Date of Completion

8-22-2017

Embargo Period

2-18-2018

Keywords

Riparian, scaling, water quality, dimensional analysis

Major Advisor

John Clausen

Associate Advisor

Gary Robbins

Associate Advisor

Julia Kuzovkina

Associate Advisor

Ashley Helton

Associate Advisor

Glenn Warner

Field of Study

Natural Resources: Land, Water, and Air

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

This research contributes new knowledge to two major challenges: 1) up-scaling water quality results from riparian treatment plots to larger watersheds and 2) determining if a short-rotation woody crop (SRWC) can be an effective riparian buffer for treating agricultural nonpoint source pollution. An exhaustive literature review was conducted to provide detailed insight into the methods of scaling, the associated mathematical equations, and their application to the problem of predicting water quality. Dimensional analysis was identified as an underutilized but promising technique for water quality scaling. Dimensional analysis was used to predict total phosphorus (TP) concentrations across heterogenous watersheds ranging from ~ 200 to 3,400 km2. Variables describing attenuated point (kWp) and nonpoint (Wnp) sources of pollution, discharge for rivers (Qs) and treatment plants (Qw), longitudinal distance of watershed river networks (S) and the cross-sectional area at outlets (A) were transformed into dimensionless groups and a power law equation was derived using multiple linear regression. The scale invariant equation resulted in an R2 of 0.931 between observed and predicted TP concentrations. The results improve our understanding of spatial scaling methodologies and provide a guide for future work aimed at scaling water quality. A randomized complete block design was used to determine water quality changes resulting from converting plots previously cultivated in corn to SRWC willow (Salix. spp) adjacent to a stream in Storrs, CT. Overland flow and ground water samples were analyzed for total nitrogen (TN) and total phosphorus (TP). Additionally, overland flow was analyzed for suspended solids concentration (SSC) and ground water samples were analyzed for nitrate + nitrite (NO2+NO3-N). Lower (p = 0.05) concentrations of TN (41%) and TP (53%) were observed in overland flow from willow plots than from corn plots. Shallow ground water concentrations at the edge of willow plots were lower in TN (56%) and NO3+NO2-N (64%), but 35% higher in TP, than at the edge of corn plots. Overland flow associated with willow was also lower in SSC (71%) compared to corn. Changes in water quality from a riparian buffer of willow was found to be similar to those found in restored and established buffers.

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