Unit+1+Fluvial+Systems+Review



**  Module 2- Review Sheet   **  · **   Hydrological Cycle   **  · **   Fluvial Processes   **  · **   Coastal Processes   **  · **   Limestone   ** ** __ Hydrological Cycle __ ** Definitions and Processes  Ø ** // Flows  // **  I. ** Precipitation **- All forms of rainfall, snow, frost, hail and dew. It is the conversation and transfer of moisture in the atmosphere to the land. Conditions for Precipitation to occur:  · Air must be saturated i.e. relative humidity (RH) 100%.  · Air contains condensation nuclei- soot, dust, ash, ice etc.  · Temperature is below dew point (i.e. RH @ 100%) – saturation complete and clouds form.  II. ** Interception **- Water stored by vegetation. There are 3 main components:-  · Interception Loss- water which is retained by the plant and is either absorbed or evaporated.  · Throughfall (Drip-flow)- water which either falls through gaps in the vegetation or drops from leaves twigs or stems.  · Stemflow- Water which trickles along twigs, branches or the trunk of the tree. // __ Factors Influencing Interception Loss: __ //  Þ ** Interception Capacity **- the ability to hold/store water. Dry leaves have greater surface tension, as the leaves get wetter the weight of the water reduces the surface tension causes throughfall.  Þ Meteorological Conditions- windspeeds may decrease interception loss by dislodging raindrops. ( Winds can blow the rain away)  Þ Amount/ Intensity of Rainfall- Heavier rainfall decreases interception loss. <span style="margin: 0in 0in 0pt 99pt; mso-list: l6 level1 lfo4; tab-stops: list 99.0pt; text-indent: -0.25in;"> Þ Frequency of storms – High storm frequency decreases interception loss. Interception loss varied by vegetation cover: <span style="margin: 0in 0in 0pt 63pt; mso-list: l15 level2 lfo2; mso-text-indent-alt: -9.0pt; tab-stops: list 63.0pt; text-indent: -63pt;"> III. ** Infiltration **- Processes whereby water soaks into or is absorbed by the soil. <span style="margin: 0in 0in 0pt 1.5in; mso-list: l15 level3 lfo2; tab-stops: list 1.5in; text-indent: -0.25in;"> § Infiltration Capacity- the maximum rate at which rain can be absorbed in a given condition. Factors Influencing Infiltration Capacity: <span style="margin: 0in 0in 0pt 1.5in; mso-list: l19 level1 lfo6; tab-stops: list 1.5in; text-indent: -0.25in;"> § Soil surface – hard soil, loose soil, tarmac surfaces. <span style="margin: 0in 0in 0pt 2in; mso-list: l19 level2 lfo6; tab-stops: list 2.0in; text-indent: -0.25in;"> ü 0-4mm/hr- clays <span style="margin: 0in 0in 0pt 2in; mso-list: l19 level2 lfo6; tab-stops: list 2.0in; text-indent: -0.25in;"> ü 3-12mm/hr- sands <span style="margin: 0in 0in 0pt 1.5in; mso-list: l19 level1 lfo6; tab-stops: list 1.5in; text-indent: -0.25in;"> § Surface Cover- vegetation increases infiltration rates by approx. 50-100mm/hr. <span style="margin: 0in 0in 0pt 2in; mso-list: l19 level2 lfo6; tab-stops: list 2.0in; text-indent: -0.25in;"> ü On bare soils rain drop impact (rain splash) inf. Is approx. 10mm/hr. <span style="margin: 0in 0in 0pt 1.5in; mso-list: l16 level1 lfo7; tab-stops: list 1.5in; text-indent: -0.25in;"> § Flow Conditions- Overland flow, duration and intensity of rainfall. <span style="margin: 0in 0in 0pt 1.5in; mso-list: l16 level1 lfo7; tab-stops: list 1.5in; text-indent: -0.25in;"> § Antecedent Conditions- <span style="margin: 0in 0in 0pt 2in; mso-list: l16 level2 lfo7; tab-stops: list 2.0in; text-indent: -0.25in;"> ü Soil moisture level <span style="margin: 0in 0in 0pt 2in; mso-list: l16 level2 lfo7; tab-stops: list 2.0in; text-indent: -0.25in;"> ü Soil porosity <span style="margin: 0in 0in 0pt 2in; mso-list: l16 level2 lfo7; tab-stops: list 2.0in; text-indent: -0.25in;"> ü Raindrop size <span style="margin: 0in 0in 0pt 2in; mso-list: l16 level2 lfo7; tab-stops: list 2.0in; text-indent: -0.25in;"> ü Slope Angle Moderately grazed. ||  19   ||   Heavily grazed   ||   13   || PAGE 7 PAGE 59 IV. ** Soil Moisture **- The subsurface water in the zone of aeration (Vadose Zone). The unsaturated soil and subsurface layers above the water table, marking the upper level of the zone of saturation. In this zone water may be: Note: In coarser textured soils, much of the water is held in fairly large pores at fairly low suctions. While very little is held in small pores. However where the number of pores is greater such as in the finer textured clay soils, more water is held at higher suctions. <span style="margin: 0in 0in 0pt 99pt; mso-list: l12 level1 lfo9; tab-stops: list 99.0pt; text-indent: -0.25in;"> Þ ** Field Capacity **- the amount of water held in the soil after excess water