IN THE NEAR FUTURE THE CONFLUENCE OF RAPID URBANIZATION AND CLIMATE CHANGE IS LIKELY TO INCREASE HEALTH RISK AND ENERGY CONSUMPTION BY AGGRAVATING URBAN HEAT ISLAND (UHI) EFFECTS IN MORE URBAN AREAS WITH LARGE POPULATIONS. MITIGATION OF UHI REQUIRES UNDERSTANDING ITS DETERMINANTS NAMELY ANTHROPOGENIC HEAT EFFICACY OF HEAT ADVECTION AND CONVECTION SURFACE ALBEDO AND EVAPOTRANSPIRATION (THE SUM OF EVAPORATION AND PLANT TRANSPIRATION). WHILE MOST OF THESE FACTORS ARE DIFFICULT TO CHANGE EVAPOTRANSPIRATION CAN BE ENHANCED BY PROVIDING URBAN VEGETATION WHICH HAS BEEN FOUND TO REDUCE TEMPERATURE BY 1.3 ~1.6 C IN PREVIOUS STUDIES. HOWEVER THIS APPROACH USUALLY NEEDS TO BE SUSTAINED BY IRRIGATION WHICH ACCOUNTS FOR A MAJOR PORTION OF URBAN WATER USE AMOUNTING TO MORE THAN 50% IN ARID/SEMI-ARID CLIMATES. DESPITE THE POTENTIAL OF IRRIGATION IN UHI MITIGATION IT MAY NOT BE A REASONABLE USE OF WATER IN ALL CITIES. BY 2050 MORE THAN 1 BILLION URBAN POPULATIONS WILL LIVE UNDER WATER STRESS DUE TO URBANIZATION AND CLIMATE CHANGE. SINCE THESE GLOBAL CHANGES WILL ALSO AGGRAVATE UHI MANY CITIES ARE LIKELY TO FACE THE DIFFICULT CHOICE BETWEEN UHI MITIGATION AND WATER CONSERVATION. SUPPORTING THIS DECISION-MAKING REQUIRES ADVANCING OUR SCIENTIFIC UNDERSTANDING OF THE RELATIONSHIP BETWEEN WATER USAGE AND UHI MITIGATION EFFECTIVENESS IN VARIOUS URBAN ENVIRONMENTS. WE PLAN TO MODEL THIS RELATIONSHIP WITH MULTI-SENSOR AND MULTI-TEMPORAL REMOTE SENSING DATA. IMAGES FROM LANDSAT/TM SENTINEL-1/SAR AND QUICKBIRD WILL BE USED TO GENERATE URBAN SURFACE PARAMETERS REQUIRED IN THE MODEL. TIME SERIES SMAP SOIL MOISTURE MODIS NORMALIZED DIFFERENCE VEGETATION INDEX (NDVI) AND MUNICIPAL WATER STATISTICS WILL BE USED TO ESTIMATE IRRIGATION WATER USAGE. AFTER VALIDATING THE MODEL WITH MODIS LAND SURFACE TEMPERATURE (LST) WE WILL REPEAT THE SIMULATION WHILE APPLYING VARIOUS AMOUNTS OF IRRIGATION TO QUANTIFY THE WATER-UHI RELATIONSHIP. THIS STUDY WILL YIELD MAPS OF URBAN SURFACE STRUCTURES AND IRRIGATION WATER USAGE AS WELL AS THE WATER-UHI RELATIONSHIPS FOR URBAN AREAS WITH DIFFERENT BIOPHYSICAL CHARACTERISTICS. THE RESULTING RELATIONSHIPS WILL ADVANCE THE SCIENTIFIC KNOWLEDGE ON WATER-ENERGY BALANCE IN URBAN ENVIRONMENTS AND HELP MANAGE URBAN WATER BUDGET AND ALTER LOCAL CLIMATE THEREFORE ADDRESSING ISSUES PRIORITIZED BY THE CLIMATE VARIABILITY AND CHANGE AND WATER AND ENERGY CYCLE FOCAL AREAS OF NASA S EARTH SCIENCE DIVISION AS WELL AS THE WATER RESOURCE FOCUS OF THE APPLIED SCIENCE PROGRAM. THIS STUDY WILL ALSO POTENTIALLY ACHIEVE BROAD SOCIETAL BENEFITS WITH REMOTE SENSING DATA BY INFORMING CITIES DECISIONS REGARDING WATER RESOURCE HEALTH RISK AND ENERGY CONSUMPTION THAT CAN AFFECT THE MAJORITY OF THE WORLD S POPULATION.