Paper No. 99019 of the Journal of the American Water Resources Association.Discussions are open until October 1, 2001.
MODELING TRANSIENT pH DEPRESSIONS IN COASTAL STREAMS OF BRITISH COLUMBIA USING NEURAL NETWORKS1
Version of Record online: 8 JUN 2007
JAWRA Journal of the American Water Resources Association
Volume 37, Issue 1, pages 73–89, February 2001
How to Cite
Cannon, A. J. and Whitfield, P. H. (2001), MODELING TRANSIENT pH DEPRESSIONS IN COASTAL STREAMS OF BRITISH COLUMBIA USING NEURAL NETWORKS. JAWRA Journal of the American Water Resources Association, 37: 73–89. doi: 10.1111/j.1752-1688.2001.tb05476.x
- Issue online: 8 JUN 2007
- Version of Record online: 8 JUN 2007
- transient pH depressions;
- rainfall events;
- neural networks;
- trend detection;
- landscape changes;
ABSTRACT: Transient events in water chemistry in small coastal watersheds, particularly pH depressions, are largely driven by inputs of precipitation. While the response of each watershed depends upon both the nature of the precipitation event and the season of the year, how the response changes over time can provide insight into landscape changes. Neural network models for an urban watershed and a rural-suburban watershed were developed in an attempt to detect changes in system response resulting from changes in the landscape. Separate models for describing pH depressions for wet season and dry season conditions were developed for a seven year period at each watershed. The neural network models allowed separation of the effects of precipitation variations and changes in watershed response. The ability to detect trends in pH depression magnitudes was improved by analyzing neural network residuals rather than the raw data. Examination of sensitivity plots of the models indicated how the neural networks were affected by different inputs. There were large differences in effects between seasons in the rural-suburban watershed whereas effects in the urban watershed were consistent between seasons. During the study period, the urban watershed showed no change in pH depression response, while the rural-suburban watershed showed a significant increase in the magnitude of pH depressions, likely the result of increased urbanization.