Large-Scale Artificial Groundwater Recharge over Long-Time Periods in Response to Climate Change in Arid Regions and Florida Thomas M. Missimer and Kristoph D. Kinzli Florida Gulf Coast University U. A. Whitaker College of Engineering American Ground Water Trust 15th Annual Aquifer Recharge Program with a Focus on Florida Water Management Issues, Orlando, Florida September 21, 2015

Long-Term Artificial Recharge Introduction ●Florida and arid regions share a common problem with management of water resources during a changing climate ●Water management strategies currently tend to focus on 5 to 20 year periods based on water resources needs and allocations ●New strategies with a longer-term set of objectives are required in Florida and arid regions to meet future water supply needs Long-Term Artificial Recharge

Long-Term Artificial Recharge Introduction ●Water management plans need to assess 50 to 100 year strategies based on comparative economics. ●New water supplies in high growth regions may be accommodated using seawater desalination but at considerable cost. ●Therefore, the base cost of water can be evaluated using a rate of about $1/m3 or about $3.25/1000 gallons over the planning threshold. Long-Term Artificial Recharge

Long-Term Artificial Recharge Resource Depletion and Climate Change Require New Resource Management Strategies Resource depletion is becoming critical in western Saudi Arabia where past water table fluctuations ranged from 1 to 3 m below surface. Drought periods are projected to be longer and floods more severe in the future. Long-Term Artificial Recharge

Rural Communities Have Run Out of Freshwater Abandoned Municipal Wellfield Abandoned Date Palm Farm Long-Term Artificial Recharge

Combined Stormwater and Groundwater Management in Wadi Systems Wadi dams combined with downstream transport of water into a stabilized dune field or alluvial aquifer system could be used for capture and storage of stormwater. Long-Term Artificial Recharge

Transport of Reservoir Water by Gravity Feed without Pumping Up to 70% of the captured stormwater would be lost to evaporation if not stored in the subsurface within either a dune or depleted alluvial aquifer. The water is fresh and has a low nutrient concentration. Long-Term Artificial Recharge

Duration of Planning Horizon in Saudi Arabia Water Management ●The investment in wadi dams is up to $1 billion each and requires a long operational life on the order of 100 to 200 years. ●An alternative is the construction and operation of many seawater desalination plants with a capital cost of over $20 billion and a long-term operations cost of about $1.20/m3 with high energy consumption (small plants). ●Direct reuse of treated wastewater as an alternative is generally unacceptable. Long-Term Artificial Recharge

Other Arid Regions with Even Worse Issues ●Within the arid coastal regions of Peru and northern Chile, the valley water users are dependent on seasonal stormwater discharge, seasonal snow fall melt, and glacial melt. ●Artificial recharge can mitigate seasonal stormwater availability, but not the loss of glacial meltwater and within 40 years most of the glaciers will be gone based on current recession rates. ●Some new strategy will have to be developed for this region. Long-Term Artificial Recharge

Other Arid Regions with Even Worse Issues Southern Peru Atacama Region, Chile Long-Term Artificial Recharge

Florida During Climate Change ●Substantial loss of coastal freshwater aquifers sources caused by sea level rise (0.6 m by 2100 and about 2.2 m by the end of 2300) ●Recent NASA Greenland ice melt rate data may cause an upward revision for the 2100 estimate. ●Greater extremity in duration of droughts and more intense floods (increase in atmospheric moisture creates greater variability) ●Longer term groundwater strategy required that incorporates the variability Long-Term Artificial Recharge

Florida During Climate Change ●Partial treatment and storage of stormwater could be used based on project durations of 50 to 100 years. ●The location for freshwater storage should be in coastal brackish-water aquifers, perhaps east of the St. Johns River in northwest Florida and adjacent to the Florida East Coast and the Caloosahatchee River in southwest Florida. Long-Term Artificial Recharge

Freshening the Upper Floridan Aquifer East of the St. Johns River Long-Term Artificial Recharge

Lake Okeechobee Discharge Control and Groundwater Storage Long-Term Artificial Recharge

Long-Term Artificial Recharge Major Future Water Shortage Area Based on Overuse of the Sandstone Aquifer Long-Term Artificial Recharge

Long-Term Artificial Recharge Major Future Water Shortage Area Based on Overuse of the Sandstone Aquifer ● Sandstone Aquifer is the only freshwater unit that has a sufficiently high transmissivity for use in the area ●Use of thousands of wells has lowered the potentiometric surface of the aquifer causing dry season use to be already problematical ●Use of shallow brackish-water aquifers for BWRO treatment is not possible due to low aquifer transmissivity (Lower Hawthorn Aquifer not present, Suwannee Aquifer has low transmissivity) ●More the 50,000 new residents expected Long-Term Artificial Recharge

Use of Some Reservoir Water for Storage and Freshwater Control ● Drill large-diameter injection wells into the high hydraulic conductivity portion of the Avon Park Limestone. ● Transmissivity is estimated to range from 65,000 to 500,000 ft/day. ● Individual well capacities should range from 2 to 6 MGD or higher. ● Goal is to create a freshwater system that could supply the region south and west of the site Long-Term Artificial Recharge

Lake Okeechobee Discharge Control and Groundwater Storage Long-Term Artificial Recharge

Long-Term Artificial Recharge Integration of Large Scale Artificial Recharge within Saline Groundwater System ●Caloosahatchee River commonly has seasonal excess freshwater flow which is detrimental to estuary. ASTR could reduce this flow and restore a more natural freshwater flow regime ●The Avon Park Aquifer could be used not only to store the excess stormwater flow, but also to convey the water into the use area. ●The oxygen concentrations in the injected water would be generally low in the summer months and would eventually come into equilibrium in the aquifer to produce down-gradient anoxic conditions. Long-Term Artificial Recharge

Long-Term Artificial Recharge Conclusions ●Longer term groundwater management solutions will be required in times of changing climate in both arid (Saudi Arabia) and humid (Florida) regions. ●The status quo of 5 to 20 year water management plans will be ineffective in the future. ●Combined stormwater capture and artificial recharge schemes will be required to effectively meet future water demands. Long-Term Artificial Recharge

Long-Term Artificial Recharge Conclusions ●The concept of aquifer storage and transfer (ASTR) will become a more utilized concept in the future to solve long-term local and regional water supply issues. ●Development of more energy efficient conveyance schemes must be developed to meet water demands using low technology designs within the context of developing world economies. Long-Term Artificial Recharge

Analogous Situation to the St. Johns River ASR System Long-Term Artificial Recharge