I have completed my Bachelor Degree in the field of Hydraulic and water resources engineering in Arbaminch University Ethiopia and I want to specialize(masters) on that (Hydraulic engineering on your company and for I need a scholarship from your company because it will help me to complete my masters programe free of any problems including financial problems

Good luck, while many companies have a working relationship with universities, my university for example works closely with several companies both local and international. And we have students who work or do study projects within the companies, but the companies do not pay scholarships for this. They merely allow the students to come in and help both with their training, (which costs them money) then benefit if their projects actually help.

You are on a world wide question and answer site, not a company, nor an organization that awards scholarships.
Scholarships are very rare at the graduate level. You apply to the school, fill out forms about your finances, and they might give you a paid position in your department.
You can also study world gov't sites to see which countries need water engineers (I think that is a good field) and contact them directly to see if they want to work out a contract for schooling in exchange for X years of work for them.