Irrigation Notes PDF

Under the Guidance of – Mr. Dhyan Pal ( IES AIR-179 ,GATE AIR-93&145 ,UPPSC AE Rank -02 GWD, SSC JE selected) IRRIGATION ALL IN ONE PDF (TOTHEPOINT UPDATED VERSION 2.O) Useful for objective and conventional types exams li...

Under the Guidance of – Mr. Dhyan Pal ( IES AIR-179 ,GATE AIR-93&145 ,UPPSC AE Rank -02 GWD, SSC JE selected) IRRIGATION ALL IN ONE PDF (TOTHEPOINT UPDATED VERSION 2.O) Useful for objective and conventional types exams like ESE, GATE, UPPSC-AE, SSC-JE, RRB Exams etc Dedicated to All Students who are making sincere efforts to achieve their Dreams. To watch explanation of this pdf: Join Irrigation Engineering Course at: https://llehlr.courses.store/487329?utm_source%3Dother%26utm_medium%3Dtutor-course- referral%26utm_campaign%3Dcourse-overview-webapp Join 5 subjects Combo-1 (ConcreteTechnology+BMC+SOM+Highway+Surveying) Complete Detailed course for Video lecture and PDFs at: https://llehlr.courses.store/423775?utm_source%3Dother%26utm_medium%3Dtutor-course- referral%26utm_campaign%3Dcourse-overview-webapp Join 5 subjects Combo-2 (RCC+STEEL+SOIL MECHANICS +Open channel flow +Environment ) Complete Detailed course for Video lecture and PDFs at: https://llehlr.courses.store/482159?utm_source%3Dother%26utm_medium%3Dtutor-course- referral%26utm_campaign%3Dcourse-overview-webapp Join Telegram Group: https://t.me/ToThePointByDhyanPal Download Mobile App: https://clpdiy4.page.link/WUDU  Chapter-1 Irrigation and Methods of Irrigation Irrigation may be defined as the science of artificial application of water to the land, in accordance with the crop requirements throughout the crop period for full- fledged nourishment of the crops. Need Of Irrigation: (i) Inadequate rainfall (ii) Uneven distribution of rainfall (iii) To Increase in crop yield (iv) Growing perennial crop like sugarcane (v) Growing multiple crops (2-3 crops in a year) Advantages of Irrigation: Direct advantages Indirect advantages (1) Increase in food production: Increase in (1) Power generation: Major River valleys projects are crop yield due to irrigation leads to increase food usually planned to provide hydroelectric power together production, to attain self-sufficiency. with irrigation. However relatively small quantity of ii) Protection against drought: The provision hydroelectric power may also be generated at a small of adequate irrigation facilities in any region cost on projects which are primarily planned for ensures protection against failure of crops from famine or droughts. irrigation. (iii) Revenue generation: When regular supply of water is assured for irrigation the cultivators can grow certain superior or high-priced crops (like cash crops). Thus, revenue is generated. Note: Cash Crops: a crop that is grown mainly to be sold, rather than used by the people who grew it or those living in the area it is grown in. Example: कॉफी, चाय, कपास और गन्ना (iv) Mixed cropping: Means sowing of two or more crops together in the same field. (ii) Transportation: Most of the irrigation canals are This practice is followed so that if weather provided with unsurfaced roads primarily for purposes of conditions are not favorable for one crop it inspection and maintenance. These roads provide a good may be suitable for another crop. But if pathway to the local people. irrigation facilities are made available, the need of mixed cropping is eliminated. (iii) Employment: During the constructions of irrigation Advantage of mixed cropping is that, even works, employment is provided when one crops fails, then also there is no loss in terms of revenue. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Disadvantages of Irrigation/Ill effect of irrigation: Note: If irrigation water is used judiciously with proper scientific consideration, then there won't be ill effects of irrigation.  Abundant/Excess supply of irrigation water tempts the cultivators to use more water than required which would ground water table would be raised and will lead to water logging.  The ground water can get polluted due to seepage of the nitrates into the ground water (applied to the soil as fertilizers).  Intensive irrigation results in cold and damp climate, which causes spreading of disease such as dengue and malaria. Types Of Irrigation Projects Project Irrigation Potential (in hectares) Project cost (in crores) Major irrigation project >10000 >5 Medium irrigation project 2000-10000 0.25-5 Small irrigation project Inundation or uncontrolled or flood irrigation irrigation Duty 4. Method of Furrow irrigation method Duty > Any other method Duty irrigation Surface irrigation method has less duty than Sprinkler and drip irrigation method. 5. Quality of If Salt and alkalis dissolve in water increases ↑ then Duty decreases ↓ As irrigation water Most of the water is wasted (used in leaching) 6. Method of If properly ploughed up to the required depth and made quite loose before cultivation irrigating, the soil will have high water retention capacity in the root zone of plants. This will reduce no. of watering and hence result in a higher duty of water. (Proper Ploughing therefore D ↑) 7. Time of irrigation In the initial stages, the land to be cultivated may not be properly levelled and and frequency of hence more than the required quantity of water may be applied, which will irrigation result in a lower duty of water. Frequent cultivation of land reduces the loss of moisture through weeds and evaporation from soil and hence results in a higher duty of water. (At initial stage more water required hence D ↓ later D ↑) 8. Type of soil & sub If the canal is unlined and it passes through coarse grained soil then since there soil of area through will be greater percolation, loss the duty of water will be low. which canal passes On the other hand, if an unlined canal is passing through fine grained soil, then the percolation loss will be less and hence the duty of water will be high. 9. Base period of In general, when the base period of crop is long, more water is required thus crop resulting in lower duty of water. 10. Canal Earthen canal → D ↓ because percolation loss is more. Conditions Lined canal → D ↑ because percolation loss is less. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Important Terminology: 1. Gross Command area (GCA):  The gross commanded area is defined as the total area which can be irrigated by a canal system such that unlimited quantity of water is available.  It is the total area lying b/w the drainage boundaries which can be irrigated by a canal system.  It includes culturable as well as unculturable area (ponds, residential area, roads, forest) 2. Culturable Command area (CCA): That portion of GCA which is culturable. CCA=GCA-Unculturable area (not fit for cultivation ponds, residential area, roads, forest) Culturable Command area Culturable Cultivated area: Culturable uncultivated area Portion of CCA which is actually cultivated Portion of CCA which is not cultivated during during crop season crop season 3. Intensity of irrigation: % of CCA proposed to be irrigated annually. Example: If intensity of irrigation for Rabi = 50% If intensity of irrigation for Kharif = 65% Therefore, yearly intensity of irrigation = 50 + 65 = 115% Note: yearly intensity of irrigation can be greater than 100%. 4. Crop ratio (Kharif-rabi ratio):  Crop ratio is the ratio of areas under different crops to be irrigated during a year.  1t is usually expressed as the ratio of Kharif crops area to the Rabi crops area.  The crop ratio is usually selected such that the discharge required is approximately the same in both crops. Because the water requirements for Kharif crops are approximately twice those for Rabi crops, the Rabi crop area is kept about twice the Kharif crop area. In other words, the crop ratio is about 0.5. 5. Time factor: The ratio of number of days the canal has actually run during a watering period to the total number of days of the watering period is known as time factor. 𝑁𝑜. 𝑜𝑓𝑑𝑎𝑦𝑠 𝑐𝑎𝑛𝑎𝑙 𝑎𝑐𝑡𝑢𝑎𝑙𝑙𝑦 𝑟𝑢𝑛 𝑇𝑖𝑚𝑒𝑓𝑎𝑐𝑡𝑜𝑟(𝑇𝐹) = 𝐼𝑟𝑟𝑖𝑔𝑎𝑡𝑖𝑜𝑛𝑝𝑒𝑟𝑖𝑜𝑑 𝑄 𝑄𝑑𝑒𝑠𝑖𝑔𝑛 = 𝑇.𝐹 Normally canal supplying irrigation water must run on all the days during each watering period but often on account of some unavoidable circumstances the canal may have to be closed for some days during the watering period. