סמינר מחלקתי Omer Gvirtzman
SCHOOL OF MECHANICAL ENGINEERING SEMINAR
Wednesday, March 2, 2016 at 15:00
Wolfson Building of Mechanical Engineering, Room 206
Rainfall-Runoff Model for Urban Watersheds in Israel
Nitzan Ne'eman
MSc Student of Yaakov Anker1, Itzhak Benenson2 and Gregory Zilman3
1 Samaria and the Jordan Rift Regional R&D Center
2 Department of Geography and Human Environment, TAU
3 School of Mechanical Engineering, TAU
Runoff is precipitation that did not get absorbed into the soil, or did not evaporate. Runoff can lead to uncontrolled surface streams flowing over land, to soil erosion, to water pollution and even to floods. Runoff depends on the amount of rainfall, permeability of the ground surface and vegetation. Modern urbanization leads to creating large surface areas covered by hardly penetrable asphalt and concrete, which strongly affect the permeability of the ground surface. To estimate the consequences of urbanization on runoff the so-called "rainfall-runoff" mathematical models are generally used. The input of any rainfall-runoff mathematical model is an estimated rainfall, and the output is an estimated runoff discharge varying with time, the so-called hydrograph. The spatially distributed grid based Soil Conservation Service curve number (SCS-CN) method and the modified Clark unit hydrograph (ModClark) are commonly used to simulate the runoff for large and natural watersheds.
The goal of this study was to verify the applicability of the gridded SCS-CN and ModClark methods for small urban watersheds. This task implies the existence of high-resolution digital elevation data and land used classification. Typically, such complete data is hardly available. In my work I created the required database from the information collected in municipality engineering departments. The input parameters for the selected "rainfall-runoff" methods include recorded precipitation data, an accurate Digital Elevation Model of the urban topography, detailed land use classification, soil type, antecedent moisture condition and description of the watershed's flow paths.
For the purposes of my study the city of Ariel was selected because of its hydrologic database of monitored runoff discharge since 2006. Initially, the selected "rainfall-runoff" mathematical model was used to estimate the antecedent moisture condition parameter, which fit the soil moisture response in the domestic climate. Then the model was applied to two larger watersheds in Ariel including both urban and natural flow paths. According to the Moriasi's criteria, the used mathematical "rainfall-runoff" model predicts the runoff depth and the peak discharges with 10% accuracy, approximately, and the general hydrograph's shape with Nash-Stucliff efficiency coefficient in the range 0.55-0.90.
School of Mechanical Engineering Seminar
Wednesday, March 2, 2016 at 15:00
Wolfson Building of Mechanical Engineering, Room 206
Trajectory and stability control in the locust jump and its potential contribution to designing miniature jumping robots
Omer Gvirsman
MSc Student of Prof. Amir Ayali and Dr. Gabor Kosa
Locusts are known for their ability to jump large distances to avoid predation. The jump also serves to launch the adult locust into the air in order to initiate flight. Various aspects of this important behavior have been studied extensively, from muscle physiology and biomechanics, to the energy storage systems involved in powering the jump, and more. Less well understood are the mechanisms participating in control of the jump trajectory. Here we utilize video monitoring and careful analysis of experimental directional jumps by adult desert locusts, together with dynamic computer simulation, in order to understand how the locusts control the direction and elevation of the jump, the residual angular velocities resulting from the jump and the timing of flapping-flight initiation. In addition to offering important insights into the bio-mechanical principles of locust jumping and flight initiation, the findings from this study will be used in designing future prototypes of a bio-inspired miniature jumping robot that will be employed in animal behavior studies and environmental monitoring applications.