drains away. <span style="margin: 0in 0in 0pt 99pt; mso-list: l12 level1 lfo9; tab-stops: list 99.0pt; text-indent: -0.25in;"> Þ ** Wilting Point ** refers to the range of moisture content in which permanent wilting of plants occurs. (Compare turgidity) <span style="margin: 0in 0in 0pt 99pt; mso-list: l12 level1 lfo9; tab-stops: list 99.0pt; text-indent: -0.25in;"> Þ ** Soil moisture deficit **- the degree to which soil moisture falls below field capacity. <span style="margin: 0in 0in 0pt 99pt; mso-list: l12 level1 lfo9; tab-stops: list 99.0pt; text-indent: -0.25in;"> Þ ** Soil moisture recharge ** – occurs when precipitation exceeds potential evapotranspiration- there is some refilling of water in the dried up pores of the soil. <span style="margin: 0in 0in 0pt 99pt; mso-list: l12 level1 lfo9; tab-stops: list 99.0pt; text-indent: -0.25in;"> Þ ** Soil moisture surplus **- is the period when soil is saturated and water cannot enter and so flows over the surface. <span style="margin: 0in 0in 0pt 99pt; mso-list: l12 level1 lfo9; tab-stops: list 99.0pt; text-indent: -0.25in;"> Þ ** Soil moisture utilization **- is the process by which water is drawn to the surface through capillary action. <span style="margin: 0in 0in 0pt 1.25in; mso-list: l1 level1 lfo10; tab-stops: list 1.25in; text-indent: -0.5in;"> V. ** Groundwater **- the subsurface water. <span style="margin: 0in 0in 0pt 1in; mso-list: l12 level2 lfo9; tab-stops: list 1.0in; text-indent: -0.25in;"> o Most ground water is found within with in a few hundred meters of the surface but has also been found as deep as 4km. <span style="margin: 0in 0in 0pt 1in; mso-list: l12 level2 lfo9; tab-stops: list 1.0in; text-indent: -0.25in;"> o Ground water accounts for 96.5% of all fresh water on the earth. HOWEVER- while some ground water may be recycled within a matter of days or weeks, some ground water may not be recycled for as long as 20,000 years! Hence in some places ground water is considered a non-renewable resource. <span style="margin: 0in 0in 0pt 1in; mso-list: l12 level2 lfo9; tab-stops: list 1.0in; text-indent: -0.25in;"> o PAGE 248; 9 <span style="margin: 0in 0in 0pt 1.75in; mso-list: l14 level1 lfo11; tab-stops: list 1.75in; text-indent: -0.25in;"> § Phreatic Zone- the permanently saturated zone within solid rocks and sediments. Here nearly all the pore spaces are filled with water. The upper layer is the water table. <span style="margin: 0in 0in 0pt 1.75in; mso-list: l14 level1 lfo11; tab-stops: list 1.75in; text-indent: -0.25in;"> § Water table- the level above which saturation occurs. <span style="margin: 0in 0in 0pt 1.75in; mso-list: l14 level1 lfo11; tab-stops: list 1.75in; text-indent: -0.25in;"> § Aeration or Vadose Zone- the zone or area that is seasonally wetted or dries out. <span style="margin: 0in 0in 0pt 1.75in; mso-list: l14 level1 lfo11; tab-stops: list 1.75in; text-indent: -0.25in;"> § Aquifers- rocks which contain significant quantities of water. They are permeable rocks such as sandstones or limestones. <span style="margin: 0in 0in 0pt 1.75in; mso-list: l14 level1 lfo11; tab-stops: list 1.75in; text-indent: -0.25in;"> § Aquiclude/ Aquifuge- Impermeable rocks which prevent large scale storage or transmission of water. Factors Influencing Groundwater Recharge: <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l2 level1 lfo12; tab-stops: list .5in; text-indent: -0.25in;"> ü Infiltration of part of precipitation at the ground surface level <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l2 level1 lfo12; tab-stops: list .5in; text-indent: -0.25in;"> ü Seepage through banks and the bed of surface water bodies such as rivers, lakes, oceans, ditches etc. <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l2 level1 lfo12; tab-stops: list .5in; text-indent: -0.25in;"> ü Groundwater leakage and inflow through adjacent aquicludes and from aquifers. <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l2 level1 lfo12; tab-stops: list .5in; text-indent: -0.25in;"> ü Artificial recharge from irrigation, reservoirs etc Losses of Ground water result from: <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l18 level1 lfo13; tab-stops: list .5in; text-indent: -0.25in;"> ü Evapotranspiration, particularly in low lying areas where the water table is close to the ground surface. <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l18 level1 lfo13; tab-stops: list .5in; text-indent: -0.25in;"> ü Natural discharge by means of spring flow and seepage into surface water bodies. <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l18 level1 lfo13; tab-stops: list .5in; text-indent: -0.25in;"> ü