.12 dS/m, and pH values from 6.55 to 7.26. Chloride ion concentrations in groundwater range from 0.435 to1.393 (meq/l); bicarbonate from 5.124 to 9.660 (meq/l); and nitrate (NO 3-N) values below 5 (mg/l) except in one sample that has 5.87 mg/l. In soil samples, EC values range from 1.36 to 4.65 dS/m (at 25°C) (mean 2.487), and pH values range from 6.77 to 7.79 with a mean value 7.20. SAR values are well below 3 in groundwater, except in one sample and in soil it ranges from 0.111-1.571. ESP values in the soil vary from 2.016 to 4.863. The results indicate that the groundwater in general is suitable for irrigation purpose. In the case of soils about 80% of the soil samples indicate no hazard but 20% are saline. The soils are free of sodicity hazards. However, i) to achieve a full yield potential; ii) to sustain it for long period of time; iii) to avoid the possibility of increase in salinity, and iv) to avoid the possibility of occurrence of sodicity and toxicity hazardous in future, proper irrigation scheme is required in the form of crop selection, fertilizer usage and suitable alternative management.

No abstract