英语句子尤其是破折号后面的请帮我详细分析TheAswanDam,forexample,stoppedtheNilefloodingbutdeprivedEgyptofthefertilesiltthatfloodsleft—allinreturnforagiantreservoirofdiseasewhichishowsofullofsil

Question

英语句子　尤其是破折号后面的　请帮我详细分析
The Aswan Dam,for example,stopped the Nile flooding but deprived Egypt of the fertile silt that floods left—all in return for a giant reservoir of disease which is how so full of silt that it barely generates electricity.
破折后不是完整句吧？in return for sth.of sth.还是of是修饰？wh修饰谁？

Answer 1

The Aswan Dam主语,for example插入语,stopped谓语 the Nile flooding宾语 but转折连词引导的转折关系句,地位与第一句并列,后面的主语由于一致省掉了 deprived谓语 Egypt宾语 of the fertile silt 介词短语作egypt补足语that floods left定语从句修饰slit—all同位语,与前面所说的“大坝的利与弊”同位 in return for a giant reservoir of disease 补足语,是巨大的隐患（疾病）的总合（水库）which is （how此词不解,个人觉得应该去掉才对） so full of silt that it barely generates electricity.which引导的从句修饰reservoire塞满了泥沙/淤泥以至于几乎不能发电.
不解就继续追问.