Runoff Management and Ground Cover

While droughts can be a problem for farming, mainly in the early game, the opposite can cause issues too. Excessive rain will flood valleys, mining pits stop work at levels with contaminated water, turn dirt paths into a muddy mess reducing vehicle speeds as loaded trucks are weighed down into the mire, decreases farm yields as plants lack sunlight, and surge maintenance cost across the island.
To manage the excess water, the player is given some tools to help. Runoff pumps can be built in the bottom of a mining pit to remove water into pipes, then dumped as normal.
But another tool offered is laying concrete slabs, for generalized areas that are neither roads nor open fields. After placing concrete slabs, the terrain become unchangeable unless the slabs are removed first, but vehicles can drive over them at normal speed even during a monsoon.
This ties into various road suggestions, replacing muddy roads with concrete and asphalt roads.

The weather difficulty setting for the map changes too:
Predictable (easy: sunny days and light rains)
Temperate (normal: normal weather patterns with chances of either drought or monsoon)
Seasonal (hard: the weather slowly swings between drought and monsoon)
Post-CC (Harder: the weather will only be either drought or monsoon!)
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This seems a bit harder than you realize to implement. "Runoff pump"? And how would you implement that when you're excavating material and that hole is only going to get bigger and deeper? You have to keep rebuilding the pump? While I agree that rain could affect mining (especially when mining around sand and dirt), your suggestion doesn't give a good solution to the problem, just more problems.