Complex sentence: When the Suez Canal was closed, during the war, the salinity of the lake increased substantially and the salinity of the lake depends on how much fresh water flows into it from the Red Sea and the Mediterranean Sea.
Split into simpler sentences: When the Suez Canal was closed, during the war, the salinity of the lake increased substantially. The salinity of the lake depends on how much fresh water flows into it from the Red Sea and the Mediterranean Sea.