DETERMINATION OF REASON FOR SOIL SALINIZATION AT SOUTHWEST OF THE CHAMO LAKE IN SILE-ELGO CATCHMENT, IN CASE OF ARBAMINCH, ETHIOPIA

Abstract

Soil salinization gets worsens the soil settings and causes the loss of fertility which leads to desertification and becoming a warning problem in arid and semi-arid regions of the globe. Soil salinization affected 19 million ha of land in sub-Saharan Africa. Ethiopia stands first in Africa in the magnitude of salt-affected soils due to human-induced and natural causes. In the study area has land degradation at southwest side of the Chamo lake. The white layers on the soil surface were observed. The aim of this research was to determine the source of salinity in the irrigated farm lands which is located between Sile-Elgo catchment. The water and soil samples were collected based on the proximity and possible influencing sources of the study area In surface water the samples has been drawn from Sile and Elgo rivers and the southeastern wetlands of Lake Chamo. Similarly, for groundwater, the samples has been collected from 7 piezo metric stations and 8 hand dug wells in both wet and dry seasons. Water and soil quality parameters such as pH, TDS, Ec, contents of SO4-2, Cl-, NO3-, Mg+2, Ca+2, Na+ and K+ in both seasons were determined in Arba Minch University water quality laboratory. As the study indicates the dominant cations and anions of the study area are Na+, Ca+2, Cl-, and SO4-2. Piper diagarams expressed the salt dominnat in Ca+2, Mg+2, and Na+ with SO4-2 and Cl-. The regional groundwater is belongs to Mg+2 and Na+ in cations and carbonate and HCO3- and SO4-2 from anions. The salt is dominant in Na+ and K+ with SO4-2 and Cl- types. In other hand the groundwater flow direction of the regional groundwater has been developed by using ArcGIS 10.4.1 groundwater flow direction analysis tool. From the result the regional groundwater flow direction is intended flowing towards the lake from Northwest to south and southeast direction. Gibb’s plots confirmed the source of the salts are from the rock dominance. In this finding the expected reasons for land degradation was from the geological formations, shallow groundwater and the high evapotranspiration enhancing the cappilarity in the vadose zone of the soil settings.