<p>Modeling the Upper Kissimmee Chain of Lakes for Operational Hydrology</p><p>Angela M. Montoya, Paul Trimble, Alaa Ali, Luis Cadavid, Jayantha Obeysekera and Steve Lin South Florida Water Management District, West Palm Beach, Florida</p><p>Abstract</p><p>Water managers at the South Florida Water Management District (SFWMD) need analytical tools to help in the understanding of how daily operational decisions affect the objectives of maintaining water supply and a healthy environment. The key to proactive management is the ability to model the hydrology and management of all components of the system with an adequate set of climatic inputs. The SFWMD has extensively used the South Florida Water Management Model (SFWMM) in operational hydrology. Only until recently the Upper Kissimmee Chain of Lakes model (UKISS) was converted to this class of models.</p><p>The UKISS model was developed in 1981 by the SFWMD to simulate the operations of the lakes in the Upper Kissimmee River Basin, Florida. The model serves as a management tool to predict the lake conditions so that alternative management schemes, aimed at achieving specific objectives, can be evaluated. A water budget computation is used to route flows through the system. Routing proceeds from the uppermost lake (Alligator) to the lowermost lake (Kissimmee) by solving the mass balance equation in daily time steps.</p><p>The capability of using the UKISS model in Position Analysis (PA) mode is a desirable step in the operational hydrology of the lakes. The purpose of this study was to have the UKISS model running in PA mode. In PA mode, all the storage areas in the model, including soil moisture levels, are initialized to current or specific conditions. Once the initial conditions are set, the model simulates, under different climatological input scenarios (rainfall and evapotranspiration) and current or given operational practices, different outcomes (stage and flow) of the system. Statistical analysis of the results provides information on the future response of the system, given the initial and the operational conditions. The UKISS in PA mode allows an improved evaluation of S65E inflows entering Lake Okeechobee and the risks associated with operational decisions (e.g., drawdown of lake stage). Lake initial stages and antecedent moisture conditions for a specific day are specified in UKISS model in PA mode. Simulated flows from Lake Kissimmee, once corrected according to the Lower Kissimmee contribution, are passed as input to the SFWMM model in PA mode.</p><p>This presentation will provide a brief summary of the recent efforts to incorporate the UKISS model in PA mode into the Operational Planning project of the SFWMD. First, a brief overview of UKISS model and calibration results are presented, along with the description of the model initialization. The model is run from January 1, 1965 through December 31, 2001. Finally, model results are presented, as percentile stage time series and percentile average flows for each lake, given the conditions of the system on January 1, 2003. As an example, percentile flows from Lake Kissimmee are shown in Figure 1. </p><p>9000 Min. P5 8000 P10 P25 7000 P50 )</p><p> y P75 a d - P90 6000s f c</p><p>( P95</p><p> w Max. o</p><p>5000l f</p><p> e g a r</p><p>4000e v a</p><p> y l</p><p>3000k e e w 2000</p><p>1000</p><p>0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51</p><p> week</p><p>Figure 1. Percentile Flows from Lake Kissimmee on January 1, 2003 Contact: Angela M. Montoya, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, FL 33416. Phone: 561-682-2002, Fax: 561- 682-6442, E-Mail: [email protected]</p>