Their resources downstream?

1) Does " their resources downstream" mean "their downstream resources"?
2) Does "precipitation" mean "the falling to earth of any form of water (rain or snow or hail or sleet or mist)"? If so, how the increase in precipitation" could be "projected/planned"?

Context:

Increased water in High Asia
A projected increase in precipitation and glacier melt, due to climate change, will result in greater runoff from rivers in High Asia until at least 2050.
Consistent increase in High Asia's runoff due to increasing glacier melt and precipitation
Rivers originating in the high mountains of Asia are among the most meltwater-dependent river systems on Earth, yet large human populations depend on their resources downstream1. Across High Asia’s river basins, there is large variation in the contribution of glacier and snow melt to total runoff2, which is poorly quantified. The lack of understanding of the hydrological regimes of High Asia’s rivers is one of the main sources of uncertainty in assessing the regional hydrological impacts of climate change3. Here we use a large-scale, high-resolution cryospheric–hydrological model to quantify the upstream hydrological regimes of the Indus, Ganges, Brahmaputra, Salween and Mekong rivers. Subsequently, we analyse the impacts of climate change on increase in runoff at least until 2050 caused primarily by an increase in precipitation in the upper Ganges, Brahmaputra, Salween and Mekong basins and from accelerated melt in the upper Indus Basin. These findings have immediate consequences for climate change policies where a transition towards coping with intra-annual shifts in water availability is desirable.