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  6. Capacity factor: if A canal is designed for a certain maximum discharge capacity but it need not carry the max. discharge always. Hence, ratio of the mean supply discharge of a canal for a certain duration to its max. discharge capacity (full supply discharge) is known as capacity factor. 𝑀𝑆𝑄𝑜𝑓𝑐𝑎𝑛𝑎𝑙 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦𝑓𝑎𝑐𝑡𝑜𝑟(𝐶𝐹) = 𝐹𝑆𝑄 𝑜𝑓 𝑐𝑎𝑛𝑎𝑙 𝑸 𝑸𝒅𝒆𝒔𝒊𝒈𝒏 = 𝑪. 𝑭 Ex. if during kharif season area sown is such that discharge required is 0.90 Q max then capacity factor = 0.90, where Qmax = maximum capacity of canal. During Rabi it will be say 0.60 Qmax But to improve the capacity factor more area can be sown in Rabi. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  8.Fully supply coefficient (Duty on capacity): it is design duty at head of canal. 𝒂𝒓𝒆𝒂 𝒆𝒔𝒕𝒊𝒎𝒂𝒕𝒆𝒅 𝒕𝒐 𝒃𝒆 𝒊𝒓𝒓𝒊𝒈𝒂𝒕𝒆𝒅 𝒅𝒖𝒓𝒊𝒏𝒈 𝒃𝒂𝒔𝒆 𝒑𝒆𝒓𝒊𝒐𝒅 𝑭𝑺𝑪 = 𝒅𝒆𝒔𝒊𝒈𝒏 𝒇𝒖𝒍𝒍 𝒔𝒖𝒑𝒑𝒍𝒚 𝒅𝒊𝒔𝒄𝒉𝒂𝒓𝒈𝒆 𝒂𝒕 𝒕𝒉𝒆 𝒉𝒆𝒂𝒅 𝒐𝒇 𝒄𝒂𝒏𝒂𝒍 Numerical: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Irrigation Efficiencies: The ratio of the water available for use to the water applied is defined as irrigation efficiency. Various types of irrigation efficiencies are: I. Water 𝒒𝒏𝒕. 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒅𝒆𝒍𝒊𝒗𝒆𝒓𝒆𝒅 𝒕𝒐 𝑭𝒊𝒆𝒍𝒅 𝜼𝒄 = conveyance 𝒒𝒏𝒕. 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒅𝒊𝒗𝒆𝒓𝒕𝒆𝒅 𝒇𝒓𝒐𝒎 𝒓𝒊𝒗𝒆𝒓 𝒊𝒏𝒕𝒐 𝒄𝒂𝒏𝒂𝒍 efficiency It accounts for the water losses (evaporation, seepage) which occur during conveyance from the point of diversion into the canal system to the field. II 𝒒𝒏𝒕. 𝒐𝒇 𝑾𝒂𝒕𝒆𝒓 𝒔𝒕𝒐𝒓𝒆𝒅 𝒊𝒏 𝒓𝒐𝒐𝒕𝒛𝒐𝒏𝒆 𝒐𝒇 𝒑𝒍𝒂𝒏𝒕 𝜼𝒂 = Application 𝒒𝒏𝒕. 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒅𝒆𝒍𝒊𝒗𝒆𝒓𝒆𝒅 𝒕𝒐 𝑭𝒊𝒆𝒍𝒅 efficiency It accounts for the water losses which occur during the application of irrigation water (Ex. Surface run off & deep percolation) Note: In the case of sprinkler irrigation method, the water application efficiency may be as high as 80% while in the case of a surface irrigation method it may not exceed 60%. III. Water 𝜼𝒖 𝒒𝒏𝒕. 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒖𝒔𝒆𝒅 𝒃𝒆𝒏𝒆𝒇𝒊𝒄𝒊𝒂𝒍𝒍𝒚 𝒊𝒏𝒄𝒍𝒖𝒅𝒊𝒏𝒈 𝒕𝒉𝒆 𝒘𝒂𝒕𝒆𝒓 𝒓𝒆𝒒𝒖𝒊𝒓𝒆𝒅 𝒇𝒐𝒓 𝒍𝒆𝒂𝒄𝒉𝒊𝒏𝒈 use efficiency = 𝒒𝒏𝒕. 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒅𝒆𝒍𝒊𝒗𝒆𝒓𝒆𝒅 𝒕𝒐 𝑭𝒊𝒆𝒍𝒅 𝒒𝒏𝒕. 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒖𝒔𝒆𝒅 𝒃𝒆𝒏𝒆𝒇𝒊𝒄𝒊𝒂𝒍𝒍𝒚 𝒊𝒏𝒄𝒍𝒖𝒅𝒊𝒏𝒈 𝒕𝒉𝒆 𝒘𝒂𝒕𝒆𝒓 𝒓𝒆𝒒𝒖𝒊𝒓𝒆𝒅 𝒇𝒐𝒓 𝒍𝒆𝒂𝒄𝒉𝒊𝒏𝒈 = 𝑪𝒖 + 𝑳𝑹 + 𝑷𝑺𝑹 + 𝑵𝑾𝑹 (LR: leaching requirement: PSR: presowing requirement; NWR nursery water requirement) IV. Storage 𝜼𝒔 𝒒𝒏𝒕. 𝒐𝒇 𝑾𝒂𝒕𝒆𝒓 𝒔𝒕𝒐𝒓𝒆𝒅 𝒊𝒏 𝒓𝒐𝒐𝒕𝒛𝒐𝒏𝒆 𝒐𝒇 𝒑𝒍𝒂𝒏𝒕 efficiency = 𝒒𝒏𝒕. 𝒐𝒇 𝑾𝒂𝒕𝒆𝒓𝒏𝒆𝒆𝒅𝒆𝒅𝒕𝒐𝒃𝒓𝒊𝒏𝒈𝒕𝒉𝒆𝑴𝒐𝒊𝒔𝒕𝒖𝒓𝒆 𝑪𝒐𝒏𝒕𝒆𝒏𝒕 𝒐𝒇𝒔𝒐𝒊𝒍 𝒕𝒐 𝒇𝒊𝒆𝒍𝒅𝒄𝒂𝒑𝒂𝒄𝒊𝒕𝒚 V. Water 𝒚 distribution 𝜼𝒅 = [𝟏 − ] ∗ 𝟏𝟎𝟎 𝒅 efficiency 𝑑1 +𝑑2 +.....𝑑𝑛 d = Average depth of water = 𝑛 |𝑑1 −𝑑|+|𝑑2 −𝑑|+.....|𝑑𝑛 −𝑑| y = average numerical deviation in depth of water stored from average depth d= 𝑛 Note: if 𝜼𝒅 = 𝟏𝟎𝟎% 𝒎𝒆𝒂𝒏𝒔 𝟏𝟎𝟎% 𝒖𝒏𝒊𝒇𝒐𝒓𝒎𝒊𝒕𝒚 𝒊𝒏 𝒘𝒂𝒕𝒆𝒓 𝒅𝒊𝒔𝒕𝒓𝒊𝒃𝒖𝒕𝒊𝒐𝒏. VI. 𝑪𝒐𝒏𝒔𝒖𝒎𝒑𝒕𝒊𝒗𝒆 𝒖𝒔𝒆 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒐𝒓 𝑬𝒗𝒂𝒑𝒐𝒕𝒓𝒂𝒏𝒔𝒑𝒊𝒓𝒂𝒕𝒊𝒐𝒏 Consumptive 𝜼 𝒄𝒖 = 𝑵𝒆𝒕 𝒂𝒎𝒐𝒖𝒏𝒕 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒅𝒆𝒑𝒍𝒆𝒕𝒆𝒅 𝒇𝒓𝒐𝒎 𝒓𝒐𝒐𝒕𝒛𝒐𝒏𝒆 efficiency Trick: CCD: café coffee Day For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Irrigation Requirement of Crops: basically, quantity of water that must be supplied by irrigation to satisfy evapotranspiration, leaching and other miscellaneous water requirements that are not provided by water stored in the soil and precipitation that enters the soil. (1) Consumptive Irrigation Requirement (CIR): 𝑪𝑰𝑹 = 𝑪𝒖 − 𝑹𝒆 It is defined as the amount of irrigation water that is required to meet the evapotranspiration needs of a crop during its full growth. Note: If during the growth period of a crop rain occurs then since a part of it will be retained by the soil in the root zone and the same will be available to meet a part of the evapotranspiration requirements of the crop, the quantity of irrigation water required to be applied will be correspondingly reduced. This part of the rainfall is known as effective rainfall. Thus, if Etc or Cu is the evapotranspiration or consumptive use of water for a crop and R e is the effective rainfall during the growth period of the crop then CIR= 𝑪𝒖 − 𝑹𝒆 (2) Net Irrigation Requirement (NIR): NIR= CIR+LR + PSR+ NWR (LR: leaching requirement: PSR: presowing requirement; NWR nursery water requirement) It is defined as the amount of irrigation water required to be delivered at the field to meet the evapotranspiration needs of a crop as well as the other needs such as leaching, presowing requirement and nursery water requirement. Note: (i) Presowing requirement (PSR): Presowing irrigation is important for field preparation as availability of moisture is essential for good germination of seeds. (ii) Nursery Water Requirement (NWR): The water requirement for nursery is required to be considered in the case of those crops which are sown on nursery beds and are transplanted within few days after sowing when the plants are a few cm tall. 𝑵𝑰𝑹 (3) Field Irrigation Requirement (FIR): FIR= 𝜼𝒂 It is defined as the amount of water required to meet the 'net irrigation requirements' plus the amount of water lost as surface runoff and through deep percolation. 𝑭𝑰𝑹 (4) Gross Irrigation Requirement (GIR): GIR= 𝜼𝑪 It is defined as the amount of water required to meet the field irrigation requirements plus the amount of irrigation water lost in conveyance through the canal system by evaporation and by seepage Conclusion: GIR > FIR > NIR > CIR Gross Field Net Consumptive ↓ ↓ ↓ ↓ 𝐹𝐼𝑅 𝑁𝐼𝑅 𝐶𝐼𝑅 + 𝐿𝑅+ 𝑃𝑆𝑅 + 𝑁𝑊𝑅 𝐶𝑢 − 𝑅𝑒 𝜂𝑐 𝜂𝑎 For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Consumptive Use of Water (Cu) or Evapotranspiration Etc:  It is defined as total quantity of water used by the vegetative growth of a given area in transpiration and building of plant tissue and that evaporated from the adjacent soil in the area in any specified time.  Evapotranspiration or consumptive use is expressed as equivalent depth of water over an area at a given time period (mm/day).  The value of the consumptive use of water varies from crop to crop and also for the same crop it varies with time as well as place. Transpiration is the process in which the water that enters the plant roots and is used in building plant tissue, finally passes into the atmosphere in the vapor form through the leaves of the plants. Evaporation is the process in which water from the adjacent soil passes into the atmosphere in the vapor form.  Since all the processes involve evaporation and transpiration that are not easily conceived as separate processes, they are thought of as combined process and called Evapotranspiration.  Generally, transpiration is studied in conjunction with evaporation from an area, hence the term evapotranspiration is more commonly used.  In an area covered with vegetation, it is difficult and also unnecessary from practical view point to separately evaluate evaporation and transpiration. It is more convenient to estimate the evapotranspiration directly. Factors affecting consumptive use of water: 1. Evaporation from the soil 2. Temperature 3. Wind velocity 4. Relative humidity of air 5. Precipitation 6. Day time hours 7. Intensity of sunlight 8. Soil type and topography 9. Type of crop 10. Cropping pattern 11. Method of irrigation 12. Quantity of readily available moisture For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Potential Evapotranspiration (PET) Actual Evapotranspiration (AET) If a crop completely covers the ground surface, The water that is available to plants varies evapotranspiration takes place entirely through considerably, and the rate of actual the plants, and if the roots can absorb water at a evapotranspiration (AET) can fall below the sufficiently high rate, the water transfer is PET under natural conditions. Thus, AET is not controlled by the climate alone. This rate of use only a function of meteorological factors but of moisture is called potential also of factors related with plant and soil. evapotranspiration (PET). 0 ≤ AET ≤ PET  If the supply of water to the plant is not limited, Then AET will be equal to PET.  If the water supply is less than PET, then soil starts drying and the ratio AET/PET would be less than one.  