The Purpose Of The Contract Concerns The Improvement Of Flood Monitoring And Anticipation In The Lys Watershed. The Lys Yser Establishment (Formerly Symsagel) Wishes To Refine The Existing Thresholds At These Different Measuring Stations In Order To Have A Better Interpretation Of Rainfall Events And Allow Better Anticipation Of Floods, Particularly As Part Of Its Decision-Making Constraints. The Objectives Of The Mission Consist Of The Lys Yser Establishment Obtaining: - Vigilance, Pre-Alert And Alert Thresholds For Watersheds With A High Risk Of Runoff As Well As For Its Rain Gauges; - Vigilance, Pre-Alert And Alert Thresholds For Its Hydrometric Stations. If The Vigilance, Pre-Alert And Alert Thresholds For The Risk Of Runoff As Well As For The Rainfall Stations Are To Be Determined Globally At The Scale Of The Sub-Watersheds At Risk (See Figure 1), Those For The Hydrometric Stations Will Have To Be Adapted, Station By Station According To The Exposure Of Local Issues.