Fisheries Management Flashcards
What is a slump?
A slump is a form of mass wasting that occurs when a coherent mass of loosely consolidated materials or rock layers moves a short distance down a slope.
Movement is characterized by sliding along a concave（凹面的）-upward or planar surface. Causes of slumping include earthquake shocks, thorough wetting, freezing and thawing（融化）, undercutting and loading of a slope.
What are gullies?
Gullies
An area containing a stream whose overall gradient is = to or >25%; from the fan apex to the top of the headwall at least one reach greater than 100 meters in length has either a channel gradient >20%, a side wall >3m, and a side wall slope >50%
or
A gully is a landform created by running water, eroding sharply into soil, typically on a hillside. Gullies resemble large ditches or small valleys, but are meters to tens of meters in depth and width. When the gully formation is in process, the water flow rate can be substantial, which causes the significant deep cutting action into soil.
What is Soil Creep?
Also refer to downhill creep.
Is the slow downward progression of rock and soil down a low grade slope; it can also refer to slow deformation of such materials as a result of prolonged pressure and stress.
蠕动为一种缓慢的块体移动，包括土壤蠕动及岩石蠕动，规模较小。各类岩石风化后，产生碎石，泥沙以及巨石等松散物质，在重力作用下，均会缓慢地沿坡面向下移动。土壤移动由于速度缓慢，一般不易被察觉，唯有靠地面事物的变更，才可推测这种作用正在进行。土壤蠕动的征象包括，植物，栏杆以及电线杆向山下弯曲，移动较多时会使栏杆电线杆倒下或折断。山坡底部会有非原地风化土壤堆积。在一些较少干扰的坡地上，下移的土壤会形成小台阶，称为小型阶地(terracette).
What is a snow creep?
A continuous, slow, downhill movement of snow.
What is the difference between adsorption and absorption?
Adsorption 吸附（作用）
Absorption 吸收
Absorption is the process in which a fluid is dissolved by a liquid or a solid (absorbent). Adsorption is the process in which atoms, ions or molecules from a substance (it could be gas, liquid or dissolved solid) adhere to a surface of the adsorbent. Adsorption is a surface-based process where a film of adsorbate is created on the surface while absorption involves the entire volume of the absorbing substance.
Adsorption, water is connected to the surface of soil particles through H-bonding.
The absorption or water into the structure of soil particles only occurs with expansive type clays such as smectites or montmorillinites.
What is angle of repose?
The maximum angle to the horizontal at which rocks, soil, etc, will remain without sliding.
or
The steepest angle at which a pile of unconsolidated grains remains stable, and is controlled by the frictional contact between the grains. In general, for dry materials the angle of repose increases with increasing grain size, but usually lies between about 30 and 45 degrees.
What’s the difference between dry soil, moist soil and wet soil?
In terms of adsorption,
Dry soil particles hold together by grain to grain frictional contact. Angle of repose is usually 30 to 45 degrees.
Moist soil particles hold together by surface tension of a thin film of the adsorbate.
Wet soil, also refer to liquefaction, like water saturated sand, grain to grain contact was eliminated by complete surrounding of water.
How does water affect and otherwise stable slope?
(You use otherwise before stating the general condition or quality of something, when you are also mentioning an exception to this general condition or quality.)
Water adds weight to soil, increases mass and the effects of gravity.
(Slopes that are prone to instability are more likely to fail after heavy rains or high water input events)
Water has the ability to change the angle of repose.
What is alluvial fan?
An alluvial fan is a fan or cone shaped deposit of sediment crossed and built up by streams. If a fan is built up by debris flows it is properly called a debris cone or colluvial fan. These flows come from a single point source at the apex of the fan, and over time move to occupy many positions on the fan surface. Fans are typically found where a canyon draining from mountainous terrain emerges out onto a flatter plain, and especially along fault-bounded mountain fronts.
or
A fan-shaped accumulation of silt, sand, gravel, and boulders deposited by fast-flowing mountain rivers when they reach flatter land.
什么是冲积扇？
山地河流流过山麓后， 因为坡度变缓，流速降低，河道变宽，河水携带的物质大量堆积，使河床抬高。因此河流不断滴变迁改道，或分成多股水流，形成一个延伸很广，坡度较缓的台地。外形如同折扇。冲积扇从顶端到边缘，地面缓慢降低，坡度逐渐变小，堆积物逐渐变细，如果是发生在峡谷通往平原的出口，会形成冲积扇平原。冲积物经过风化，逐渐发育成冲积土，土壤的肥力较高。
Why are alluvial fans such a problem in forestry?
Harvesting and road construction on alluvial fans will have big problems. Because the deposition of sediment and woody debris causes avulsions, several new channels will be developed. These channels may run over in unanticipated area such as road. A lots of surface materials will be brought to the areas where trees grow and reduce the potential of growing. This process also cause sedimentation to the stream as well.
What is turbidity and how is it measured?
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air.
Turbidity is usually measured in nephelometric turbidity units (NTU) with a turbidity meter also known as a nephelometer.
How can we minimize sedimentation from roads?
By well road construction and maintenance, we can minimize sedimentation from roads.
For examples, building roads in appropriate locations and appropriate amount of area.
Well-designed steepness of pitches, road prism and side casting.
Set up enough drainage structures.
Choose the right type of drainage structures.
Well culvert maintenance and ditch maintenance.
How does forest cover control water flow through a watershed?
Uncut forest leads to high transpiration, evaporation and interception of water, it acts as an infiltration control.
Forest can reduce soil water, water concentration on the surface, less surface runoff.
With forest cover removal, compaction will happen if harvesting is carried out in very wet weather or on fine textured soils. But partial removal decreases the impact.
What are the main water parameter that affect fish in streams?
Clean - low levels of suspended sediments or pollutants
Dissolved oxygen - a minimum level of 6 ppm
pH near neutral
Temperature - from 3 to 15 degree centigrade ( Celsius degree)
Stream structure
