Project Y061091 â Small streams on fansârecognition of hydrogeomorphic hazards by. D.J. Wilford, M.E. Sakals, and J.L. Innes. April 13, 2006. Note: This is a ...
Final Technical Report - 2005-2006 Project Y061091 – Small streams on fans—recognition of hydrogeomorphic hazards by D.J. Wilford, M.E. Sakals, and J.L. Innes April 13, 2006 Note: This is a report on extension activities rather than a technical report on scientific findings.
Abstract A hazard classification scheme for identifying hydrogeomorphic hazards for forest management on fans was developed over the period 2000–2004 in west central British Columbia. The scheme involves predictive hazard models, aerial photographic features, site features, and management recommendations. The scheme is based on sampling of 65 fans: 10 in a natural state and 55 with some degree of forest management on the fan (the associated watersheds did not have forestry activity). During 2003–2004 the predictive models were tested on 51 randomly selected fans in the Bulkley Timber Supply Area, and reconnaissance sampling in other areas of the province was undertaken to determine the applicability of the scheme. During 2004–2005 extension was undertaken and publications produced for forest practitioners and the scientific community. In 2006– 2006 the focus was on extension based on Land Management Handbooks 57 and 58, evaluation of our extension, and continued work on publications. Recognition of this project as a finalist in the Premier’s Award Innovation category was a significant achievement.
Introduction A fan is a cone-shaped deposit of sediment formed where a stream emerges from the confines of a mountain (Bull 1977). Sediment originates in a source-area watershed and is transported to a fan by hydrogeomorphic processes (floods, debris floods and debris flows [Hungr et al 2001]). In some cases, the deposition of sediment is linked to paraglacial episodes unrelated to modern conditions (Ryder 1971a, 1971b; Church and Ryder 1972; Ritter et al. 1993). In other situations, it is apparent that fans are actively growing (Beaty 1970). In mountainous terrain, it is not uncommon for contemporary hydrogeomorphic processes (Innes 1985; Jakob and Jordan 2001) to be actively influencing at least a portion of the fan surface. We have proposed that this zone of activity, which is characteristically, but not always, limited to the stream channel area, be referred to as the hydrogeomorphic riparian zone (Wilford et al. 2005c). Hydrogeomorphic hazards on fans have been described (VanDine 1985; Kellerhals and Church 1990) and studies of specific fans have led to hazard zonation (Thurber Consultants 1983). However, these hazards are not commonly identified during forest management. The result is that forest management activities commonly aggravate natural
hydrogeomorphic processes leading to increased erosion and destabilization of fan surfaces and stream channels (Wilford et al. 2003). To address this situation, a hazard classification scheme for forest management on fans was developed (Wilford 2003). This scheme is timely, since the Forest and Range Practices Act (FRPA) Regulations came into effect in the spring of 2004, specifying that it was an offence to destabilized fans on the coast (Forest Planning and Practices Regulation Section 54), or impact fish habitat or soils in the interior (Sections 35 and 57). The scheme was developed based on field sampling in west central British Columbia during the period 2000–2003 (Wilford 2003), and was tested during 2003–2004 with a random sample of 51 fans in the Bulkley Timber Supply Area (Final Technical Report for R04-020). The scheme is based on site and aerial photographic features, predictive models, and recommended forest management prescriptions (Wilford et al. 2005b). The scheme recognizes floods, debris floods, and debris flows (Hungr et al. 2001). The power of these hydrogeomorphic processes is based upon the ability of an event to clear a forest stand. High power events clear a forest stand while low power events spread sediment under a forest canopy. High power events have two classes: stand-level events clear a swath 20 m or wider (visible on aerial photographs), and site-level events clear a swath less than 20 m wide. Reconnaissance sampling was undertaken in other areas of the province from 2002–2004. We found all aspects of the scheme were broadly applicable, with the exception of the predictive models. This led us to conclude that provincial-scale field training and field manuals for forest practitioners were appropriate (the focus of the current project).
Progress of extension activities Four factors hindered participation in extension activities for the fan project in previous years: delays in implementing FRPA, restructuring of the Ministry of Forests (MOF), the lack of a published handbook with supporting peer-reviewed scientific articles, and a downturn in the forest industry. FRPA regulations came into effect in the spring of 2004. While this did not lead to immediate increases in workshop attendance, there was a slowly growing recognition that conventional practices on fans are no longer appropriate—for legal, economic, and environmental reasons. Given the significant issues facing senior forest managers— softwood tariffs, general economic downturn, land claims—it was a challenge to gain their attention, and thus gain approval for their staff to attend workshops. However, progress was made in presentations to senior staff from: the Coast Forest and Lumber Association (November 29, 2005), the Forestry Committee of the Council of Forest Industries (January 26, 2006), the MOFR Forest Practices Branch (March 29, 2006), and the MOFR Executive (April 3, 2006) (Group 2 of our target audience identified in our Extension Plan—Wilford et al. 2006).
