Portal de Periódicos da CAPES

APPLICATION OF SWAT FOR THE UPPER NORTH BOSQUE RIVER WATERSHED

2000; Volume: 43; Issue: 5 Linguagem: Inglês

10.13031/2013.3000

2151-0059

Saleh Arekhi, J. G. Arnold, Philip W. Gassman, Larry M. Hauck, W. D. Rosenthal, J. R. Williams, Anne McFarland,

Water Quality and Pollution Assessment

Agriculture, including livestock production, has been implicated as a major source of pollution to streams andlakes. This study was conducted to assess the effect of dairy production on water quality within Upper North BosqueRiver Watershed (UNBRW) of north central Texas. The UNBRW encompasses an area of approximately 93 250 ha andincluded 94 dairies at the time of the study. A river basin model (Soil and Water Assessment Tool, SWAT) was applied intwo phases. During the first phase, SWAT was validated for the baseline condition within UNBRW. The baseline conditionwithin UNBRW was simulated from 1988 through 1996; model output was compared to flow, sediment, and nutrientmeasurements for 11 stream sites within the watershed for the period of October 1993 to July 1995 for SWAT modelvalidation. The Nash-Sutcliffe coefficient evaluating model efficiency of SWAT for predicting average monthly flow,sediment, and nutrient loading (organic-N, NO3-N, organic-P, and PO4-P) at 11 stream sites over the validation periodranged from 0.65 to 0.99, indicating reasonable predicted values. SWAT also adequately predicted monthly trends inaverage daily flow, sediment, and nutrient loading over the validation period with Nash-Sutcliffe coefficients rangingfrom 0.54 to 0.94 except for NO3-N which had a value of 0.27. Nutrient loadings were consistently highest in the subwatershedswith the most dairies operations. In phase two, to evaluate the effect of dairies, SWAT was executed byreplacing the manure waste application fields with grassland. The results from this phase of study indicate that loadingfrom the watershed could be reduced about 33% for total-N (organic-N plus NO3-N) and 79% for total-P (organic-P plusPO4-P) in the UNBRW if dairy waste application fields were replaced by grassland. Empirical equations based on theoutput with and without dairy loading were developed to illustrate the impact of cow density and percent area covered bydairy waste application fields on sediment and nutrient loading.