Evaluation and management of the impact of land use change on the nitrogen and phosphorus load delivered to surface waters: the export coefficient modelling approach

Abstract A manageable, relatively inexpensive model was constructed to predict the loss of nitrogen and phosphorus from a complex catchment to its drainage system. The model used an export coefficient approach, calculating the total nitrogen (N) and total phosphorus (P) load delivered annually to a water body as the sum of the individual loads exported from each nutrient source in its catchment. The export coefficient modelling approach permits scaling up from plot-scale experiments to the catchment scale, allowing application of findings from field experimental studies at a suitable scale for catchment management. The catchment of the River Windrush, a tributary of the River Thames, UK, was selected as the initial study site. The Windrush model predicted nitrogen and phosphorus loading within 2% of observed total nitrogen load and 0.5% of observed total phosphorus load in 1989. The export coefficient modelling approach was then validated by application in a second research basin, the catchment of Slapton Ley, south Devon, which has markedly different catchment hydrology and land use. The Slapton model was calibrated within 2% of observed total nitrogen load and 2.5% of observed total phosphorus load in 1986. Both models proved sensitive to the impact of temporal changes in land use and management on water quality in both catchments, and were therefore used to evaluate the potential impact of proposed pollution control strategies on the nutrient loading delivered to the River Windrush and Slapton Ley.

[1]  Penny J Johnes,et al.  The determination of total nitrogen and total phosphorus concentrations in freshwaters from land use, stock headage and population data: testing of a model for use in conservation and water quality management , 1996 .

[2]  G. Pinay,et al.  Groundwater nitrate dynamics in grass and poplar vegetated riparian buffer strips during the winter , 1993 .

[3]  Wales.,et al.  A century of agricultural statistics Great Britain, 1866-1966. , 1968 .

[4]  P. Johnes,et al.  Contribution of nitrogen species and phosphorus fractions to stream water quality in agricultural catchments , 1996 .

[5]  A James,et al.  An Introduction to Water Quality Modelling , 1984 .

[6]  A. Heathwaite,et al.  The Hydrology and Hydrochemistry of British Wetlands , 1995 .

[7]  H. Taylor.  A Century of Agricultural Statistics , 1939 .

[8]  Kenneth H. Reckhow,et al.  An Examination of Land Use - Nutrient Export Relationships , 1982 .

[9]  Penny J Johnes,et al.  MODELLING THE IMPACT OF LAND USE CHANGE ON WATER QUALITY IN AGRICULTURAL CATCHMENTS , 1997 .

[10]  G. W. Cooke.  Review of the effects of agriculture on the chemical composition and quality of surface and underground waters , 1976 .

[11]  T. Addiscott,et al.  Laying the ground rules for nitrate. , 1989 .

[12]  J. B. Thornes,et al.  Vegetation and erosion. Processes and environments. , 1992 .

[13]  V. Vaněk.  Riparian zone as a source of phosphorus for a groundwater-dominated lake , 1991 .

[14]  D. Devey,et al.  The significance of man-made sources of phosphorus: Detergents and sewage , 1973 .

[15]  B. M. Church,et al.  Fertiliser practice in England and Wales: A new series of surveys , 1971 .

[16]  A. Olness,et al.  Farming, Fertilizers and the Nitrate Problem , 1993 .

[17]  J. Reuter,et al.  Atmospheric deposition of nitrogen and phosphorus in the annual nutrient load of Lake Tahoe (California‐Nevada) , 1994 .

[18]  F. R. Crow,et al.  The Effect of Land Use Parameters on Runoff Simulation by the USDAHL Hydrology Model , 1983 .

[19]  Penny J Johnes,et al.  The Natural History of Slapton Ley Nature Reserve XVIII: nitrogen and phosphorus losses from the catchment - an export coefficient modelling approach , 1989 .

[20]  R. Stevens,et al.  Per capita phosphorus loading from domestic sewage , 1976 .

[21]  G. Mulamoottil,et al.  The transformation and export of phosphorus from Wetlands , 1989 .

[22]  Ann Louise Heathwaite,et al.  Nitrate:processes, patterns and management , 1995 .

[23]  P. Johnes,et al.  Nitrate in surface waters. , 1993 .

[24]  Lora D. Delwiche,et al.  Loading functions for predicting nutrient losses from complex watersheds , 1983 .

[25]  K. Gostick.  Agricultural Development and Advisory Service (A.D.A.S) Recommendations to Farmers on Manure Disposal and Recycling , 1982 .

[26]  Kenneth H. Reckhow,et al.  A Procedure Using Modeling and Error Analysis for the Prediction of Lake Phosphorus Concentration from Land Use Information , 1980 .

[27]  P. Johnes,et al.  Water quality trends in the Windrush catchment: Nitrogen speciation and sediment interactions , 1991 .

[28]  J. Anderson,et al.  Nitrogen Cycling in United Kingdom Forests: The Relevance of Basic Ecological Research [and Discussion] , 1982 .

[29]  J. Omernik.  The influence of land use on stream nutrient levels , 1976 .

[30]  J. Thornes,et al.  The effect of land use on nitrogen, phosphorus and suspended sediment delivery to streams in a small catchment in southwest England. , 1990 .

[31]  Walter Rast,et al.  Nutrient Loading Estimates for Lakes , 1983 .