What does 苦 mean here?

Question

初，安肅州苦徐水之害，訴於大司農司，大司農司欲奪水故道，導水使東。東則清苑境也，地勢不利，果導之，則清苑被其害，而水亦必反故道為災。

from: https://ctext.org/wiki.pl?if=gb&chapter=415731&remap=gb

My translation thus far:

At first, Ansu City (???) some sort of bad thing, so [he] went to the Grand Minister of Agriculture. The grand minister wished to change the direction of the river to direct it East. To the east was Qingyuan, and because of the uneven terrain, if it were to be directed there, it would harm Qingyuan, and the water would also return to the old direction, causing a disaster.

Answer 1

1. The whole sentence may be translated to 'The Ansu Prefecture was troubled by (the damages of) the waters of Xu'.

2. In classical Chinese, parts of speech are easily mutable (詞類活用). Here is a typical case of 意動用法. You can consider 苦 being equivalent to 以⋯⋯為苦 (lit. 'to consider ... as bitter/unpleasant'; 'to be troubled by').

3. In terms of grammar, 苦 in this instance is not an adjective but a verb.

4. In terms of meaning, the verb is supposed to indicate the feelings or thoughts (意) of the doer. That is also to say, there is personification of the Ansu Prefecture.

5. Another example is 異, as in 漁人甚異之 (meaning 漁人甚以之為異 'the fisherman thinks that as odd very much'). Originally an adjective meaning 'different; odd', here 異 as a verb indicates the (dis)belief of the fisherman.

6. The rest of the sentence is parsed into 徐水 and 害 (n., damage), both translated in 1. 徐 in 徐水 is obviously not the adjective 'slow; gentle'. 徐水 as a whole is currently the name of a district in the Hubei province (which matches with the text), but I think it is better to parse it literally here, given the context of flood.

7. Excellent observation on monalisa's part. Just to supplement: the classical Chinese for a terrain that is even is 夷. Here 利 as mentioned refers to conduciveness.

Answer 2

X 苦 Y 之害: X suffers from the actions of Y, or in the case of an inanimate entity, X suffers from the situation posed by Y. In other words, Y causes X to suffer.

In your case, 安肅州 suffered from the situation caused by 徐水 (Xu River). Probably a flood?

I know you haven't asked the following, but I'll make a suggestion anyway. A little further down you have "地勢不利". This does not exactly say "uneven terrain". It just says that the terrain is not conducive to the plan to divert the river.