AG垂直于EF,垂足G;BK垂直于EF,垂足K;
梯形ABFE的面积的深度H=AG=BK;
梯形ABFE的面积=1.3,
(EF+AB)*H/2=1.3
(EG+GK+KF+AB)*H=2.6
(0.5AG+AB+0.5BK+AB)*H=2.6,[AG:EG=1:0.5,EG=0.5AG,KF=0.5BK],
(0.5H+0.8+0.5H+0.8)*H=2.6,[H=AG=BK]
H²+1.6H-2.6=0,
(H-1)(H+2.6)=0,
H=1(m),[负值舍去];
水渠的深度h=H+0.2=1+0.2=1.2(m).