Evaluation of Methods for Predicting Seepage Loss Rates for the Hard Lined Irrigation Canals of the Lower Rio Grande Valley of Texas
Abstract
This project investigated the measured loss rates and observed canal lining
conditions by the Texas AgriLife Extension Service to evaluate the Davis-Wilson
empirical formula and to further develop a canal condition rating system for predicting
loss rates. This research is to help irrigation districts of the Lower Rio Grande Valley of
Texas to identify and prioritize the high loss deteriorated lined canals for rehabilitation
and management. The ponding test method was used to estimate the loss rates on 32
canal sections. The condition rating scores were evaluated for 26 of these canals.
Test calculation revisions and testing errors were first evaluated to understand the
potential impacts to the seepage loss rates and condition rating system. The condition
rating system had good results for canals with a ranking of 1, predicting losses less than
0.38 (ft^(3)/ft^(2)/day). Canals with rankings of 2 and 3 had a larger range in loss rates. This
could be attributed to either the subsoil types having more influence as the lining
conditions become more deteriorated or errors in the rating system. The Davis-Wilson
empirical formula had poor results at predicting loss rates for the local lining conditions.
The seepage loss rates were used to calibrate the formula and derive new coefficients (Cvalues).
The C-values were correlated with the scores of the condition rating system (i.e.
Ranking 1 = C-values 1-11). Relationships were also found between the canal
dimensions, water loss rates, and conditions ratings. In general, larger, deeper canals
were in better condition and had lower loss rates. Smaller canals had more variability in
both loss rates and condition ratings.
Subject
IrrigationCanals
Seepage
Davis-Wilson empirical formula
condition rating system
Texas
Ponding Test
Citation
Leigh, Eric (2014). Evaluation of Methods for Predicting Seepage Loss Rates for the Hard Lined Irrigation Canals of the Lower Rio Grande Valley of Texas. Master's thesis, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /152484.