Abstract: INVESTIGATING THE DYNAMIC CHARACTERISTICS OF WATER SUPPLY AND DEMAND IN SALINE-ALKALI AREAS OF HEBEI'S LOW-LYING PLAINS AND DEVELOPING TARGETED WATER MANAGEMENT STRATEGIES ARE OF SIGNIFICANT IMPORTANCE FOR ALLEVIATING REGIONAL WATER SCARCITY AND IMPROVING AGRICULTURAL PRODUCTIVITY ON SALINE-ALKALI LANDS. USING HUANGHUA CITY (A COASTAL SALINE-ALKALI AREA) AND NANPI COUNTY (AN INLAND SALINE-ALKALI AREA) AS REPRESENTATIVE CASES, THIS STUDY EXAMINED TEMPORAL VARIATIONS IN POTENTIAL EVAPOTRANSPIRATION, EFFECTIVE PRECIPITATION, AND WATER DEMAND DURING THE GROWTH PERIODS OF WINTER WHEAT AND SUMMER MAIZE BASED ON METEOROLOGICAL DATA FROM 2015 TO 2024. IT COMPARED DIFFERENCES IN CROP WATER DEMAND, EFFECTIVE PRECIPITATION, AND AVERAGE DAILY WATER DEFICIT ACROSS GROWTH STAGES, AND IDENTIFIED CRITICAL DROUGHT PERIODS USING DAILY WATER BALANCE INDICES. RESULTS SHOW THAT OVER THE PAST DECADE, POTENTIAL EVAPOTRANSPIRATION IN THE STUDY AREA HAS INCREASED, WITH ANNUAL GROWTH RATES RANGING FROM 8.02 TO 11.37 MM/A. MEANWHILE, EFFECTIVE PRECIPITATION DECREASED AT RATES OF 2.48 MM/A (HUANGHUA CITY) AND 2.85 MM/A (NANPI COUNTY), LEADING TO A CONTINUOUSLY WIDENING IMBALANCE BETWEEN WATER SUPPLY AND DEMAND. PERSISTENT WATER DEFICITS OCCURRED THROUGHOUT THE ENTIRE GROWTH PERIOD OF WINTER WHEAT, WITH PARTICULARLY SEVERE CONDITIONS DURING THE HEADING STAGE. THE AVERAGE DAILY DEFICIT EXCEEDED 9.0 MM/D, AND THE PROPORTION OF DAYS EXPERIENCING SEVERE OR WORSE DROUGHT REACHED OVER 34%. CRITICAL WATER-DEFICIENT PERIODS WERE MAINLY CONCENTRATED DURING THE OVERWINTERING AND JOINTING-HEADING STAGES, WITH PEAK OCCURRENCES FROM LATE DECEMBER TO MID-JANUARY OF THE FOLLOWING YEAR, APRIL 1–8, AND APRIL 24–30. SUMMER MAIZE GENERALLY MAINTAINED ADEQUATE MOISTURE CONDITIONS, WITH ONLY BRIEF WATER SHORTAGES DURING THE GRAIN FILLING STAGE. CONSIDERING DIFFERENCES IN GROUNDWATER MINERALIZATION AND SOIL SALINITY BETWEEN THE TWO REGIONS, A ZONED WATER MANAGEMENT OPTIMIZATION PLAN IS PROPOSED: HUANGHUA CITY AND NANPI COUNTY SHOULD IMPLEMENT SOIL COMPACTION MEASURES FOR MOISTURE RETENTION NO LATER THAN LATE NOVEMBER; NANPI COUNTY IS SUITABLE FOR A PHASED IRRIGATION APPROACH USING SLIGHTLY SALINE WATER DURING THE JOINTING STAGE AND RAINWATER DURING THE HEADING STAGE. HUANGHUA CITY IS ADVISED TO USE STORED RAINWATER FOR IRRIGATION DURING BOTH THE JOINTING AND HEADING STAGES. THIS STUDY ANALYZED DAILY-SCALE WATER SUPPLY AND DEMAND CHARACTERISTICS IN HEBEI'S LOW-LYING SALINE-ALKALI PLAINS UNDER CLIMATE CHANGE, IDENTIFIED CRITICAL CROP WATER MANAGEMENT PERIODS, AND PROPOSED DIFFERENTIATED ZONAL IRRIGATION STRATEGIES. THESE FINDINGS PROVIDE THEORETICAL SUPPORT AND PRACTICAL PATHWAYS FOR REGIONAL RAINWATER RESOURCE UTILIZATION, SAFE USE OF SLIGHTLY SALINE WATER, MITIGATION OF GROUNDWATER OVEREXPLOITATION, AND EFFICIENT AGRICULTURAL WATER MANAGEMENT IN SALINE-ALKALI SOILS.