The extensive validation, widespread use, and public accessibility of the LOCA dataset make it a particularly important element in demonstrating and testing the importance of climate change, which is critical to water management in California. Existing LOCA validation (Pierce n.d.; Vano et al. 2020) shows minimal error between observations and degradation of the GCM representation of historical precipitation, minimum and maximum temperature and daytime temperature range (which are used to cause model descent and bias correction) and minimal systemic distortion between the coarsely dissolved and degenerated GCM output. The distortions in the different metrics analyzed in this study are generally minimal and not systemic (see Additional documents for a full discussion). The notable exception is at high altitudes, where a minority of models overestimate SWE and simulation of the 20th driest of the 20ths in winter is wetter in most models than what manifests itself in historical records. Gleick PH (1987) The Development and Experimentation of a Water Balance Model for Climate Impact Assessment: Sacramento Basin Modeling. Water Resour Res 23:1049-1061 Since the modelling structure used by Knowles et al. (2018) assumes that the operation of the reservoir will not be modified in the future, it is possible that some of the expected storage losses can be recovered by modifying the operating rules of the reservoir to allow additional storage of the winter influx. However, the storage of February flows (0.18 MAF) would increase, for example, the use of about 30% of the average capacity of the Oroville dam currently reserved in February for flood protection (US Army Corps of Engineers 1970), which would increase the operational risk of a catastrophic dam transfer.
In addition, the model framework used here does not simulate the impact of a risk of extreme precipitation of several days on reservoir management, which, according to our analysis, leads to an increase of 20% or more in most of the Oroville watershed (Figures 1 a and b) under RCP 8.5 conditions and which would require an increase instead of a reduction in storage capacity, which is kept unladen for flood protection (see also Section 4). These factors, as well as regulatory barriers to the reseeding of deposits (e.g.B. Shibatani 2015), suggest that changing reservoir operations may not be enough to recover the expected storage loss and summer water availability in Oroville in a more severe future evolution of climate change. . . .