Hydrological design of two low-impact development techniques in a semi-arid climate zone of Central Mexico.

This paper deals with the design of a bioretention cell and an infiltration trench in a semi- arid micro watershed. The study area was analyzed by characteristics such as slope changes (S), direction and maximum length of the urban runoff (L), and soil use (runoff coefficient, Rc). The bioretention cell was designed by the calculation of variables such as drainage area (A), concentration time (Tc), rainfall intensity (i), maximum peak drained (Qmax), inlet and outlet runoff (Qa and Qout, respectively), temperature (T), evaporation (Ev), potential evapotranspiration (PEm), consumptive use (U) for tolerant plants to semi-arid climates, and soil infiltration capacity (Inf). To design the infiltration trench, only Tc, Qmax, and i were taken into account. The results showed that the designed bioretention cell could retain between 5.37% and 2.25% of runoff volume. As the efficiency of the bioretention cell can be defined by the need for additional irrigation, our results showed that the cell is inefficient in some of the dry months (November and December), even in years characterized by abundant rainfall. Besides, it was shown that the designed infiltration trench could store or infiltrate the water from typical rain events. Based on these results, it is the implementation of more Low-Impact Development (LID) for runoff management in the study area is recommended.