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بسم الله الرحمن الرحيم. An Najah National University Faculty of Engineering Civil Engineering Department Prepared by : 1. Bashar abu hajji 2. Ahmad abu asbih 3. Adham suliman Supervisor :
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بسم الله الرحمن الرحيم An Najah National University Faculty of Engineering Civil Engineering Department Prepared by : 1. Bashar abu hajji 2. Ahmad abu asbih 3. Adham suliman Supervisor : Dr. Hafez Q. Shaheen
Study and conceptual design of Al-Malaqi bridge dam
Study area : Jeser Al Malaqi is located 3.5 km from the main intersection of Al-Badan village with Al-Faria and linking with the Jordan Valley (Al Ghor) and Jericho City.
The selected location of the dam is approximately 500m downstream from Jesser Al-Malaqi at the confluence Wadi Al-Faria and wadi Al-Badan. Wadi Al Faria Wadi Al Badan
Wastewater and springs flow : The wastewater comes from Nablus city and the amount of wastewater flow about (6000m³/day – 8000m³/day), only Small portion of it reaches the dam. the spring flow is natural Storage in al faria catchment, the number of spring is 13 springs distributed as groups (Al-faria, Al-badan, Nablus).
The area of the watersheds is : A1 = 14.35 km2 A2 = 20.04km2 A3 = 21.55 km2. B1 = 82.88 km2 the four sub- catchments for the upper part of Wadi Al-Faria and Wadi Al-Badan.
SCS is used to construct the unit hydrograph (example) Tc= ( L / V ) / 60 TP = qP=
approximate average velocities in ft/s runoff flow for calculating time of concentration (chow, 1989)
this table shows the coordinates to construct the 1 cm-unit hydrograph of area (A3).
S= K {XI + (1 - X) O} K: is a constant, approximates travel time of the flood wave through the reach. X: is a factor that weighs the relative influence of inflow and outflow upon the storage for most river channels, X lies between 0.1 and 0.3, indicating both attenuation and translation. The modal value is about 0.2.
CIA method (peack value) : Runoff volume = C * I * A Where: C: runoff coefficient. I: intensity of rainfall (mm). • A: area of the catchment (m2). Runoff coefficient = 0.2 (example)For I = 2.5 mm/day Q = C * I * A = 0.2 * 0.0025 (m / day) * 138 * 106 m2 = 0.069 MCM/day
Dam design Nelson (1985)
Storage volume The calculation of storage volume done by using the following equation (prismoidal formula): V = L/3 (A1 + An + 2 ( A3+A5+ …… + An-2) +4(A2+A4+……+An-1) For n = 3: V = L/3 * (A1 + 4A2 + A3)
Evaporation volume : Evaporation Volume=Evaporation rate*area Evaporation Volume= (67.8/ (1000*30))* 45725.25=103.33 m3/day (average daily )
From the above figure we get the infiltration rate: Infiltration rate = 10 mm/hr Infiltration volume = infiltration rate * area = (10/1000)*45,725.25 *24 = 10,974 m3/day
Seepage volume (L.Casagrande’s method 1932) q = k Lsinϴ² in (m²/s) L = (√ (d²+H²) –√ (d²- H²cotϴ²)) in (m) For k : the value depend on the type of the soil . The type of soil is silty clay K = 0.0005 From Principles of geotechnical engineering
H=15 m , D=69.55m , ϴ=21⁰ , K=0.0005 L= √5062.2-√3310.24 = 13.61m q = (0.0005) *(13.61) (sin21)2 = 8.73*10^-4 (m²/s) Take length of the dam = 85m Q= 8.73*10^-4 (m²/s)* 85 (m) = 0.0007429 m3/s Q= 0.0745*60*60*24=64.2 m3/d
Design of spillway The time of concentration = 2.5hr = 150 min I = 8 mm/hr Q = C *I *A = 0.2 * 0.008 (m/hr) * 138 * 10 6 m2 / 3600s = 61.33 m3/s
For three pipes : Q = 20.44 m3/s Assume velocity = 5 m/s A = Q / V = 20.44 / 5 = 12.26 m2 D = 2.28 m We will use 3 pipes with diameter 2.5 m each. (this is for emergency outflow to avoid damage of dam).
Requirements • 1. Change the road connect Nablus to Jordan valley such as the new road become over the reservoir level. • 2. Badan sub-catchment wastewater flowing from Nablus East should be treated and stored with the runoff water and to recharge into the aquifer and used for agricultural activities. • 3. Studies are needed to investigate the infiltrated water quality at the site of the dam. 4. Evaluate the required infiltration rate (hydraulic conductivity) and treat the soil of the dam accordingly.
