An assessment of the difficulties in quantifying the surface water resources of Lebanon

Abstract Following a major expansion of the hydrometric network in the 1960s, flow gauging operations in Lebanon were curtailed from 1975 to 1990 due to the civil war and only a partial service has resumed since then. The implications of these limitations on flow data availability are examined from the standpoint of estimating the overall surface water resources of Lebanon and for developing regional estimation procedures for ungauged flows. Attempts are made to characterize both the spatial and temporal variations in key measures of flow availability such as the mean and the flow duration statistics, and comparisons are made between long-term flow records in Lebanon and regional rainfall records. The results show that flows in the 1960s, when measurements were at a peak, were well above average, and that, due to the high inter-annual variability in flows, records of many decades are required to adequately define some aspects of the flow regime. However, given the large variations in topography and climat...