Using MODIS Land-Use/Land-Cover Data and Hydrological Modeling for Estimating Nutrient Concentrations

This paper presents results on nutrient concentrations estimations in the Upper Tombigbee watershed (northern Mississippi-Alabama region, USA). It details the hydrological model development and its use for providing stream flow, runoff, and nutrient concentrations (total phosphorus, TP, and total nitrogen, TN) for subsequent biological studies. Geographical locations of data collection on fish and mussel were used to perform a watershed delineation of the area of study. The delineated catchment was enriched with land use information from USGS GIRAS (1986) and NASA MODIS MOD12Q1 (2001-2004) datasets. An increase of 34% in agricultural lands is shown to have occurred from 1986 to 2003. The Hydrological Program Fortran (HSPF) was used for estimating stream flow and run-off rates for two hydrological models (one per each land use dataset). Export coefficients representative for the regions were used for estimating TN and TP concentrations. It is shown that only maximum concentrations of total nitrogen and total phosphorus have increased from 1986 to 2003. The percent increase ranges from 5 to 16% when comparing a sub-set of sub-basins, and 34% to 37% when taking into account all sub-basins. This seems to be consistent with the increase in agricultural areas in the same time period.