According to wikipedia: "Pakistan is a regional[21][22][23] and middle power nation,[24][25][26] and has the world's sixth-largest standing armed forces. It is a declared nuclear-weapons state, and is ranked amongst the emerging and growth-leading economies,"

To fight flooding you need to build channels and dams. And you need a bit of planning and understanding the situation on the site. And you don't need dollars for this, just a working force and machinery (if you can build nuclear weapons, i presume you have some). All i can say is that the main issue is corruption and lack of interest (a dam does not generate any money and is difficult to calculate the return of investment). It happens also in western europe ( if that makes you feel better). ("you" here is the general form. I have nothing against you, just replied to your comment)