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ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Publications at this Location » Publication #308417
Title: Recycling irrigation reservoir stratification and implications for crop health and production.

Author
item ZHANG, HAIBO - Virginia Polytechnic Institution & State University
item RICHARDSON, PATRICIA - Virginia Polytechnic Institution & State University
item Copes, Warren
item LEA-COX, JOHN - University Of Maryland
item RISTVEY, ANDREW - University Of Maryland
item BELAYNEH, BRUK - University Of Maryland
item MOORMAN, GARY - Pennsylvania State University
item HONG, CHUANXUE - Virginia Polytechnic Institution & State University

Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2016
Publication Date: 4/24/2016
Citation: Zhang, H., Richardson, P.A., Belayneh, B.E., Ristvey, A., Lea-Cox, J., Copes, W.E., Moorman, G. W., and Hong, C. 2016. Recycling irrigation reservoir stratification and implications for crop health and production. Journal of the American Water Resources Association 1-12. DOI: 10-1111/1752-1688.12411. 2016.

Interpretive Summary: Water quality of shallow water containment ponds is important for utilizing it for irrigation of ornamental plants. Water temperatures, pH, and oxygen could all be affected by water stratification, which is better known in deep water bodies. Results indicate that temperature stratification occurred in all recycling irrigation reservoirs studied, despite shallow depths of 3 to 12 feet. Water generally was stratified once a year from April to October. Top to bottom temperatures differed by up to 38.7°F and was positively correlated with water depth, air temperature and sun light intensity. The pH level was higher at the top than at the bottom with differences of up to 4 units. Top to bottom differences in dissolved oxygen and pH increased when water was stratified and decreased when water was uniformily mixed, and were affected by increasing pond depth. Practical implications of water management include seasonally adjusting the depth of water uptake pipes for irrigation and adjusting water disinfection rates according to variation in DO and pH levels. This information will benefit agricultural businesses that draw irrigation water from shallow ponds, university extension specialists, crop advisers, and research scientists.

Technical Abstract: Stratification is often assumed to only take place in deep water bodies. Recycling irrigation reservoirs often are shallow; however, they receive agricultural runoff containing elevated concentrations of nutrients and sediments. This study investigated the temperature, dissolved oxygen and pH characteristics of eight irrigation reservoirs in Virginia and Maryland from 2011 to 2014. The results indicate that thermal stratification occurred in all recycling irrigation reservoirsstudied, despite their shallow depths (0.75m =depths =3.89m). Water was stratified once a year from April to October in general. Strongest stratification was observed in the Nursery VA2, with top-bottom temperature difference up to 21.53°C. The top-bottom temperature difference was positively correlated with water depth, air temperature and photosynthetically-active radiation (P <0.05). Wind speed did not have a significant impact on stratification, mainly due to the relatively small surface areas. Similar stratifications were also observed in DO and pH of the same reservoirs. The pH level in these reservoirs was higher at the top than at the bottom. The pH difference was up to 4.16 units in the Reservoir VA21. The top-bottom differences in both DO and pH increased when water stratified and decreased when water mixed, and they were positively correlated with water depth. The practical implications of these findings on water quality management are discussed. Specifically, water withdrawal depths and water disinfection treatment may be adjusted according to variation in DO and pH levels during the stratification and non-stratification periods.