When the soil moisture status reaches the ultimate wilting point AET reduces zero. Methods of Determining the Consumptive use of Water 1-Direct measurement of consumptive use of water. (i) Soil moisture studies on plots (ii) Tank or Lysimeter method (iii) Field experimental plots (iv) Integration method (v) Inflow and outflow studies for large areas 2-Use of empirical formulae for determining consumptive use of water. (i) Blaney-Criddle method (ii) Hargreaves class A pan evaporation method. (iii) Modified Penman method Note: This topic is covered in detail in Engineering Hydrology. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Numerical:1 For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Numerical:2 For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Numerical:3 For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Chapter-3 Soil Moisture Relationship: Water added to a soil mass during irrigation is held in the pores of the soil and is termed as soil moisture. Classification of soil water or soil Moisture: 1. Gravitational water: (Not available for plant use)  It is that water which is not held by soil but drains out freely under the influence of gravity.  When water is added to soil the soil pores are completely filled with water and the soil contains the maximum possible water content, which thus constitutes the upper limit of the gravitational water.  Some of this water is held very loosely by the soil & readily moves downward under the pull of gravity, unless prevented by an impermeable barrier such as hard pan or a high-water table. 2. Capillary water or Available water or Available moisture: (Available for plant use)  It is that the water which is retained in the soil after the gravitational water has drained off from the soil.  Capillary water is held in the soil by surface tension.  The plant roots gradually absorb the capillary water which thus constitutes the principal source of water for plant growth.  lower limit of the capillary water=Permanent Wilting Point  upper limit of the capillary water= Field capacity 3. Hygroscopic water: (Not available for plant use)  It is that water which is adsorbed by the particles of dry soil from the atmosphere and is held as a very thin film on the surface of the soil particles due to adhesion or attraction between surface of particles and water molecules.  Below the permanent wilting point, the soil contains only hygroscopic water (non available water).  It cannot be removed easily from the soil particles as it is held with a considerable force. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Soil Moisture Tension (SMT):  SMT is defined as force per unit area that must be exerted to extract water from the soil.  Soil moisture tension is usually expressed in terms of atmospheres.  For a soil of given texture and structure, soil moisture tension is inversely proportional to its moisture content. SMT at Permanent wilting Point (PWP)=7-32 atm. SMT at Field capacity (FC)=1/10 to 1/3 SMT at Saturation capacity = approx. zero Soil Moisture Stress (SMS):  it is sum of the soil moisture tension and osmotic pressure of soil solution.  The force with which water moves across cell membrane is called osmotic pressure and is measured in atmospheres. osmotic pressure is the pressure created by the movement of water molecules across a semi-permeable membrane, from an area of higher water concentration to an area of lower water concentration, in order to equalize the concentration of solutes on both sides of the membrane.  Plants growth is a function of both soil moisture tension as well as osmotic pressure (i.e. Function of soil moisture stress).  Thus, for good growth of plants in soils having appreciable salts, the osmotic pressure of the soil solution must be maintained as low as possible by controlled leaching so that in the root zone soil moisture stress is maintained in range that will provide adequate moisture to the plants. Soil Moisture Constants: Ideal case: Crops Always want moisture content in field should be equal to field capacity (FC) so that they feel very easy or required very less or nil efforts in extracting water for their use. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU (1) Saturation Capacity (SC) or maximum water holding capacity of the soil:  Saturation capacity is defined as the total water content of a soil when all the pores of the soil are filled with water.  At saturation capacity, soil moisture tension is almost equal to zero means nearly zero force is required to extract water. (2) Field Capacity (FC):  Field capacity is defined as the maximum amount of moisture which can be held by a soil against gravity, After the gravity water has drained off. (means FC=SC-Gravitational water)  Field capacity is the upper limit of the capillary water (Capillary water: the moisture content available to the plant roots known as available water or available moisture AM)  Capillary water=available water= FC-PWP  The soil moisture tension at field capacity (FC) ranges between 1/10 to 1/3 atmospheres. (3) Permanent wilting point (PWP):  Permanent wilting point is the moisture content at which the films of water around the soil particles are held so tightly that the plant roots cannot extract enough moisture at sufficiently rapid rate to satisfy transpiration requirements thus resulting in the wilting of the plants.  The permanent wilting point is usually expressed as the weight of the moisture held by the soil per unit weight of the dry soil when the plants are permanently wilted.  The soil moisture tension of a soil at the permanent wilting point ranges from 7 to 32 atmospheres depending on soil texture, kind and condition of the plants etc. (4) Available moisture (AM) or Maximum Storage Capacity of Soil = FC-PWP  The difference in moisture content of the soil between the field capacity and the permanent wilting point is termed as the available moisture.  AM represents the moisture which is stored in the soil in the form of capillary water for being used subsequently by the plants. (5) Readily available moisture (RAM)  It is that portion of the available moisture which is most easily extracted by plant roots.  Only about 75% -80% of the available moisture is usually readily available. (6) Moisture equivalent: it is an approximate measure of field capacity  Moisture equivalent is defined as the percentage of moisture retained in an initially saturated sample of soil 10mm thick after being subjected to a centrifugal force of 1000 times gravity for a period of 30minutes.  The moisture equivalent of a soil can be quickly determined in a laboratory and it is used as an approximate measure of field capacity. (7) Soil moisture Deficiency or field moisture deficiency=FC-Actual water Content it is water required to being soil moisture content of a given soil to its field capacity. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Depth of Water stored in Rootzone and Available to Plant: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Chapter-4 Irrigation Water Quality, Waterlogging, Soil Reclamation Irrigation Water Quality: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Points related to Irrigation water Quality as per Standards Books: Water containing impurities, which are injurious to plant growth, is not satisfactory for irrigation. (1) Sediment concentration in water. When fine sediment from water is deposited on sandy soils, the fertility is improved. On the other hand, if the sediment has been derived from the eroded areas (construction sites), it may reduce the fertility or decrease the soil permeability. (2) Total concentration of soluble salts in water Salts of calcium, magnesium, sodium and potassium, present in the irrigation water may prove injurious to plants. When present in excessive quantities, they reduce the osmotic activities of the plant and may prevent adequate aeration, causing injuries to plant growth. The salt concentration is generally measured by determining the electrical conductivity of water. Salt concentration and electrical conductivity are directly proportional to each other. EC (Micro mho/cm) @ 250C Class Salinity Uses < 250 C1 Low Can be used for all crops 250 – 750 C2 Medium Can be used for all crops after leaching. 750 – 2250 C3 High For high salt tolerant plant with special measure to control salinity > 2250 C4 Very high Not suitable for irrigation High salt tolerant plant: Rapeseed/canola, Guar, Barley, cotton, fodder, barseem, bajra (3) Proportion of sodium ions to other cations: Exchangeable sodium percentage (ESP): 𝑵𝒂+ 𝑬𝑺𝑷 = 𝑵𝒂+ + 𝑴𝒈+𝟐 + 𝑲+ + 𝑪𝒂+𝟐 In above formula concentration is put in epm, epm means equivalent per million. 