Groundwater leakages and outflows through aquicludes and into adjacent aquifers <span style="line-height: 150%; margin: 0in 0in 0pt 0.5in; mso-list: l18 level1 lfo13; tab-stops: list .5in; text-indent: -0.25in;"> ü Artificial abstraction. <span style="line-height: 150%; margin: 0in 0in 0pt 1.25in; mso-list: l1 level1 lfo10; tab-stops: list 1.25in; text-indent: -0.5in;"> VI. Evaporation – process whereby a liquid or solid is changed into a gas. <span style="line-height: 150%; margin: 0in 0in 0pt 1.25in; mso-list: l1 level1 lfo10; tab-stops: list 1.25in; text-indent: -0.5in;"> VII. Evapo-transpiration- EVT/ET- the combined effects of evaporation and transpiration. <span style="line-height: 150%; margin: 0in 0in 0pt 1.25in; mso-list: l1 level1 lfo10; tab-stops: list 1.25in; text-indent: -0.5in;"> VIII. Potential EVT- the water loss that would occur if there was an unlimited supply of water in the soil for use by vegetation. <span style="line-height: 150%; margin: 0in 0in 0pt 1.25in; mso-list: l1 level1 lfo10; tab-stops: list 1.25in; text-indent: -0.5in;"> IX. Condensation- process where water vapor passes into a liquid form. Average water renewal cycles for different water bodies. Page: 59 ; 58. Storm Hydrograph Storm Hydrograph shows the variation of river discharge with time. Normally it refers to an individual storm or group of storms of not more than a few days in length (short term scale). It considers the sequence of relationships between run off and other components of the basin water balance together with their adjustments to the physical characteristics of the basin. Before the storm starts the main supply of water to the stream is through ground water flow or base flow. During the storm some of the water infiltrates into the soil while some flows over the surface as overland flow or run off- which reaches the river as ** // quickflow // ** causing rapid rise and bank-full discharge. Features of the Storm Hydrograph: <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level1 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> ü Controlled by the amount of water stored in the basin in the soil and bedrock. <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level1 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> ü Further rain during the recession can cause one or more peaks to occur <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level1 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> ü No more rain will result in discharge reducing till flow returns to normal level. <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level2 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> § Base Flow- the normal level of the river which is fed by ground water. <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level2 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> § Quickflow or stromflow- the water which gets into the river as a result of overland runoff. <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level2 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> § Bankfull discharge- the discharge measured when a river is at bankfull stage <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level2 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> § Bankfull stage – a condition in which a river’s channel fills completely so that any further increase in discharge results in overflowing banks ( flooding). <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level2 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> § Discharge – the quantity of water that passes a given point on the bank of a river within a given interval of time. <span style="margin: 0in 0in 0pt 0.5in; mso-list: l4 level2 lfo15; tab-stops: list .5in; text-indent: -0.25in;"> § Flood – a discharge great enough to cause a body of water to overflow its channels and submerge surrounding land. The Shape and Size of the Hydrograph are controlled by two sets of factors: <span style="margin: 0in 0in 0pt 117pt; mso-list: l3 level1 lfo16; tab-stops: list 117.0pt; text-indent: -0.25in;"> Þ Permanent factors- those involving the character of the basin <span style="margin: 0in 0in 0pt 1.25in; mso-list: l3 level2 lfo16; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Size of the Basin- Large basins receive more rain than smaller ones and have larger flood run-off discharges. Note however, large basins tend not to have such steep slopes as smaller ones and slope angle controls run off rates. <span style="margin: 0in 0in 0pt 1.25in; mso-list: l3 level2 lfo16; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Shape of the basin – In general a round basin will