Climatic effects on ice phenology and ice-jam flooding of the Athabasca River in western Canada     

Prabin Rokaya  Luis Morales-Marín  Barrie Bonsal  Howard Wheater  Karl-Erich Lindenschmidt 《水文科学杂志》2013,58(11):1265-1278

ABSTRACT

In cold region environments, any alteration in the hydro-climatic regime can have profound impacts on river ice processes. This paper studies the implications of hydro-climatic trends on river ice processes, particularly on the freeze-up and ice-cover breakup along the Athabasca River in Fort McMurray in western Canada, which is an area very prone to ice-jam flooding. Using a stochastic approach in a one-dimensional hydrodynamic river ice model, a relationship between overbank flow and breakup discharge is established. Furthermore, the likelihood of ice-jam flooding in the future (2041–2070 period) is assessed by forcing a hydrological model with meteorological inputs from the Canadian regional climate model driven by two atmospheric–ocean general circulation climate models. Our results show that the probability of ice-jam flooding for the town of Fort McMurray in the future will be lower, but extreme ice-jam flood events are still probable.  相似文献   

THUNDERSTORM CLIMATOLOGY BASED ON LIGHTNING DETECTOR DATA,MANITOBA, CANADA     

Irene Hanuta  Steve LaDochy 《自然地理学》2013,34(2):101-119

Comparisons are made between thunderstorm data collected from a lightning detector network and from conventional climatic stations for the province of Manitoba, Canada. The greater resolution in time and space of lightning detector (direction finder) data makes it a valuable source of thunderstorm information and lends itself to some important applications. Data were collected for the forest fire season of 1985 using a network of 7 lightning direction finders distributed throughout the province. Some 67,912 cloud-to-ground lightning strikes were recorded by time and location during 122 thunderstorm days. July was the most active month with 27,260 strikes over 28 days. Two regions of the province had the greatest concentration of lightning strikes, indicating some influence by topography and position of large lakes. Case studies are presented of the most active lightning storms of 1985 and 1986. These storms are exclusively frontal storms, with most having similar synoptic weather patterns to those of large hailstorms and tornadoes in Manitoba. Relationships between meteorological parameters and lightning strike distribution are presented. These relationships may prove useful in the suppression of lightning-caused forest fires, especially in remote areas of the province. [Key words: lightning, thunderstorm, synoptic climatology, natural hazards, fire prevention.]  相似文献   

Effect of climate change on drinking water supply in Santiago de Chile     

Gerardo Ahuma  David Bustos  María González 《寒旱区科学》2013,5(1):0027-0034

Climate change is likely to increase the occurrence of floods and flashfloods that affect Santiago de Chile's drinking water supply system throughout the 21st century. A relationship between flashfloods in the Maipo River--Santiago's main raw water source, drainage area in the Maipo Alto Sub Basin and precipitation 48 hours previous to the event was found. Despite having legal guidelines to guarantee continuity and stability in water supply, Chilean law does not specify the maximum admissible magnitude of an event. A 12% drop of average monthly flow at Maipo en El Manzano Station was estimated for the 2035-2065 period due to climate change, meaning water suppliers would not be able to meet 90% monthly water supply security, required by Chilean law. Water suppliers would need to increase their current allotted quota of the Maipo River, from 24.5% to a percentage between 26% and 30% to comply. If the 0 °C isotherm keeps increasing its elevation through the 21st century, more intense floods could occur because of additional drainage area granted by the elevation of the snow line, even if precipitation does not suffer a significant change. In order to withstand a five day turbidity event, 2 m 3 /s of groundwater, or any non river source, should be temporarily incorporated to the emergency drinking water production.  相似文献   

The influence of local hydrogeologic forcings on near‐stream event water recharge and retention (Upper San Pedro River,Arizona)     

Scott C. Simpson  Thomas Meixner 《水文研究》2013,27(4):617-627

The rise in stream stage during high flow events (floods) can induce losing stream conditions, even along stream reaches that are gaining during baseflow conditions. The aquifer response to flood events can affect the geochemical composition of both near‐stream groundwater and post‐event streamflow, but the amount and persistence of recharged floodwater may differ as a function of local hydrogeologic forcings. As a result, this study focuses on how vertical flood recharge varies under different hydrogeologic forcings and the significance that recharge processes can have on groundwater and streamflow composition after floods. River and shallow groundwater samples were collected along three reaches of the Upper San Pedro River (Arizona, USA) before, during and after the 2009 and 2010 summer monsoon seasons. Tracer data from these samples indicate that subsurface floodwater propagation and residence times are strongly controlled by the direction and magnitude of the dominant stream–aquifer gradient. A reach that is typically strongly gaining shows minimal floodwater retention shortly after large events, whereas the moderately gaining and losing reaches can retain recharged floodwater from smaller events for longer periods. The moderately gaining reach likely returned flood recharge to the river as flow declined. These results indicate that reach‐scale differences in hydrogeologic forcing can control (i) the amount of local flood recharge during events and (ii) the duration of its subsurface retention and possible return to the stream during low‐flow periods. Our observations also suggest that the presence of floodwater in year‐round baseflow is not due to long‐term storage beneath the streambed along predominantly gaining reaches, so three alternative mechanisms are suggested: (i) repeated flooding that drives lateral redistribution of previously recharged floodwater, (ii) vertical recharge on the floodplain during overbank flow events and (iii) temporal variability in the stream–aquifer gradient due to seasonally varying water demands of riparian vegetation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献