A comparison analysis of edge-of-field run-off from two sugarcane fields

Abstract

Agricultural run-off is an important source of nonpoint source pollution. Surface run-off driven by rainfall events was analyzed at two sugarcane fields (SC1 and SC2) in Louisiana, USA. The study site was within a watershed confined by the Mississippi River levee and a drainage canal (St. James Canal). In total, 14 representative rainfall run-off events were analyzed. For comparison with onsite monitoring, a modeling technique was used to estimate run-off. The results show that run-off/rainfall ratios at SC1 were significantly higher (p < 0.0001, n = 14) than at SC2, probably mainly due to a higher sand content of the soil and a higher infiltration rate at SC2 than at SC1. Model-calculated run-off showed substantial overestimation compared with the monitoring results, especially at SC2. Comparison analysis suggests that significant infiltration following precipitation is expected in sandy fields, and water discharge into the groundwater aquifer cannot be ignored. Without considering groundwater discharge in model algorism, the model calculation may significantly overestimate actual surface run-off.

Keywords:

• nonpoint source
• groundwater table
• CN method
• run-off
• water quality

Acknowledgement

This study was supported by Louisiana Department of Environmental Quality (LDEQ), Contract Number CFMS 597524, Grant Number C9-996102-08.