# EECQ_4142_Tutorials_All.pdf - TUTORIALS Introduction and...

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1 TUTORIALS Introduction and water balance 1. Using an illustration, define the components of the hydrologic cycle. 2. What are the three sub-systems of the hydrologic cycle? What are the hydrologic components in each sub system 3. State and discuss the water balance equation (s) used in hydrological studies 4. The average annual discharge at the outlet of a catchment is 0.5 m 3 /s. The catchment is situated in a desert area (no vegetation) and the size is 800 km 2 . The average annual precipitation is 200 mm/year. a. Compute the average annual evaporation from the catchment in mm/year. In the catchment area an irrigation project covering 10 km 2 is developed. After some years the average discharge at the outlet of the catchment appears to be 0.175 m 3 /s. b. Compute the evapotranspiration from the irrigated area in mm/year, assuming no change in the evaporation from the rest of the catchment. 5. A catchment has a size of 100km 2 . In its original condition, the average annual total runoff from the catchment is 1.1 m 3 /s. the average annual rainfall is 800 mm/year. In an average year, 50% of the rainfall infiltrates and 12.5% of the rainfall reaches the groundwater. Tests have turned out that the average annual evapotranspiration from the unsaturated zone amounts to 340 mm/year. Evapotranspiration in this case is the sum of transpiration and the bare soil evaporation. Assume that storage effects are small and therefore can be neglected. i. Using a well-illustrated diagram show all the water balance components for this catchment ii. How much water, in mm/year, reaches the root zone through capillary rise in an average year? iii. How much water, in mm/year, seeps out from the groundwater to the surface water in an average year? iv. How much water, in mm/year, evaporates directly from interception in an average year? v. How much, in mm/year, is the total evapotranspiration in the catchment in an average year? 6. For the same catchment in Question 1(a), there is a plan to install a well field that will withdraw 0.16 m 3 /s from the catchment for drinking water consumption elsewhere. As a result, the groundwater level is expected to go down and capillary rise into the root zone will no longer be possible. The percolation is expected to remain the same.
2 i. With a well-illustrated diagram, list and explain the components of the hydrologic cycle that will be affected by this groundwater withdrawal. ii. What will be the effect of this withdrawal on the components in Question1b (i) above? Quantify in mm/year 7. Consider a reservoir with one inlet stream, one outlet with one inlet stream, one outlet at a dam and a surface area of 2.5 km 2 . There hasn’t been any rain for weeks, and the res ervoir level is falling at a rate of 3.0 mm/day. The average evaporation rate from the reservoir surface is 1.2 mm/day, the inlet discharge is 10,000m 3 /day, and the outlet discharge is 16,000m 3 /day. Assuming that the only other important fluxes are the groundwater discharges in and out of the reservoir. What is the total net rate of groundwater discharge into the reservoir?