Actually, by my (admittedly totally untrained) eyes, you'ld still have those continent-spanning megarivers, since those would be the places that *would* have the water to run earthlike plate tectonics. The sections that set up convergent margins (or something similar) would tend to be self-sustaining, while other places would act in more igneous ways. Also, it wouldn't be rivers so much as very thin seas - and there'd probably be a fair bit of water being forced down there with them, whih means that anywhere that has people is also fairly likely to have geysers or the like somewhere nearby.
Also, there's the question of how fresh this water is. With the amount of geothermic activity that I suspect would be going on, it's going to have a high mineral content to begin with. If it's fresh(ish) then you're going to need to be able to explain *why*. If it's salt, then your peeps are going to have to have some sort of in-depth structure on how to turn it drinkable (and if the answer is boil-and-condense may well be running mineral refinement out of the sludge that remains.)
explanations for our micro-seas being fresh(ish):
- less salt in the rocks to erode
-- this is going to mean that salt is not as easy to come by, and will be more precious still (ameliorated to a degree by the fact that the entire place is dry, and food keeps better naturally). At extreme levels, salt could turn into another of the "vital neccessities of civilization" and become something of a tool of potential oppression. No one needs much salt, but everyone needs a little, and if they can only get it from *you*...
- less salt being eroded out of the rocks by the local water cycle
-- this ties back into the question of how the local water cycle works - which in turn depends on some bits of planetary topology.
- less time to accumulate
-- realistically, "fresh" would mean "less salty than blood" - and our blood was ocean-normal as of the point where we left the waters for the land. You wouldn't have much if anything in the way of native land-critters if this were the case.
- something is pulling the salt *out*.
-- insert handwavium here
Mind you, you can mix a few of these, and wind up with relatively minor effects. In particular, making the place a bit younger and a bit more salt-poor will get you to the fresh side of brackish pretty easily without overwhelming effects.
Warning: this post is almost entirely untrained speculation. I tend to think that I'm pretty good at untrained speculation, but if anyone who actually knows what they're doing wants to correct me, please do.
Also, there's the question of how fresh this water is. With the amount of geothermic activity that I suspect would be going on, it's going to have a high mineral content to begin with. If it's fresh(ish) then you're going to need to be able to explain *why*. If it's salt, then your peeps are going to have to have some sort of in-depth structure on how to turn it drinkable (and if the answer is boil-and-condense may well be running mineral refinement out of the sludge that remains.)
explanations for our micro-seas being fresh(ish):
- less salt in the rocks to erode
-- this is going to mean that salt is not as easy to come by, and will be more precious still (ameliorated to a degree by the fact that the entire place is dry, and food keeps better naturally). At extreme levels, salt could turn into another of the "vital neccessities of civilization" and become something of a tool of potential oppression. No one needs much salt, but everyone needs a little, and if they can only get it from *you*...
- less salt being eroded out of the rocks by the local water cycle
-- this ties back into the question of how the local water cycle works - which in turn depends on some bits of planetary topology.
- less time to accumulate
-- realistically, "fresh" would mean "less salty than blood" - and our blood was ocean-normal as of the point where we left the waters for the land. You wouldn't have much if anything in the way of native land-critters if this were the case.
- something is pulling the salt *out*.
-- insert handwavium here
Mind you, you can mix a few of these, and wind up with relatively minor effects. In particular, making the place a bit younger and a bit more salt-poor will get you to the fresh side of brackish pretty easily without overwhelming effects.
Warning: this post is almost entirely untrained speculation. I tend to think that I'm pretty good at untrained speculation, but if anyone who actually knows what they're doing wants to correct me, please do.