There are many ways to change the surface of the world to provide the Scavs and slums with fresh water and plentiful crops. There are multiple ways to reintroduce rainfall to the deserts or clear the forests of curse and disease. Contained in this page are the ways to change the world permanently(not otherwise mentioned in Hidden Lore). It is important to note that any of the following changes will ultimately fail unless the party defeats the Lavos Remnants detailed in Hidden Lore. The source of the worlds rot is the Lavos Remnants. Any attempt to heal the world will ultimately lead to a confrontation with this entity if the party wants to save the world for good.
-The Abyssal Sea-
deep under the crust, near the world core is the Abyssal Sea. The party could easily discover this subterranean ocean-sized-lake after defeating the Lavos Remnants. This fresh-water could be pumped or transported to the surface. Depending on how the party chooses to reclaim the water different things can happen.
-Fresh Lake-
The Fresh Lake can be used to provide water to those in need. Lydia, the guardian of these waters will aid any party hoping ot unite the fresh water with the native Scavs. If the party wants to deliver the water or the path to the lake to the Grand Leader, Lydia will resist.
-The Frozen Sea-
This area is a massive ice shelf that is slowly melting to form the Fresh Lake. There is an ancient device that can be activated with the Lavos Core(found in the remains of the Lavos Remains) that will return the sea to liquid water. This action will return water to: The Whispering Sands, Sludge Lake, Fissure-Rocks Wasteland, and The Grand Scar.
-The Frozen Expanse/Briggs Frost Plains-
Although there is no known way to change the climate to cause these glacial bands to melt to fresh water. I include these areas in this list because it is a possibility players can think of, even if I can't think of a way to do it.
The following areas are suitable landscapes to contain the water:
Fissure-Rocks Wasteland - If the water is brought to this land the fissures will create a sparkling mineral effect in the lake that forms over it. This water will be prized by alchemists and the native Scavs who live closest will develop Masterwork Alchemists.
The Whispering Sands - If the water is brought to this area, it will become a shallow sea with shifting sand berms. The beeches of this lake will be made of pure silken-clay. Allowing nearby natives to craft beautiful pottery and nearly indestructible cement structures.
The Southern Wastes - This area will create a deep lake nearest to the Grand Arena and Slum Town. Turning the slums into a prosperous sailing town creating boats and developing fisheries that will reinvigorate the slums and the surrounding Hillbadon and Harrowed Fields with plentiful irrigation.
Desolation Salt Flats - The vast area of this area will create a sea too shallow to remain in one place for long. The wind will carry a traveling lake across it's surface. Leaving puddles of mineral water behind that can easily be converted into various crystals. With fine-tuning and receptive magics these crystals can be developed into powerful magical conduits reshaping the way technology and magic interact for the entire world.
The Grand Scar - The waters can be used to fill the Grand Scar to make a deep and narrow sea. This will seal the easiest path from the surface to The World Core under pressures of deepest water. The length of the Grand Scar will make areas very accessible by boat such as the Spice Flats. The proximity to this lake will also calm the Fissure-Rocks Wasteland making it suitable for agriculture or mining.
Gloomwood Mire/Scalding Mire - Fresh water can reinvigorate the stagnant marshlands of the Gloomwood Mire and turn it into a thriving wetland ecosystem. The interaction between the wetlands and the Scalding Mire will eventually begin cleansing the acidic waters. This will break down the razor-sharp metal shoreline into a pristine metallic sands that can be easily meted down to create a nearly indestructible metal that will fuel technology and industry across the world.