sentences:  Also of concern is the lake's fluctuating water level, which had dropped by more than a metre between the early 1960s and the late 1970s.The lake, being located on a rise of land, has a very small cachement area and so its level is very susceptible to variations in annual rainfall.The lake is also relatively shallow with a largely flat bottom, making even a small change in water level noticeable at the lakeshore.