Then porepressure ratio is equal to pore pressure coefficients B. The knowledge of pore pressure parameters is essential for the determination of effective stress from total stress. Skempton gave the pore pressure parameters which express the response of pore pressure due to changes in the total stress under undrained conditions. These parameters are used to predict pore water pressure in the field under similar condi-tions. Pore pressure coefficient A fluctuates with both the stress value and the rate of strain, due mainly to the variation of Δud with the deviator stress for a given soil.
By investigation at this point, the surrounding map couture’s can be utilised to scribe a relating drainage basin or catchment. This catchment effectively sets out the area of flow in which will run into this point. Therefore based on this principle, it is shown that the further upstream this point if specified, the smaller the relating catchment. However the further downstream, the larger the catchment, as the larger the upstream area of flow serving it. As mentioned previously, catchment run-off occurs as both surface and groundwater run-off.
Pipes may transmit a large proportion of water to the stream in some catchments. The pipe networks can be complex and can provide a rapid connectivity of water, sediment and solutes coupling distant parts of hillslopes with stream channels. • Subsurface Flow – The runoff movement is principally below the ground surface. This will occur wherever the soil’s infiltration capacity is greater than zero. This is the dominant runoff process in the temperate humid regions where lush vegetation cover has produced a porous soil structures with infiltration capacity of many inches per
CHAPTER-6 DEMARCATION OF GROUNDWATER POTENTIAL ZONES 6.1 GENERAL Groundwater potential is the rate of water that can be abstracted from an aquifer in sustainable rate without any adverse impact on the whole environment. But in many parts of the world, groundwater abstraction has exceeded the safe yield, resulting in overexploitation and overstressing of the aquifer. Therefore quantum of available groundwater resource has to be assessed accurately for its optimum extraction and utilization. Groundwater crisis has been caused by human actions and demand for water in domestic , agriculture and industry use. Weighted overlay technique is used in demarcating the groundwater potential of the study area.
Drainage integration of the basin also increases flood risk. Possibility of surface water stagnation is also quite high due to low stream frequency and drainage density at its lower reach. This observation is supported by frequent flood in the lower segment of the
From the selected segments, different channel reaches are used to calculate the sinuosity indexes and the values of the index are varying from 1.3 to a maximum of 2.8 indicating the transition of stream segments from normal sinuous nature to irregular meander. In the lowland segment analysed, the sinuosity index varies from 1.3 (sinuous) to 2 (meandering). A similar trend was also noted in the midland segment with the sinuosity index, ranging between 1.4 (sinuous) to 1.9 (meandering). At the same time, it was noted that the maximum sinuosity index was shown by the highland segment of the river, which varies from 1.3 (sinuous) to 2.8 (meandering with channel bars). The high value of sinuosity indexes represents a change in the planform pattern of river in this region.
Introduction Hydraulic properties of soil are one of the most important agents controlling infiltration, runoff rate, pesticides leaching in agricultural lands, and migration of pollutants from contaminated sites to groundwater. Therefore, there is a need for good water management practices in order to solve water-related problems such as irrigation and erosion issues. Infiltration is the term applied to the process of water entry into the soil. This process is the movement of water into the soil from the surface by downward or gravitational flow. The rate at which it occurs is known as the infiltration rate, which continues to decrease and asymptotically approaches the saturated hydraulic conductivity.
The measure of infiltration called the infiltration rate is usually done in the field by flooding basins or furrows or measuring water entry from infiltrometer rings. Measurement by ponding in large areas is the most reliable but due to its cost, the infiltrometer rings are mostly used. Ring infiltrometers are used for measuring the water intake rate at the soil surface 1.1 Measurement of Infiltration Double- ring infiltrometer The double-ring infiltrometer consists of two rings of diameter 22.5 to 90 cm which are driven into the ground by a driving plate and hammer. They are made to penetrate the soil uniformly to a depth of 15 cm without disturbing the soil surface. After driving, a metal tamper is used to tamp any disturbed soil adjacent to the sides of the rings.
LITERATURE REVIEW 2.1 General The natural soil behaves like an Expansive soil or cracking soil because these have tendency of shrinking and cracking when moisture content decreases and also have tendency of swelling when moisture content increases. The moisture may come from water leakage or sewer lines, rain, flooding. Soil generally exhibits these properties, when it contains montmorillonite clay minerals. The engineering properties of Natural soil includes plasticity characteristics, compaction properties, volume stability its strength may be enhanced by adding materials such as Rice husk ash, Sugarcane bagasse ash, cement, sodium chloride etc. The changes in properties of these soils primarily depend upon the type and amount of binder,
This type of soil contains higher amounts of carbonate and bicarbonate. This soil type has also been known as “Alkaline sodic soil”. Excessive amounts of carbonate and bicarbonate salts may be brought into soil with groundwater by capillary effect or by irrigation water (Fujiyama and Magara,). World wide, the total amount of saline soils is around 15% in arid and semi-arid regions and approximately 40% in irrigated lands. Effect Of Soil Salinity On Plants : The growth of plant is inhibited by the salt when the salt concentration is high then the salt tolerant of plants and in the region of root soil.