In‐Stream Nonpoint Source Nutrient Prediction with Land‐Use Proximity and Seasonality

Abstract

This research developed multiple regression models relating land use to in‐stream concentrations of total nitrogen (TOTN) and total phosphorus (TOTP) in eight, low‐order watersheds on the coastal plain of South Carolina. The study area (4860 km2) included dominant land‐use categories of agriculture, forest, urban, and wetland comprising the lower portion of the Lake Marion drainage. Land‐use data were obtained from a pre‐existing GIS database derived by classification of satellite images. The models partitioned land‐use categories according to distance from stream channels using a series of buffer zones around each stream. Effects of point source contributions were removed from observed in‐stream concentrations so that nonpoint source effects could be more clearly delineated. All models except two were significant at P < 0.05. The models for TOTN (r2 from 0.25–0.63) explained more variability of stream nutrient concentrations than those for TOTP (r2 from 0.16–0.39). Greater predictive strength for TOTN than TOTP likely reflects differing pathways from terrestrial to aquatic systems. Land close to the stream channel (<150 m) was better predictor of nutrient concentrations than land away from the channel (>150 m). Land‐use change scenarios (converting forest and wetland to agriculture) support the conclusion that management of stream water quality will be most effective with emphasis on riparian and adjacent lands. Seasonal models were generally significant (P < 0.05) and demonstrate that the seasonal profile of stream nutrient concentrations is dependent on the mosaic of land uses in a specific subbasin.

Spatial water quality assessment of Langat River Basin (Malaysia) using environmetric techniques

“…Moderate positive loading on NO − 3 is possibly due to agricultural runoff because nitrogen and potassium fertilizers are commonly used. The positive correlation of NO − 3 and agricultural land in the HPS region (located downstream) is consistent with many others studies (Hill 1978;Neill 1989;Johnson and Gage 1997;Tufford et al 1998). There are also weak positive and negative loadings on T, and E. coli temperature is most possibly related to seasonal effects, while E. coli is strongly related to municipal sewage and wastewater treatment plants (Frenzel and Couvillion 2002) are due to agricultural runoff such as livestock waste and fertilizers (Buck et al 2003), industrial effluents, municipal sewage, and existing sewage treatment plants because PO 3− 4 is an important component of detergents (Vega et al 1998).…”

Effects of watershed and riparian zone characteristics on nutrient concentrations in the River Scheldt Basin

“…A main issue facing watershed planners is how land use and management ties to the quality at the river basin outlet. The past decades, several researchers tried to relate water quality variables to land management using empirical techniques like correlation and regression analysis, often embedded in a GIS environment (Hill, 1978;Wilkin and Jackson, 1983;Osborne and Wiley, 1988;Hunsaker and Levine, 1995;Bolstad and Swank, Correspondence to: J. Feyen (jan.feyen@biw.kuleuven.be) 1997; Tufford et al, 1998;Norton and Fisher, 2000;Sliva and Williams, 2001;Davis and Neal, 2004).…”

“…the riparian zone. This zone is considered important with respect to the regulation of the transport of sediments, water and nutrients across the landscape, and has been subject of research and target of management and restoration efforts (Omernik et al, 1981;Lowrance et al, 1984;Peterjohn and Correll, 1984;Mulholland, 1992;Haycock et al, 1993;Hill, 1996;Johnson et al, 1997;Tufford et al, 1998). Despite the well-known functions of riparian zones in moderating stream nutrient concentrations (e.g.…”

The Characteristics of Riparian Buffer Studies

“…As a prime example for the use of GIS in riparian buffer modeling and environmental planning, Xiang (1993a,b;1996) demonstrated, through real world case studies, how spatial technology and modeling can help advance the riparian buffer studies. Tufford et al (1998) employed GIS to visualize the relationships among streams, land use and pollution within riparian buffers. Xiang (1998) studied the buffer-induced setback effects on riparian aesthetics with GPS and GIS technology.…”