𝑚𝑔/𝑙𝑡 𝑒𝑝𝑚 = (𝑎𝑡𝑜𝑚𝑖𝑐 𝑤𝑒𝑖𝑔ℎ𝑡/𝑣𝑎𝑙𝑒𝑛𝑐𝑦) Classification of saline soil: Classification EC (micro mho/cm) ESP PH Saline soil or white alkali soil >4000 4000 >15 26 Very high Sodium water Not suitable (4) Concentration of potentially toxic elements present in water.  Elements like boron, selenium, processed may be toxic to plants.  Traces of boron are essential to plant growth.  Boron concentrations above 0.3 ppm may prove toxic Even for the most tolerant crops.  the boron concentration should not exceed 4 ppm.  Boron is generally present in various soaps.  Selenium, even in low concentration, is toxic, and must be avoided. (5) Bicarbonate concentration as related to the concentration of calcium plus magnesium High concentration of bi-carbonate ions may result in precipitation of calcium and magnesium. Thereby reducing concentration in water. This leads to increase in SAR value. (6) Bacterial contamination.  Bacterial contamination of irrigation water is not a grave problem, unless the crops irrigated with highly contaminated water are directly eaten, without being cooked.  Cash crops like cotton, nursery stock, etc. which are processed after harvesting, can therefore, use contaminated waste waters, without any trouble. Numerical: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Methods Adopted to Maintain Fertility of a Soil: (1) By keeping the land fallow: If the land is kept fallow (means land is left uncultivated for one or more crop seasons) then the soil is allowed to recover w.r.t. the nutrients which are deficient and thus regain its fertility. (2) Addition of manure and fertilizers: If the soil is deficient in some nutrients, then by adding manure as well as fertilizers the deficiency is removed and the fertility of the soil is improved. (3) Crop rotation: it is a process of growing different crops in rotation in the same field. If the same crop is grown every year in any field, then since the same type of nutrients are consumed the soil becomes deficient in these nutrients, On the other hand, if different crops are grown in the same field, then since different crops require different nutrients and in different proportions a balanced utilization of the nutrients results and the soil does not become deficient in particular type of nutrients. Moreover, if a soil becomes deficient in some of the nutrients by a certain crop grown in the field, then it is allowed to recoup when next time a different crop is grown in the same field. Different crops have different depths of the root zone. Thus, by combining deep rooted crops and shallow rooted crops in the rotation of crops the optimum utilization of the nutrients available in the soil is made, (4) Mixed Cropping: Mixed Cropping is defined as the growing of two or more crops together in the same field during the same crop season. In mixed cropping, the optimum utilization of the nutrients available in the soil is made. Example: (Wheat and mustard), (Gram and barley जौ) may be grown simultaneously in the same field. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Land Reclamation:  it is a process by which an uncultivable land is made fit for cultivation.  Saline and water-logged lands give very less crop yields, and are therefore, almost unfit for cultivation, unless they are reclaimed. Alkali Salt Story:  Every agricultural soil contains certain mineral salts in it. Some of these salts are beneficial for plants as they provide the plant foods, while others prove injurious to plant growth. These injurious salts are called alkali salts. Alkali Salt Example: Na2CO3, Na2SO4, NaCl.  Na2CO3(Black alkali salt) is the most harmful alkali salt and NaCl is the least harmful. These salts are soluble in water. Saline Soil: Land affected by efflorescence is called saline soil. If the water table rises up or if the plants roots happen to come within the capillary fringe, water from the water table starts flowing upward. The soluble alkali salts also move up with water and get deposited in the soil within the plant roots as well as on the surface of the land. This phenomenon of salts coming up in solution and forming a thin crust on the surface, after the evaporation of water, is called efflorescence. Land affected by efflorescence is called saline soil. Alkaline Soil: If the salt efflorescence continues for a longer period, a base exchange reaction sets up, particularly if the soil is clayey, thus sodiumising the clay, making it impermeable and, therefore, ill aerated and highly unproductive. Such soils are called alkaline soils.  Base exchange reactions occur when cations in the soil, such as calcium (Ca²⁺) and magnesium (Mg²⁺), are replaced by other cations present in the soil solution, such as sodium (Na⁺).  sodiumization" of clay, where sodium ions predominate on the soil particle surfaces. Classification of saline soil: Classification EC (micro mho/cm) ESP PH Saline soil or white alkali soil >4000 4000 >15 10 0.75 (meter) Note: Amount of Freeboard depend on the type of canal. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU 2. Berms: it is Horizontal distance left at ground level between toe of bank to the top edge of cutting. Lined Canal Unlined canal  Berms are provided in canals, if these are partly in excavation and partly in embankment.  Provide a scope for future widening of canal 3. Dowlas: As a measure of safety in driving, dowlas is provided along the bank, they help in preventing slope erosion due to rains Guidelines In case of unlined canal: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU 4-Sideslope: Case-1 Lined Canal: Case-2 Unlined Canal: 5-Bank: The primary purpose of banks is to retain water. They can be used as means of communication and as inspection paths. They should be wide enough, so that a minimum cover of 0.5 meter is available above the saturation line, as shown in Figure. High banks will have to be designed as earth dams For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU 6. Service Road: Service roads are provided on canals for inspection purposes, and may simultaneously serve as the means of communication in remote areas. They are provided 0.4 m to 1.0 m above FSL, depending upon the size of the channel. 7.Back Berm or Counter Berm: Even after providing sufficient section for bank embankment, the saturation gradient line may cut the d/s end of the bank. In such a case, the saturation line can be kept covered at least by 0.5 meters with the help of counter berms. 8.Spoil Bank: When the earthwork in excavation exceeds earthwork in filling, even after providing maximum width of bank embankments, the extra earth has to be disposed of economically. To dispose of this earth by mechanical transport, etc. may become very costly, and an economical mode of its disposal may be found in the form of collecting this soil on the edge of the bank embankment itself. The soil is, therefore, deposited in such a case, in the form of heaps on both banks or only on one bank These heaps of soil are discontinued at suitable intervals and longitudinal drains running by their sides are excavated for the disposal of rain water. 9. Borrow pits: When earthwork in filling exceeds the earthwork in excavation, the earth has to be brought from somewhere. The pits, which are dug for bringing earth, are known as borrow pits. If such pits are excavated outside the channel, they are known as external borrow pits, and if they are excavated somewhere within the channel, they are known as internal borrow pits. It is a very costly affair to bring soil from distance. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Lining of Canal: Irrigation water is a costly commodity and it should not be wasted while conveying from the reservoirs to the fields. Most of the canals, constructed in India to carry irrigation water, are unlined, and hence, a large part of the costly irrigation water is lost in percolation and absorption as seepage loss. Such seepage loss of the costly irrigation water must be minimized and that is done by lining the irrigation canals. By lining the canal, we mean that the earthen surface of the channel is lined with a stable lining surface, such as concrete, tiles, asphalt, etc. Different Types of Lining: Rigid Lining Flexible Lining Compacted Earth Lining: Soil cement lining: Brick Lining: Boulder lining: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Function of Lining: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Design of Lined Irrigation Canal: Irrigation canals should be aligned and laid out, so that the velocity of flow is uniform under all conditions, and so that the water reaches the irrigated area at an elevation sufficient to ensure even and economical distribution. High velocities of flow can be permitted by taking the advantage of hard-wearing surface, so as to ensure a hydraulically efficient channel. In case of channels lined with hard surfaced materials, two types of channel sections are adopted: Design of lined canal For small discharge For large discharge Q ≤ 85 m /s 3 Q > 85 m3/s Triangular channel section with circular bottom Trapezoidal channel section with rounded corners Note: In order to increase A/P ratio, the corners are rounded and attempts are made to use deeper sections by limiting depth. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Trick: SBC =Safe Bearing Capacity =1.5/1.8/2.7 (factors in water demand) For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Numerical: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Canal Design: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Numerical: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Mechanism of Bed Formation:  The channel bed may get distorted into various shapes by the moving water, depending upon the discharge or the velocity of the water.  At low velocities, the bed does not move at all, but it goes on assuming different shapes as the velocity increases.  When velocity is gradually increased then a stage is reached when the sediment load comes just at the point of motion. This stage is known as threshold stage of motion.  On further increase of velocity, bed develops the saw-tooth type ripples. As the velocity is increased further, larger periodic irregularities appear, and are called dunes. When they first appear, ripples are superimposed on them. But at higher velocities, the ripples disappear and only the dunes are left.  When the velocity is increased beyond formation of dunes, the dunes are erased by the flow. leaving very small undulations or virtually a flat surface with sediment particles in motion. Now, increase in velocity results in formation of sand waves in association with surface waves  As velocity is further increased, Froude no. exceeds unity, the flow becomes super critical, and the surface waves become so steep that they break intermittently and move us although the sediment particles keep on moving d/s only. Sand Waves are then called antidunes. (since direction of movement of bed forms in this regime is opposite to that of the dunes). Note:  Dunes may form in any grain size of sediment, but ripples do not occur if the size of the bed particles is coarser than 0.6 mm.  Dunes are much larger and more rounded than ripples.  In case of canals and natural streams, anti-dunes rarely occur. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Design of Stable Channel in India: For designing a properly functioning channel, one must think to design a channel in which neither silting nor scouring takes place. Such channels are known as stable channels or regime channels.  In India, alluvial channels are designed on the basis of hypothetical theories like Kennedy’s Theory and Lacey Theory Kennedy’s Theory: R.G. Kennedy (an Executive Engineer of Punjab P.W.D.) in 1895 carried out extensive investigations on some of the canal reaches in the Upper Bari Doab Canal System. 1- Upper bari doab Canal: which had not required any maintenance for past 30 years thus considered as stable canal/channel. 2- Doab: area between 2 water bodies (usually rivers) 3- Doab region: fertile area for crop  He selected some straight reaches of the canal section, which had not posed any silting and scouring problems for a long time in the past.  On basis of these observations, he concluded that the silt supporting power in a channel cross- section was mainly dependent upon the generation of the eddies, rising to the surface. These eddies are generated due to the friction of the flowing water with the channel surface. The vertical component of these eddies tries to move the sediment up, while the weight of the sediment tries to bring it down, thus keeping the sediment in suspension. So, silting will be avoided if the velocity is sufficient to generate these eddies, so as to keep the sediment just in suspension. So, Kennedy considered Silt is kept in suspension due to eddies generated from bottom only. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Critical velocity (V0) as per Kennedy: it is the mean velocity (across the section) which will just keep the channel free from silting or scouring, and related it to the depth of flow by the equation: V0=0.55my0.64 V0= critical velocity in the channel (in m/s) y = water depth in channel (in meter) m = C.V. R=Critical Velocity Ratio =V/V0 m=Critical velocity in other channel/critical velocity in standard channel (upper bari doab system) Type of silt Value of m coarser than standard 1-1.2 finer than standard 0.7-1 Note: Standard silt means silt found in Upper Bari Doab Canal System hence m=1 for standard silt Hence Critical velocity for Upper bari canal System V0=0.55y0.64 Remember: V=V0 (m=1) No silting No Scouring (upper bari doab region) V >V0 (m >1) Scouring (soil/silt coarser than upper bari doab region) V 100 3.5 Above table is only to reduce efforts in trial- error. 𝑄 II. 𝐴 = ⁄𝑉 = 𝐵𝑦 + 𝑦 2 𝑧 (𝑎𝑠𝑠𝑢𝑚𝑒 𝑡𝑟𝑎𝑝𝑒𝑧𝑖𝑜𝑑𝑎𝑙 𝑐ℎ𝑎𝑛𝑛𝑒𝑙 𝑠𝑒𝑐𝑡𝑖𝑜𝑛 𝑤𝑖𝑡ℎ 𝑠𝑖𝑑𝑒 𝑠𝑙𝑜𝑝𝑒 1𝑉: 0.5𝐻 𝑚𝑒𝑎𝑛𝑠 𝑧 = 0.5) 𝑜 B =? 𝐴 III. 𝑅 = 𝑤ℎ𝑒𝑟𝑒 𝑃 = 𝐵 + 2𝑦√1 + 𝑧 2 𝑃 IV. 𝑈𝑠𝑒 𝑘𝑢𝑡𝑡𝑒𝑟 𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛 𝑎𝑛𝑑 𝐶𝑎𝑙𝑐𝑢𝑙𝑎𝑡𝑒 𝑉 = 𝐶√(𝑅𝑆) 𝟏 𝟎. 𝟎𝟎𝟏𝟓𝟓 + (𝟐𝟑 + ) 𝑪=[ 𝒏 𝑺 ] 𝟎. 𝟎𝟎𝟏𝟓𝟓 𝒏 𝟏 + (𝟐𝟑 + ) 𝑺 √𝑹 If bed slope is not given then assume s=1/2000 to 1/5000 If V=V0 then ok otherwise redesign the section with other trial depth. Hint: If V >V0 then increase trial depth , if V 1.5m)  It makes use of Horizontal impact for energy dissipation. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  X. Metering  Vertical drop type/ Sharda type fall → not for metering purpose due to partial & non vacuum under the nappe. metering fall  Glacis type fall → used for measuring discharge. Note: Generally, a flumed glacis falls or a flumed baffle wall is used as a meter while unflumed glacis fall is used as a nonmeter fall. Cistern or Cistern Element: Portion of fall on d/s of the crest wall in which the surplus energy of water leaving the crest is dissipated and the subsequent flow stilled before it passes on to the lower-level channel. Objective of Cistern Elements: I. To reduce Intensity of impact of dropping Jet of water against the d/s floor. II. Provide water cushion to dissipate energy of falling jet. III. To produce reverse flow by providing suitable end wall to ensure an impact in the cistern. Element Details: 1. Cisterns  A tank for storing water basically water Cushion Cisterns are the Water cushion provided by depress the floor below the d/s bed of channel to protect the floor from impact of stream of water falling freely under gravity.  Vertical impact cistern → most effective  Inclined impact cistern → least effective II.  Provided In cistern to dissipate energy (it may be residual energy in case of cistern Roughening with impact) device  These devices Depend on turbulence & boundary friction  Commonly used Roughening devices: Staggered Friction Block and Arrows For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU III. Dentated  It Breaks up the stream jet into smaller jet. it causes reverse rollers. Sill IV. Deflector Provided if high velocity flow continues up to the end of cistern which helps in or Baffle wall dissipating residual energy. V. Biff wall  Vertical wall with a horizontal projection ending in cistern.  The biff wall at the d/s edge of the cistern produce reverse rollers which causes a controlled scour away from the wall and piles up the scoured material against the toe of structure and thus prevent damages.  This is provided where the high velocity flow continues unabated up to the end of cistern. VI. Ribbed  The bed and/or sides of channel may be provided with bricks alternatively laid pitching flat and on edge to dissipate surplus energy of flow.  The bricks projecting into flow cross section increases the Boundary friction. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Auxiliary Devices in Stilling Basin: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Canal Escape /Surplus Water Escape/Canal Surplus Escapes (Control of Full supply level, Safety valve of irrigation channel)  Canal escape is a structure constructed on an irrigation channel for the disposal of surplus water from the channel.  Sometimes escapes are provided in the head reaches of main canals to scour out bed silt deposited in the head reaches. Why Escapes are Required: If the surplus water is allowed to go to the lower reaches the water may overflow the bank and damage banks. Although the supplies may be reduced from the head of the channel but the effect of such reduction would be felt only after a certain time depending on the distance of the affected reach from the head. As such immediate action is necessary to prevent damage and it is done by escapes. Reasons to Provide it :  Mistake or difficulty in regulation at the head of a channel.  Heavy rainfall in upper reaches of a channel.  Sudden closure of outlets by cultivators due to sudden stoppage of demand.  Sudden closure of any off taking channel due to breach, Types of Escapes: I. Surplus water  Provided at bank of channel at regular interval escape  Escape Capacity = 0.33 – 0.50 times*{capacity of channel at site of escape}  Usually there should be a cross regulator across the channel on d/s side of location of escape. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU II. Canal Scouring  Provided in Bank channel but usually provided only in head reaches of main escape (Regulator canal. type escape)  To remove excessive silt deposited in head reaches from time to time. (This canal scouring escape may be replaced by silt ejector as this also do same function.)  Escape Capacity = 0.33 – 0.50 times* {capacity at the head of main canal}  Usually there should be a cross regulator across the channel on d/s side of location of escape III. Tail escape  Provide Across the channel at tail end of canal. (weir type escape)  To maintain Full Supply Level (FSL) at tail end of channel.  Provided In case of irrigation channel which end in natural drain. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Metering Flume (Metering flumes works on the principle of venturi meter)  A metering flume is a structure constructed in a canal for measuring the discharge in the canal accurately.  A metering flume is an artificially flumed (narrowed) section of the channel, which can be utilized for calculating the discharge in the channel.  The normal u/s section of the channel is narrowed by masonry walls with a splay of 1: 1 to 2: 1 to a rectangular section called Throat.  The channel is slowly diverged from here with a splay of 2: 1 to 10: 1 in order to attain its normal section by means of masonry wing walls.  More gradual the convergence and divergence, less will be the loss head in the flume. Types of Metering Flume: 1. Drowned venturi-flume or non- modular venturi- flume or Venturi flume For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU   Venturi flume consist of Gradually contracting channel leading to throat and gradually expanding channel leading away from it.  Stilling well is provided For measuring head at entrance and at throat. 2. Free flow  When Hydraulic jump (Standing wave) forms on the d/s glacis in the diverging venturi flume channel called standing wave flume. Or Modular  In this more head loss (hL) occurred if head loss=0 then it will be venturi flume. venturi flume  It is Better than venturi flume As Discharge(Q) depend only on u/s head over OR Standing the crest of throat and also for same u/s head, its discharging capacity more wave flume than that of a venturi flume. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Canal Outlet or Canal Module: (Control of discharge)  It is small structure built at head of water course So as to connect it with minor/ major distributary.  Outlets are devices to regulate the flow of water from a bigger channel into smaller channel. Discharge through Outlet Range=0.030-0.085 cumec  Module is connecting link between Government and Farmer (Cultivator) Note: Sluices are outlets provided in dams outlet outlet Requirements of Good Canal Outlet or Canal Module: (1) Module should fit well to the decided principles of water distribution. Example: if the supply is to be fixed in accordance with the cultivable area commanded by the outlet, the outlet must be able to pass a constant and a fixed discharge. Similarly, if the supply is to be regulated in accordance with the area irrigated in the past year, the capacity of the outlet should be capable of being changed from year to year. (2) Module should be simple, so that it can be easily constructed or fabricated by local masons or technicians. (3) Module should work efficiently with a small working head. (4) The outlet should be cheaper, since they are required in large number. (5) The outlet should be sufficiently strong with no moving parts, so as to avoid periodic maintenance. (6) The outlet should be such as to avoid interference by cultivators, thus preventing under tapping of water by cultivators. (7) It should draw its fair share of silt. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Canal Outlet types: I. Non modular  In which discharge (Q) depend on difference of head between Examples: distributary and water course. 1. Open sluice  Discharge varies with either change in water level of distributary or that 2.Drowned or of water course hence Fluctuation possible both sides. submerged pipe outlet Trick: Namo: DSP always OS Examples are Given Below: Open sluice: Rectangular pucca opening Drowned or submerged pipe outlet: Pipes are generally embedded in concrete and are generally fixed horizontally at right angles to the direction of flow. II. Semi modular  In which discharge(Q) = function of distributary level (as long as (Flexible Outlet) minimum working head available) Examples  Discharge will increase with rise in distributary level (vice- versa). 1. free Pipe outlet Examples are Given Below: 2.Venturi flume free Pipe outlet: Discharging freely into atmosphere (simplest and oldest) outlet or Kenedy gauge outlet 3. crumps Open flume outlet 4. Adjustable orifice semi module. III. Modular  In which Discharge is constant and fixed within limits, no effect of outlet (Rigid fluctuations on any side. That’s best Outlet) Example 1-Gibbs rigid module 2- Khanna’s rigid module For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Criteria For Judging Performance of Canal Outlet 1. Flexibility (F) 𝒅𝒒/𝒒 𝒎𝒚 𝑭= = F= 0 rigid or modular 𝒅𝑸/𝑸 𝑯𝒏 outlet F= Ratio of change of discharge of the outlet to the rate of change of discharge of distributary channel. F ≠ 0 flexible/ semi modular outlet F > 1 hyperproportional Discharge through outlet 𝑞 = 𝐶𝐻 𝑚 𝑤ℎ𝑒𝑟𝑒 m = outlet index outlet Discharge in distributary Q=Kyn where n = channel index F < 1 Sub proportional Note: outlet Wide Trapezoidal channel: 𝟓 𝑸 ∝ 𝒚𝟑 𝒕𝒉𝒂𝒕𝒔 𝒘𝒉𝒚 𝒄𝒉𝒂𝒏𝒏𝒆𝒍 𝒊𝒏𝒅𝒆𝒙 𝒏 = 𝟓⁄𝟑 Outlet Index: Orifice type outlet (𝑚) = 1⁄2 Weir type outlet 𝑚 = 3⁄2 Triangular outlet 𝑚 = 5⁄2 2. Proportionality Proportional outlet When F = 1 𝒎𝒚 𝒎 𝑯 =𝟏⇒ = 𝑯𝒏 𝒏 𝒚 m = outlet index, n = channel index 3. Setting 𝒎 𝑯 Setting = = 𝒏 𝒚 H = Difference of level in watercourse and distributory y = distributory water depth 4. Sensitivity(S) 𝒅𝒒/𝒒 S =nF= 𝒅𝒚/𝒚 S= Ratio of change of discharge of the outlet to the rate of change of depth of distributary channel. (for rigid/ modular outlet F = 0 ⸫ S = 0) For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Chapter-7 Canal Headwork or Headworks In order to divert water from river into canal, structure is constructed across river and at head of off-taking canal. Such structure is known as Canal Headwork or Headworks. Classification of Canal Headworks: 1-Storage headwork: (Storage+Diversion) 2-Diversion headwork: mainly Diversion  it consists of dam constructed across river only, preferred in plain areas to store water during the period of excess  it raises the water level in river then divert flow in river. and as per requirement water the required quantity into canal. is supplied to canal through Dam reservoir. Purposes of diversion headworks:  It raises the water level in the river in  It fulfills requirements of the diversion order to increase the commanded area. headworks also but in each situation  It regulates the supply of water into the construction of dam is not feasible/possible canal. so preferred in hilly area.  