generate a more peaked flood hydrograph than a long thin one with the same area. Due to the length of time for the water to reach the gauging stations. <span style="margin: 0in 0in 0pt 1.25in; mso-list: l3 level2 lfo16; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Basin Slope – Other things being equal, channel flow will be faster down a steep slope than down a gentle slope. The geology is also very important since it affects the nature of the soil, the texture of the stream network, the nature of the groundwater and its speed of movement. <span style="margin: 0in 0in 0pt 1.25in; mso-list: l3 level2 lfo16; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Rock structure is largely important as a guiding factor in the movement of ground water towards the streams. Therefore it is probable that the time lag between rainfall and groundwater runoff peaks will be smaller in the case of synclical catchment where the rock dip towards the channel then in the case of the catchment with horizontally bedded strata. <span style="margin: 0in 0in 0pt 1.25in; mso-list: l3 level2 lfo16; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Vegetative Cover- the amount of vegetation cover affects transpiration and interception rates. As well as the ease over which water can flow across the slope, the soil structure etc. <span style="margin: 0in 0in 0pt 117pt; mso-list: l3 level1 lfo16; tab-stops: list 117.0pt; text-indent: -0.25in;"> Þ Transient factors- those that are variable eg climatic condititions. <span style="margin: 0in 0in 0pt 135pt; mso-list: l13 level1 lfo17; tab-stops: list 135.0pt; text-indent: -0.25in;"> ü Meteorological conditions- if precipitation is snowfall rather than rainfall the hydrograph is modified. A blanket of snow has a storage effect and discharge rates are relatively low, until snow melt in the spring. Even if rain falls, the snow may absorb the water and release it when melting occurs. <span style="margin: 0in 0in 0pt 135pt; mso-list: l13 level1 lfo17; tab-stops: list 135.0pt; text-indent: -0.25in;"> ü Intensity of rainfall- heavy rainfall may exceed the infiltration rate of the soil, so that it runs off quickly and is added to discharge. Whereas, rain falling at lower intensities will be largely absorbed by the soil and thus its addition to streamflow will probably be delayed. The duration of rainfall is also important. As the soil loses its ability to absorb water decreases through time. <span style="margin: 0in 0in 0pt 135pt; mso-list: l13 level1 lfo17; tab-stops: list 135.0pt; text-indent: -0.25in;"> ü Land-use changes- Paved surfaces, deforestation, afforestation of areas, dredging of rivers etc can affect overland flow, infiltration and stream flow and discharge rates. River Regime ( Water flow of river on an Annual scale). Influences: <span style="margin: 0in 0in 0pt 0.5in; mso-list: l5 level1 lfo18; tab-stops: list .5in; text-indent: -0.25in;"> ü The amount and nature of precipitation <span style="margin: 0in 0in 0pt 0.5in; mso-list: l5 level1 lfo18; tab-stops: list .5in; text-indent: -0.25in;"> ü The local rocks, especially porosity and permeability <span style="margin: 0in 0in 0pt 0.5in; mso-list: l5 level1 lfo18; tab-stops: list .5in; text-indent: -0.25in;"> ü Morphology of the drainage basin, area and slope. <span style="margin: 0in 0in 0pt 0.5in; mso-list: l5 level1 lfo18; tab-stops: list .5in; text-indent: -0.25in;"> ü Amount of vegetative cover <span style="margin: 0in 0in 0pt 0.5in; mso-list: l5 level1 lfo18; tab-stops: list .5in; text-indent: -0.25in;"> ü Amount and type of soil cover. * On An annual basis Climate is one of the most important determining factors of the river regime. Urbanisation and Hydrology. <span style="margin: 0in 0in 0pt 0.75in; mso-list: l10 level1 lfo19; tab-stops: list .75in; text-indent: -0.25in;"> v In urban areas surfaces are paved ( tarmac) which lead to: <span style="margin: 0in 0in 0pt 1.25in; mso-list: l10 level2 lfo19; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Reduced water storage <span style="margin: 0in 0in 0pt 1.25in; mso-list: l10 level2 lfo19; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Increased percent run off <span style="margin: 0in 0in 0pt 1.25in; mso-list: l10 level2 lfo19; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Increased velocity of overland flow <span style="margin: 0in 0in 0pt 1.25in; mso-list: l10 level2 lfo19; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Decrease evapotranspiration <span style="margin: 0in 0in 0pt 1.25in; mso-list: l10 level2 lfo19; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Reduced percolation ( therefore groundwater). <span