Texas A&M University – 2008 – Biological and Agricultural Engineering Department

L. Demich, G. Fipps, A. Nazarov, A. Karimov, and E. Leigh College Station, TX 77843-2117

Aquatic VegetationImpacts on the Flow Capacity in Canals

Project Objectives:

• To better understand the effects of hydrilla on flow in canals

• Develop a method (i.e. equation) to calculate flows in canalsinfested with hydrilla

Problem Statement:

Hydrilla verticillata is an aggressively propagating weed, that rapidlygrows to the full depth of waterways and can grow in thick stands ofmany plants. These stands can block part or all of the cross-section ofirrigation canals, which greatly reduces flow capacity. The vegetationalso reduces water velocity in the remainder of the cross-section, whichfurther reduces flow capacity.

Standard methods of predicting flow in canals are highly inaccurate when applied to canals infested with this vegetation.

Constructed Field Channel for Hydrilla Flow Studies

Hydrilla growing in Greenhouse Channel

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Percent of Original Cross-Sectional Area Remaining

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Bench Scale Experimental Channel

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Results:Simple relationship was found between the reduction in flow and the area of vegetation

Research Plan:

• Observe and measure flows of infestedcanals in the LRGV of Texas and Jamaica

• Construct laboratory and field scale canalsystems for controlled experiments

Bench scale canal Greenhouse canal Field canal

Field Channel with Test Vegetation In Place

Project Accomplishments:

Completed flow studies and analysis.

Developed methodology for estimating remaining flow in section based on remaining available flow area.

Mathematical Modeling of Real Canals

Irrigation Technology Center Rio Grande Basin Initiativehttp://itc.tamu.edu http://riogrande.tamu.edu