It controls the entry of silt into the canal.  It provides some storage of water for a short period. Remember:  It reduces the fluctuations in the level of supply in the river. Types Of Diversion Headworks 1-Temporary diversion headworks consists of temporary structure such as spur or bund constructed across the river to raise the water level in the river and divert it into the canal. These bunds are constructed almost every year after the floods, because they may be damaged by the floods. 2-Permanent diversion headworks consists of a permanent structure such as weir or barrage constructed across the river to raise the water level in the river and divert it into the canal. In our country, most of the diversion head works for important canal system are permanent diversion headworks. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Component of Diversion Headwork: 1. Weir or Barrage 2. Divide wall or divide groyne 3. Fish ladder 4. Pocket or Approach channel 5. Under sluices or Scouring sluices 6. Silt excluder and silt extractors 7. Canal head regulator 8. River training works (Marginal bunds & Guide bund) 1. Weir:  A weir is an obstruction constructed across a river to raise its water level and divert the water into the canal.  Shutters are usually provided on the crest and only small part of the ponding of water is carried out by shutters. Major part of ponding of water is achieved by the raised crest in case of weir.  During floods, shutters are dropped down to allow water to flow over the crest of the weir. Afflux: The rise in the max. flood level u/s of the weir, caused due to construction of the weir across the river. Weir types: (i) Gravity weir: weight of weir = uplift pressure caused by head of water seeping below weir. (ii) Non gravity weir: If the weir floor is designed continuous with the divide piers as reinforced structure, such that the weight of concrete slab together with the weight of divide piers keep the structure safe against the uplift then the structure may be called as a Non-gravity Weir. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Barrage (River Regulator):  Barrage is a structure similar to weir with the only difference that the crest is kept at a low level and the ponding of water is achieved mainly by means of gates.  During floods these gates can be raised above the HFL (high flood level) and thus enable the high flood to pass with minimum of afflux.  A barrage provides better control on the water level in the river but it is comparatively more costly. 2. The under sluices are the openings provided in the weir wall with their crest at a low level. Scouring  Openings are fully controlled by gates. sluices or  Located on same side of off taking canal.  Helps in removing silt near head regulator. Under  By construction of under sluice portion of the weir a comparatively less turbulent sluices pocket of water is created near the canal head regulator. (ek dam shant pani then silt settle infront of head regulator, silt excluder Bhi he ,under sluice Bhi he) Functions of under sluices:  They preserve a clear and well-defined river channel towards the canal head regulator.  They scour the silt deposited on the river bed in the pocket u/s of the canal head regulator.  They pass low floods without the necessity of dropping the weir crest shutters.  They help to lower the high flood level by supplementing the discharge over the weir Discharging capacity of the under sluices: Choose maximum of the following: (1) Two times the maximum discharge of the off taking canal (2) Maximum-winter discharge (3) 20% of the maximum flood discharge. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU 3. Divide Masonry/ concrete wall constructed at perpendicular to axis of weir to separate under wall or sluice from the rest of the weir or weir proper. ( need piece full environment) divide groyne functions of a divide wall 1. Divide wall separates the floor level of the under sluices from the floor level of the weir as the floor level of the under sluices is generally lower than the flour level of the weir. 2. It provides a comparatively quiet pocket in front of the canal head regulator resulting in deposition of silt in the pocket and entry of clear water into the canal 3. It provides a straight approach through the pocket and thus helps to concentrate scouring action of the under sluices for washing out the silt deposited in the pocket. 4. It keeps the cross currents away from the weir. A cross current will develop when the main current in the river tends to approach the bank opposite the canal head regulator and the weir forces the water to flow towards the regulator. The cross current cause formation of vortices and result in deep scour. 4. Fish  Flow energy dissipated in such a manner so as to provided smooth flow at ladder → sufficiently low velocity (3 – 3.5m/s). located  Anadromous fish moves from u/s to d/s in beginning of winter in search of warmth water and return u/s before monsoon for clearer water. adjacent to  To check velocity flow in fish ladder Baffles or staggering devices are provided. divide wall near under sluice toward off taking channel. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU 5. Canal  Constructed At head of off taking canal Head  Regulate supply to off taking canal (Head regulator consist of no. of spans separated Regulator by pier which supports the gates provided for regulation of flow into canal)  It also Control entry of silt into off taking canal  Completely exclude high flood from entering into off taking canal 6. Silt (A) Silt Excluder: controlling  Which exclude silt from water Before entering the off taking canal device  Constructed On river bed, Infront of head regulator in off taking canal.. (B) Silt Extractor or Silt Ejector:  Remove silt which have already enters into the off taking canal.  Provided in canal a little distance downstream from head regulator. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Chapter- 8 Seepage Theory Failure Of Weir on Permeable Foundation: Due To Seepage or Subsurface Flow Due to Surface flow: Basically, flow over weir. The seepage or subsurface flow may cause the failure of a weir in the following two ways: (i) By Suction Due To Standing Wave or 1-By Piping Or Undermining: If the water percolating Hydraulic Jump: As the water flows over the through the foundation has sufficient force when it emerges at the d/s weir and forms a hydraulic jump or standing wave end of the impervious floor it may lift up the soil particles at the end of the floor. With the removal of the surface soil there is further downstream, the pressure decreases. This decrease concentration of flow into the resulting depression and more soil is in pressure downstream can create a suction effect, removed. This process of erosion progressively extends backwards towards the u/s side and results in the removal of soil and developing pulling water back towards the weir. pipe like formation beneath the floor. The floor may subside in the hollows so formed and fail which is Remedies: known as Failure due to piping.  Provide additional thickness of the impervious floor to counterbalance the suction pressure due to standing wave  Construct floor as monolithic concrete mass instead of in different layers of Remedies: masonry  Provide sufficient length of impervious floor so that path of percolation is (ii) By Scour On The u/s And d/s Of the Weir increased and thus exit gradient is Both at u/s and d/s ends of the impervious floor reduced. the bed of the river may be scoured to  Provide piles at d/s ends of the impervious considerable depths during floods. If no floor. preventive measures are taken, these scours may 2-By Uplift Pressure: The water percolating through cause considerable damage. the foundation exerts an upward pressure on the impervious floor. This pressure is known as uplift Remedies: pressure. If the uplift pressure is not counterbalanced by  Provide deep piles both at u/s and d/s the weight of the floor, it may fail by rupture. ends of the impervious floor. The piles Remedies: are to be driven up to a depth much below  Provide sufficient thickness of the the calculated scour depth. impervious floor (to increase weight)  Provide launching aprons of suitable  Provide pile at the u/s end of the length and thickness at u/s and d/s ends of impervious floor (so that uplift pressure is the impervious floor. reduced on the d/s side) Note: Diversion headworks are loaded in boulder and trough stages of a river where only permeable foundations are available for the construction of the weirs For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Bligh Creep Theory for Permeable Foundation:  A Theory of subsurface flow, this theory assumed that percolating water follows outline of the base of structure which is in the constant with the subsoil.  