Spatial Analysis of Snow-and Rain-Generated Highflows In Southern Ontario

Highflows (including floods) in southern Ontario are often thought to be generated primarily by spring snow-melt. This paper shows that, on the contrary, a significant proportion of highflows results from rain and rain-on-snow. Highflows are divided and analysed according to the generating process. Five parameters are estimated and used to characterize both snowmelt- and rainfall-generated highflows: mean number of events per year; mean date of highflows; standard deviation of date of highflows; mean specific excess discharge; and mean duration of event. The spatial variability of these parameters was described by a first-order trend surface, and the results are discussed in the context of practical applications .
On a sou vent pensé que les fortes crues des eaux (y-compris les mondatrous) dans le sud de I'Ontario provenaient principalement de la fonte des neiges prin-tannière. Or, cet article démontre qu'une proportion importante de ces crues sont le résultat des précipitations et de l'action de la pluie sur la neige. Cinq paramètres ont été mis au point et servent a décrire la fonte des neiges ainsi que les precipitations qui engendrent ces crues: une moyenne du nombre de crues par année; une moyenne des fortes crues; écart type des dates de ses fortes crues; une moyenne du débit excessif; et la durée moyenne de la crue. La variabilité spatiale de ces paramètres a été mesurée par surface ajustée de premier ordre et les résultats obtenus sont examinés dans un contexte d'applications pratiques .     

SNOW pH AND DUST LOADING AT SCHEFFERVILLE, QUEBEC

Problems of acid precipitation in association with industrial activity in areas such as the Great Lakes region are now well-known (e.g. Hornbeck et al., 1977), and the Canadian Network for Sampling Precipitation (CANSAP) has established monitoring stations across Canada. In communities in northern Canada, however, especially in winter, a considerable amount of SO₂ is liberated locally. It is therefore important to be able to separate local effects from the regional or continental ones, but most CANSAP stations utilize a single collector, the position of which may not be representative of the general conditions in the locality.
The Schefferville, Quebec, area presents a good opportunity to evaluate the local effects of a small area (˜ 1 km²) source in winteras no industrial activity other than ore-extraction takes place. The only gaseous contaminants liberated locally are derived from fuel oil, and the only particulates come from well-defined mine and dump areas.
Here we present measurements of snow pH and dust loading in the Schefferville area, consider the importance of local gaseous and particulate pollutants, compare these with pollutants from distant sources, and assess the significance of the pollution patterns.