Treesearch

One of the basic issues facing managers of fisheries watersheds is how inputs of sediment affect stream channels. In some cases we can measure and even roughly predict effects of land use on erosion and delivery of sediment from hillslopes to streams. But we are at a loss about how a given increase in sediment load will affect channel morphology, flow conditions, and substrate. As a result, we are unable to relate watershed processes to productivity of fish habitat. The method described here is meant to begin to fill this gap.

Abstract The environment of the earth is exceedingly complex and variable. Indicator species are used to reduce thaf complexity and variability to a level that can be more emily understood. In recent years, use of indicators has increased dramatically. For the Forest Service, as an example, regulations that interpret the National Forest Management Act require the use of indicdor species for monitoring the effects of management actions. Although indicators have been in use for a reldvely long period of time and such use is increasing, there are a number of problems associated with (he use...

Abstract - Alternate bars were formed by sediment transport in a flume with Froude-modelled flow and relative roughness characteristic of gravel-boulder channels with steep slopes. The flume (0.3 m wide x 7.5 m long) was filled with a sand-gravel mixture, which was also fed into the top of the flume at a constant rate under constant discharge. Channel slope was set at 0.03. Initially, coarse particles accumulated on incipient bar heads near one side of the flume and diverted flow and bedload transport across the flume toward a pool scoured against the opposite flume wall downstream....

Sediment transport occurring after spawning can cause scour of incubating embryos and infiltration of fine sediment into spawning gravel, decreasing intergravel flow and preventing hatched fry from emerging from the gravel. Documentation of these effects requires measuring gravel conditions before and after high flow periods and combining methods to record scour and fill and sediment infiltration by different grain sizes at different depths in the streambed. Scour and fill is best measured with scour chains, which can record the depth of maximum scour that occurs during high flow. Repetitiv...

In New Zealand responsibility for funding flood protection and erosion prevention and control projects rests largely with local regional authorities. However, in 1988 Central Government decided to provide direct funding for a major forestry conservation scheme in the erosion-susceptible East Coast region. Government's investment decision was influenced by a number of factors, the most important being the extent and severity of erosion in the East Coast region and its negative impact on the region's social and economic development.

Addressing the problems associated with watersheds in both countries is the aim of this paper as well as assessing the respective watershed policies. Attention has been drawn to specific economic, environmental and sociocultural considerations in the recent past. An interesting feature of the most recent policy developments is the tendency to follow a balanced approach to water resource development in either situation. In Australia, it is envisaged to follow a co-ordinated and sustainable use and management of land water, and vegetation resources on a water catchment basis. In Sri Lanka...

Abstract. Prescribed fire is a tool used to manage vegetation in southern California. The nature and quantity of gaseous and particulate emissions have not been described for California chaparral. A study examining carbon monoxide (CO), carbon dioxide (CO2), and particulate matter emissions from fuel beds constructed from common chaparral shrubs was initiated. Chamise (Adenostoma fasciculatum), ceanothus (Ceanothus crassifolius),manzanita (Arctostaphylos glandulosa), and scrub oak (Quercus dumosa) fuel beds were burned in December 1989, and March, May, and August, 1990. Gas and particulate...

A simple device for estimating snow settling force on tree branches was used to determine the distribution of snow settling force at various heights in a snowy mountainous region in Japan. A trapezoidal distribution of snow settling force was found to exist at all sites tested. It is thought that a zoning scheme based on the damaging potential of snow on young man-made forests would become possible, with the acquisition of sufficient data.