The temperature of three different small streams in northwest England

Abstract

1. Recording thermographs were used to record the water temperatures in three small stony streams in northwest England. These were two Lake District streams, Black Brows Beck and King's Well Beck which rise at altitudes of 246 and 328 m.a.s.l. respectively, and Rough Sike a Pennine stream rising at 686 m.a.s.l. 2. The annual mean water temperatures in Black Brows and King's Well becks were within the range 8 to 10°C but the annual mean in Rough Sike was only 6°C. Rough Sike had lower monthly means than the other two becks during winter and it had a midsummer temperature peak of 11 to 12°C which lasted about one month, whilst the other becks had summer temperature means of 13 to 15°C for three to four months. 3. Rough Sike had an annual temperature sum of about 1700 degree-days above 0°C whilst a value of over 3,000 degree-days was obtained in the other two becks. 4. The daily water temperature range was similar in all three becks. The monthly means of daily ranges were 1.5°C or less during winter and 5 to 7°C during summer, though on some days ranges of 10 to 12°C occurred. 5. Macan (1958) found that in the stream he studied the highest summer water temperatures occurred on days when the sun shone after rain, rather than on sunny rainless days. This conclusion does not appear to be applicable to the becks studied in the present work. 6. Evidence is presented to show that water temperature can be appreciably modified by passage through underground sections of stream. 7. Some general problems of stream temperature measurement were discussed and some tentative calculations were made to illustrate the possible effects of stream temperature on trout metabolism and on the time taken for trout eggs to develop.