Restructuring of the MOF was based on the view that forest management would be the responsibility of forest licensees. This led to a change in the focus MOF staff to compliance, enforcement, and oversight work, and a shifting of staff to the newly created BC Timber Sales (BCTS). MOF staff were no longer “doers”. This change was significant for extension activities because historically at least 50% of the participants at field workshops were MOF staff. Participation of BCTS staff in extension activities was limited for two reasons: BCTS was in start-up mode with staff focused on the organization rather than meeting production quotas, and most of the BCTS fieldwork was undertaken by consultants (BCTS staff are primarily contract administrators). Given the role of MOF District Managers in approving Forest Stewardship Plans, a necessary extension emphasis was to ensure they were aware of our research results. A prime goal of 2004-05 was the production of a Land Management Handbook for forest management on fans. This was published as LMH 57 (Wilford et al. 2005b). The document presents the hazard classification scheme and general forest management prescriptions. To our knowledge, this is the first guide for forest management on fans. A second handbook (Wilford et al. 2005a) provides techniques for using trees to date geomorphic and hydrologic events. These techniques allow forest practitioners to determine the frequency of events—a key aspect of hazard identification. A paper title “Fans with forests: contemporary hydrogeomorphic processes on fans with forests in west central British Columbia, Canada” was published by the internationally respected Geological Society of London (Wilford et al. 2005d). A key aspect of this paper is the presentation of a case for the recognition of the hydrogeomorphic riparian zone—the first publication that introduces the concept. The quality of forest management activities within this zone has been shown to be critical—inappropriate prescriptions result in fan destabilization. A poster on the hydrogeomorphic riparian zone was presented at the IUFRO Congress in Australia in August, 2005 (all costs associated with this presentation were covered by non-FSP funding) (Wilford et al. 2005c). One-day office-field workshops were held in Queen Charlotte City (Sept 22), Prince George (Sept 30), and Chilliwack (Oct 18). The workshops familiarized participants with a range of methods and techniques to assist them identify hazards and develop appropriate forest management on fans. A two-day workshop was held in Salmon Arm (Oct 26 and 27). The first day was similar to the other sessions, but the second day focused on risk assessment (half day in the office and half day in the field). Training sessions were advertised for Woss, Terrace, and Smithers, but were cancelled due to low registration. We undertook an evaluation of our extension work. A web-based survey was sent to 144 individuals who had been involved in our extension (dating back to 2001). The survey was completed by 44 individuals (a 31% response rate that is considered quite good). The survey explored the effectiveness of our publications, presentations and workshops. The findings show that extension efforts affected the attitudes, skills, and, in some cases, forest management approaches of a large percentage of forestry practitioners and
researchers who received information on forested fans or attended a workshop. Our results are presented in Wilford et al. 2006 (which also presents our Extension Plan). A key achievement in 2005–2006 was a nomination by the Ministry of Forest and Range of this project in the Innovation Category of the Premier’s Awards. We were selected as one of three finalists, and on March 29 found that we did not win. However, being recognized as one of the top three innovative projects in the British Columbia civil service is a significant honour, and speaks to both the issue we addressed and the quality of our research and extension work. A carry-over into 2006-2007 will be the publication of an article on forested fans in the March–April issue of Innovation, the bi-monthly publication from the Association of Professional Engineers and Geoscientists of BC. At the end of 2005–2006 we decided to begin work on the production of a third Land Management Handbook from the Fan Project—providing guidance on how to manage watersheds to maintain stability on fans. This is an outcome of presenting the second day workshop in Salmon Arm (dealing with risk). While this publication will have provincial significance, it will be of great interest to forest practitioners in the southern interior because they frequently are faced with difficult decisions regarding forest development in watersheds that drain onto fans with private and public infrastructure.
Conclusions The publication of two Land Management Handbooks was a major accomplishment in 2004–05. These resources were used in 2005–2006 as we continued to offer opportunities for forest practitioners to attend field workshops. Interaction with Group 2 of our target audience was positive, and is anticipated to result in increased participation in field workshops in 2006–07 (these events will be full cost recovery). Continued publication of professional and peer-reviewed articles is raising awareness of forested fans. Recognition of this project as a finalist in the Premier’s Award Innovation category was a significant achievement.
Literature Cited Beaty, C.B. 1970. Age and estimated rate of accumulation of an alluvial fan. White Mountains, California. Amer. Journ. of Sci. 268: 50-77. Bull, W.B. 1977. The alluvial-fan environment. Progress in Physical Geography. 1: 222-270. Church, M. and J.M. Ryder. 1972. Paraglacial sedimentation: A consideration of fluvial processes conditioned by glaciation. Geol. Soc. Amer. Bull. 83: 3059-3072. Hungr, O., S.G. Evans, M.J. Bovis, and J.N. Hutchinson. (2001) A review of the classification of landslides of the flow type. Environmental and Engineering Geoscience. 7(3): 221-238. Innes, J.L. 1985. Magnitude-frequency relations of debris flows in northwest Europe.
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