Variable responses of karst springs to recharge in the Middle Atlas region of Morocco

Springs in the Middle Atlas region of Morocco are important public water supplies, but their responses to storm-event and seasonal forcings have received only limited study. From March 2014 to May 2015, water temperature was measured hourly at three springs (Ribaa, Sidi Rached, and Zerouka); water level (stage) was measured hourly at Sidi Rached and Zerouka; and maximum daily turbidity was recorded at Ribaa. From March 2014 to March 2015, daily water samples were taken at Zerouka for analyses of deuterium and oxygen-18. Hourly weather data (precipitation and air temperature) were available from March 2014 to May 2015 from Ifrane, near Zerouka. Temperature responses varied between the springs, showing a time-lagged seasonal signal at Sidi Rached, near-constant values at Zerouka, and relatively stable dry-season values followed by flashy wet-season behavior at Ribaa. Stage at Sidi Rached and Zerouka tracked together, with a broad minimum in late summer and responses to individual storms superposed on the signal. Stable isotopes fluctuated daily but were frequently out of phase with each other. Autocorrelation analyses of spring parameters indicate that Sidi Rached and Zerouka have greater inertia than Ribaa. Cross-correlation analyses show characteristic time lags between (1) precipitation and stage, (2) air temperature and water isotopes, and (3) air and water temperatures. However, as shown in previous work, there is a broad range of time lags between precipitation and turbidity. The variety of spring behaviors is consistent with differences in hydraulic connectivity within each spring basin.