Set II Soil Water Gravitational potential is determined by the height of the points above the reference level. Capillary or matric potential must be measured and, therefore, is provided. Total potential energy is simply the sum of the component potentials. Water flows from higher energy to lower energy. The Gradient is determined by the _______ between the two points divided by the _____ between the points. Multiplying the gradient by the hydraulic conductivity yields the total flow. 1. Soil water potentials: 100 cm 75 cm 50 cm 25 cm 0 cm reference Note the soil diagram above. Point A is at 75 cm; point B is at 25 cm above the reference. The capillary potential energy at point A is -100 cm. The capillary potential energy at point B is -200 cm. What is the total potential energy at point A? ______ What is the total potential energy at point B? ________ Will water flow between the points? _____ ___________________________ If so, in what direction? ____ _________ What is the gradient between the two points? ____ _______ If K = 10 cm/hr, determine the flow, Q between the points. __ __ 2. Soil Water potential: 400 cm 300 cm 200 cm Reference 100 cm Note the soil diagram above. Point A is at 300 cm; point B is at 100 cm. The capillary potential energy at point A is -400 cm. The capillary potential energy at point B is -300 cm. Note the reference level on the Figure What is the gravitational potential energy at point B? _____________ What is the height of point A above the reference level? _________ What is the gravitational potential energy at point A? ___________ What is the total potential energy at point A? ___ ____ What is the total potential energy at point B? ______________ Will water flow between the points? _____ _______________________ If so, in what direction? _____ _____ What is the gradient between the two points? _ ____ If K = 5 cm/hr, determine the flow, Q between the points. 3. Soil Water potential: 400 cm A B Reference 300 cm 200 cm 100 cm 10 cm 20 cm Note the soil diagram above. Points A and B are at 300 cm. The capillary potential energy at point A is -200 cm The capillary potential energy at point B is -100 cm. Note the reference level for gravitational Potential. Will water flow between the points? ________ If so, in what direction? __ What is the difference in total potential energy between the points? _ What is the gradient between the two points?____ If K = 10 cm/hr, determine the flow, Q between the points. _
