Jim..the landslide blog has quite a big section on the slide in Pakistan and the attempts to cut a drain into the head of the slide.very tricky work,they brought a crew in from China with experience working with the same problem there.from what i gather if you make the drain to big it starts a washout and the whole thing lets loose,too small and the river forms a lake and over tops the slide with the same result.from our point of view its a real BOB situation.