Sentence:  The silt is brought down and the strong tide of the Humber brings it up in very large quantities, so that the river the whole way through nearly is exceedingly thick. Added to that I may say that we suffer from <WSD>warp</WSD> to a tremendous extent. 
Meaning of the word marked with <WSD> tags:  The sediment which subsides from turbid water; the alluvial deposit of muddy water artificially introduced into low lands in order to enrich or fertilise them.