style="margin: 0in 0in 0pt 0.75in; mso-list: l10 level1 lfo19; tab-stops: list .75in; text-indent: -0.25in;"> v Drainage density increases (i.e. the total length of the stream channel per km2, through the network of storm sewers, gutters, gullies, and drains. Effects are: <span style="margin: 0in 0in 0pt 1.25in; mso-list: l9 level1 lfo20; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Reduces overland flow, water reaches channel faster  <span style="margin: 0in 0in 0pt 1.25in; mso-list: l9 level1 lfo20; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Increases velocity since sewers etc are smooth and friction is reduced  <span style="margin: 0in 0in 0pt 1.25in; mso-list: l9 level1 lfo20; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Basin storage is reduced so the volume of water reaching the channel is increased.  <span style="margin: 0in 0in 0pt 1.25in; mso-list: l9 level1 lfo20; tab-stops: list 1.25in; text-indent: -0.25in;"> ü Peak flows increase, eg. 243% increase from construction of Stevenage, U.K. Likewise, from 25mm rainfall increased by three times after paving an extra 6% of Silk Stream in North London and the lag time decreased by 40%. <span style="margin: 0in 0in 0pt 0.75in; mso-list: l9 level2 lfo20; tab-stops: list .75in; text-indent: -0.25in;"> v Increased rates of erosion- during the construction phase. After clearing soil is exposed to storms increasing overland flow, heavy machinery churns soils which increases erodibility. ( Although erosion decreases after paving). <span style="margin: 0in 0in 0pt 0.75in; mso-list: l9 level2 lfo20; tab-stops: list .75in; text-indent: -0.25in;"> v Consequences of Construction and reclamation of land near to the river: <span style="margin: 0in 0in 0pt 1.5in; mso-list: l9 level3 lfo20; tab-stops: list 1.5in; text-indent: -0.25in;"> ü Channel width is reduced ( water in channel rises higher) <span style="margin: 0in 0in 0pt 1.5in; mso-list: l9 level3 lfo20; tab-stops: list 1.5in; text-indent: -0.25in;"> ü Bridges can obstruct flow of river, increasing flood levels upstream. Page: 64;65;66
 * German Beech forests- 40% in summer, 20% in winter
 * Grasses- very low interception
 * Deciduous woodlands- higher interception than grasses
 * Coniferous Forests- High because: - (a) pine needles allow for individual accumulation, (b) freer air circulation increases air circulation.
 * Crops, cereals etc- increases with density.
 * **  Ground Cover   **  ||  **   Infiltration Rates mm/hr   **  ||
 * Old permanent pasture  ||   57   ||
 * Permanent Pasture:
 * Permanent Pasture:
 * Strip Cropped  ||   10   ||
 * Weeds or grains  ||   9   ||
 * Clean tilted  ||   7   ||
 * Bare, crusted ground  ||   6   ||
 * Absorbed
 * Held
 * Transmitted downwards towards the water table
 * Transmitted upwards towards the soil surface and the atmosphere.
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Permanent Snow  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  9700 years  **  ||
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Oceans  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  2500 years  **  ||
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Groundwater  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  1400 years  **  ||
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Lakes  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  17 years  **  ||
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Swamp Water  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  5 years  **  ||
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Soil moisture  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  1 year  **  ||
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Streams  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  16 days  **  ||
 * <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> ** Atmospheric Moisture  **  || <span style="line-height: 150%; margin: 0in 0in 0pt; mso-element-anchor-horizontal: column; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-top: .05pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly; text-align: center;"> **  8 days  **  ||
 * Rising Limb- The portion of the graph that shows how rapidly the flow (flood waters) rises.
 * Peak flow also called the Crest- the maximum discharge of the river as a result of the storm. Measured when the amount of water passing the gauge has reached maximum.
 * Lag Time- the time between the height of the storm and the maximum flow in the river. ( NB: NOT the start or the end of the storm).
 * Recessional Limb- the speed with which the water level in the river declines after the peak.