| This article has been：Browse 1394Times Download 2178Times |
scan it! |
|
|
| DOI：10.13522/j.cnki.ggps.2019019 |
|
| The Impact of Orientation and Geometrical Dimensions of Channel on Water Temperature Rise |
|
GUO Jiawen, PU Xunchi*, HUANG Ruixian
|
|
State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China
|
| Abstract: |
| 【Background】The growth and development of crops depends on thermal accumulation, and in areas irrigated with groundwater in north China and reservoir water in south China, the water temperature is low. Low irrigation water temperature could reduce photosynthesis and inhibit root uptake of water and minerals, thereby impeding crop growth and ultimately reducing yield. Understanding the change in water temperature in irrigation channels is hence an important design parameter. 【Objective】The objective of this work is to investigate the influence of orientation and physical dimensions of channel on water temperature change within it. 【Method】 Field experiments were conducted, from which we measured the change in water temperature; the measured data were used to derive a model to calculate how water surface temperature rises once it flows into a channel. The model was then used to calculate the change in water surface temperature in channels with a width-depth ratio of 2∶1, 1.5∶1 and 1∶1, respectively, flowing in the north- south, the east-west and the southeast-northeast directions, respectively. 【Result】 The calibration against experimental data revealed that the model is accurate and robust. The simulated results showed that when other conditions were the same, the channel flowing in the east-west direction was most heating efficient, with the width-depth ratio 2∶1 increasing heating efficiency by 42.42%~256% compared to the wide-depth ratio 1∶1. When the width- depth ratio was the same, the channel flowing in the east-west direction was 58.45%~296% more heating efficient than channels flowing in other two directions. 【Conclusion】We can draw the following conclusions: ①The model derived for calculating water temperature change in channel was accurate and robust. ②When other conditions were the same, the bigger the width-depth ratio of the channel is, the more heating efficient it is. Wherever possible, the width-depth ratio of the channel should be maximized. ③When other conditions were the same, the more east-west orientated the channel is, the more heating efficient it is. |
| Key words: channel orientation; geometric dimension; irrigation water; solar radiation; water temperature |
|
|
