ARCTIC DELTAS ARE VULNERABLE COASTAL ECOGEOMORPHOLOGIC SYSTEMS THAT ARE AT RISK DUE TO SEA LEVEL RISE PERMAFROST THAW AND SEA ICE MELT. THEY ARE LIKE MOST DELTAS CHARACTERIZED BY AN INTRICATE MAZE OF CHANNELS WHICH ACT AS THE BLOOD VESSELS OF THE DELTA TRANSPORTING SEDIMENT AND NUTRIENT FLUXES INTO THE DELTA TOP AND OUT INTO THE OCEAN. HOWEVER ARCTIC DELTAS ARE UNIQUE FROM LOWER-LATITUDE DELTAS DUE TO THE SIGNIFICANT PRESENCE OF PERMAFROST-THAW DRIVEN LAKES WHICH CONNECT WITH THE CHANNELS AND AFFECT SEDIMENT AND CARBON FLUXES. THESE LAKES ARE OBSERVED TO HAVE HETEROGENOUS RESPONSES TO PERMAFROST WARMING AND THAW (I.E. BOTH GROWTH AND EXPANSION DEPENDING ON LOCAL CONDITIONS) BUT THEIR CHANGES AND INTERACTIONS WITH THE DELTA CHANNELS ARE NOT WELL UNDERSTOOD. FOR EXAMPLE CONNECTIONS BETWEEN LAKES AND CHANNELS MAY ONLY OCCUR FOR PART OF THE YEAR DURING THE SPRINGTIME MELT WHICH HAS RAMIFICATIONS FOR SEDIMENT DELIVERY TO THE OUTER DELTA. THIS PROPOSAL AIMS TO DEVELOP A FRAMEWORK FOR UNDERSTANDING CHANGES IN ARCTIC DELTAS THROUGH CHARACTERIZATION OF THE TOPOLOGY AND FLUX PARTITION CHARACTERISTICS OF THEIR DELTA CHANNEL NETWORKS AND THEIR CONNECTIVITY WITH THERMOKARST LAKES. THE PRIMARY HYPOTHESIS OF THE STUDY IS THAT LOCALIZED CHANGES IN CONNECTIVITY DRIVES SYSTEM-WIDE RESPONSE AND REORGANIZATION AND THUS QUANTIFYING LOCAL CHANGES IS NECESSARY TO UNDERSTAND THE FUTURE STATES OF ARCTIC DELTAS INCLUDING CHANGES IN HYDRO-GEOMORPHOLOGY CARBON CYCLING AND ECOSYSTEMS. I PROPOSE TO INITIALLY STUDY THE COLVILLE AND YUKON DELTAS BECAUSE OF THEIR CONTRASTING HYDRO-GEOMORPHOLOGIC FORCINGS E.G. IN SEA ICE CONDITIONS SEDIMENT LOADING AND HEADWATER CONDITIONS BUT THE ANALYSIS CAN BE EXTENDED TO OTHER ARCTIC DELTAS. THE FOLLOWING SPECIFIC OBJECTIVES ARE PROPOSED: 1: DELINEATION OF ARCTIC DELTA CHANNEL NETWORKS (DCNS). I WILL USE SATELLITE IMAGERY FROM LANDSAT AT 30-M SPATIAL RESOLUTION TO CREATE MONTHLY-RESOLUTION WATER-MASKS WHICH I WILL PROCESS TO EXTRACT LAKE LOCATION AND SHAPE AND DCN CONNECTIVITY. I WILL COLLABORATE WITH THE GROUP OF DR. JOEL ROWLAND (LOS ALAMOS NATIONAL LABORATORY) WHICH HAS WATERMASKED LANDSAT IMAGERY FROM 1948 TO 2015 TO ACCELERATE THE COMPUTATIONALLY INTENSIVE DCN AND LAKE DELINEATION. 2: QUANTIFYING CHANGES IN ARCTIC DELTAS THROUGH THEIR CHANNEL NETWORKS AND LAKE DISTRIBUTIONS. I WILL STUDY LAKE DYNAMICS DURING THE LAST 30 YEARS TO IDENTIFY TRENDS AND EXPLICIT SPATIAL HETEROGENEITY IN THEIR CONNECTIVITY WITH THE CHANNELS. I WILL DEVELOP NOVEL GRAPH THEORETIC METRICS TO QUANTIFY SPATIAL PROPERTIES OF ARCTIC DCNS AND ASSOCIATED METRIC-SPACES DEFINED BY THESE METRICS. 3: NUMERICAL SIMULATION OF ARCTIC DELTAS USING A DEPTH-RESOLVING IMPLEMENTATION OF DELFT3D. I WILL USE A MORPHODYNAMIC MODEL TO GENERATE NUMERICALLY SIMULATED DELTAS OF KNOWN UNDERLYING PHYSICS AND STUDY THEIR DCNS AND THEIR RESPONSE TO CHANGE. THE MODELING RESULTS WILL BE USED TO ASSESS THE INFLUENCE OF VARIOUS GEOMORPHOLOGICAL FORCINGS (E.G. IN SEA ICE CONDITIONS AND PERMAFROST THAW) ON THE DCN STRUCTURE AND THE LAKE DISTRIBUTION AND CONNECTIVITY WITH A FRAMEWORK TOWARDS UNDERSTANDING INTERPRETING AND PREDICTING FUTURE CHANGE. THE RESULTS OF THIS WORK WILL IMPROVE PROCESS UNDERSTANDING IN A REGION UNDERGOING RAPID ENVIRONMENTAL CHANGE. ARCTIC DELTAS STORE ON THE ORDER OF 100 PG OF CARBON OR 7% OF THE ARCTIC'S TERRESTRIAL PERMAFROST CARBON STORES. CHANGES IN THE DELTAS WILL IMPACT THESE CARBON STORES AND IN TURN AFFECT THE GLOBAL CARBON CYCLE. THIS PROJECT UTILIZES LANDSAT DATA TO STUDY ARCTIC HYDROLOGY DIRECTLY PERTAINING TO QUESTIONS THREE (PERMAFROST DYNAMICS) AND FOUR (ARCTIC HYDROLOGY) OF THE NASA TERRESTRIAL ECOLOGY FIELD CAMPAIGN ARCTIC BOREAL VULNERABILITY EXPERIMENT AND ADDRESSES THE FIRST THREE QUESTIONS OF THE STRATEGIC OBJECTIVE OF THE EARTH SCIENCE DIVISION: HOW IS THE EARTH SYSTEM CHANGING WHAT IS CAUSING THESE CHANGES AND HOW WILL IT CHANGE IN THE FUTURE