Important gaps in information or tools related to drought preparedness and response – availability of groundwater data, seasonal forecasting capability, drought risk reduction for small water systems – are also issues that must be dealt with over the longer-term for climate change adaptation. Under average hydrologic conditions close to 40 percent of California’s urban and agricultural water needs are supplied by groundwater, an amount that increases in dry years when surface water shortages cause increased reliance on groundwater. Increasing stress will be placed on the state’s groundwater resources as climate change results in less precipitation in Southern California and reduces winter season water storage in mountain snowpack. It was not until 2009, when state legislation required local entities to begin monitoring their groundwater basins and submitting that information to the Department, that it was possible to assess trends in groundwater levels at a statewide scale. As noted in the Department’s recent groundwater report, however, there are still 40 high and medium-priority groundwater basins where local entities are not yet participating in the monitoring required by statute. Improving our understanding of groundwater conditions and of management of the resource is crucial to climate change adaptation. The California Legislature is currently considering measures that would strengthen management of groundwater resources.
Improving sub-seasonal and seasonal precipitation prediction capability (and hence drought prediction capability) is critical for improving drought preparedness and will be an essential component of climate change adaptation, as reservoir operators look to forecast-informed operations to help mitigate impacts of loss of winter season storage in mountain snowpack. Improving precipitation prediction at time scales and with a skill useful for water management purposes is not a simple task from the scientific perspective; these time scales lie between the two-week scale of operational weather forecasts and the decadal to century scale of climate change models. The Department is using funding made available for drought response this year to advance applied research on aspects of seasonal forecasting that could provide some near-term guidance for the coming water year, but ongoing work with the science community will be required to secure improvements in forecasting over the long-term.