The length of the path traversed by the percolating water is called the creep length (L).  Bligh further assumed that the head loss (hL OR H) per unit length of creep L (known as hydraulic gradient i) is constant throughout the percolating passage. i.e. the loss of head (hL or H) ∝ creep length(L)  Blight creep coefficient (C) = Reciprocal of hydraulic gradient(i) 𝟏 𝑪 = =L/H 𝒊 For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU According to Bligh, to ensure the safety of the impervious floor against the two possible ways in which failure may be caused by subsurface flow, following criteria are required to be satisfied. Criteria-1: Safety against piping: 𝐿𝑟𝑒𝑞 ≥ 𝐶𝐻 C value lies between 5 to 18 (depends on Type of Soil). Criteria-2: Safety Against Uplift Pressure For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Limitation of Bligh Creep Theory: I. No distinction between horizontal and vertical creep (hence weightage factor for horizontal creep and vertical creep = 1) II. Bligh theory is Valid if horizontal distance between cutoff or piles lines > 2*depth of cut off III. Bligh Did not tell/indicate about exit gradient IV. Headloss α Creep length (But it is not correct) V. Bligh did not specify the absolute necessity of providing cutoff at d/s end of floor. (it is must to provide deep vertical cutoff at d/s end to prevent Undermining or pipe failure because absence of d/s pile will lead to infinite exit gradient) Lane’s Weighted Creep Theory:  Improvement over Bligh Theory. But practically Bligh’s theory used (lane’s theory is nowhere used)  Lane’s said that Horizontal creep is less effective in reducing uplift and causing less loss of head than vertical creep.  Lane’s made distinction between horizontal and vertical creep. Hence Weightage factor is given: 𝟏 → Horizontal creep 𝟑 1 → Vertical creep So, length of creep will differ, rest numerical will be solved as per same concepts (like Bligh theory) Khosla Theory: For design of weir on permeable foundation For quite a long time, Bligh's theory was the accepted basis for designing the structures on permeable foundations. But few failures led to the investigation by a researcher named Khosla. Dr. A. N. Khosla and his associates carried few and came to the following conclusions: 1. The outer face of the end sheet piles was much more effective than the inner ones and the horizontal length of the floor. 2. The intermediate sheet piles, if smaller in length than the outer ones were ineffective except for local redistribution of pressures. 3. Undermining of floors started from the tail end. (If the hydraulic gradient at the exit was more than the 'critical gradient' for the particular soil, the soil particles would move with the flow of water thus causing progressive degradation of the subsoil, resulting in cavities and ultimate failure) Note: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Khosla Method of Independent Variables: In this method a composite weir or barrage section is split up into a number of simple standard form for which mathematical solutions have been obtained. These cases have been analyzed by Khosla and expressions have been derived for determining residual seepage head or uplift pressure head at the key points and the exit gradient. key points:  The junction points of pile and floor  The bottom point of pile and  Bottom corners of depressed floor Case-1 A straight horizontal floor of negligible thickness with a sheet pile at either end (upstream or downstream end of floor) For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Case-2 A straight horizontal floor of negligible thickness with a sheet pile at some intermediate point. Case-3 A straight horizontal floor depressed below the bed but without any vertical cutoff For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Khosla’s Exit Gradient (GE): 𝑯 Note: if no vertical cutoff is provided at d/s 𝑮𝑬 = 𝒅 𝝅√𝝀 end then Khosla exit gradient becomes 1+√1+𝛼2 𝜆= infinite. 2 Table: Remember 𝑏 𝛼= 𝑑 Where H=Total seepage head b = length of Horizontal floor d = length of downstream pile or cutoff Note: "Shingle soil" typically refers to soil that is composed primarily of small, smooth stones or pebbles, often referred to as "shingle." This type of soil is usually poor in organic matter and nutrients, making it less fertile for plant growth compared to soils with higher organic content. Shingle soil is often found in areas where there has been erosion or where gravel deposits have accumulated over time. Hence FOS against Piping= iexit/icr=GE/ icr where icr=(G-1)/(1+e)=(G-1)(1-n) Khosla Corrections: The percentage pressure at these key points for the simple form into which the complex profile has been broken is valid then in such case corrections are applied Known as Khosla corrections. Trick: IST= interference/slope/thickness (1) Correction for mutual Interference of piles. (2) Correction for the Slope of the floor (3) Correction for Thickness of floor For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU Note: Looseness Factor: For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Chapter-9 River Engineering Classification of Rivers On the basis of Topography of River Basin: 1- Rivers in Hills (Upper Reaches) 2- Rivers in alluvial flood plains (Lower reaches) 3- Tidal Rivers Type-1 Rivers in Hills (Upper Reaches): The rivers generally take off from the mountains and flow through the hilly regions before traversing the plains. These upper reaches of the rivers may be termed as Rivers in Hills. They can be further sub-divided into: Rocky River Stage or Hilly or Boulder River Stage Mountainous stage  It is a first stage of the river course.  In this stage the river flows through steep valleys in the hills.  The river bed in generally composed of rocks.  The slope of the bed is also very steep and it may range from 1 in 100 to 1 in 500.  In this type, the flow channel is generally formed by the process of degradation.  The river bed in these reaches consists of a mixture of boulders, gravels and alluvial sand deposits created by itself.  In the boulder stage, the river flows through wide shallow beds and interlaced channels and develops a straighter course.  During a flood, the boulders and gravels are transported d/s, but as the flood subsides, the material gets deposited in heaps.  The sediment transported in this reach is  The water, then unable to shift these heaps, different from the river bed material, go round them, and the channel often since most of it comes from the wanders in new directions, often attacking catchment due to denundation and soil the banks and consequently widening the erosion.  These river-reaches are highly steep bed. with swift flow.  The beds and banks of such rivers are less susceptible to erosion. For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Type-2 Rivers in Alluvial flood plain: 1. Meandering river Flows in zigzag fashion. Meandering type river – On this ,river training work required. Material gets eroded constantly from outer edge of the bend and gets deposited either on the inner edge of the successive bend or between 2 successive bends to form a bar. When once a straight moving river slightly deviates from its axis, the unbalance created goes on multiplying with constant erosion from outer edge, if unchecked, this process continues and resulting in the formation of large meanders. In river meandering, concave bank goes on erosion and convex bank goes on silting. Four variables which govern meandering process. 1- Valley slope 2- Silt charge and silt grade 3- Discharge 4- Bed and side materials and their susceptibility to erosion For More Updates Join our Telegram Group: https://t.me/ToThePointByDhyanPal For Civil engineering Courses Download our Mobile App: https://clpdiy4.page.link/WUDU  Meander Parameters: 𝑴𝑩 𝑴𝒆𝒂𝒏𝒅𝒆𝒓 𝒓𝒂𝒕𝒊𝒐(𝑴. 𝑹) =